Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2PP2
The NM_001161352.2(KCNMA1):āc.3653G>Cā(p.Arg1218Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,884 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.
KCNMA1 (HGNC:6284): (potassium calcium-activated channel subfamily M alpha 1) This gene encodes the alpha subunit of calcium-activated BK channel. The encoded protein is involved in several physiological processes including smooth muscle contraction, neurotransmitter release and neuronal excitability. Mutations in this gene are associated with a spectrum of neurological disorders including Paroxysmal Nonkinesigenic Dyskinesia 3, Idiopathic Generalized Epilepsy 16 and Liang-Wang syndrome. [provided by RefSeq, Aug 2022]
Verdict is Uncertain_significance. Variant got 3 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PP2
Missense variant in the KCNMA1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 12 curated pathogenic missense variants (we use a threshold of 10). The gene has 25 curated benign missense variants. Gene score misZ: 5.0622 (above the threshold of 3.09). Trascript score misZ: 6.5162 (above the threshold of 3.09). GenCC associations: The gene is linked to cerebellar atrophy, developmental delay, and seizures, generalized epilepsy-paroxysmal dyskinesia syndrome, Liang-Wang syndrome.
.;.;.;.;.;.;.;.;.;.;.;.;.;.;.;Gain of glycosylation at R1218 (P = 0.0069);Gain of glycosylation at R1218 (P = 0.0069);.;.;.;.;.;.;.;.;.;.;.;.;.;.;Gain of glycosylation at R1218 (P = 0.0069);.;.;.;Gain of glycosylation at R1218 (P = 0.0069);.;.;.;.;.;.;.;.;.;.;.;.;.;