rs104894354

Positions:

• chr12-4912054-A-G

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_000217.3(KCNA1):​c.676A>G​(p.Thr226Ala) 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. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T226K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: KCNA1 NM_000217.3 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:2 O: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 13 ACMG points.

• PM1: In a transmembrane_region Helical; Name=Segment S2 (size 21) in uniprot entity KCNA1_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) in NM_000217.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-4912055-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 13492.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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, 0.956
• PP5: Variant 12-4912054-A-G is Pathogenic according to our data. Variant chr12-4912054-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 13486.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNA1	NM_000217.3	c.676A>G	p.Thr226Ala	missense_variant	2/2	ENST00000382545.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNA1	ENST00000382545.5	c.676A>G	p.Thr226Ala	missense_variant	2/2	4	NM_000217.3	P1
	ENST00000640877.1	n.606+1582A>G		intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Episodic ataxia type 1 Pathogenic:1 Other:1

Pathogenic, no assertion criteria provided	literature only	OMIM	Apr 01, 1998	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

CeGaT Center for Human Genetics Tuebingen

Aug 01, 2023

KCNA1: PP1:Strong, PM1, PM2, PM5, PP2, PP3, PS3:Supporting, PS4:Supporting -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.49
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.95	D
Eigen	Uncertain	0.27
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.86	D
M_CAP	Pathogenic	0.36	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.6	L
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-4.7	D
REVEL	Pathogenic	0.85
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.048	D
Polyphen		0.27	B
Vest4		0.89
MutPred		0.80		Gain of catalytic residue at F221 (P = 0);
MVP		0.96
MPC		2.3
ClinPred		0.99	D
GERP RS		4.9
Varity_R		0.73
gMVP		0.84

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: rs104894354; hg19: chr12-5021220;