chr15-26583372-G-T

Variant names:

• chr15-26583372-G-T
• rs1060502665
• NM_000814.6:c.504C>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000814.6(GABRB3):​c.504C>A​(p.Tyr168*) variant causes a stop gained change involving the alteration of a non-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 Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GABRB3 NM_000814.6 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.623
• Publications: 0 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: Pathogenic. The variant received 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-26583372-G-T is Pathogenic according to our data. Variant chr15-26583372-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 409956.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GABRB3	NM_000814.6	c.504C>A	p.Tyr168*	stop_gained	Exon 5 of 9	ENST00000311550.10	NP_000805.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRB3	ENST00000311550.10	c.504C>A	p.Tyr168*	stop_gained	Exon 5 of 9	1	NM_000814.6	ENSP00000308725.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Jan 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr168*) in the GABRB3 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GABRB3 are known to be pathogenic (PMID: 26950270, 28053010). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GABRB3-related conditions. ClinVar contains an entry for this variant (Variation ID: 409956). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Uncertain	0.26
Eigen_PC	Benign	0.026
FATHMM_MKL	Uncertain	0.92	D
PhyloP100		0.62
Vest4		0.94
GERP RS		1.8
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1060502665; hg19: chr15-26828519;