NM_198904.4:c.1236C>A

Variant names:

• chr5-162153176-C-A
• rs749951528
• NM_198904.4:c.1236C>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_198904.4(GABRG2):​c.1236C>A​(p.Tyr412*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. Y412Y) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GABRG2 NM_198904.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: -0.248
• 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: Likely_pathogenic. The variant received 8 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 10 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-162153176-C-A is Pathogenic according to our data. Variant chr5-162153176-C-A is described in ClinVar as Pathogenic. ClinVar VariationId is 2949001.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.1236C>A	p.Tyr412*	stop_gained	Exon 10 of 10	ENST00000639213.2	NP_944494.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GABRG2	ENST00000639213.2	c.1236C>A	p.Tyr412*	stop_gained	Exon 10 of 10	1	NM_198904.4	ENSP00000491909.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: 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

Dec 13, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr404*) in the GABRG2 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 64 amino acid(s) of the GABRG2 protein. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GABRG2-related conditions. This variant disrupts a region of the GABRG2 protein in which other variant(s) (p.Trp429*) have been determined to be pathogenic (PMID: 18566737). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	28
DANN	Uncertain	0.98
Eigen	Benign	-0.18
Eigen_PC	Benign	-0.43
FATHMM_MKL	Benign	0.75	D
PhyloP100		-0.25
Vest4		0.63
GERP RS		-5.6
Mutation Taster		=3/197	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: rs749951528; hg19: chr5-161580182;