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Early onset or syndromic epilepsy v4.115 UBAP2L Arina Puzriakova Tag Q1_23_promote_green was removed from gene: UBAP2L.
Early onset or syndromic epilepsy v4.110 UBAP2L Arina Puzriakova reviewed gene: UBAP2L: Rating: GREEN; Mode of pathogenicity: ; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Early onset or syndromic epilepsy v4.109 UBAP2L Arina Puzriakova Source NHS GMS was added to UBAP2L.
Source Expert Review Green was added to UBAP2L.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Early onset or syndromic epilepsy v4.108 UBAP2L Arina Puzriakova Phenotypes for gene: UBAP2L were changed from Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Seizures; Microcephaly; Abnormality of head or neck; Short stature; Abnormality of the skeletal system to Neurodevelopmental disorder with impaired language, behavioral abnormalities, and dysmorphic facies, OMIM:620494
Early onset or syndromic epilepsy v4.4 UBAP2L Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Konstantinos Varvagiannis, 7 out of 12 unrelated cases from PMID:35977029 had seizures, while 3 of them had a formal diagnosis of epilepsy. This is sufficient evidence to promote this gene to GREEN at the next major review.

This gene has not yet been associated with relevant phenotypes in OMIM, but it has been reported in Gene2Phenotype with 'moderate rating'.; to: Comment on list classification: As reviewed by Konstantinos Varvagiannis, 7 out of 12 unrelated cases from PMID:35977029 had seizures, while 3 of them had a formal diagnosis of epilepsy. This is sufficient evidence to promote this gene to GREEN at the next major review.

This gene has not yet been associated with relevant phenotypes in OMIM, but it has been reported in Gene2Phenotype with 'moderate' rating.
Early onset or syndromic epilepsy v4.4 UBAP2L Achchuthan Shanmugasundram Tag Q1_23_promote_green tag was added to gene: UBAP2L.
Early onset or syndromic epilepsy v4.4 UBAP2L Achchuthan Shanmugasundram Classified gene: UBAP2L as Amber List (moderate evidence)
Early onset or syndromic epilepsy v4.4 UBAP2L Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Konstantinos Varvagiannis, 7 out of 12 unrelated cases from PMID:35977029 had seizures, while 3 of them had a formal diagnosis of epilepsy. This is sufficient evidence to promote this gene to GREEN at the next major review.

This gene has not yet been associated with relevant phenotypes in OMIM, but it has been reported in Gene2Phenotype with 'moderate rating'.
Early onset or syndromic epilepsy v4.4 UBAP2L Achchuthan Shanmugasundram Gene: ubap2l has been classified as Amber List (Moderate Evidence).
Early onset or syndromic epilepsy v2.590 CAPRIN1 Konstantinos Varvagiannis gene: CAPRIN1 was added
gene: CAPRIN1 was added to Genetic epilepsy syndromes. Sources: Literature
Mode of inheritance for gene: CAPRIN1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CAPRIN1 were set to 35979925; 35977029; 28135719; 31398340; https://doi.org/10.1101/2021.12.20.21267194
Phenotypes for gene: CAPRIN1 were set to Global developmental delay; Delayed speech and language development; Intellectual disability; Autistic behavior; Seizures
Penetrance for gene: CAPRIN1 were set to Incomplete
Review for gene: CAPRIN1 was set to AMBER
Added comment: A cohort of 12 individuals harboring pathogenic CAPRIN1 variants is described in a recent report by Pavinato et al (2022 - PMID: 35979925).

DD, impaired speech/language development (100%), ID (83%), ASD (67%) and seizures (33%) are part of the phenotype (details below).

Enrichment for de novo LGD but also missense variants has also been demonstrated upon meta-analysis of different cohorts of 40,853 individuals with ID (N=31,625) or ASD (N=9,228) as discussed by Jia et al (2022 - PMID: 35977029).

