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Intellectual disability - microarray and sequencing v5.423 MCPH1 Arina Puzriakova Publications for gene: MCPH1 were set to
Intellectual disability - microarray and sequencing v5.422 MCPH1 Arina Puzriakova Phenotypes for gene: MCPH1 were changed from genetic heterogeneity Microcephaly 1, primary, autosomal recessive, 251200; MICROCEPHALY PRIMARY TYPE 1 (MCPH1) to Microcephaly 1, primary, autosomal recessive, OMIM:251200
Intellectual disability - microarray and sequencing v5.363 SLC12A6 Arina Puzriakova Phenotypes for gene: SLC12A6 were changed from Agenesis of the corpus callosum with peripheral neuropathy, 218000 -3; AGENESIS OF THE CORPUS CALLOSUM WITH PERIPHERAL NEUROPATHY (ACCPN) to Agenesis of the corpus callosum with peripheral neuropathy, OMIM:218000
Intellectual disability - microarray and sequencing v5.337 VCP Achchuthan Shanmugasundram Phenotypes for gene: VCP were changed from Neurodevelopmental disorder (MONDO: 0700092) to neurodevelopmental disorder, MONDO:0700092; intellectual disability, MONDO:0001071
Intellectual disability - microarray and sequencing v5.336 VCP Achchuthan Shanmugasundram edited their review of gene: VCP: Changed phenotypes to: neurodevelopmental disorder, MONDO:0700092, intellectual disability, MONDO:0001071
Intellectual disability - microarray and sequencing v5.336 VCP Achchuthan Shanmugasundram Tag Q4_23_promote_green tag was added to gene: VCP.
Intellectual disability - microarray and sequencing v5.336 VCP Achchuthan Shanmugasundram Classified gene: VCP as Amber List (moderate evidence)
Intellectual disability - microarray and sequencing v5.336 VCP Achchuthan Shanmugasundram Gene: vcp has been classified as Amber List (Moderate Evidence).
Intellectual disability - microarray and sequencing v5.335 VCP Achchuthan Shanmugasundram reviewed gene: VCP: Rating: GREEN; Mode of pathogenicity: None; Publications: 37883978; Phenotypes: Intellectual disability, MONDO:0001071; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v5.332 VCP Zornitza Stark gene: VCP was added
gene: VCP was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: VCP was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: VCP were set to 37883978
Phenotypes for gene: VCP were set to Neurodevelopmental disorder (MONDO: 0700092)
Review for gene: VCP was set to GREEN
Added comment: 13 unrelated individuals with childhood onset ID/DD disorder including macrocephaly, hypotonia and dysmorphic features. Non-specific / mild MRI findings.
12 de novo - 1 inherited
Sources: Literature
Intellectual disability - microarray and sequencing v5.313 TUBGCP2 Achchuthan Shanmugasundram Tag gene-checked tag was added to gene: TUBGCP2.
Intellectual disability - microarray and sequencing v5.287 CPLX1 Arina Puzriakova Tag Q1_23_promote_green was removed from gene: CPLX1.
Intellectual disability - microarray and sequencing v5.286 CPLX1 Arina Puzriakova reviewed gene: CPLX1: Rating: GREEN; Mode of pathogenicity: ; Publications: ; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v5.286 CPLX1 Arina Puzriakova Source NHS GMS was added to CPLX1.
Source Expert Review Green was added to CPLX1.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Intellectual disability - microarray and sequencing v4.88 CPLX1 Sarah Leigh gene: CPLX1 was added
gene: CPLX1 was added to Intellectual disability. Sources: Expert list,Expert Review Amber
Q1_23_promote_green tags were added to gene: CPLX1.
Mode of inheritance for gene: CPLX1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CPLX1 were set to 26539891; 28422131
Phenotypes for gene: CPLX1 were set to Developmental and epileptic encephalopathy 63, OMIM:617976; developmental and epileptic encephalopathy, 63, MONDO:0033372
Intellectual disability - microarray and sequencing v3.1701 CPSF3 Sarah Leigh changed review comment from: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for CPSF3-associated neurodevelopmental disorder with seizures and microcephaly. PMID: 35121750 reports two CPSF3 variants in cases, c.1403G>A, p.Gly468Glu (NM_016207.3) in two Icelandic families and c.1061T>C, p.Ile354Thr (NM_016207.3) in a large consanguineous Mexican family. Intellectual disabililty was evident in all 8/8 cases and seizures and microcephaly was apparent 7/8 cases (PMID: 35121750).; to: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for CPSF3-associated neurodevelopmental disorder with seizures and microcephaly. PMID: 35121750 reports two CPSF3 variants in cases, c.1403G>A, p.Gly468Glu (NM_016207.3) in two Icelandic families and c.1061T>C, p.Ile354Thr (NM_016207.3) in a large consanguineous Mexican family. Intellectual disabililty was evident in all 8/8 cases and seizures and microcephaly was apparent 7/8 cases (PMID: 35121750).
The rating of this gene could be changed to green, if further disease associated variants are identified or supportive functional studies are reported.
Intellectual disability - microarray and sequencing v3.1682 CPSF3 Sarah Leigh changed review comment from: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for CPSF3-associated neurodevelopmental disorder with seizures and microcephaly. PMID: 35121750 reports two CPSF3 variants in cases, c.1403G>A, (NM_016207.3) in two Icelandic families and c.1061T>C (NM_016207.3) in a large consanguineous Mexican family.; to: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for CPSF3-associated neurodevelopmental disorder with seizures and microcephaly. PMID: 35121750 reports two CPSF3 variants in cases, c.1403G>A, p.Gly468Glu (NM_016207.3) in two Icelandic families and c.1061T>C, p.Ile354Thr (NM_016207.3) in a large consanguineous Mexican family. Intellectual disabililty was evident in all 8/8 cases and seizures and microcephaly was apparent 7/8 cases (PMID: 35121750).
Intellectual disability - microarray and sequencing v3.1682 CPSF3 Sarah Leigh reviewed gene: CPSF3: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability - microarray and sequencing v3.1682 CPSF3 Sarah Leigh Classified gene: CPSF3 as Amber List (moderate evidence)
Intellectual disability - microarray and sequencing v3.1682 CPSF3 Sarah Leigh Gene: cpsf3 has been classified as Amber List (Moderate Evidence).
Intellectual disability - microarray and sequencing v3.1681 CPSF3 Sarah Leigh Phenotypes for gene: CPSF3 were changed from Failure to thrive; Abnormal muscle tone; Global developmental delay; Intellectual disability; Microcephaly; Seizures to Neurodevelopmental disorder with microcephaly, hypotonia, nystagmus, and seizures, OMIM:619876
Intellectual disability - microarray and sequencing v3.1594 RYR2 Sarah Leigh changed review comment from: PMID: 30170228 reports 34/421 RYR2-associated catecholaminergic polymorphic ventricular tachycardia (CPVT1) patients had intellectual disability. It was also possible to establish that de novo variants had arisen in 13/24 of these cases. RYR2 has not been made green on this panel at present, as ID is not a common feature of CPVT1 and it would appear that penetrance is incomplete.; to: PMID: 30170228 reports 34/421 RYR2-associated catecholaminergic polymorphic ventricular tachycardia (CPVT1) patients had intellectual disability. It was also possible to establish that de novo RYR2 variants had arisen in 13/24 of these cases. RYR2 has not been made green on this panel at present, as ID is not a common feature of CPVT1 and it would appear that penetrance is incomplete.
Intellectual disability - microarray and sequencing v3.1593 RYR2 Dmitrijs Rots gene: RYR2 was added
gene: RYR2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: RYR2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: RYR2 were set to 30170228
Penetrance for gene: RYR2 were set to Incomplete
Review for gene: RYR2 was set to GREEN
Added comment: In a large cohort of RYR2-related CPVT, 8% of individuals (34 of 421) were having ID of various severity. Funcional data suggest that highly damaging RYR2 variants underlie ID.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1580 DROSHA Konstantinos Varvagiannis gene: DROSHA was added
gene: DROSHA was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DROSHA was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DROSHA were set to 35405010
Phenotypes for gene: DROSHA were set to Global developmental delay; Intellectual disability; Seizures; Cerebral white matter atrophy; Abnormality of the corpus callosum; Abnormality of movement; Stereotypic behavior; Abnormality of head or neck; Short foot
Penetrance for gene: DROSHA were set to unknown
Mode of pathogenicity for gene: DROSHA was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: DROSHA was set to AMBER
Added comment: Profound DD, ID and seizures have been reported in 2 unrelated subjects with de novo missense variants. The gene has a role in miRNA biogenesis. Both variants described have been shown to have effect on DROSHA's function in Drosophila / C. elegans (partial loss-of-function vs possibility of antimorphic effect discussed || in gnomAD several individuals with LoF alleles / Z=3.98 – pLI : 0.09).

There is currently no DROSHA-related phenotype in OMIM, G2P, SysNDD. In PanelApp Australia the gene has amber rating in genetic epilepsy and microcephaly panels (not currently included in the ID one).

Consider inclusion in the current panel with amber rating. Also consider inclusion in other possibly relevant panels (given postnatal microcephaly, abn. corpus callosum, progressive white matter atrophy, etc) [ NOT added ]

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Barish, Senturk, Schoch et al (2022 - PMID: 35405010) describe the phenotype of 2 unrelated individuals with de novo missense DROSHA variants.

Features included generalized hypotonia, postnatal microcephaly (-2,6 and -6 SD), feeding difficulties, profound DD and ID, seizures, abnormal movements (choreoathetosis / stereotypic movements), variable respiratory symptoms (in one case episodes of hyperventilation/apnea), cardiovascular or skeletal findings. Brain MRI demonstrated white matter atrophy and thin corpus callosum in both. Brachycephaly with broad face as well as short feet were also among the shared features.

