| Date | Panel | Item | Activity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Intellectual disability - microarray and sequencing v3.1561 | DALRD3 |
Konstantinos Varvagiannis changed review comment from: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910). Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant. Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger. WES guided by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents. DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR It's DALR anticodon-binding domain is similar to those found in arginyl-tRNA synthetases RARS1/2. As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs. In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2). Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele. As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc). Consider inclusion in the current panel with amber rating. Sources: Literature; to: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910). Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant. Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger. WES in both followed by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents. DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs. In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2). Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele. As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc). Consider inclusion in the current panel with amber rating. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v3.1561 | DALRD3 |
Konstantinos Varvagiannis gene: DALRD3 was added gene: DALRD3 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: DALRD3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: DALRD3 were set to 32427860 Phenotypes for gene: DALRD3 were set to ?Developmental and epileptic encephalopathy 86, # 618910 Penetrance for gene: DALRD3 were set to Complete Review for gene: DALRD3 was set to AMBER Added comment: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910). Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant. Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger. WES guided by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents. DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR It's DALR anticodon-binding domain is similar to those found in arginyl-tRNA synthetases RARS1/2. As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs. In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2). Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele. As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc). Consider inclusion in the current panel with amber rating. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.978 | PUS3 |
Catherine Snow Source Expert Review Green was added to PUS3. Source Expert Review was added to PUS3. Added phenotypes Mental retardation, autosomal recessive 55, 617051 for gene: PUS3 Publications for gene PUS3 were changed from 27055666; 30308082 to 30697592; 30308082; 27055666 Rating Changed from No List (delete) to Green List (high evidence) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.853 | ALKBH8 |
Konstantinos Varvagiannis gene: ALKBH8 was added gene: ALKBH8 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: ALKBH8 was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: ALKBH8 were set to Global developmental delay; Intellectual disability; Seizures Penetrance for gene: ALKBH8 were set to Complete Review for gene: ALKBH8 was set to AMBER Added comment: Monies et al. (2019 - PMID: 31079898) report on 7 individuals from 2 different consanguineous Saoudi families, harboring homozygous truncating ALKBH8 pathogenic variants. The same individuals are included in another concurrent publication from the same group (Monies et al. 2019 - PMID: 31130284). All presented with DD and ID (Fam1 : moderate in the proband, degree not commented on for his 3 sibs / Fam2 : mild in the proband, severe in all his 3 sibs). Epilepsy was reported for 6/7 individuals although the type has not been commented on (onset 9-12 months to 2 years). Variable other features were noted in few. Affected subjects from the first family were homozygous for a stopgain variant (NM_001301010.1:c.1660C>T or p.Arg554Ter) while individuals from the second family were homozygous for a frameshift one (c.1794delC or p.Trp599Glyfs*19). The variants affected in both cases the last exon of ALKBH8 and RT-PCR confirmed that they escape NMD. Alternative causes were ruled out, at least for the proband from the second family (chromosomal analysis, SNP-array, metabolic investigations). Linkage analysis of both families confirmed linkage to the same autozygous interval of chr11q22.3 with a LOD score of 6. Segregation analyses in both families, confirmed homozygosity for the truncating variants in affected members and heterozygosity in their parents (or several unaffected sibs, none of those studied was homozygous for the ref. allele). In mouse or human cells, ALKBH8 has previously been shown to be involved in tRNA modifications of the wobble uridines of specific tRNAs (PMIDs cited: 20308323, 20583019, 21653555). LC-MS/MS analyses of tRNA extracted from LCLs derived from affected individuals, unaffected relatives (UR) and independent controls (IC) revealed that wobble nucleotide modifications were completely absent (or dramatically decreased in the case of mcm5U) in affected individuals but readily detected in UR/IC. As specific modifications were absent, substantial amounts of precursors (eg. cm5U - the precursor of mcm5U) were detected in affected individuals but not in unaffected ones. Absence of wobble modifications (eg. mchm5U) has equally been observed in Alkbh8 knockout mice. Alkbh8-deficient mice show similar increases in precursors. Alkbh8 KO mice are however phenotypically normal (the authors comment that eventual cognitive defects were not formally evaluated and might have been missed - PMIDs cited: 20123966, 21285950). As a result, the studies carried out confirmed the loss-of-function effect and were in line with previous functional studies in animal models, although the pathogenesis of ID remains unclear. The expression profile of ALKBH8 is also unclear (wide profile of expression suggested developmentally, the authors studied LCLs, other studies suggest that embryonic expression is broad but becomes progressively more restricted to specific neuronal cells). Mutations in other genes involved in tRNA modification (eg. ADAT3, PUS3, PUS7) have been shown underlie disorders affecting the CNS, with ID as a feature. ALKBH8 is not currently associated with any phenotype in OMIM / G2P. As a result, this gene can be considered for inclusion in the ID/epilepsy panels as amber pending further evidence. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.621 | PUS3 |
