15-26772759-C-T

Variant names:

• chr15-26772759-C-T
• rs71651682
• NM_000814.6:c.94G>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000814.6(GABRB3):​c.94G>A​(p.Gly32Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000072 in 1,388,980 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 7.2e-7 (0 hom.)
• Consequence: GABRB3 NM_000814.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3 O:1
• Conservation: PhyloP100: 1.50
• Publications: 27 publications found

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]

GABRB3 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy, 43

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• epilepsy, childhood absence, susceptibility to, 5

  Inheritance: AD, Unknown Classification: DEFINITIVE, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• genetic developmental and epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• childhood absence epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Lennox-Gastaut syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.29078913).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GABRB3	NM_000814.6	c.94G>A	p.Gly32Arg	missense_variant	Exon 2 of 9	ENST00000311550.10	NP_000805.1
GABRB3	NM_021912.5	c.94G>A	p.Gly32Arg	missense_variant	Exon 2 of 9		NP_068712.1
GABRB3	NM_001278631.2	c.-258G>A		5_prime_UTR_variant	Exon 2 of 10		NP_001265560.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRB3	ENST00000311550.10	c.94G>A	p.Gly32Arg	missense_variant	Exon 2 of 9	1	NM_000814.6	ENSP00000308725.5

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD2 exomes AF: 0.00 AC: 0 AN: 214802 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 7.20e-7 AC: 1 AN: 1388980 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 691072

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.0000352 AC: 1 AN: 28442

American (AMR) AF: 0.00 AC: 0 AN: 39388

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 23098

East Asian (EAS) AF: 0.00 AC: 0 AN: 32328

South Asian (SAS) AF: 0.00 AC: 0 AN: 81164

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51542

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5438

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1071766

Other (OTH) AF: 0.00 AC: 0 AN: 55814

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Nov 19, 2018

Center for Personalized Medicine, Children's Hospital Los Angeles

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 02, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Reported in a family with epilepsy, but also seen in unaffected family members (PMID: 18514161); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 23934645, 19717338, 29390378, 26950270, 22765836, 20308251, 20352446, 22206818, 26645412, 30755392, 35383156, 22303015, 31435640, 18514161) -

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

Feb 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 32 of the GABRB3 protein (p.Gly32Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with clinical features of GABRB3-related conditions (PMID: 18514161; Invitae). ClinVar contains an entry for this variant (Variation ID: 16193). 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 not expected to disrupt GABRB3 protein function with a negative predictive value of 95%. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on GABRB3 function (PMID: 18514161, 22303015, 35383156). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Epilepsy, childhood absence, susceptibility to, 5 Other:1

Jun 01, 2008

OMIM

Significance: risk factor

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.18
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.15	T;.;.
Eigen	Benign	-0.40
Eigen_PC	Benign	-0.25
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Benign	0.69	T;T;T
M_CAP	Pathogenic	0.70	D
MetaRNN	Benign	0.29	T;T;T
MetaSVM	Benign	-0.70	T
MutationAssessor	Benign	1.5	L;.;L
PhyloP100		1.5
PrimateAI	Pathogenic	0.93	D
PROVEAN	Benign	-0.45	N;N;N
REVEL	Uncertain	0.44
Sift	Benign	0.094	T;D;D
Sift4G	Benign	0.12	T;D;D
Polyphen		0.025	B;B;B
Vest4		0.24
MutPred		0.44		.;Gain of solvent accessibility (P = 0.019);.;
MVP		0.99
MPC		1.5
ClinPred		0.97	D
GERP RS		3.8
PromoterAI		-0.0028	Neutral
Varity_R		0.23
gMVP		0.80
Mutation Taster		=2/98	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs71651682; hg19: chr15-27017906;