Both were investigated by trio ES/GS which were otherwise non diagnostic and without other candidate variants. The 1st individual harbored a de novo htz missense DROSHA variant (c.3656A>G/p.Asp1219Gly) while the 2nd subject had another missense variant (c.4024C>T/p.Arg1342Trp) [NM_013235.4] confirmed by Sanger seq.

DROSHA (on 5p13.3) encodes a ribonuclease, subunit of the microprocessor complex, involved in miRNA biogenesis. Specifically, miRNAs are transcribed as part of pri-miRNAs (primary-miRNAs) which are cleaved to pre-miRNAs (precursor-miRNAs) in the nucleus by DROSHA (and its partner DGCR8 or Pasha) and then exported to the cytoplasm for further processing. Cleavage of pre-miRNAs by DICER1 generates mature miRNAs subsequently loaded to the RISC (RNA-induced silencing) complex which uses miRNA as template for recognition and cleavage of complementary mRNA with RNAse.

As the authors discuss, miRNA defects have a well-established role in development of model organisms e.g. (several Refs. provided):
- in C. elegans miRNA mutants causing lethality, developmental arrest and heterochronicity
- in Drosophila playing a role in the development of ovary, eye, nervous system etc.
- in mice mRNAs play a role in BMP and TGF-beta signaling while neuronal loss of miRNA processing leads to neurodegeneration/anatomical defects.

Feingold syndrome 2 is the single Mendelian disease associated to date with miRNAs, through deletion of a cluster containing 6 MIR genes.

miRNA dysregulation is also observed in Rett syndrome - and DROSHA implicated in the pathogenesis of the syndrome - as MECP2 and FOXG1 are cofactors of the microprocessor complex regulating processing of miRNA. One of the individuals here reported had a clinical diagnosis of Rett spectrum while both had overlapping features with Rett s.

Studies of DROSHA-dependent miRNAs in fibroblasts from one individual revealed significantly altered expression of mature miRNA (e.g. increased miR98, a miRNA with reduced expression in studies of somatic DROSHA variants) although this was not likely due to processing errors (given only a modest decrease of precursor miRNAs).

Previous studies have demonstrated that drosha (the Drosophila ortholog) null mutants die during post-embryonic development with 100% lethality before adulthood (3rd instar larval stage/beginning of pupariation). Mosaic flies with mutant eyes are small-eyed, while viable hypomorphic alleles display synaptic transmission defects (several Refs provided).

Here, homozygous flies for null alleles died at the end of 3rd instar larval stage/beginning of pupariation, while loss of drosha resulted in lack of imaginal disc tissue (which surrounds the larval brain) and severely reduced brain size, the latter similar to the microcephaly phenotype. [To the best of my understanding] introduction of a mutated genomic rescue construct (carrying similar substitutions as those observed in human subjects) in eye-specific drosha null (W1123X) flies was partially able to rescue eye/head size for wt or Asp1219Gly (human:Asp1084Gly) suggesting that the latter is a partial LoF allele. Arg1210Trp (corresponding to human Arg1342Trp) was able to rescue the eye phenotype and was not damaging to the function in the specific assay. Drosha expression levels were similar for genomic rescue flies either for wt or for the Asp-Gly variant suggesting that the effect was not due to expression levels (but rather function). Expression of mature miRNAs known to be regulated by Drosha were not affected when comparing wildtype larvae with genomic construct for wt or Asp1084Gly.

Upon expression of human cDNA using GAL4/UAS system in drosha mutant (null) eye clones, the reference partially rescued the eye size defect, Asp-Gly behaved as partial loss-of-function allele (~50% function compared to ref), while the Arg-Trp variant was shown to behave as a weaker loss-of-function allele.

The authors generated eye-specific drosha mutant clones to study the aging adult eye using ERG recordings. While null mutants display almost no response to light (7- and 20-day old flies), wt genomic rescue was shown to rescue ERG responses, Asp-Gly variant had significant defects (at both 7 and 20 days) and the Arg-Trp had defects approaching statistical significance only at the age of 20 days. Overall these data suggested that Arg-Trp had less severe effect compared to Asp-Gly (as above) while both variants led to progressive neuronal dysfunction.

Using CRISPR/Cas9 the authors generated C.elegans knock-ins for a variant analogous to the Asp1219Gly human one. Homozygous animals were inviable at larval stages, displayed a heterochronic phenotype (heterochronicity : development of cells or tissues at an abnormal time relative to other unaffected events in an organism / miRNAs are known to be involved in the heterochronic gene pathway) while this variant was deleterious to the Drosha's ability to process miRNAs.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1568 PHF14 Dmitrijs Rots gene: PHF14 was added
gene: PHF14 was added to Intellectual disability. Sources: Literature,Expert list
Mode of inheritance for gene: PHF14 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: PHF14 were set to 35074918
Phenotypes for gene: PHF14 were set to Autism
Review for gene: PHF14 was set to GREEN
Added comment: Multiple individuals in the literature reported with NDD and de novo PHF14 variants + experimental findings (in 35074918).
Additional info from AutDB:"De novo missense variants in the PHF14 gene have been identified in an ASD proband from the SPARK cohort (Feliciano et al., 2019) and the Autism Sequencing Consortium cohort (Satterstrom et al., 2020), while additional rare de novo non-coding variation in this gene has also been observed in ASD probands (Sanders et al., 2015; Yuen et al., 2017). Zhou et al., 2022 reported that PHF14 forms a complex with MECP2 and TCF20; in the same report, the authors described two individuals with de novo variants in PHF14 who presented with neurodevelopmental phenotypes, including a patient with a de novo PHF14 missense variant that abolished the MECP2-PHF14-TCF20 interaction."
Sources: Literature, Expert list
Intellectual disability - microarray and sequencing v3.1564 BUB1 Konstantinos Varvagiannis gene: BUB1 was added
gene: BUB1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: BUB1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: BUB1 were set to 35044816
Phenotypes for gene: BUB1 were set to Congenital microcephaly; Global developmental delay; Intellectual disability; Abnormal heart morphology; Growth delay
Penetrance for gene: BUB1 were set to Complete
Review for gene: BUB1 was set to AMBER
Added comment: A recent study provides evidence that this gene (biallelic variants) is relevant for inclusion in the DD/ID panel likely with amber / green rating (2 unrelated individuals with similar phenotype, 3 variants, role of this gene, extensive variant studies and demonstrated effects on cohesion and chromosome segregation, similarities with other disorders caused by mutations in mitosis-associated genes at the clinical and cellular level || number of affected subjects/families, different protein levels/kinase activity likely underlying few differences observed, role of monoallelic variants unclear).

This gene could probably be included in other panels e.g. for microcephaly (not added).

There is no BUB1-related phenotype in OMIM, G2P, SysID, PanelApp Australia.

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Carvalhal, Bader et al (2022 - PMID: 35044816) describe the phenotype of 2 unrelated individuals with biallelic BUB1 pathogenic variants and provide evidence for the underlying mechanism for this condition.

Common features comprised congenital microcephaly (2/2 | -2,8 and -2.9 SDs respectively / -7 and -4,9 SDs on last evaluation), DD/ID (2/2 - in one case with formal evaluation mild), some degree of growth retardation (2/2) and cardiovascular findings (2/2 - small ASD type II). Other findings limited to one subject included Pierre-Robin sequence, Axenfeld-Rieger anomaly, choanal stenosis, hypospadias, tracheal stenosis, etc.

Initial genetic testing was normal (incl. CMA in both, metabolic testing and individual genes incl. PITX2, GREM1, FOXD3, FOXC1 for one proband).

Exome sequencing revealed homozygosity for a start-lost variant (NM_004336.4:c.2T>G / p.?) in the first subject (P1). The variant lied within a 14-Mb region of homozygosity (no reported consanguinity). The second individual (P2) was compound htz for a splice-site and a frameshift variant (c.2625+1G>A and c.2197dupG) with Sanger sequencing used for confirmation and segregation studies.

BUB1 encodes BUB1 Mitotic checkpoint serine/threonine kinase (/Budding uninhibited by benzimidazoles 1, s. cerevisiae, homolog of) a multifunctional component of the segregation machinery contributing to multiple mitotic processes. The protein has a kinetochore localization domain, multiple binding motifs and a C-terminal kinase domain (aa 784-1085) this structure allowing both kinase dependent/independent activities.

cDNA sequencing revealed that the splice variant leads to skipping of ex21 and in-frame deletion of 54 residues in the kinase domain (c.2625+1G>A / p.Val822_Leu875del).

Both individuals exhibited normal BUB1 mRNA levels (fibroblasts in both, tracheal tissue in one) but severely reduced protein levels (fibroblasts). A shorter protein product corresponding to the in-frame deletion variant was also detected.

The authors performed additional experiments to confirm small amounts of full-length protein produced by the start-lost variant. This was shown in SV40-transformed fibroblasts from the corresponding individual (treatment with a proteasome inhibitor resulted also in higher levels). Upon generation RPE1 cells using CRISPR for the start-lost variant, again, small amounts of full length protein were detected, which was not the case for complete knockout HAP1 cells. No shorter versions could be detected in the patient cells or RPE1 cells, arguing against utilization of an alternative start codon. (Use of non-AUG start codons discussed based on literature).

In line with small amounts of full-length protein the authors provided evidence for residual kinase activity for the start-loss variant (through proxy of phosphorylation of its substrate and use of a BUB1 kinase inhibitor). Cells from the individual with the frameshift variant and the splice variant had no residual kinase activity.