Konstantinos Varvagiannis edited their review of gene: PUS3: Added comment: PMID: 30697592 reports 2 additional individuals with intellectual disability, leukoencephalopathy and adult onset nephropathy. These individuals harbored 2 missense variants in the compound heterozygous state (c.497G>A - p.Arg166Gln and c.1097T>C - p.Leu366Pro - Ref. sequence not mentioned). As a result amber/green rating could be considered.; Changed publications: 27055666, 30308082, 30697592 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.621 | PUS3 | Konstantinos Varvagiannis Deleted their comment | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.621 | PUS3 |
Konstantinos Varvagiannis edited their review of gene: PUS3: Added comment: PMID: 30697592 reports 2 additional individuals with intellectual disability, leukoencephalopathy and adult onset nephropathy. These individuals harbored 2 missense variants in the compound heterozygous state (c.497G>A - p.Arg166Gln and c.1097T>C - p.Leu366Pro - Ref. sequence not mentioned). As a result amber/green rating could be considered.; Changed publications: 30697592 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.579 | PUS3 | Konstantinos Varvagiannis reviewed gene: PUS3: Rating: AMBER; Mode of pathogenicity: None; Publications: 27055666, 30308082; Phenotypes: ?Mental retardation, autosomal recessive 55 (MIM 617051); Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.579 | PUS3 | Konstantinos Varvagiannis Deleted their review | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.579 | PUS3 |
Konstantinos Varvagiannis gene: PUS3 was added gene: PUS3 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen Mode of inheritance for gene: PUS3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PUS3 were set to 27055666; 30308082 Phenotypes for gene: PUS3 were set to Global developmental delay; Intellectual disability; Microcephaly Penetrance for gene: PUS3 were set to Complete Review for gene: PUS3 was set to AMBER gene: PUS3 was marked as current diagnostic Added comment: PUS3 (Pseudouridylate synthase 3) is proposed as a gene related to ID in a recent publication on PUS7. Biallelic mutations in this gene are associated in OMIM with ?Mental retardation, autosomal recessive 55 (MIM 617051). PMID: 27055666 reports on 3 sisters from a consanguineous Saudi Arabian family with failure to thrive, DD/ID, microcephaly and some common (coarse) facial features. These individuals were homozygous for a stopgain mutation in the last exon of the gene. Pseudouridylation appeared to be defective (as has also been the case with other genes related to ID, eg. PUS7). PMID: 30308082 describes 1 individual born to consanguineous Palestinian parents, homozygous for a further LoF variant. Despite the localisation of this variant (again in the last exon of the gene) qPCR analyses were suggestive of degradation of the abnormal transcript possibly by NMD. The phenotype consisted of DD/ID and microcephaly. In a further publication (http://dx.doi.org/10.7124/bc.0008D6) Gulkovskyi et al. report on 2 siblings with ID, born to non-consanguineous Ukranian parents. Pathogenicity of the variant is disputed. [NM_031307.4:c.212A>G or p.(Tyr71Cys) is found in an apparent homozygous state in the sibs but was only found in their father. De novo occurence in the maternal allele is proposed although the possibility of microdeletion missed by aCGH or other plausible mechanisms are not considered. This variant has maximum pathogenicity scores in silico (not discussed) and has an allele frequency of 0.00006717 in gnomAD. The authors did not perform studies of pseudouridylation but examined for the presence of hypoproteinemia, observed in some disorders affecting this process). PUS3 is not associated with any phenotype in G2P but is associated with disease in OMIM. The gene is included in gene panels for ID offered by various diagnostic laboratories (including Radboudumc). PUS1 is included in the current panel as green and PUS7 has been suggested for inclusion. As a result, these gene can be considered for inclusion as amber (2 families) or green (given the supportive functional studies and/or the proposed role for the gene). Sources: Literature, Radboud University Medical Center, Nijmegen |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability - microarray and sequencing v2.579 | PUS7 |
Konstantinos Varvagiannis gene: PUS7 was added gene: PUS7 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: PUS7 was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: PUS7 were set to Intellectual disability; Microcephaly; Short stature; Behavioral abnormality Penetrance for gene: PUS7 were set to Complete Review for gene: PUS7 was set to GREEN gene: PUS7 was marked as current diagnostic Added comment: de Brouwer et al. (https://doi.org/10.1016/j.ajhg.2018.10.026) report on 6 individuals from 3 unrelated families homozygous for truncating variants in PUS7. The common phenotype consisted of ID with speech delay, microcephaly, short stature as well as aggressive behavior. One frameshift, one nonsense and one intragenic deletion affecting the penultimate exon of PUS7 were private respectively to each family. qPCR demonstrated reduction of mRNA levels for the two first variants, with absence of the normally sized protein upon Western blot for the first one. The deletion, not identified due to its small size by aCGH, was found in the exome analysis and confirmed by MAQ. RT-PCR demonstrated the absence of the respective exon in mRNA. The deletion resulted in introduction of a stop codon in the last exon and mRNA expression levels were shown to be normal. Western blot demonstrated absence of a normally sized protein. (As a result, truncating mutations in the last exon may also be deleterious). Functional studies demonstrated defective tRNA and mRNA pseudouridylation. Drosophila knockouts recapitulated the behavioral phenotype. Biallelic mutations in PUS1 and PUS3 have been reported in individuals with intellectual disability (as well as some other features noted in PUS7-related disorder). PUS7 is included in the gene panel for ID offered by Radboud UMC (among the principal authors of the study). Therefore this gene can be considered for inclusion in this panel as green (rather than amber). Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||