rs1554991422

Positions:

• chr11-17772515-C-A
• chr11-17772515-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP3

The NM_001112741.2(KCNC1):​c.1421C>A​(p.Ser474Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (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]

KCNC1 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 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
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KCNC1. . Gene score misZ 4.5189 (greater than the threshold 3.09). Trascript score misZ 5.1707 (greater than threshold 3.09). GenCC has associacion of gene with progressive myoclonic epilepsy type 7, progressive myoclonus epilepsy, complex neurodevelopmental disorder.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.746

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNC1	NM_001112741.2	c.1421C>A	p.Ser474Tyr	missense_variant	2/4	ENST00000265969.8	NP_001106212.1
KCNC1	NM_004976.4	c.1421C>A	p.Ser474Tyr	missense_variant	2/2		NP_004967.1
KCNC1	XM_047426916.1	c.1421C>A	p.Ser474Tyr	missense_variant	2/4		XP_047282872.1
KCNC1	XR_930866.3	n.2643C>A		non_coding_transcript_exon_variant	2/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNC1	ENST00000265969.8	c.1421C>A	p.Ser474Tyr	missense_variant	2/4	5	NM_001112741.2	ENSP00000265969.7

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461878 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 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: 0.00000180

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 09, 2017

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a KCNC1-related disease. This sequence change replaces serine with tyrosine at codon 474 of the KCNC1 protein (p.Ser474Tyr). The serine residue is highly conserved and there is a large physicochemical difference between serine and tyrosine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.51
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.43	T;.;.
Eigen	Uncertain	0.66
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.88	D;D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.75	D;D;D
MetaSVM	Uncertain	0.44	D
MutationAssessor	Uncertain	2.2	M;M;.
PrimateAI	Pathogenic	0.84	D
PROVEAN	Uncertain	-2.8	D;D;.
REVEL	Uncertain	0.63
Sift	Uncertain	0.0050	D;D;.
Sift4G	Uncertain	0.014	D;D;.
Polyphen		0.98	D;.;.
Vest4		0.39
MutPred		0.26		Loss of disorder (P = 0.0439);Loss of disorder (P = 0.0439);.;
MVP		0.95
MPC		2.9
ClinPred		0.96	D
GERP RS		5.2
Varity_R		0.34
gMVP		0.87

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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; COSMIC: COSV56393253; COSMIC: COSV56393253;