The authors provide evidence for mitotic defects in cells from both individuals with prolonged mitosis duration and chromosome segregation defects. Some patient-specific findings were thought to be related with BUB1 protein levels (affecting BUB1-mediated kinetochore recruitment of BUBR1, important for chromosome alignment) and others due to residual kinase activity [->phosphorylation of H2A at Threonine 120-> affecting centromeric recruitment of Aurora B, SGO1 (role in protection of centromeric cohesion), TOP2A (a protein preventing DNA breakage during sister chromatid separation), these correlated with high anaphase bridges (in P2), aneuploidy observed in lymphoblasts and primary fibroblasts from P2 but not P2's lymphocytes or lymphocytes from P1) and defective sister chromatid cohesion defects (in primary fibroblasts from P2, milder effect for P1).

Overall the authors provide evidence for overlapping clinical and cellular phenotype for this condition with primary microcephalies (MCPH - mutations in genes for mitotic regulators incl. kinetochore proteins or regulators of chromosome organization), mosaic variegated aneuploidy (biallelic variants in genes for kinetochore proteins, with random aneuploidies occurring in >5% cells of different tissues) and cohesinopathies (mostly Roberts or Warsaw breakage syndromes - characterized by cohesion loss and/or spontaneous railroad chromosomes).

Mouse model: Hmz disruption in mice is lethal shortly after E3.5 (cited PMID: 19772675), while a hypomorphic mutant mouse (lacking exons 2-3, expressing <5% of wt protein levels) is viable but exhibits increased tumorigenesis with aging and aneuploidy (cited PMID: 19117986). Mutant mice that lack kinase activity though with preserved Bub1 protein abundance, did not display increased susceptibility, despite substantial segregation errors and aneuploidies (cited PMID: 23209306).

The authors note that monoallelic germline BUB1 variants have been described in small number of individuals with CRC, exhibiting reduced expression levels and variegated aneuploidy in multiple tissues (cited PMID: 23747338) although the role of BUB1 is debated (cited PMIDs: 27713038, 29448935).

Based on the discussion, complete loss of BUB1 activity is presumed to be embryonically lethal based on the mouse study (PMID: 19772675) and reduced BUB1 expression associated with spontaneous miscarriages (cited PMID: 20643875, to my understanding in this study mRNA levels remained relatively constant despite reduced Bub1 protein levels, mRNA RT-PCR followed by sequencing revealed only 2 synonymous BUB1 variants).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4D Konstantinos Varvagiannis gene: HIST1H4D was added
gene: HIST1H4D was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4D was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4D were set to 35202563
Phenotypes for gene: HIST1H4D were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4D were set to Complete
Mode of pathogenicity for gene: HIST1H4D was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: HIST1H4D was set to AMBER
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

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Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

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In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

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Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4E Konstantinos Varvagiannis gene: HIST1H4E was added
gene: HIST1H4E was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4E was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4E were set to 35202563
Phenotypes for gene: HIST1H4E were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4E were set to unknown
Mode of pathogenicity for gene: HIST1H4E was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: HIST1H4E was set to GREEN
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4F Konstantinos Varvagiannis gene: HIST1H4F was added
gene: HIST1H4F was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4F was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4F were set to 35202563
Phenotypes for gene: HIST1H4F were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4F were set to unknown
Mode of pathogenicity for gene: HIST1H4F was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: HIST1H4F was set to AMBER
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4I Konstantinos Varvagiannis gene: HIST1H4I was added
gene: HIST1H4I was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4I was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4I were set to 35202563
Phenotypes for gene: HIST1H4I were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4I were set to unknown
Mode of pathogenicity for gene: HIST1H4I was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: HIST1H4I was set to GREEN
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1519 CPE Ivone Leong Tag Q3_21_rating was removed from gene: CPE.
Intellectual disability - microarray and sequencing v3.1519 CPE Sarah Leigh commented on gene: CPE
Intellectual disability - microarray and sequencing v3.1519 CPE Ivone Leong Source Expert Review Green was added to CPE.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Intellectual disability - microarray and sequencing v3.1518 CPSF3 Konstantinos Varvagiannis gene: CPSF3 was added
gene: CPSF3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CPSF3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CPSF3 were set to 35121750
Phenotypes for gene: CPSF3 were set to Failure to thrive; Abnormal muscle tone; Global developmental delay; Intellectual disability; Microcephaly; Seizures
Penetrance for gene: CPSF3 were set to Complete
Review for gene: CPSF3 was set to AMBER
Added comment: Arnadottir (2022 - PMID: 35121750) describe the phenotype associated with biallelic CPSF3 pathogenic variants.

Based on WGS of 56,969 Icelanders and imputing the genotype of another 153,054 chip-genotyped Icelanders, the authors identified missense variants with a deficit of homozygous carriers to what would be expected based on AF. (For variants with MAF>0.4%, for which >=3 hmz carriers would be expected by H-W equilibrium, no identified hmz carriers within this cohort/dataset). A total of 114 such missense variants was identified.

5 of these SNVs, among which a CPSF3 one (NM_016207.3:c.1403G>A / p.Gly468Glu), were however observed in a series of 764 individuals investigated with clinical WGS at the National University Hospital.

The CPSF3 variant with a MAF of 0.41% (3 hmz expected but none observed in the population set) was found in homozygosity in 2 closely related individuals, both investigated for FTT, severe DD, ID, microcephaly, seizures but remaining unresolved following WGS with no other candidate variants.

Using genealogical information from the db of deCODE genetics, the authors identified 3 couples from the 153k genotyped Icelanders where both partners were htz carriers for this SNV. These 3 couples had 10 offspring, 4 of whom deceased but with the same phenotypic features as above (hypotonia 4/4, ID 4/4, seizures 3/4, microcephaly 2/4). Paraffin embedded samples of 2 of these children and WG & Sanger sequencing confirmed hmz for Gly468Glu in 2 sibs, without other candidate variants. Samples of the 2 other individuals were N/A.

Through GeneMatcher 2 additional first-cousin patients from Mexico were identified, being hmz for another CPSF3 variant (c.1061T>C/p.Ile354Thr) and having overlapping phenotype of abnormal muscle tone, ID, seizures and microcephaly. There were no other variants in WES analysis.

mRNA studies in WBCs from Gly468Glu htz carriers did not reveal reduced levels and W.Blot of lymphocytes from a hmz individual confirmed expression, overall suggesting that the variant does not affect the protein levels but presumably the function.

CPSF3 encodes cleavage and polyadenylation specificity factor 3, a 684 aa protein, subunit of the cleavage and polyadenylation specificity factor compex. As discussed, cleavage and polyadenylation of the 3' of pre-mRNAs is necessary before transport out of the nucleus with CPSF playing a crucial role in the process of cleavage.

CPSF3 ko mice exhibit embryonic lethality, while in yeast mutations in key residues of the CPSF3 homolog are lethal.

In gnomAD, CPSF3 has a pLI of 0, z-score of 3.61 with no homozygotes for pLoF variants in 141k individuals (or ~57k WGS Icelanders).

The 2 missense variants concerned highly conserved residues (GERP ~5.8). Both are hypothesized to affect the ability of the protein to bind other factors involved in pre-mRNA cleavage.

Overall the authors speculate that not only complete loss of CPSF3 would result in drastic phenotypic effects - as in the murine model - but also variants altering its enzymatic function.

There is currently no CPSF3-related phenotype in OMIM, G2P, SysID, The gene is included with green rating in the ID, epilepsy and microcephaly panels in PanelApp Australia.

Consider inclusion probably with amber rating (Highly consistent phenotype, biological function, evidence from animal models. 2 identified variants, authors state that follow-up functional studies are needed). Also consider inclusion in other possibly relevant panels.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1405 NUP85 Eleanor Williams changed review comment from: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from the 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro), which segregated from the maternal and the paternal side.
Sources: Literature; to: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction.

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro) in NUP85.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1405 NUP85 Eleanor Williams gene: NUP85 was added
gene: NUP85 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NUP85 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NUP85 were set to 34170319
Phenotypes for gene: NUP85 were set to Primary autosomal recessive microcephaly and Seckel syndrome spectrum disorders (MCPH-SCKS)
Review for gene: NUP85 was set to AMBER
Added comment: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from the 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro), which segregated from the maternal and the paternal side.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1310 CPE Arina Puzriakova Publications for gene: CPE were set to 26120850; 32936766
Intellectual disability - microarray and sequencing v3.1309 CPE Arina Puzriakova Classified gene: CPE as Amber List (moderate evidence)
Intellectual disability - microarray and sequencing v3.1309 CPE Arina Puzriakova Gene: cpe has been classified as Amber List (Moderate Evidence).
Intellectual disability - microarray and sequencing v3.1308 CPE Arina Puzriakova Tag watchlist was removed from gene: CPE.
Tag Q3_21_rating tag was added to gene: CPE.
Intellectual disability - microarray and sequencing v3.1308 CPE Arina Puzriakova edited their review of gene: CPE: Added comment: Bosch et al. 2021 (PMID: 34383079) reported on 4 individuals from 3 additional families harbouring 2 different homozygous truncating variants in this gene. Clinical presentation was prominent for obesity and intellectual disability. Hypogonadotropic hypogonadism was confirmed in one individual and was suspected but not tested for in another two subjects.; Changed rating: GREEN; Changed publications to: 26120850, 32936766, 34383079; Changed phenotypes to: Intellectual developmental disorder and hypogonadotropic hypogonadism, OMIM:619326; Changed mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.1282 CPE Dmitrijs Rots reviewed gene: CPE: Rating: GREEN; Mode of pathogenicity: None; Publications: 34383079; Phenotypes: Obesity, intellectual disability; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova Tag watchlist tag was added to gene: CPE.
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova changed review comment from: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature with different homozygous variants in the CPE gene. Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag); to: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature to date with different homozygous variants in the CPE gene (PMIDs: 26120850; 32936766). Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag)
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova Classified gene: CPE as Amber List (moderate evidence)
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature with different homozygous variants in the CPE gene. Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag)
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova Gene: cpe has been classified as Amber List (Moderate Evidence).
Intellectual disability - microarray and sequencing v3.1141 CPE Arina Puzriakova Phenotypes for gene: CPE were changed from Intellectual developmental disorder and hypogonadotropic hypogonadism, MIM# 619326 to Intellectual developmental disorder and hypogonadotropic hypogonadism, OMIM:619326
Intellectual disability - microarray and sequencing v3.1120 CPE Zornitza Stark gene: CPE was added
gene: CPE was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CPE was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CPE were set to 26120850; 32936766
Phenotypes for gene: CPE were set to Intellectual developmental disorder and hypogonadotropic hypogonadism, MIM# 619326
Review for gene: CPE was set to AMBER
Added comment: Four affected individuals from two unrelated families reported, bi-allelic LoF variants.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1069 FBXO31 Zornitza Stark edited their review of gene: FBXO31: Added comment: PMIDs 33675180; 32989326: three unrelated individuals with de novo missense variant, (p.Asp334Asn) and spastic-dystonic CP, including ID.

