Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1PM2PP2PP3_Strong
The NM_198904.4(GABRG2):c.596T>A(p.Met199Lys) 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. 12/21 in silico tools predict a damaging outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.
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]
Verdict is Likely_pathogenic. Variant got 9 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 the GABRG2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 34 curated pathogenic missense variants (we use a threshold of 10). The gene has 21 curated benign missense variants. Gene score misZ: 2.9939 (below the threshold of 3.09). Trascript score misZ: 3.9213 (above the threshold of 3.09). GenCC associations: The gene is linked to 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, 0.967