rs113994120

Positions:

• chr12-4912121-ACTT-A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM4_Supporting PP5_Moderate

The NM_000217.3(KCNA1):​c.748_750delTTC​(p.Phe250del) variant causes a conservative inframe deletion 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 Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: KCNA1 NM_000217.3 conservative_inframe_deletion
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.96

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 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_000217.3. Strenght limited to Supporting due to length of the change: 1aa.
• PP5: Variant 12-4912121-ACTT-A is Pathogenic according to our data. Variant chr12-4912121-ACTT-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2236795.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNA1	NM_000217.3	c.748_750delTTC	p.Phe250del	conservative_inframe_deletion	2/2	ENST00000382545.5	NP_000208.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNA1	ENST00000382545.5	c.748_750delTTC	p.Phe250del	conservative_inframe_deletion	2/2	4	NM_000217.3	ENSP00000371985.3

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 27, 2021

The c.748_750delTTC (p.F250del) alteration, located in exon 2 (coding exon 1) of the KCNA1 gene, results from an in-frame deletion of 3 nucleotides between nucleotide positions 748 to 750. This results in the deletion of a phenylalanine (F) residue at codon 250. This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This alteration was reported in multiple patients with episodic ataxia type 1 and their affected family members (Shook, 2008; Graves, 2014; Zima, 2018). This amino acid position is highly conserved in available vertebrate species. Based on the available evidence, this alteration is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

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: rs113994120; hg19: chr12-5021287;