15-26547908-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP2 PP3

The NM_000814.6(GABRB3):c.1307A>C(p.Lys436Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GABRB3 NM_000814.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 6.17

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.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, GABRB3
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.746

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GABRB3	NM_000814.6	c.1307A>C	p.Lys436Thr	missense_variant	9/9	ENST00000311550.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GABRB3	ENST00000311550.10	c.1307A>C	p.Lys436Thr	missense_variant	9/9	1	NM_000814.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461890 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Feb 01, 2024	GABRB3: PM2, PP2, PP3 -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Oct 29, 2020	Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 01, 2023

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. 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on GABRB3 protein function. ClinVar contains an entry for this variant (Variation ID: 1317379). 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 replaces lysine, which is basic and polar, with threonine, which is neutral and polar, at codon 436 of the GABRB3 protein (p.Lys436Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
Cadd	Uncertain	25
Dann	Uncertain	1.0
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.42
FATHMM_MKL	Uncertain	0.97	D
M_CAP	Uncertain	0.24	D
MetaRNN	Pathogenic	0.75	D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.32	D
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Pathogenic	0.86	D
Sift4G	Uncertain	0.060	T;T;T;T;T;.;.;T;T
Polyphen		0.78, 0.080, 0.57	.;P;.;B;P;.;.;.;.
Vest4		0.32
MutPred		0.50		.;.;.;Loss of methylation at K492 (P = 0.0042);.;.;.;.;.;
MVP		0.86
MPC		1.8
ClinPred		0.98	D
GERP RS		4.9
Varity_R		0.54
gMVP		0.91

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: chr15-26793055;