NM_001112741.2:c.744C>G

Variant names:

• chr11-17771838-C-G
• rs2229007
• NM_001112741.2:c.744C>G

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 1P and 4B. PP3 BS2

The NM_001112741.2(KCNC1):​c.744C>G​(p.Ile248Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,846 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I248V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: KCNC1 NM_001112741.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.320
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen, Ambry Genetics
• progressive myoclonic epilepsy type 7

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet, G2P
• progressive myoclonus epilepsy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.764
• BS2: High AC in GnomAdExome4 at 7 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNC1	NM_001112741.2	c.744C>G	p.Ile248Met	missense_variant	Exon 2 of 4	ENST00000265969.8	NP_001106212.1
KCNC1	NM_004976.4	c.744C>G	p.Ile248Met	missense_variant	Exon 2 of 2		NP_004967.1
KCNC1	XM_047426916.1	c.744C>G	p.Ile248Met	missense_variant	Exon 2 of 4		XP_047282872.1
KCNC1	XR_930866.3	n.1966C>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.744C>G	p.Ile248Met	missense_variant	Exon 2 of 4	5	NM_001112741.2	ENSP00000265969.7

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461846 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727208

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

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

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

European-Non Finnish (NFE) AF: 0.00000630 AC: 7 AN: 1111968

Other (OTH) AF: 0.00 AC: 0 AN: 60396

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

Jun 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 248 of the KCNC1 protein (p.Ile248Met). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with KCNC1-related conditions. 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 KCNC1 protein function with a negative predictive value of 80%. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.41
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Benign	14
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.70	D;.
Eigen	Benign	0.039
Eigen_PC	Benign	-0.032
FATHMM_MKL	Benign	0.31	N
LIST_S2	Benign	0.82	T;T
M_CAP	Pathogenic	0.39	D
MetaRNN	Pathogenic	0.76	D;D
MetaSVM	Pathogenic	0.94	D
MutationAssessor	Benign	1.1	L;L
PhyloP100		-0.32
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-2.2	N;N
REVEL	Pathogenic	0.71
Sift	Uncertain	0.0010	D;D
Sift4G	Uncertain	0.023	D;D
Polyphen		0.99	D;.
Vest4		0.74
MutPred		0.56		Loss of catalytic residue at I248 (P = 0.2071);Loss of catalytic residue at I248 (P = 0.2071);
MVP		0.93
MPC		2.6
ClinPred		0.97	D
GERP RS		2.9
PromoterAI		-0.0079	Neutral
Varity_R		0.67
gMVP		0.92
Mutation Taster		=54/46	polymorphism

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: rs2229007; hg19: chr11-17793385;