15-26547888-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP2 BP4

The NM_000814.6(GABRB3):c.1327A>T(p.Thr443Ser) variant causes a missense change. The variant allele was found at a frequency of 0.00000658 in 151,996 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. T443T) has been classified as Likely benign.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: GABRB3 NM_000814.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.09

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 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, GABRB3
• BP4: Computational evidence support a benign effect (MetaRNN=0.28461576).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GABRB3	NM_000814.6	c.1327A>T	p.Thr443Ser	missense_variant	9/9	ENST00000311550.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GABRB3	ENST00000311550.10	c.1327A>T	p.Thr443Ser	missense_variant	9/9	1	NM_000814.6	P1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151996 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151996 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74246

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

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

Jun 20, 2022

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) performed at Invitae indicates that this missense variant is not expected to disrupt GABRB3 protein function. 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 threonine, which is neutral and polar, with serine, which is neutral and polar, at codon 443 of the GABRB3 protein (p.Thr443Ser). -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Feb 10, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Uncertain	0.030	T
BayesDel_noAF	Benign	-0.20
Cadd	Benign	22
Dann	Benign	0.96
Eigen	Benign	-0.047
Eigen_PC	Benign	0.18
FATHMM_MKL	Pathogenic	0.97	D
M_CAP	Benign	0.056	D
MetaRNN	Benign	0.28	T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.44	T
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Pathogenic	0.85	D
Sift4G	Benign	0.63	T;T;T;T;T;.;.;T;T
Polyphen		0.022, 0.017, 0.029	.;B;.;B;B;.;.;.;.
Vest4		0.13
MutPred		0.39		.;.;.;Gain of disorder (P = 0.0466);.;.;.;.;.;
MVP		0.81
MPC		2.2
ClinPred		0.56	D
GERP RS		6.0
Varity_R		0.13
gMVP		0.73

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: rs1218316231; hg19: chr15-26793035;