NM_004974.4:c.68A>G

Variant names:

• chr1-110604715-T-C
• rs753829876
• NM_004974.4:c.68A>G

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP6 BS2

The NM_004974.4(KCNA2):​c.68A>G​(p.Tyr23Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000889 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. Y23Y) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: KCNA2 NM_004974.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 8.02
• Publications: 1 publications found

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 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy, 32

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• genetic developmental and epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: ClinGen, Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• BP6: Variant 1-110604715-T-C is Benign according to our data. Variant chr1-110604715-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 476053.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Likely_benign=1}.
• BS2: High AC in GnomAdExome4 at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNA2	NM_004974.4	c.68A>G	p.Tyr23Cys	missense_variant	Exon 3 of 3	ENST00000316361.10	NP_004965.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNA2	ENST00000316361.10	c.68A>G	p.Tyr23Cys	missense_variant	Exon 3 of 3	2	NM_004974.4	ENSP00000314520.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 251440 AF XY: 0.0000221

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000889 AC: 13 AN: 1461878 Hom.: 0 Cov.: 34 AF XY: 0.00000825 AC XY: 6 AN XY: 727242

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.0000756 AC: 3 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000809 AC: 9 AN: 1112008

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000282 Hom.: 0

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Developmental and epileptic encephalopathy, 32 Uncertain:1

Jun 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 23 of the KCNA2 protein (p.Tyr23Cys). This variant is present in population databases (rs753829876, gnomAD 0.006%). This missense change has been observed in individual(s) with clinical features of KCNA2-related conditions (Invitae). In at least one individual the variant was observed to be de novo. This missense change has been observed in at least one individual who was not affected with KCNA2-related conditions (Invitae). ClinVar contains an entry for this variant (Variation ID: 476053). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt KCNA2 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Inborn genetic diseases Benign:1

Apr 22, 2025

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.073
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Pathogenic	0.25
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.69	D;.;D;D;D;D
Eigen	Uncertain	0.32
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.88	.;D;.;.;.;D
M_CAP	Uncertain	0.22	D
MetaRNN	Uncertain	0.68	D;D;D;D;D;D
MetaSVM	Uncertain	0.74	D
MutationAssessor	Benign	1.2	L;L;L;L;L;L
PhyloP100		8.0
PrimateAI	Pathogenic	0.82	D
PROVEAN	Benign	-2.1	.;N;.;N;.;N
REVEL	Pathogenic	0.69
Sift	Benign	0.084	.;T;.;T;.;T
Sift4G	Benign	0.18	T;T;.;T;.;T
Polyphen		0.99	D;.;D;D;D;D
Vest4		0.68
MutPred		0.37		Loss of phosphorylation at Y23 (P = 0.0082);Loss of phosphorylation at Y23 (P = 0.0082);Loss of phosphorylation at Y23 (P = 0.0082);Loss of phosphorylation at Y23 (P = 0.0082);Loss of phosphorylation at Y23 (P = 0.0082);Loss of phosphorylation at Y23 (P = 0.0082);
MVP		0.88
MPC		2.6
ClinPred		0.64	D
GERP RS		5.8
Varity_R		0.34
gMVP		0.91
Mutation Taster		=30/70	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: rs753829876; hg19: chr1-111147337;