Four variants (p.Glu402fs*3, p.Arg136*, p.Val462fs*33, and p.Pro59fs*12) were securely considered pathogenic because they introduced an erroneous stop codon in the reading frame. While p.Arg136* and p.Pro59fs*12 were predicted to be degraded by the nonsense-mediated-decay system (NMD), p.Glu402fs*3 and p.Val462fs*33, located in the last exon of GABRG2, may escape the NMD and lead to a truncated or a longer γ2 subunit, respectively. The p.Met199Val missense variant was likely to be pathogenic according to 3 in silico prediction tools. All mutations were novel except p.Arg136*, which was previously reported in a family with GEFS+, learning difficulties, and autism spectrum disorder, although it was segregated mostly with the FS component.20