AR ID: Single consanguineous family reported with homozygous truncating variant, limited functional evidence.; Changed rating: GREEN; Changed publications to: 24623383, 33675180, 32989326
Intellectual disability - microarray and sequencing v3.1037 JMJD1C Zornitza Stark gene: JMJD1C was added
gene: JMJD1C was added to Intellectual disability. Sources: Expert Review
Mode of inheritance for gene: JMJD1C was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: JMJD1C were set to 26181491; 32996679
Phenotypes for gene: JMJD1C were set to Intellectual disability
Review for gene: JMJD1C was set to GREEN
gene: JMJD1C was marked as current diagnostic
Added comment: Reported in ID cohort (with Rett-like phenotypic overlap) with supporting functional studies (PMID: 26181491). 7 individuals with rare variants identified, and variants demonstrated to be de novo in 2, one with a Rett-like phenotype and the other with ID. Functional study of the JMJD1C mutant Rett syndrome patient demonstrated that the altered protein had abnormal subcellular localization, diminished activity to demethylate the DNA damage-response protein MDC1, and reduced binding to MECP2. JMJD1C protein shown to be widely expressed in brain regions and that its depletion compromised dendritic activity.

Splice-disrupting JMJD1C variant reported in association with learning disability and myoclonic epilepsy (PMID 32996679).

Disruption of gene due to balanced translocation (PMID 33591602) implicated in autism spectrum disease phenotype.
Sources: Expert Review
Intellectual disability - microarray and sequencing v3.953 TUBGCP4 Catherine Snow Source: Expert Review Red was removed from gene: TUBGCP4
Intellectual disability - microarray and sequencing v3.846 TECPR2 Ivone Leong Source: Expert Review Red was removed from gene: TECPR2
Intellectual disability - microarray and sequencing v3.500 AGAP1 Zornitza Stark gene: AGAP1 was added
gene: AGAP1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: AGAP1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: AGAP1 were set to 31700678; 25666757; 30472483
Phenotypes for gene: AGAP1 were set to Cerebral palsy
Review for gene: AGAP1 was set to AMBER
Added comment: Two individuals reported with de novo variants in this gene and a CP phenotype. Rare variants over-represented in a case-control study. Supportive zebrafish model. Another individual with a deletion (+1 other gene) reported with ID and autism. This seems the most appropriate panel?
Sources: Literature
Intellectual disability - microarray and sequencing v3.355 INTS6 Arina Puzriakova Added comment: Comment on list classification: The Red review by Konstantinos Varvagiannis supports the current Red rating of CPD. There is currently no evidence to support this gene-disease association, and therefore have kept rating as Red.
Intellectual disability - microarray and sequencing v3.354 CPD Arina Puzriakova Classified gene: CPD as Red List (low evidence)
Intellectual disability - microarray and sequencing v3.354 CPD Arina Puzriakova Added comment: Comment on list classification: The Red review by Konstantinos Varvagiannis supports the current Red rating of CPD. There is currently no evidence to support this gene-disease association, and therefore have kept rating as Red.
Intellectual disability - microarray and sequencing v3.354 CPD Arina Puzriakova Gene: cpd has been classified as Red List (Low Evidence).
Intellectual disability - microarray and sequencing v3.332 MECP2 Arina Puzriakova reviewed gene: MECP2: Rating: GREEN; Mode of pathogenicity: None; Publications: 32469049; Phenotypes: Rett syndrome, 312750; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability - microarray and sequencing v3.268 TUBGCP2 Arina Puzriakova Classified gene: TUBGCP2 as Amber List (moderate evidence)
Intellectual disability - microarray and sequencing v3.268 TUBGCP2 Arina Puzriakova Gene: tubgcp2 has been classified as Amber List (Moderate Evidence).
Intellectual disability - microarray and sequencing v3.268 TUBGCP2 Arina Puzriakova Classified gene: TUBGCP2 as No list
Intellectual disability - microarray and sequencing v3.268 TUBGCP2 Arina Puzriakova Gene: tubgcp2 has been removed from the panel.
Intellectual disability - microarray and sequencing v3.267 TUBGCP2 Arina Puzriakova Tag watchlist tag was added to gene: TUBGCP2.
Intellectual disability - microarray and sequencing v3.267 TUBGCP2 Arina Puzriakova reviewed gene: TUBGCP2: Rating: AMBER; Mode of pathogenicity: None; Publications: 31630790; Phenotypes: Pachygyria, microcephaly, developmental delay, and dysmorphic facies, with or without seizures, 618737; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.35 YIF1B Konstantinos Varvagiannis gene: YIF1B was added
gene: YIF1B was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: YIF1B was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: YIF1B were set to 32006098
Phenotypes for gene: YIF1B were set to Central hypotonia; Failure to thrive; Microcephaly; Global developmental delay; Intellectual disability; Seizures; Spasticity; Abnormality of movement
Penetrance for gene: YIF1B were set to Complete
Review for gene: YIF1B was set to GREEN
Added comment: AlMuhaizea et al (2020 - PMID: 32006098) report on the phenotype of 6 individuals (from 5 families) with biallelic YIF1B truncating variants.

Affected subjects presented hypotonia, failure to thrive, microcephaly (5/6), severe global DD and ID (as evident from best motor/language milestones achieved - Table S1) as well as features suggestive of a motor disorder (dystonia/spasticity/dyskinesia). Seizures were reported in 2 unrelated individuals (2/6). MRI abnormalities were observed in some with thin CC being a feature in 3.

Variable initial investigations were performed including SNP CMA, MECP2, microcephaly / neurotransmitter disorders gene panel testing did not reveal P/LP variants.

YIF1B variants were identified in 3 families within ROH. Following exome sequencing, affected individuals were found to be homozygous for truncating variants (4/5 families being consanguineous). The following 3 variants were identified (NM_001039672.2) : c.186dupT or p.Ala64fs / c.360_361insACAT or p.Gly121fs / c.598G>T or p.Glu200*.

YIF1B encodes an intracellular transmembrane protein.

It has been previously demonstrated that - similarly to other proteins of the Yip family being implicated in intracellular traffic between the Golgi - Yif1B is involved in the anterograde traffic pathway. Yif1B KO mice demonstrate a disorganized Golgi architecture in pyramidal hippocampal neurons (Alterio et al 2015 - PMID: 26077767). The rat ortholog interacts with serotonin receptor 1 (5-HT1AR) with colocalization of Yif1BB and 5-HT1AR in intermediate compartment vesicles and involvement of the former in intracellular trafficing/modulation of 5-HT1AR transport to dendrites (PMID cited: 18685031).

Available mRNA and protein expression data (Protein Atlas) suggest that the gene is widely expressed in all tissues incl. neuronal cells. Immunochemistry data from the Human Brain Atlas also suggest that YIF1B is found in vesicles and localized to the Golgi apparatus. Immunohistochemistry in normal human brain tissue (cerebral cortex) demonstrated labeling of neuronal cells (Human Protein Atlas).

Functional/network analysis of genes co-regulated with YIF1B based on available RNAseq data, suggest enrichement in in genes important for nervous system development and function.

Please consider inclusion in other panels that may be relevant (e.g. microcephaly, etc).
Sources: Literature
Intellectual disability - microarray and sequencing v3.35 CDC42BPB Konstantinos Varvagiannis gene: CDC42BPB was added
gene: CDC42BPB was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CDC42BPB was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CDC42BPB were set to 32031333
Phenotypes for gene: CDC42BPB were set to Central hypotonia; Global developmental delay; Intellectual disability; Seizures; Autistic behavior; Behavioral abnormality
Penetrance for gene: CDC42BPB were set to unknown
Review for gene: CDC42BPB was set to GREEN
Added comment: Chilton et al (2020 - PMID: 32031333) report on 14 individuals with missense and loss-of-function CDC42BPB variants.

Features included hypotonia (8/11), DD (12/13 - the 14th was a fetus), ID (7/13), ASD (8/12), clinical seizures (in 3 - a 4th had abnormal EEG without seizures), behavioral abnormalities. Variable non-specific dysmorphic features were reported in some (sparse hair being the most frequent - 4/8). Additional features were observed in few (=<4) incl. cryptorchidism, ophthalmological issues, constipation, kidney abnormalities, micropenis, etc.

All individuals had non-diagnostic prior genetic testing (incl. CMA, FMR1, MECP2, Angelman/Prader-Willi methylation studies, autism gene panel - suggesting relevance to the current panel) or metabolic testing.

Variants were identified following clinical exome sequencing with Sanger confirmation. Most occurred as de novo events (11/14) while inheritance was not available for few (3/14). Missense variants did not display (particular) clustering.

Almost all variants were absent from gnomAD and were predicted to be deleterious in silico (among others almost all had CADD scores >25).

