12-4912561-G-T

Variant names:

• chr12-4912561-G-T
• rs1135401950
• NM_000217.3:c.1183G>T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP2 PP5

The NM_000217.3(KCNA1):​c.1183G>T​(p.Ala395Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 30)
• Consequence: KCNA1 NM_000217.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 10.0

Genes affected

KCNA1 (HGNC:6218): (potassium voltage-gated channel subfamily A member 1) This gene encodes a voltage-gated delayed potassium channel that is phylogenetically related to the Drosophila Shaker channel. The encoded protein has six putative transmembrane segments (S1-S6), and the loop between S5 and S6 forms the pore and contains the conserved selectivity filter motif (GYGD). The functional channel is a homotetramer. The N-terminus of the channel is associated with beta subunits that can modify the inactivation properties of the channel as well as affect expression levels. The C-terminus of the channel is complexed to a PDZ domain protein that is responsible for channel targeting. Mutations in this gene have been associated with myokymia with periodic ataxia (AEMK). [provided by RefSeq, Jul 2008]

ENSG00000256654 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the KCNA1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 33 curated pathogenic missense variants (we use a threshold of 10). The gene has 3 curated benign missense variants. Gene score misZ: 3.3255 (above the threshold of 3.09). Trascript score misZ: 3.8671 (above the threshold of 3.09). GenCC associations: The gene is linked to episodic kinesigenic dyskinesia 1, episodic ataxia type 1, developmental and epileptic encephalopathy, isolated autosomal dominant hypomagnesemia, Glaudemans type.
• PP5: Variant 12-4912561-G-T is Pathogenic according to our data. Variant chr12-4912561-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 431378.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNA1	NM_000217.3	c.1183G>T	p.Ala395Ser	missense_variant	Exon 2 of 2	ENST00000382545.5	NP_000208.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNA1	ENST00000382545.5	c.1183G>T	p.Ala395Ser	missense_variant	Exon 2 of 2	4	NM_000217.3	ENSP00000371985.3

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome Cov.: 41

GnomAD4 genome Cov.: 30

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Episodic ataxia type 1 Pathogenic:1

Mar 14, 2017

Center For Human Genetics And Laboratory Diagnostics, Dr. Klein, Dr. Rost And Colleagues

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

May 10, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 32316562, 37240170) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.53
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.89	D
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.25	D
MetaRNN	Uncertain	0.68	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Benign	0.92	L
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-2.7	D
REVEL	Pathogenic	0.69
Sift	Benign	0.084	T
Sift4G	Benign	0.22	T
Polyphen		0.52	P
Vest4		0.64
MutPred		0.47		Gain of catalytic residue at V397 (P = 2e-04);
MVP		0.99
MPC		2.3
ClinPred		0.97	D
GERP RS		4.9
Varity_R		0.57
gMVP		0.87

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

Publications

LitVar

Other links and lift over

dbSNP: rs1135401950; hg19: chr12-5021727;