Role of the gene:
Evidence supports among others, a role for CAPRIN1 in formation RNA-protein (stress) granules through interaction with other relevant proteins (e.g. G3BP1/2, FMRP) and regulation of gene expression (Pavinato et al - PMID: 35979925, Jia et al - PMID: 35977029).
Jia et al further demonstrated significant reduction of stress granule formation in CAPRIN1 KO HeLa lines.
Following generation of CAPRIN1+/- hiPSC line using CRISPR/Cas9 and differentiation into cortical neurons, Pavinato et al noted, altered neuronal structure, abnormal firing properties as well as increased neuronal degeneration possibly linked to presence of increased Ca+2 signals and increase in reactive oxygen species (ROS). Global de novo protein synthesis in neurons appeared to be impaired.

Variant type and inheritance :
All individuals reported by Paviato et al harbored pLoF (nonsense, frameshift, splicing and a synonymous variant resulting in abnormal splicing) variants. In most cases variants occurred de novo with the exception of 2 subjects having inherited pLoF variants from their affected/unaffected parent. Expressive variability, reduced penetrance and possibility of - a yet to be proven - sex bias are discussed (9M/3F).
Missense variants and enrichment for dn missense SNVs have also been shown in large cohorts. The impact of p.I373K has been studied.

Variant effect:
pLoF : Pavinato et al demonstrated reduced mRNA and protein levels for the truncating variants, and out-of frame exon skipping for a variant affecting splice donor site and a further SNV affecting the last nucleotide of ex8.
Missense SNVs : p.I373K abolished interaction with G3BP1/2 and disrupted stress granule formation in the study by Jia et al demonstrating a role of stress granules in pathogenesis of neurodevelopmental disorders.

Animal model:
As discussed by Pavinato et al abnormal neuronal structure and firing properties are observed in htz mouse models. Htz mice display features of ASD, difficulties in reversal learning (for ID), sporadic occurrence of seizures. Hearing impairment (as in 2-3 individuals described) due to reduced protection from noise exposure was reported in an ear-conditional ko model.

The report by Pavinato et al is summarized below.

For the study by Jia et al a summary can by found under the review of UBAP2L.

Reports of individuals in the context of larger cohorts were not here reviewed (eg. DDD study 2017, PMID: 28135719 || Ruzzo et al 2019, PMID: 31398340 || Fu et al 2021, https://doi.org/10.1101/2021.12.20.21267194).

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Pavinato et al (2022 - PMID: 35979925) describe the phenotype associated with heterozygous CAPRIN1 pathogenic variants.

Overlapping features incl. impaired speech/language development (100%), ID (83%), ASD (67%), ADHD (82%), seizures (33% or 4/12 : absence seizures in 2, infantile spasms with absence epilepsy, secondary generalized epileptic seizures during sleep). Respiratory problems (50%), limb/skeletal anomalies (50%), feeding difficulties (33%), mild hearing hearing impairment (in 2 or 3). There was no evident dysmorphism, despite few recurrent features.

CAPRIN1 encodes cell cycle-associated protein 1. As the authors discuss, the gene is ubiquitously expressed with high expression in brain. The protein is known to interact with other RNA-binding proteins (eg. FMRP, G3BP1) for the formation of ribonucleoparticles / RNA granules. The gene localizes in neuronal RNA granules in dendrites. Previous studies have demonstrated a role in regulation of mRNA translation (acting as translational inhibitor with its overexpression leading to reduced protein synthesis). CAPRIN1 interacts with FMRP and CYFIP1, both also involved in regulation of mRNA translation.

One individual with microdeletion (~1.4 Mb spanning 8 genes with CAPRIN1 the only predicted to be haploinsufficient) as well as 11 additional subjects with nonsense/splicing variants were identified, following CMA, ES or GS. [The gene has a pHaplo of 0.98 and pLI of 0.97 (LOEUF 0.31)].

