rs121918067

Positions:

• chr12-4912141-A-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_000217.3(KCNA1):​c.763A>G​(p.Asn255Asp) 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. Variant has been reported in ClinVar as Pathogenic (no stars).

• Frequency: Genomes: not found (cov: 31)
• Consequence: KCNA1 NM_000217.3 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 9.26

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]

(HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000217.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KCNA1. . Gene score misZ 3.3255 (greater than the threshold 3.09). Trascript score misZ 3.8671 (greater than threshold 3.09). GenCC has associacion of gene with episodic kinesigenic dyskinesia 1, episodic ataxia type 1, developmental and epileptic encephalopathy, isolated autosomal dominant hypomagnesemia, Glaudemans type.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.98
• PP5: Variant 12-4912141-A-G is Pathogenic according to our data. Variant chr12-4912141-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 13494.Status of the report is no_assertion_criteria_provided, 0 stars. Variant chr12-4912141-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNA1	NM_000217.3	c.763A>G	p.Asn255Asp	missense_variant	2/2	ENST00000382545.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNA1	ENST00000382545.5	c.763A>G	p.Asn255Asp	missense_variant	2/2	4	NM_000217.3	P1
	ENST00000640877.1	n.606+1669A>G		intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 60

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Myokymia 1 with hypomagnesemia Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Apr 01, 2009

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.28
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.94
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	4.0	H
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-4.8	D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0040	D
Polyphen		1.0	D
Vest4		0.90
MutPred		0.80		Gain of catalytic residue at D258 (P = 0.007);
MVP		1.0
MPC		2.5
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.99
gMVP		1.0

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: rs121918067; hg19: chr12-5021307;