15-26547893-T-TC

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_000814.6(GABRB3):c.1321_1322insG(p.Asp441GlyfsTer33) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GABRB3 NM_000814.6 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• 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 Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.071 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GABRB3	NM_000814.6	c.1321_1322insG	p.Asp441GlyfsTer33	frameshift_variant	9/9	ENST00000311550.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GABRB3	ENST00000311550.10	c.1321_1322insG	p.Asp441GlyfsTer33	frameshift_variant	9/9	1	NM_000814.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 19, 2021

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. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. This variant has not been reported in the literature in individuals affected with GABRB3-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Asp441Glyfs*33) in the GABRB3 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 33 amino acid(s) of the GABRB3 protein. -

Computational scores

Source: dbNSFP v4.3

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr15-26793040;