1-110603569-G-A

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 21 ACMG points: 21P and 0B. PS1_ModeratePM1PM2PM5PP2PP3_StrongPP5_Very_Strong

The NM_004974.4(KCNA2):c.1214C>T(p.Pro405Leu) 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 Likely pathogenic (★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in UniProt. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P405R) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)

Consequence

KCNA2
NM_004974.4 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:14

Conservation

PhyloP100: 10.0

Variant links:

Genes affected

KCNA2 (HGNC:6220): (potassium voltage-gated channel subfamily A member 2) Potassium channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. Four sequence-related potassium channel genes - shaker, shaw, shab, and shal - have been identified in Drosophila, and each has been shown to have human homolog(s). This gene encodes a member of the potassium channel, voltage-gated, shaker-related subfamily. This member contains six membrane-spanning domains with a shaker-type repeat in the fourth segment. It belongs to the delayed rectifier class, members of which allow nerve cells to efficiently repolarize following an action potential. The coding region of this gene is intronless, and the gene is clustered with genes KCNA3 and KCNA10 on chromosome 1. [provided by RefSeq, Jul 2008]

KCNA2 links:

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ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 21 ACMG points.

PS1

Transcript NM_004974.4 (KCNA2) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in UniProt

PM1

In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_004974.4

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr1-110603570-G-A is described in Lovd as [Likely_pathogenic].

PP2

Missense variant in the KCNA2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 37 curated pathogenic missense variants (we use a threshold of 10). The gene has 14 curated benign missense variants. Gene score misZ: 3.831 (above the threshold of 3.09). Trascript score misZ: 5.1665 (above the threshold of 3.09). GenCC associations: The gene is linked to undetermined early-onset epileptic encephalopathy, developmental and epileptic encephalopathy, developmental and epileptic encephalopathy, 32.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.953

PP5

Variant 1-110603569-G-A is Pathogenic according to our data. Variant chr1-110603569-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 190325.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-110603569-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNA2	NM_004974.4 link	c.1214C>T	p.Pro405Leu	missense_variant	Exon 3 of 3	ENST00000316361.10	NP_004965.1	P16389-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNA2	ENST00000316361.10 link	c.1214C>T	p.Pro405Leu	missense_variant	Exon 3 of 3	2	NM_004974.4	ENSP00000314520.4		P16389-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

Cov.:

GnomAD4 genome

Cov.:

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:14

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Developmental and epileptic encephalopathy, 32

Pathogenic:8

Apr 19, 2018

Blueprint Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 01, 2015

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Aug 09, 2017

Génétique des Maladies du Développement, Hospices Civils de Lyon

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 29, 2019

Biochemical Molecular Genetic Laboratory, King Abdulaziz Medical City

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Jun 16, 2021

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 02, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 405 of the KCNA2 protein (p.Pro405Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with epileptic encephalopathy (PMID: 25751627). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 190325). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on KCNA2 protein function. Experimental studies have shown that this missense change affects KCNA2 function (PMID: 25751627). For these reasons, this variant has been classified as Pathogenic. -

Jan 10, 2023

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 14, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

- -

not provided

Pathogenic:4

Sep 01, 2021

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 07, 2017

Laboratory of Molecular Genetics (Pr. Bezieau's lab), CHU de Nantes

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Nov 17, 2021

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Published functional study demonstrates loss of channel function through a dominant negative effect (Syrbe et al., 2015); Not observed at significant frequency in large population cohorts (Lek et al., 2016); 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: 25997620, 30182498, 29050392, 28600779, 28806589, 30055040, 28488083, 29895856, 27864847, 33232902, 33802230, 33355533, 34576077, 31932120, 25751627) -

Oct 23, 2020

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Inborn genetic diseases

Pathogenic:1

Jun 30, 2021

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1214C>T (p.P405L) alteration is located in exon 3 (coding exon 1) of the KCNA2 gene. This alteration results from a C to T substitution at nucleotide position 1214, causing the proline (P) at amino acid position 405 to be replaced by a leucine (L). Based on data from the Genome Aggregation Database (gnomAD), the KCNA2 c.1214C>T alteration was not observed, with coverage at this position. This alteration has been reported in multiple unrelated patients with epileptic encephalopathy and is the most common recurrent variant in KCNA2 (Syrbe, 2015; Masnada, 2017; Sachdev, 2017; Miao, 2018; Gong, 2020). This amino acid position is highly conserved in available vertebrate species. Functional characterization of the P405L alteration with a voltage-clamp oocyte testing system found a dramatic reduction of current amplitudes with a dominant negative effect (Syrbe, 2015). The p.P405L alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -

Seizure

Pathogenic:1

Dec 27, 2023

Génétique des Maladies du Développement, Hospices Civils de Lyon

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Pathogenic

0.55

BayesDel_noAF

Pathogenic

0.56

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.96

D;.;.;D;D;D;D;.

Eigen

Pathogenic

0.97

Eigen_PC

Pathogenic

0.91

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.99

.;D;D;.;.;.;D;D

M_CAP

Pathogenic

0.91

MetaRNN

Pathogenic

0.95

D;D;D;D;D;D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Uncertain

2.8

M;.;.;M;M;M;M;.

PrimateAI

Pathogenic

0.94

PROVEAN

Pathogenic

-8.8

.;.;.;.;D;.;D;.

REVEL

Pathogenic

0.98

Sift

Pathogenic

0.0

.;.;.;.;D;.;D;.

Sift4G

Uncertain

0.017

D;.;.;.;D;.;D;.

Polyphen

1.0

D;.;.;D;D;D;D;.

Vest4

0.93

MutPred

0.72

Gain of helix (P = 0.2294);.;.;Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);.;

MVP

1.0

MPC

2.4

ClinPred

1.0

GERP RS

5.2

Varity_R

0.91

gMVP

0.99

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over