As the authors comment, CDC42BPB encodes myotonic dystrophy-related Cdc42-binding kinase β (MRCKβ) a serine/threonine protein kinase playing a role in regulation of cytoskeletal reorganization and cell migration in nonmuscle cells (through phosporylation of MLC2).

Previous studies have demonstrated that it is ubiquitously expressed with prenatal brain expression.

The gene appears to be intolerant to pLoF (pLI of 1) as well as to missense variants (Z-score of 3.66).

CDC42BPB is a downstream effector of CDC42. Mutations of the latter cause Takenouchi-Kosaki syndrome with DD/ID and some further overlapping features (with CDC42BPB-associated phenotypes).

Homozygous Cdc42bpb KO in mouse appears to be nonviable (MGI:2136459). Loss of gek in the eyes of Drosophila results in disrupted growth cone targeting to the lamina (gek is the fly CDC42BPB ortholog).

Please consider inclusion with amber / green rating in the ID panel (>=4 relevant individuals / variants) and other panels (e.g. for epilepsy, ASD).
Sources: Literature
Intellectual disability - microarray and sequencing v3.3 TUBGCP2 Zornitza Stark gene: TUBGCP2 was added
gene: TUBGCP2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TUBGCP2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TUBGCP2 were set to 31630790
Phenotypes for gene: TUBGCP2 were set to Lissencephaly; pachygyria; subcortical band heterotopia; microcephaly; intellectual disability
Review for gene: TUBGCP2 was set to GREEN
gene: TUBGCP2 was marked as current diagnostic
Added comment: Four unrelated families reported.
Sources: Expert list
Intellectual disability - microarray and sequencing v3.0 MN1 Konstantinos Varvagiannis gene: MN1 was added
gene: MN1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MN1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MN1 were set to 31834374; 31839203; 15870292
Phenotypes for gene: MN1 were set to Central hypotonia; Feeding difficulties; Global developmental delay; Intellectual disability; Hearing impairment; Abnormality of facial skeleton; Craniosynostosis; Abnormality of the face; Abnormality of the cerebellum; Abnormality of the corpus callosum; Polymicrogyria
Penetrance for gene: MN1 were set to Complete
Review for gene: MN1 was set to GREEN
Added comment: Two studies by Mak et al (2019 - PMID: 31834374 / Ref1) and Miyake et al (2019 - PMID: 31839203 / Ref2) provide sufficient evidence for heterozygous MN1 C-terminal truncating variants (predicted to escape NMD - localizing within the last nucleotides of exon 1 or in exon 2) being associated with a distinctive phenotype and DD and ID among the features.

Mak et al also discuss on the phenotype of individuals with variants causing N-terminal truncation or with MN1 deletions (discussed at the end of this review).

Overlapping features for C-terminal truncating variants included hypotonia, feeding difficulties, global DD and ID, hearing loss, cranial shape defects (/craniosynostosis in few), highly suggestive/distinctive facial features (eg. frontal bossing, hypertelorism, downslanting palpebral-fissures, shallow orbits, short upturned nose, low-set/posteriorly rotated/dysplastic ears, etc) and brain MRI abnormalities (eg. rhomboencephalosynapsis or cerebellar dysplasia, polymicrogyria, dysplastic CC).

The majority of the affected individuals were investigated by WES/WGS with a single one tested by targeted MN1 Sanger sequencing due to highly suggestive features. Variable previous investigations incl. CMA in several, gene panel testing (Rasopathies, hearing loss, craniofacial panels, FMR1, etc) and metabolic work were normal in most. In a single case a likely pathogenic ACSL4 also explained part of the phenotype (Ref2). In the majority of these individuals, the variant had occured as a de novo event. Two sibs had inherited the truncating variant from a milder affected mosaic parent. A parental sample was not available for an additional individual.

p.(Arg1295*) or NM_002430.2:c.3883C>T was a recurrent variant, seen in several individuals and in both studies.

Several lines of evidence are provided for the MN1 variants and the role of the gene including:
- For few individuals for whom cell lines were available, variants were shown to escape NMD by cDNA/RT-PCR/RNA-seq [Ref1 & 2].
- The gene has a high expression in fetal brain [Ref2 / fig S2]
- MN1 (* 156100 - MN1 protooncogene, transcriptional regulator) has been proposed to play a role in cell proliferation and shown to act as transcription cofactor (increasing its transactivation capacity in synergy with coactivators EP300 and RAC3) [Discussion and Refs provided in Ref2].
- In vitro studies suggested increased protein stability (upon transfection of wt/mut constructs in HEK293T cells), enhanced MN1 aggregation in nuclei (when wt/mut GFP-tagged MN1 was expressed in HeLa cells), increased inhibitory effect on cell growth (MG63 cells - role of MN1 in cell proliferation discussed above) and retained transactivation activity (upon transient MN1 overexpression of wt/mt MN1 in HEK293T cells) for the variants. These seem to support a gain-of-function effect for the C-terminal truncating variants [Ref2].
- The truncating variants are proposed to raise the fraction of Intrinsically disordered regions (IDRs = regions without fixed tertiary structure) probably contributing to the above effects [Ref2].
- Expression of FLAG-tagged MN1 wt/mut MN1 followed by immunoprecipitation and mass spectrometry analysis (mCAT-Hela cells), provided evidence that MN1 is involved in transcriptional regulation: a. through binding ZBTB24 and RING1 E3 ubiquitin ligase (with mutant MN1 displaying impaired interaction with ZBTB24 and no binding to RING1) and/or b. through interaction with DNA-binding transcription factors PBX1 and PKNOX1. Proper MN1 degradation is proposed to mediate precise transcriptional regulation. [Ref2]
- Transcriptome analysis in LCLs from an affected individual suggested dysregulation of genes relevant to neuronal development (eg. LAMP, ITGA, etc) and GO analysis suggested enrichment for pathways possibly linked to the observed phenotypes [Ref2].
- Discussed in both Refs1/2, homozygous Mn1-ko mice display abnormal skull bone development and die at/shortly after birth as a result of cleft palate. Heterozygous Mn1-ko mice display hypoplastic membranous bones of the cranial skeleton and cleft palate (CP), the latter with incomplete penetrance [Meester-Smoor et al 2005 - PMID: 15870292]. This is thus compatible with the cranial shape defects observed in C-terminal truncations (while CP has been reported in gene deletions, bifid uvula was reported once in C-terminal and N-terminal truncating variants, in the latter case with submucous CP).
-----
The phenotype of other MN1 variants is discussed by Mak et al (Ref1) :
- 3 individuals with MN1 N-terminal truncating variants (eg. Ser179*, Pro365Thrfs*120, Ser472*) presented speech delay, mild conductive hearing loss and facial features different from C-terminal truncations. None of these individuals had significant ID.
- Microdeletions: One individual (#27) with 130 kb deletion harboring only MN1, presented microcephaly, DD and ID and mildly dysmorphic facial features. Deletions spanning MN1 and other genes (eg a 1.17 Mb deletion in ind. #28) and relevant cases from the literature reviewed, with mild DD/ID, variable palatal defects and/or facial dysmorphisms (distinct from the C-terminal truncating variants) among the frequent findings.

[Please consider inclusion in other possibly relevant gene panels eg. for hearing loss (conductive/sensorineural in 16/20 reported by Mak et al) or craniosynostosis, etc].
Sources: Literature
Intellectual disability - microarray and sequencing v2.1135 TRAPPC4 Konstantinos Varvagiannis gene: TRAPPC4 was added
gene: TRAPPC4 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TRAPPC4 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TRAPPC4 were set to 31794024
Phenotypes for gene: TRAPPC4 were set to Feeding difficulties; Progressive microcephaly; Intellectual disability; Seizures; Spastic tetraparesis; Abnormality of the face; Scoliosis; Cortical visual impairment; Hearing impairment
Penetrance for gene: TRAPPC4 were set to Complete
Review for gene: TRAPPC4 was set to GREEN
Added comment: Van Bergen et al. (2019 - PMID: 31794024) report on 7 affected individuals from 3 famillies (only 1 of which consanguineous), all homozygous for a TRAPPC4 splicing variant.

Overlapping features included feeding difficulties, progressive microcephaly, severe to profound developmental disability (7/7 - DD also prior to the onset of seizures / regression also reported in 3), epilepsy (7/7 - onset in the first year), spastic quadriparesis. Other findings in some/few incl. scoliosis, cortical visual and hearing impairment. Some facial features were shared (eg. bitemporal narrowing, long philtrum, open mouth with thin tented upper lip, pointed chin, etc). Brain imaging demonstrated abnormalities in those performed (among others cerebral with/without cerebellar atrophy).

Work-up prior to exome sequencing was normal (highly variable incl. metabolic testing, CMA, MECP2, CDKL5, mitochondrial depletion studies, etc).

Exome of affected individuals (and parents +/- affected sibs in some families) revealed a homozygous TRAPPC4 splicing variant [NM_016146.5:c.454+3A>G / chr11:g.118890966A>G (hg19)]. Sanger sequencing confirmed variant in affecteds, heterozygosity in parents and compatible genotypes with disease status in sibs/other members.

Families were of Caucasian/Turkish and French-Canadian ethnicities. SNP array to compare haplotypes between affecteds in 2 families did not reveal a shared haplotype (/founder effect) and the variant is present in gnomAD (68/281054 - no hmz) in many populations (European/Asian/African/Latino) [https://gnomad.broadinstitute.org/variant/11-118890966-A-G].

mRNA studies in fibroblasts from an affected individual confirmed the splicing defect (2 RT-PCR products corresponding to wt and a shorter due to skipping of exon 3, the latter further confirmed by Sanger sequencing. The shorter transcript is not present in controls). qPCR revealed that the normal transript in patient fibroblasts was present at 6% of the level observed in control fibroblasts (or 54% in the case of a heterozygote parent compared to controls).