Variants were mostly de novo, although one individual had inherited a nonsense variant from his affected father while one further from her unaffected mother.

qRT-PCR showed reduced mRNA levels in patient fibroblasts and PBMCs while cycloheximide treatment in fibroblasts resulted in partial rescue in expression of mutant allele. Western blot in fibroblasts confirmed reduced protein levels.

cDNA analysis revealed that c.279+1G>T variant resulted in out-of-frame skipping of ex3, while c.879G>A (last base of ex8) resulted in out-of-frame skipping of ex8 and degradation by NMD, with cycloheximide restoring expression of mutant allele. [ NM_005898.5 ]

The authors generated a CAPRIN1+/- hiPSC line using CRISPR/Cas9 and hiPSCs were differentiated into cortical neurons. Htz immature neurons displayed altered neuronal structure, accompanied by reduced neurite length similar to previous observations in mice.

Increased neuronal degeneration was observed. Ca+2 signals (described in literature to trigger or contribute to neuronal death) were increased compared to controls. Increase in reactive oxygen species (ROS) following Ca+2 overload was also demonstrated, likely contributing to neuronal death.

Given the gene's role in regulation of mRNA translation, the authors assessed global de novo protein synthesis in neurons based on pyromicin incorporation (SUnSET assay) with findings supporting the impact of CAPRIN1 haploinsufficiency.

Heterozygous neurons were shown to display abnormal firing properties similar to a previously reported mouse model.

Mouse model : apart from the findings discussed above (abnormal neuronal structure and firing properties), heterozygous mice displayed similar features to the cohort described eg. reduced sociability and weaker preference for social novelty (as in ASD), difficulties in reversal learning (for ID), sporadic occurrence of seizures upon Morris water maze/contextual fearing tests and epileptic-like fEPSP after LTP. Breathing problems were noted in Carpin1-/- mice. Ear conditional ko was associated with early-onset progressive hearing loss and reduced protection from noise exposure which might be in line with few individuals with hearing impairment.
Sources: Literature
Early onset or syndromic epilepsy v2.590 UBAP2L Konstantinos Varvagiannis gene: UBAP2L was added
gene: UBAP2L was added to Genetic epilepsy syndromes. Sources: Literature
Mode of inheritance for gene: UBAP2L was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: UBAP2L were set to 35977029
Phenotypes for gene: UBAP2L were set to Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Seizures; Microcephaly; Abnormality of head or neck; Short stature; Abnormality of the skeletal system
Penetrance for gene: UBAP2L were set to unknown
Review for gene: UBAP2L was set to AMBER
Added comment: Seizures have been reported in several individuals although a formal diagnosis of epilepsy was retained in ~30% in a small cohort discussed below. Consider inclusion with amber rating.

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Based on Jia et al (2022 - PMID: 35977029) speech, motor delay as well as ID are observed in individuals harboring de novo pLoF variants in UBAP2L. The gene encodes a regulator of the stress granule (SG) assembly. Extensive evidence is provided on the effect of variants as well as the role of UBAP2L and other genes for components and/or regulation of SG in pathogenesis of NDDs. Among others a Ubap2l htz deletion mouse model (behavioral and cognitive impairment, abnormal cortical development due to impaired SG assembly, etc). Data from 26 previous studies, aggregating 40,853 probands with NDDs (mostly DD/ID, also ASD) suggest enrichment for DNMs in UBAP2L or other genes previously known and further shown to be important for SG formation (incl. G3BP1/G3BP2, CAPRIN1).

Details provided below.

Not associated with any phenotype in OMIM, G2P or SysNDD.

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Jia et al (2022 - PMID: 35977029) describe 12 affected individuals with heterozygous de novo pLoF variants in UBAP2L.

Phenotype: Features included hypotonia, speech (11/11) and motor delay (8/12), ID (8/10 with formal evaluation), variable behavioral concerns (ADHD 5/11, ASD in 4/10, etc). Seizures were reported in 7/12 with 3/10 having a formal diagnosis of epilepsy. Few had microcephaly (3/10). Facial dysmorphisms were common (9/9) and included abnormal palpebral fissures, deep prominent concha, high broad forehead, hypertelorism, thin upper lip and mild synophrys (each in 4 or less individuals). Short stature or skeletal alterations were described in some (4/10 each).

