rs1334273668

Positions:

• chr5-162101294-C-G

Variant summary

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

The NM_198904.4(GABRG2):​c.608C>G​(p.Ser203Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,458,462 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: GABRG2 NM_198904.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.81

Genes affected

GABRG2 (HGNC:4087): (gamma-aminobutyric acid type A receptor subunit gamma2) This gene encodes a gamma-aminobutyric acid (GABA) receptor. GABA is the major inhibitory neurotransmitter in the mammlian brain, where it acts at GABA-A receptors, which are ligand-gated chloride channels. GABA-A receptors are pentameric, consisting of proteins from several subunit classes: alpha, beta, gamma, delta and rho. Mutations in this gene have been associated with epilepsy and febrile seizures. Multiple transcript variants encoding different isoforms have been identified for this gene. [provided by RefSeq, Jul 2008]

GABRG2 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a topological_domain Extracellular (size 233) in uniprot entity GBRG2_HUMAN there are 9 pathogenic changes around while only 2 benign (82%) in NM_198904.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), GABRG2. . Gene score misZ 2.9939 (greater than the threshold 3.09). Trascript score misZ 3.9213 (greater than threshold 3.09). GenCC has associacion of gene with epilepsy, Dravet syndrome, undetermined early-onset epileptic encephalopathy, generalized epilepsy with febrile seizures plus, developmental and epileptic encephalopathy, 74, febrile seizures, familial, 8, childhood epilepsy with centrotemporal spikes.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.864

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GABRG2	NM_198904.4	c.608C>G	p.Ser203Cys	missense_variant	5/10	ENST00000639213.2	NP_944494.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GABRG2	ENST00000639213.2	c.608C>G	p.Ser203Cys	missense_variant	5/10	1	NM_198904.4	ENSP00000491909.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250864 Hom.: 0 AF XY: 0.00000738 AC XY: 1 AN XY: 135566

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1458462 Hom.: 0 Cov.: 29 AF XY: 0.00000138 AC XY: 1 AN XY: 725796

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Epilepsy, childhood absence 2;C1969810:Febrile seizures, familial, 8 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 04, 2017

In summary, this variant is a novel missense change with uncertain impact on protein function. 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: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a GABRG2-related disease. This sequence change replaces serine with cysteine at codon 203 of the GABRG2 protein (p.Ser203Cys). The serine residue is highly conserved and there is a moderate physicochemical difference between serine and cysteine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.64
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.82	.;.;.;.;.;D;.;.;.;.;.;.;.
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.33	D
MetaRNN	Pathogenic	0.86	D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.62	D
MutationAssessor	Pathogenic	2.9	.;.;.;M;.;M;.;.;.;.;M;.;.
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-3.8	.;.;.;.;.;.;.;.;.;.;D;D;.
REVEL	Pathogenic	0.76
Sift	Uncertain	0.0010	.;.;.;.;.;.;.;.;.;.;D;D;.
Sift4G	Uncertain	0.0030	.;.;.;.;.;.;.;.;.;.;D;D;.
Polyphen		1.0	.;.;.;D;.;D;.;.;.;.;.;.;.
Vest4		0.77
MutPred		0.56		.;.;.;Loss of disorder (P = 0.003);.;Loss of disorder (P = 0.003);.;Loss of disorder (P = 0.003);.;Loss of disorder (P = 0.003);Loss of disorder (P = 0.003);Loss of disorder (P = 0.003);Loss of disorder (P = 0.003);
MVP		0.78
MPC		2.5
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.90
gMVP		0.72

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: rs1334273668; hg19: chr5-161528300;