Western blot in patient fibroblasts, revealed presence of full-length protein in significantly reduced levels compared to fibroblasts from carrier parents or controls. There was no band using an antibody targeting the N-terminal region of the protein prior to exon 3, suggesting that NMD applies (skipping of ex3 is also predicted to lead to frameshift).

TRAPPC4 encodes one of the core proteins of the TRAPP complex. Use of different accessory proteins leads to formation of 2 distinct complexes (TRAPPII / III). The complex has an important role in intracellular trafficking. Both TRAPPII & TRAPPIII have a function in the secretory pathway, while complex III has a role also in autophagy. Core proteins are important for the complex stability. The TRAPP complex serves as a GEF for Ypt/Rab GTPases [several refs in article].

Mutations in genes for other proteins of the complex lead to neurodevelopmental disorders with associated ID ('TRAPPopathies' used by the authors / TRAPPC12, C6B, C9 green in the current panel).

Western blot suggested that levels of other TRAPP subunits (TRAPPC2 or C12) under denaturing conditions, although PAGE/size exclusion chromatography suggested that the levels of fully-assembled TRAPP complexes were lower in affected individuals.

Studies in patient fibroblasts showed a secretory defect (between ER, Golgi and the plasma membrane) which was restored upon lentiviral transduction with wt TRAPPC4 construct. Basal and starvation-induced autophagy were also impaired in patient fibroblasts (increased LC3 marker and LC3-positive structures / impaired co-localization with lysosomes) partly due to defective autophagosome formation (/sealing).

TRAPPC4 is the human orthologue of the yeast Trs23. In a yeast model of reduced Trs23 (due to temperature instability) the authors demonstrated impaired assembly of the TRAPP core. The yeast model recapitulated the autophagy as well as well as the secretory defect observed in patient fibroblasts.
Sources: Literature
Intellectual disability - microarray and sequencing v2.1098 NTNG2 Konstantinos Varvagiannis gene: NTNG2 was added
gene: NTNG2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NTNG2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NTNG2 were set to 31372774; 31668703
Phenotypes for gene: NTNG2 were set to Central hypotonia; Global developmental delay; Intellectual disability; Behavioral abnormality; Microcephaly; Seizures
Penetrance for gene: NTNG2 were set to Complete
Review for gene: NTNG2 was set to GREEN
Added comment: [1] Abu-Libdeh et al. (2019 - PMID: 31372774) reported 8 individuals from 4 unrelated consanguineous families of Arab Muslim origin, all homozygous for NM_032536.3:c.376dup - p.(Ser126PhefsTer241). Common features included hypotonia, failure to achieve milestones and developmental stagnation without regression during the first year (~9m) of life and severe ID. Minimal purposeful hand use (grasping and bringing objects to mouth), hand stereotypies and bruxism were also observed. Microcephaly and impaired growth were almost universal (with the exception of 2 having an OFC at ~10% percentile). Relevant previous investigations were normal in all and included MECP2, SMN1, aCGH, metabolic testing, etc. The variant was identified by exome in all, and Sanger confirmed with compatible segregation studies in parents and sibs. The variant was found within a shared haplotype of ~4.35 Mb, probably due to a founder effect.

[2] Dias et al. (2019 - PMID: 31668703) described 16 individuals from 7 unrelated families from Iran, Mexico, Turkey, Egypt and Bangladesh. Parents were known to be consanguineous or shown to be distantly related. All patients were homozygous for missense variants private to each family (7 variants) identified following exome sequencing. Shared features incl. hypotonia, GDD, severe to profound ID and behavioral anomalies incl. autistic features/stereotypies (most), screaming/laughing spells (most), bruxism. Microcephaly (5/14), growth below average/FTT and GI problems were also observed.

Epilepsy was reported in 5 individuals belonging to 4 different families in these 2 studies (5/24 overall / 4 variants).

Netrin-G2, the encoded protein, is bound to the plasma membrane by GPI-anchors. Netrins-G2 and G1 (another member of the Netrin-G subfamily) are enriched in presynaptic terminals. Interaction with their cognate Netrin-G ligand trans-synaptic partners / receptors (NGL2, NGL1 respectively) has been shown to promote axon outgrowth, induce and maintain excitatory synapse formation. Complementary and non-overlapping expression in the developping and mature CNS has been shown for Netrin-G2/1 in mice (several references provided by Abu-Libdeh / Dias).

Variant effect : The frameshift variant was not studied by Abu-Libdeh et al. Variants in the 2nd ref. were all missense, displayed no-specific localization and were suggested to affect protein stability and/or expression at the cell surface as 4/7 involved loss or addition of cystein residues (possibly creating unpaired cysteins) and 2 of the remaining 3 were predicted to affect the hydrophobic core. In line with this, overexpression of wt/variant constructs in HeLa cells demonstrated substantially decreased cell surface expression for all variants.

Mouse models/phenotypes : Dias et al. showed that siRNA-mediated Ntng2 knockdown in N2a cells led to significant reduction in neurite number and length. Studied previously, Ntng2 knockout mice display impaired learning, memory, visual and motor functioning (PMID cited : 26746425).

NTNG2 is not associated with any phenotype in OMIM/G2P. SysID lists it among the candidate ID genes, citing PMID: 29302074 (not here reviewed & NTNG2 not in the main text).

Overall this gene can be considered for inclusion in the ID panel probably as green (>3 individuals/families/variants, consistent phenotype in both reports, role of the gene, in silico and in vitro studies, animal model, etc) or amber.

[Please consider inclusion in other panels if relevant eg. ASD panel (many individuals having autistic / Rett-like features or epilepsy) or epilepsy (>3 individuals/families/variants although most families were also consanguineous)]
Sources: Literature
Intellectual disability - microarray and sequencing v2.1046 CPD Konstantinos Varvagiannis changed review comment from: The gene was present in the current panel with red rating, though with no reviews.

In Pubmed there are no publications concerning eventual CPD-related phenotypes. There is no associated phenotype in OMIM or G2P, either. The gene is not included in the SysID and SFARI databases. The denovo-db lists 1 individual with autism and de novo LoF variant (NM_001304.4:c.2478C>G - p.Tyr826* - Iossifov et al. - PMID: 25363768) and 2 further with congenital heart disease. Still the gene encodes an enzyme (carboxyptidase D), so AR inheritance would seem more likely (?). [The gene has also a pLI of 0 in gnomAD and Z-score of 2.59]. CPD is not included in gene panels for ID offered by diagnostic laboratories (including also the current ID panel of VCGS which was listed as a source).

As a result, red rating (or removal from the current panel) seems appropriate.; to: The gene was present in the current panel with red rating, though with no reviews.

In Pubmed there are no publications concerning eventual CPD-related phenotypes. There is no associated phenotype in OMIM or G2P, either. The gene is not included in the SysID and SFARI databases. The denovo-db lists 1 individual with autism and de novo LoF variant (NM_001304.4:c.2478C>G - p.Tyr826* - Iossifov et al. - PMID: 25363768) and 2 further with congenital heart disease. Still the gene encodes an enzyme (carboxyptidase D), so AR inheritance would seem more likely (?). [The gene has also a pLI of 0 in gnomAD and Z-score of 2.59. In Decipher %HI is 31.31]. CPD is not included in gene panels for ID offered by diagnostic laboratories (including also the current ID panel of VCGS which was listed as a source).

As a result, red rating (or removal from the current panel) seems appropriate.
Intellectual disability - microarray and sequencing v2.1046 CPD Konstantinos Varvagiannis reviewed gene: CPD: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability - microarray and sequencing v2.1022 PIGP Konstantinos Varvagiannis gene: PIGP was added
gene: PIGP was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PIGP was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGP were set to 28334793; 31139695
Phenotypes for gene: PIGP were set to Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment
Penetrance for gene: PIGP were set to Complete
Review for gene: PIGP was set to GREEN
gene: PIGP was marked as current diagnostic
Added comment: Johnstone et al. (2017 - PMID: 28334793) report on 2 sibs born to non-consanguineous parents of French-Irish ancestry. Both presented with seizures (onset at the age of 2 and 7 weeks respectively), hypotonia and profound DD. Other features included CVI and feeding difficulties. Extensive metabolic testing as well as prior genetic testing (ARX, STXBP1, MECP2, aCGH) in the family were non-diagnostic. WES suggested the presence of 2 PIGP variants with Sanger sequencing used for confirmation and segregation studies.

PIGP encodes a subunit of the enzyme that catalyzes the first step of glycophosphatidylinositol (GPI) anchor biosynthesis. Mutations in other genes whose proteins are in complex with PIGP (PIGA, PIGC, PIGQ, PIGY, DPM2) lead to similar phenotypes. The phenotype overall was also overlapping with the inherited GPI deficiencies (belonging to the broader group of CDGs).

PIGP has 2 isoforms, which differ by 24 amino acids due to utilization of alternative start codons [corresponding to NM_153681.2 (158 aa) and NM_153682.2 (134 aa)].

The variants identified affected both transcripts with the first SNV leading either to loss of the start codon (NM_153682.2:c.2T>C - p.Met1Thr) or to substitution of a methionine at position 25(NM_153681.2:c.74T>C;p.Met25Thr). The second variant led to frameshift in the last exon of both transcripts predicting a longer protein product (NM_153681.2:c.456delA / p.Glu153AsnfsTer34 or NM_153682.2:c.384delA / p.Glu129AsnfsTer34).

