Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PP2PP3
The NM_001161352.2(KCNMA1):āc.3457A>Cā(p.Lys1153Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000483 in 1,450,304 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (ā ).
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 2 ACMG points.
PP2
Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KCNMA1. . Gene score misZ 5.0622 (greater than the threshold 3.09). Trascript score misZ 6.5162 (greater than threshold 3.09). GenCC has associacion of gene with cerebellar atrophy, developmental delay, and seizures, generalized epilepsy-paroxysmal dyskinesia syndrome, Liang-Wang syndrome.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.778
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Aug 24, 2021
In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. This variant has not been reported in the literature in individuals affected with KCNMA1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with glutamine at codon 1095 of the KCNMA1 protein (p.Lys1095Gln). The lysine residue is highly conserved and there is a small physicochemical difference between lysine and glutamine. -
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