5-162093965-G-T

Variant names:

• chr5-162093965-G-T
• rs121909673
• NM_198904.4:c.245G>T

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_198904.4(GABRG2):​c.245G>T​(p.Arg82Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R82W) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GABRG2 NM_198904.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.44
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• epilepsy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 74

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• febrile seizures, familial, 8

  Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• Dravet syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• generalized epilepsy with febrile seizures plus

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• self-limited epilepsy with centrotemporal spikes

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_198904.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr5-162093964-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 1791457.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986
• PP5: Variant 5-162093965-G-T is Pathogenic according to our data. Variant chr5-162093965-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2939813.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GABRG2	NM_198904.4	c.245G>T	p.Arg82Leu	missense_variant	Exon 2 of 10	ENST00000639213.2	NP_944494.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRG2	ENST00000639213.2	c.245G>T	p.Arg82Leu	missense_variant	Exon 2 of 10	1	NM_198904.4	ENSP00000491909.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

EPILEPSY, CHILDHOOD ABSENCE, SUSCEPTIBILITY TO, 2;C1969810:Febrile seizures, familial, 8 Pathogenic:1

Apr 08, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts the p.Arg82 amino acid residue in GABRG2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11326275, 15342642, 15470132, 23408872). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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 expected to disrupt GABRG2 protein function. This variant has not been reported in the literature in individuals affected with GABRG2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 82 of the GABRG2 protein (p.Arg82Leu). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	.;.;.;D;.;.;.;.;.;.;.
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.55	D
MutationAssessor	Pathogenic	3.3	.;M;.;M;.;.;.;.;M;.;.
PhyloP100		9.4
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-5.5	.;.;.;.;.;.;.;.;D;D;.
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	.;.;.;.;.;.;.;.;D;D;.
Sift4G	Pathogenic	0.0010	.;.;.;.;.;.;.;.;D;D;.
Polyphen		1.0	.;D;.;D;.;.;.;.;.;.;.
Vest4		0.94, 0.95
MutPred		0.96		.;Loss of ubiquitination at K80 (P = 0.0566);.;Loss of ubiquitination at K80 (P = 0.0566);.;Loss of ubiquitination at K80 (P = 0.0566);.;Loss of ubiquitination at K80 (P = 0.0566);Loss of ubiquitination at K80 (P = 0.0566);Loss of ubiquitination at K80 (P = 0.0566);Loss of ubiquitination at K80 (P = 0.0566);
MVP		0.95
MPC		2.8
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.95
gMVP		0.95
Mutation Taster		=25/75	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: rs121909673; hg19: chr5-161520971;