Overall extensive studies demonstrated decreased levels of PIGP mRNA in patient fibroblast, decreased amounts of mutant protein in transfected HEK293 cells. The decreased levels of GPI-APs further supported the effect of variants :

- mRNA levels in patient fibroblasts were reduced compared to controls. Conclusions could not be drawn from Western blot, since no antibodies could specifically detect PIGP. HEK293 cells transfected of mt or wt HA-tagged PIGP cDNA led to undetectable amounts for the first variant (both M1T/M25T) and a protein product of increased molecular weight for the frameshift one.
- Flow cytometry of patient granulocytes indicated reduced signal of CD16 (a GPI-anchored protein) and FLAER (binding directly to the GPI anchor).
- Reduced levels of GPI-APs were also observed in PIGP deficient HAP1 cells transfected with either wt, or mutant PIGP cDNA (of both isoforms for the M1T/M25T or isoform 2 for the frameshift mutation).

--------

Krenn et al. (2019 - PMID: 31139695) described a patient born to non-consanguineous Polish parents. Features were highly similar to those reported by Johnstone et al. and incl. intractable infantile seizures (onset at 7m), hypotonia, severe DD and feeding difficulties. Metabolic work-up failed to identify an alternative diagnosis. WES revealed homozygosity for the frameshift variant reported by Johnstone et al. Sanger sequencing confirmed the variant and carrier state in both parents. Identified ROH of less than 7 Mb in the WES data, suggested a founder mutation rather than unreported consanguinity. The variant is present 9 times in gnomAD (AF of 3.2e-5 / no homozygotes). Flow cytometry of patient granulocytes, revealed markedly reduced expression of GPI-APs (CD157, CD59, FLAER) compared to parents/controls.

ALP was normal in all aforementioned individuals (probably in line with PIGP being involved in the 1st step of the GPI anchor biosynthesis).

--------

A further individual with phenotype of EIEE-55;GPIBD-14 is reported in LOVD [Individual #00246132]. This individual, born to consanguineous parents, was tested by WES and found to be homozygous for a frameshift variant, also affecting the last exon in both transcripts (NM_153681.2:c.384delA (p.Glu129ArgfsTer7) / NM_153682.2:c.312delA (p.Glu105ArgfsTer7). This was probably in agreement with segregation studies according to the respective entry. The specific variant is reported as pathogenic [variant ID #0000500090].

--------

?Epileptic encephalopathy, early infantile, 55 (MIM 617599) is the corresponding phenotype in OMIM. There is no relevant G2P entry.
PIGP is included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).

--------

As a result, PIGP can be considered for inclusion in the ID/epilepsy panels probably as green (3 individuals, role of the gene and similarity to other inherited GPI deficiencies, extensive supporting studies) or amber.

(Please consider inclusion in other possibly relevant panels eg. CDGs, etc).
Sources: Literature
Intellectual disability - microarray and sequencing v2.978 DCPS Catherine Snow Source Expert Review Green was added to DCPS.
Added phenotypes Al-Raqad syndrome, 616459 for gene: DCPS
Publications for gene DCPS were changed from 25712129; 25701870; 30289615 to 25701870; 30289615; 25712129
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability - microarray and sequencing v2.938 TRPM3 Konstantinos Varvagiannis changed review comment from: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however classified as a VUS. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature; to: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however also present once in gnomAD (1/251370 alleles or AF:3.98e-6) and is classified as VUS according to the ACMG criteria. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature
Intellectual disability - microarray and sequencing v2.938 TRPM3 Konstantinos Varvagiannis gene: TRPM3 was added
gene: TRPM3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TRPM3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: TRPM3 were set to doi.org/10.1038/s41431-019-0462-x
Phenotypes for gene: TRPM3 were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Autistic behavior
Penetrance for gene: TRPM3 were set to unknown
Mode of pathogenicity for gene: TRPM3 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: TRPM3 was set to GREEN
gene: TRPM3 was marked as current diagnostic
Added comment: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however classified as a VUS. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature
Intellectual disability - microarray and sequencing v2.595 STAG2 Konstantinos Varvagiannis gene: STAG2 was added
gene: STAG2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: STAG2 was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Publications for gene: STAG2 were set to 29263825; 28296084; 30158690; 30447054; 19449417; 26443594; 25677961; 23637084; 25450604
Phenotypes for gene: STAG2 were set to Global developmental delay; Intellectual disability; Abnormality of head or neck; Microcephaly; Growth delay; Hearing impairment; Abnormal heart morphology
Penetrance for gene: STAG2 were set to unknown
Review for gene: STAG2 was set to GREEN
gene: STAG2 was marked as current diagnostic
Added comment: Several affected individuals (from at least 8 unrelated) families have been reported in the literature. The phenotype consists - among others - of DD/ID. STAG2 is located on long arm of chromosome X (Xq25). Based on these reports, both males and females can be affected.

Soardi et al. (2017 - PMID: 29263825) report an affected male belonging to a large pedigree with 4 other similarly affected males. The disorder in this pedigree followed a typical X-linked inheritance pattern. All affected males were hemizygous for a missense variant (NM_001042749.1:c.980G>A or p.Ser327Asn). Common phenotype consisted of moderate ID, short stature, sensory hearing loss and some similar facial features. Unaffected males did not harbor the variant. Heterozygous females were not affected. Co-segragation of the variant with the affected status under an X-linked model, appeared unlikely to have occurred by chance (probability of 1/131,072 - logarithm of odds score of 5.12).

Mullegama et al. (2017 - PMID: 28296084) report on an 8-year-old girl harboring a de novo nonsense variant in STAG2 (NM_001042749.1:c.205C>T or p.Arg69Ter). This individual presented - among others with - DD, microcephaly, growth delay, digit anomalies, particular facial features, and anomalies of other systems (eg. hearing loss, cardiac defect, etc). The authors summarize the features of 2 subjects from the DDD study as available in DECIPHER, without additional details. [Variants of these individuals NM_001042749.1:c.1913_1922del10 or p.(A638Vfs*10) / NM_001042749.1:c.1811G>A p.(R604Q)].

Yuan et al. (2018 - PMID: 30158690) report on 4 females with de novo LoF STAG2 variants as well as 1 male subject with a de novo missense one. DD (5/5) and ID (4/4) were features in all individuals for whom this information was available. One additional female had an intragenic STAG2 deletion, although this subject was not reported to have DD or ID (table S6 : microcephaly, seizures and facial phenotype). It is not known whether the deletion was inherited or had occurred as a de novo event. All variants from this study have been submitted in ClinVar (phenotype : STAG2-related disorder).

Mullegama et al. (2018 - PMID: 30447054) report on a 4-year-old male with DD, microcephaly, growth delay, digit anomalies due to a de novo missense STAG2 variant (c.3027A>T or p.Lys1009Asn). As discussed by the authors at the time of the study 33 males with Xq25 duplications and ID had been reported (PMIDs cited: 19449417, 26443594, 25677961, 23637084, 25450604).

Discussed in these articles :

STAG2 (or STAG1) is one of the 4 core proteins of the cohesin complex, the other 3 being SMC1A, SMC3 and RAD21. Mutations in genes encoding these proteins or their interactors (eg. NIBPL, HDAC8, ESCO2, etc) have been associated cohesinopathies, a group of multisystem developmental disorders (eg. Cornelia de Lange syndrome, Roberts/SC phocomelia, etc).

It has been commented that the phenotype of STAG2-related disorder presents overlap with other cohesinopathies (eg. DD, microcephaly and growth retardation, craniofacial features, anomalies of the digits, etc).

Decreased proportion of nuclei with premature sister chromatid separation compared to controls was found on one occasion (suggestive of tighter sister chromatid cohesion) [Mullegama-A]. Sister chromatid cohesion was not affected in another report [Soardi et al.].

Western blot demonstrated significant reduction of STAG2 levels for a nonsense variant [Mullegama-A]. Levels were not perturbed for a missense variant [Soardi et al.].

Upon immunofluorescence STAG2 presented normal (nuclear) localization for a missense variant for which this was studied [Soardi et al.].

Perturbation of the cell cycle profile (higher percentage of G2/M cells) was demonstrated for patient fibroblasts compared to controls on one occasion where this was studied. [Soardi et al.].

Microarray expression studies in patient fibroblasts demonstrated altered transcription (upregulation) of genes implicated in cell division, mitosis and DNA replication upon comparison with normal fibroblasts [Soardi et al.].

The effect of a missense variant on STAG2 binding to other cohesin subunits (SCC1, SMC1 and SMC3) and regulators was studied. Binding was found to be reduced in vivo (in HeLa cells) for SCC1 (its direct binding partner) as well as SMC1, SMC3 (possibly indirectly). Reduced STAG2 binding to cohesin regulators was also shown in vivo. However, in vitro studies were not suggestive of impaired binding of STAG2 to SCC1 (a finding difficult to explain) [Soardi et al.].

STAG2 appears to be intolerant to LoF variants (pLI of 1 in ExAC). Z-Score for missense variants is 5.11.

Mullegama et al. (B) comment that Xq25 duplications in males may be associated with milder phenotypes compared to intragenic variants. They further hypothesize that males are able to survive less damaging variants while females are able to survive more deleterious (eg. LoF) ones though with more severe phenotypes (similarity to the MECP2 model is discussed).
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STAG2 is not associated with any phenotype in OMIM.
In G2P this gene is associated with STAG2-related developmental delay with microcephaly and congenital anomalies (disease confidence : confirmed / Both DD and ID among the phenotypes assigned to this entry).
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STAG2 is included in gene panels for ID offered by some diagnostic laboratories.
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As a result, this gene can be considered for inclusion in the ID panel as green (or amber).
Sources: Literature
Intellectual disability - microarray and sequencing v2.530 DCPS Konstantinos Varvagiannis gene: DCPS was added
gene: DCPS was added to Intellectual disability. Sources: Expert Review,Literature
Mode of inheritance for gene: DCPS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DCPS were set to 25712129; 25701870; 30289615
Phenotypes for gene: DCPS were set to Al-Raqad syndrome (OMIM 616459)
Penetrance for gene: DCPS were set to Complete
Review for gene: DCPS was set to GREEN
gene: DCPS was marked as current diagnostic
Added comment: Biallelic pathogenic DCPS variants cause Al-Raqad syndrome (OMIM 616459).