Role of the gene: UBAP2L encodes an essential regulator of stress granule assembly. Stress granules are membraneless cytoplasmic compartments in eukaryotic cells, induced upon a variety of stressors and playing a role in regulation of gene expression.

Variants identified : 9 nonsense/frameshift UBAP2L variants and 3 splicing ones were reported, in all cases as de novo events, upon trio/quad exome sequencing. All were absent from gnomAD. There were no other causative variants.

Variant effect/studies (NM_014847.4 / NP_055662.3) :
- Minigene assays revealed that the 3 splice variants all resulted in out-of-frame exon skipping.
- In patient fibroblasts one of these splice variants was demonstrated to result to reduced protein levels.
- 8 of the 9 nonsense/frameshift variants were predicted to result to NMD.
- 1 nonsense variant (c.88C>T/p.Q30*) was shown to result to decreased protein expression in patient fibroblasts, with detection of the protein using an antibody for the C terminus but not the N terminus. Protein N-terminal sequencing confirmed that the protein lacked the N terminus, with utilization of an alternative start site (11 codons downstream).
- Generation of HeLa UBAP2L KO cell lines resulted in significant reduction of SG numbers which was also the case for 4 variants studied, under stress conditions.
- The protein has a DUF domain (aa 495-526) known to mediate interaction of UBAP2L with G3BP1 (a stress granule marker) with deletions of this domain leading to shuttling of UBAP2L from the cytoplasm to the nucleus. Truncating variants upstream of the DUF domain were shown to result in nuclear localization.

Mouse model :
- The authors generated Ubap2l KO model with hmz deletion of Ubap2l resulting in a lethal phenotype (2.6% survived) and htz deletion leading to behavioral issues (low preference for social novelty, anxious-like behaviors) and cognitive impairment.
- Ubap2l haploinsufficiency resulted in abnormal cortical development and lamination with reduction of neural progenitor proliferation.
- Ubap2l deficiency was shown to impair SG assembly during cortical development both under physiological stress conditions or upon utilization of an oxidative stress inducer.

Additional evidence of UBAP2L and SG overall in pathogenesis of NDDs:
- Based on DNMs from 40,853 individuals with NDDs from 26 studies (9,228 with ASD, 31,625 with DD/ID) the authors demonstrate significant excess of DNM in 31 genes encoding SG components, regulators or both, the latter being the case for UBAP2L and 2 further genes (G3BP1 and G3BP2 - both with crucial roles in SG assembly).
- Excess dn splice-site (N=3) and missense (N=5) variants in G3BP1 were observed in the above cohort [c.95+1G>A, c.353+1G>T, c.539+1G>A / p.S208C, R320C, V366M].
- Excess dn missense (N=7) variants in G3BP2 were observed in the above cohort [p.R13W, D151N, E158K, L209P, E399D, K408E, R438C].
- Generation of G3BP1 or G3BP2 KO HeLa cell lines and immunofluorescence upon use of oxidative stress inducer revealed significant reduction of stress granules.
- Generation of HeLa cell lines for 5 G3BP1 mutants (R78C*, R132I*, S208C*, R320C*, V366M) and 7 G3BP2 mutants (p.R13W*, D151N*, E158K, L209P*, E399D, K408E, R438C) revealed that several (those in asterisk) resulted in significantly fewer SG formation under oxidative stress compared to WT while the subcellular distribution of the proteins under stress was identical to WT.
- Among the identified genes for SG enriched for DNMs, CAPRIN1 was implicated in previous publications as a NDD risk gene with 3 dn missense SNVs reported (p.I373K, p.Q446H, p.L484P). CAPRIN1 binding to G3BP1/2 has been shown to promote SG formation. Significant reduction of SG was observed in CAPRIN1 KO HeLa lines. p.I373K abolished interaction with G3BP1/2 and disrupted SG formation.
Sources: Literature