chr11-17772515-C-G

Variant names:

• chr11-17772515-C-G
• rs1554991422
• NM_001112741.2:c.1421C>G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_001112741.2(KCNC1):​c.1421C>G​(p.Ser474Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: KCNC1 NM_001112741.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.91

Genes affected

KCNC1 (HGNC:6233): (potassium voltage-gated channel subfamily C member 1) This gene encodes a member of a family of integral membrane proteins that mediate the voltage-dependent potassium ion permeability of excitable membranes. Alternative splicing is thought to result in two transcript variants encoding isoforms that differ at their C-termini. These isoforms have had conflicting names in the literature: the longer isoform has been called both "b" and "alpha", while the shorter isoform has been called both "a" and "beta" (PMIDs 1432046, 12091563). [provided by RefSeq, Oct 2014]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a modified_residue Phosphoserine (size 0) in uniprot entity KCNC1_HUMAN
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNC1	NM_001112741.2	c.1421C>G	p.Ser474Cys	missense_variant	Exon 2 of 4	ENST00000265969.8	NP_001106212.1
KCNC1	NM_004976.4	c.1421C>G	p.Ser474Cys	missense_variant	Exon 2 of 2		NP_004967.1
KCNC1	XM_047426916.1	c.1421C>G	p.Ser474Cys	missense_variant	Exon 2 of 4		XP_047282872.1
KCNC1	XR_930866.3	n.2643C>G		non_coding_transcript_exon_variant	Exon 2 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNC1	ENST00000265969.8	c.1421C>G	p.Ser474Cys	missense_variant	Exon 2 of 4	5	NM_001112741.2	ENSP00000265969.7

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461878 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy type 7 Uncertain:1

Feb 01, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with KCNC1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces serine with cysteine at codon 474 of the KCNC1 protein (p.Ser474Cys). The serine residue is highly conserved and there is a moderate physicochemical difference between serine and cysteine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Benign	0.35	T;.;.
Eigen	Pathogenic	0.71
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.85	D;D;D
M_CAP	Uncertain	0.17	D
MetaRNN	Uncertain	0.71	D;D;D
MetaSVM	Uncertain	0.47	D
MutationAssessor	Uncertain	2.2	M;M;.
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-2.3	N;N;.
REVEL	Uncertain	0.60
Sift	Uncertain	0.0070	D;D;.
Sift4G	Uncertain	0.060	T;T;.
Polyphen		0.99	D;.;.
Vest4		0.36
MutPred		0.25		Gain of catalytic residue at V476 (P = 0.0827);Gain of catalytic residue at V476 (P = 0.0827);.;
MVP		0.82
MPC		2.5
ClinPred		0.93	D
GERP RS		5.2
Varity_R		0.19
gMVP		0.83

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: rs1554991422; hg19: chr11-17794062;