7 patients from 3 families have been reported to date, all summarized in PMID 30289615 (first reports on the disorder - PMIDs : 25712129, 25701870).

Most individuals belong to consanguineous families although a compound heterozygous patient belonging to a broader consanguineous family (in PMID 25701870) and a further individual was born to unrelated parents originating from the same region (in PMID 30289615) have been described.

Overall, 2 splice site and 2 missense variants have been reported. Functional studies were carried out and support pathogenicity of the variants in the first 2 studies.

Developmental delay and intellectual disability are universal features.

DCPS is included in gene panels for intellectual disability offered by different diagnostic labs.

As a result this gene can be considered for inclusion in this panel as green.
Sources: Expert Review, Literature
Intellectual disability - microarray and sequencing v2.510 VARS Konstantinos Varvagiannis gene: VARS was added
gene: VARS was added to Intellectual disability. Sources: Expert Review,Literature
Mode of inheritance for gene: VARS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: VARS were set to 26539891; 29691655; 30275004
Phenotypes for gene: VARS were set to # 617802. NEURODEVELOPMENTAL DISORDER WITH MICROCEPHALY, SEIZURES, AND CORTICAL ATROPHY; NDMSCA
Penetrance for gene: VARS were set to Complete
Review for gene: VARS was set to GREEN
gene: VARS was marked as current diagnostic
Added comment: PMID: 26539891 is the first report on individuals with biallelic pathogenic variants in VARS. 3 individuals from 2 consanguineous families are briefly reported. The phenotype was similar in all 3, consisting of severe developmental delay, microcephaly, seizures and cortical atrophy. Subjects from the first family were homozygous for a missense variant in the tRNA synthetase catalytic domain [p.(L885F)]. The patient from the second family was homozygous for a missense SNV affecting the anticodon-binding domain [p.(R1058Q)].

PMID: 29691655 reports on a further patient born to non-consanguineous parents, with 2 in-trans pathogenic variants in VARS. The phenotype consisted of progressive microcephaly (OFC at birth -2SD, at the age of 2 months -4SD), global developmental delay, seizures and progressive cerebral and cerebellar atrophy. An affected brother presented with more severe phenotype (OFC -6SD at birth and -8SD at 2 months of age), seizures, hearing loss but was deceased and unavailable for genetic testing. cDNA studies demonstrated absence of the reference allele for the missense mutation downstream the splice variant (in line with a reduced or absent mRNA allele harboring the splice variant). Similarly, mRNA expression studies demonstrated 50-60% reduction in the transcripts (due to NMD of the allele with the splice SNV). Western blot showed severe reduction in protein levels (more pronounced compared to what would be expected by mRNA expression) presumably secondary to decreased protein stability due to the missense variant. Severe defects in aminoacylation were further confirmatory of a pathogenic role of these variants. The missense variant was affecting the anticodon-binding domain, important for aminoacylation.

PMID: 30275004 reports on 2 siblings with developmental delay, intellectual disability, severe speech impairment and microcephaly, similar to what has been described for the disorder. Clinical findings were somewhat different from previous studies in that microcephaly was acquired, while seizures and cortical atrophy were not part of the phenotype. Both sibs were compound heterozygous for 2 missense variants, though only one of these mutations affected the anticodon binding domain and the other was in the N-terminal region of the protein. Previous metabolic studies and extensive genetic testing (karyotype, CMA, MECP2, FMR1) was normal.

Epilepsy was a feature in 4 of the 6 individuals for whom genetic testing was possible (or 5/7 in total).

VARS belongs to the family of amino acyl-tRNA synthetases (ARSs). Mutations in several cytoplasmic ARSs are associated with severe neurological manifestations including seizures, intellectual disability associated with microcephaly.

VARS is included in gene panels for intellectual disability (but not for epilepsy) offered by different diagnostic labs.

As a result this gene can be considered for inclusion in the ID and epilepsy panel as green (or amber).
Sources: Expert Review, Literature
Intellectual disability - microarray and sequencing v2.504 CPA6 Louise Daugherty Classified gene: CPA6 as Red List (low evidence)
Intellectual disability - microarray and sequencing v2.504 CPA6 Louise Daugherty Gene: cpa6 has been classified as Red List (Low Evidence).
Intellectual disability - microarray and sequencing v2.501 CP Louise Daugherty Classified gene: CP as Red List (low evidence)
Intellectual disability - microarray and sequencing v2.501 CP Louise Daugherty Added comment: Comment on list classification: Changed rating of gene from Amber to Red. This gene was rated as Red in v2.467 and incorrectly automatically promoted to Amber in v2.468. This was due to a defect in the automatic PanelApp uploading tool where a reference gene list was added as a new Source (Victorian Clinical Genetics Services), and under certain conditions associated to previous sources listed, resulted in the rating of the gene being automatically changed when it should not have been.
Intellectual disability - microarray and sequencing v2.501 CP Louise Daugherty Gene: cp has been classified as Red List (Low Evidence).
Intellectual disability - microarray and sequencing v2.500 CPA6 Louise Daugherty Classified gene: CPA6 as Red List (low evidence)
Intellectual disability - microarray and sequencing v2.500 CPA6 Louise Daugherty Gene: cpa6 has been classified as Red List (Low Evidence).
Intellectual disability - microarray and sequencing v2.468 MECP2 Louise Daugherty Source Victorian Clinical Genetics Services was added to MECP2.
Intellectual disability - microarray and sequencing v2.468 MCPH1 Louise Daugherty Source Victorian Clinical Genetics Services was added to MCPH1.
Intellectual disability - microarray and sequencing v2.468 CPS1 Louise Daugherty Source Victorian Clinical Genetics Services was added to CPS1.
Intellectual disability - microarray and sequencing v2.468 CPD Louise Daugherty gene: CPD was added
gene: CPD was added to Intellectual disability. Sources: Victorian Clinical Genetics Services
Mode of inheritance for gene: CPD was set to
Intellectual disability - microarray and sequencing v2.468 CPA6 Louise Daugherty Source Victorian Clinical Genetics Services was added to CPA6.
Intellectual disability - microarray and sequencing v2.468 CP Louise Daugherty Source Victorian Clinical Genetics Services was added to CP.
Intellectual disability - microarray and sequencing TECPR2 Rebecca Foulger commented on TECPR2
Intellectual disability - microarray and sequencing TECPR2 Rebecca Foulger commented on TECPR2
Intellectual disability - microarray and sequencing TECPR2 Rebecca Foulger commented on TECPR2
Intellectual disability - microarray and sequencing WDPCP BRIDGE consortium edited their review of WDPCP
Intellectual disability - microarray and sequencing TUBGCP6 BRIDGE consortium edited their review of TUBGCP6
Intellectual disability - microarray and sequencing TECPR2 BRIDGE consortium edited their review of TECPR2
Intellectual disability - microarray and sequencing MECP2 BRIDGE consortium edited their review of MECP2
Intellectual disability - microarray and sequencing MCPH1 BRIDGE consortium edited their review of MCPH1
Intellectual disability - microarray and sequencing CPS1 BRIDGE consortium edited their review of CPS1
Intellectual disability - microarray and sequencing CPA6 BRIDGE consortium edited their review of CPA6
Intellectual disability - microarray and sequencing CP BRIDGE consortium edited their review of CP
Intellectual disability - microarray and sequencing ACP5 BRIDGE consortium edited their review of ACP5
Intellectual disability - microarray and sequencing ACP5 Louise Daugherty classified ACP5 as amber
Intellectual disability - microarray and sequencing ACP5 Louise Daugherty commented on ACP5
Intellectual disability - microarray and sequencing WDPCP BRIDGE consortium edited their review of WDPCP
Intellectual disability - microarray and sequencing TUBGCP6 BRIDGE consortium commented on TUBGCP6
Intellectual disability - microarray and sequencing TECPR2 BRIDGE consortium edited their review of TECPR2
Intellectual disability - microarray and sequencing MECP2 BRIDGE consortium edited their review of MECP2
Intellectual disability - microarray and sequencing MCPH1 BRIDGE consortium edited their review of MCPH1
Intellectual disability - microarray and sequencing CPS1 BRIDGE consortium edited their review of CPS1
Intellectual disability - microarray and sequencing CPA6 BRIDGE consortium edited their review of CPA6
Intellectual disability - microarray and sequencing CP BRIDGE consortium edited their review of CP
Intellectual disability - microarray and sequencing ACP5 BRIDGE consortium reviewed ACP5
Intellectual disability - microarray and sequencing CPA6 Louise Daugherty classified CPA6 as amber
Intellectual disability - microarray and sequencing CPA6 Louise Daugherty commented on CPA6
Intellectual disability - microarray and sequencing CP Louise Daugherty classified CP as amber
Intellectual disability - microarray and sequencing CP Louise Daugherty commented on CP
Intellectual disability - microarray and sequencing WDPCP BRIDGE consortium reviewed WDPCP
Intellectual disability - microarray and sequencing TUBGCP6 BRIDGE consortium reviewed TUBGCP6
Intellectual disability - microarray and sequencing TECPR2 BRIDGE consortium reviewed TECPR2
Intellectual disability - microarray and sequencing MECP2 BRIDGE consortium reviewed MECP2
Intellectual disability - microarray and sequencing MCPH1 BRIDGE consortium reviewed MCPH1
Intellectual disability - microarray and sequencing CPS1 BRIDGE consortium reviewed CPS1
Intellectual disability - microarray and sequencing CPA6 BRIDGE consortium reviewed CPA6
Intellectual disability - microarray and sequencing CP BRIDGE consortium reviewed CP