12-4912062-T-A

Variant names:

• chr12-4912062-T-A
• rs1048500
• NM_000217.3:c.684T>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_000217.3(KCNA1):​c.684T>A​(p.Cys228*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. C228C) has been classified as Benign.

• Frequency: Genomes: not found (cov: 31)
• Consequence: KCNA1 NM_000217.3 stop_gained
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.74
• Publications: 22 publications found

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]

KCNA1 Gene-Disease associations (from GenCC):

• episodic ataxia type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, ClinGen, Genomics England PanelApp, Orphanet
• episodic kinesigenic dyskinesia 1

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• genetic developmental and epileptic encephalopathy

  Inheritance: AD, AR Classification: SUPPORTIVE, LIMITED Submitted by: Orphanet, G2P
• isolated autosomal dominant hypomagnesemia, Glaudemans type

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000256654 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 40 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000217.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNA1	NM_000217.3	MANE Select	c.684T>A	p.Cys228*	stop_gained	Exon 2 of 2	NP_000208.2	Q09470

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNA1	ENST00000382545.5	TSL:4 MANE Select	c.684T>A	p.Cys228*	stop_gained	Exon 2 of 2	ENSP00000371985.3	Q09470
	KCNA1	ENST00000639306.1	TSL:5	n.522T>A		non_coding_transcript_exon	Exon 1 of 2	ENSP00000492506.1	A0A1W2PRI2
	ENSG00000256654	ENST00000541095.1	TSL:3	n.105+1590T>A		intron	N/A

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 62

GnomAD4 genome Cov.: 31

Alfa AF: 0.00 Hom.: 59723

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	35
DANN	Uncertain	0.99
Eigen	Uncertain	0.28
Eigen_PC	Benign	0.083
FATHMM_MKL	Uncertain	0.87	D
PhyloP100		1.7
Vest4		0.77
GERP RS		-0.10
PromoterAI		0.010	Neutral
Mutation Taster		=9/191	disease causing

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

Other links and lift over

dbSNP: rs1048500; hg19: chr12-5021228;