chr15-26621417-C-T

Variant names:

• chr15-26621417-C-T
• rs886037938
• NM_000814.6:c.358G>A

Variant summary

Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_000814.6(GABRB3):​c.358G>A​(p.Asp120Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GABRB3 NM_000814.6 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 7.79

Genes affected

GABRB3 (HGNC:4083): (gamma-aminobutyric acid type A receptor subunit beta3) This gene encodes a member of the ligand-gated ionic channel family. The encoded protein is one the subunits of a multi-subunit chloride channel that serves as the receptor for gamma-aminobutyric acid, a major inhibitory neurotransmitter of the mammalian nervous system. This gene is located on the long arm of chromosome 15 in a cluster with two other genes encoding related subunits of the family. This gene may be associated with the pathogenesis of several disorders including Angelman syndrome, Prader-Willi syndrome, nonsyndromic orofacial clefts, epilepsy and autism. Alternatively spliced transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Pathogenic. Variant got 15 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the GABRB3 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 56 curated pathogenic missense variants (we use a threshold of 10). The gene has 26 curated benign missense variants. Gene score misZ: 3.3856 (above the threshold of 3.09). Trascript score misZ: 4.4544 (above the threshold of 3.09). GenCC associations: The gene is linked to childhood absence epilepsy, developmental and epileptic encephalopathy, 43, developmental and epileptic encephalopathy, Lennox-Gastaut syndrome, epilepsy, childhood absence, susceptibility to, 5.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 15-26621417-C-T is Pathogenic according to our data. Variant chr15-26621417-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 254261.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-26621417-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GABRB3	NM_000814.6	c.358G>A	p.Asp120Asn	missense_variant	Exon 4 of 9	ENST00000311550.10	NP_000805.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRB3	ENST00000311550.10	c.358G>A	p.Asp120Asn	missense_variant	Exon 4 of 9	1	NM_000814.6	ENSP00000308725.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 43 Pathogenic:2

Jun 10, 2022

Institute of Human Genetics Munich, Klinikum Rechts Der Isar, TU München

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 12, 2013

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Neurodevelopmental delay Pathogenic:1

-

Centre de Biologie Pathologie Génétique, Centre Hospitalier Universitaire de Lille

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Epilepsy, childhood absence, susceptibility to, 1;C2677087:Epilepsy, childhood absence, susceptibility to, 5 Pathogenic:1

Mar 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces aspartic acid, which is acidic and polar, with asparagine, which is neutral and polar, at codon 120 of the GABRB3 protein (p.Asp120Asn). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Lennox-Gastaut syndrome (PMID: 23934111). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 254261). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GABRB3 protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects GABRB3 function (PMID: 26950270). For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1

Aug 17, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Published functional studies demonstrate a damaging effect and suggest that this variant is damaging to b3 GABA channel function (Janve et al., 2016); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 25124326, 27476654, 26645412, 23934111, 30728247, 32467926, 33004838, 34906499, 34698933, 35718920, 36077081, 33301879, 37176165, 26950270) -

Epilepsy Pathogenic:1

Oct 04, 2024

Al Jalila Children’s Genomics Center, Al Jalila Childrens Speciality Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PS3,PS2,PM3(strong),PM2,PP3 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.84	.;D;.;.;.;.;.;.;.
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	.;D;D;D;D;.;D;D;.
M_CAP	Pathogenic	0.67	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.78	D
MutationAssessor	Uncertain	2.9	.;M;.;.;M;.;.;.;.
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-4.6	.;D;.;D;D;.;.;D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	.;D;.;D;D;.;.;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;.;.;D;D
Polyphen		1.0	.;D;.;D;D;.;.;.;.
Vest4		0.98
MutPred		0.96		.;.;.;Loss of phosphorylation at Y178 (P = 0.1103);.;.;.;.;.;
MVP		0.93
MPC		2.3
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.94
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs886037938; hg19: chr15-26866564; COSMIC: COSV54667501; COSMIC: COSV54667501;