rs1555371848

Positions:

• chr15-26621357-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PP2 PP3_Moderate

The NM_000814.6(GABRB3):​c.418A>G​(p.Met140Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,828 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: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GABRB3 NM_000814.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.90

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 Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a topological_domain Extracellular (size 219) in uniprot entity GBRB3_HUMAN there are 39 pathogenic changes around while only 7 benign (85%) in NM_000814.6
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), GABRB3. . Gene score misZ 3.3856 (greater than the threshold 3.09). Trascript score misZ 4.4544 (greater than threshold 3.09). GenCC has associacion of gene with childhood absence epilepsy, developmental and epileptic encephalopathy, 43, developmental and epileptic encephalopathy, Lennox-Gastaut syndrome, epilepsy, childhood absence, susceptibility to, 5.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.889

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GABRB3	NM_000814.6	c.418A>G	p.Met140Val	missense_variant	4/9	ENST00000311550.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GABRB3	ENST00000311550.10	c.418A>G	p.Met140Val	missense_variant	4/9	1	NM_000814.6	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461828 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727220

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.: 33

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

Aug 03, 2017

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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with GABRB3-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces methionine with valine at codon 140 of the GABRB3 protein (p.Met140Val). The methionine residue is highly conserved and there is a small physicochemical difference between methionine and valine. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Athena Diagnostics

Jun 11, 2019

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Uncertain	25
DANN	Uncertain	0.97
DEOGEN2	Uncertain	0.66	.;D;.;.;.;.;.;.;.
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.81	.;T;T;T;T;.;T;T;.
M_CAP	Pathogenic	0.36	D
MetaRNN	Pathogenic	0.89	D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	-0.089	T
MutationAssessor	Benign	2.0	.;M;.;.;M;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Uncertain	-2.4	.;N;.;D;N;.;.;D;D
REVEL	Pathogenic	0.76
Sift	Uncertain	0.0040	.;D;.;D;D;.;.;D;D
Sift4G	Benign	0.13	T;T;T;T;T;.;.;T;T
Polyphen		0.59, 0.53	.;P;.;P;P;.;.;.;.
Vest4		0.79
MutPred		0.70		.;.;.;Loss of catalytic residue at V192 (P = 0.0492);.;.;.;.;.;
MVP		0.93
MPC		2.4
ClinPred		0.81	D
GERP RS		5.8
Varity_R		0.84
gMVP		0.89

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: rs1555371848; hg19: chr15-26866504;