chr5-161294145-C-T

Variant names:

• chr5-161294145-C-T
• rs1757313373
• NM_001371727.1:c.1475G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001371727.1(GABRB2):​c.1475G>A​(p.Arg492His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,798 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: 0.0000014 (0 hom.)
• Consequence: GABRB2 NM_001371727.1 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.80
• Publications: 0 publications found

Genes affected

GABRB2 (HGNC:4082): (gamma-aminobutyric acid type A receptor subunit beta2) The gamma-aminobutyric acid (GABA) A receptor is a multisubunit chloride channel that mediates the fastest inhibitory synaptic transmission in the central nervous system. This gene encodes GABA A receptor, beta 2 subunit. It is mapped to chromosome 5q34 in a cluster comprised of genes encoding alpha 1 and gamma 2 subunits of the GABA A receptor. Alternative splicing of this gene generates 2 transcript variants, differing by a 114 bp insertion. [provided by RefSeq, Jul 2008]

GABRB2 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy 92

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Illumina, G2P
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.968

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GABRB2	NM_001371727.1	c.1475G>A	p.Arg492His	missense_variant	Exon 10 of 10	ENST00000393959.6	NP_001358656.1
GABRB2	NM_021911.3	c.1475G>A	p.Arg492His	missense_variant	Exon 11 of 11		NP_068711.1
GABRB2	NM_000813.3	c.1361G>A	p.Arg454His	missense_variant	Exon 10 of 10		NP_000804.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRB2	ENST00000393959.6	c.1475G>A	p.Arg492His	missense_variant	Exon 10 of 10	1	NM_001371727.1	ENSP00000377531.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461798 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727196

African (AFR) AF: 0.00 AC: 0 AN: 33470

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.0000187 AC: 1 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111948

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability Uncertain:1

Oct 31, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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 (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with GABRB2-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with histidine at codon 492 of the GABRB2 protein (p.Arg492His). The arginine residue is highly conserved and there is a small physicochemical difference between arginine and histidine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.43
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.86	D;D;.;D;.;D
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	.;D;.;D;D;D
M_CAP	Uncertain	0.11	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D
MetaSVM	Pathogenic	0.83	D
MutationAssessor	Pathogenic	3.5	H;H;.;.;.;.
PhyloP100		7.8
PrimateAI	Pathogenic	0.84	D
PROVEAN	Uncertain	-4.2	D;D;D;D;D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D
Polyphen		1.0	D;D;D;D;D;D
Vest4		0.93
MutPred		0.85		Loss of MoRF binding (P = 0.0627);Loss of MoRF binding (P = 0.0627);.;.;.;.;
MVP		0.92
MPC		1.2
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.70
gMVP		0.95
Mutation Taster		=24/76	disease causing

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: rs1757313373; hg19: chr5-160721152; COSMIC: COSV50942594;