NM_020822.3:c.3598C>T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BS2

The NM_020822.3(KCNT1):c.3598C>T(p.Arg1200Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000891 in 1,604,142 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. R1200H) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00014 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000083 ( 0 hom. )

Consequence

KCNT1
NM_020822.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5

Conservation

PhyloP100: 5.55

Publications

1 publications found

Variant links:

Genes affected

KCNT1 (HGNC:18865): (potassium sodium-activated channel subfamily T member 1) 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. This gene encodes a sodium-activated potassium channel subunit which is thought to function in ion conductance and developmental signaling pathways. Mutations in this gene cause the early-onset epileptic disorders, malignant migrating partial seizures of infancy and autosomal dominant nocturnal frontal lobe epilepsy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2012]

KCNT1 Gene-Disease associations (from GenCC):

childhood-onset epilepsy syndrome
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
developmental and epileptic encephalopathy, 14
Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
malignant migrating partial seizures of infancy
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet
autosomal dominant nocturnal frontal lobe epilepsy 5
Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
autosomal dominant nocturnal frontal lobe epilepsy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

KCNT1 links:

LOC107987140 (HGNC:):

LOC107987140 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -4 ACMG points.

BS2

High AC in GnomAd4 at 22 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_020822.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNT1	NM_020822.3	MANE Select	c.3598C>T	p.Arg1200Cys	missense	Exon 31 of 31	NP_065873.2
	KCNT1	NM_001272003.2		c.3526C>T	p.Arg1176Cys	missense	Exon 31 of 31	NP_001258932.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
KCNT1	ENST00000371757.7	TSL:1 MANE Select	c.3598C>T	p.Arg1200Cys	missense	Exon 31 of 31	ENSP00000360822.2
KCNT1	ENST00000460750.5	TSL:1	n.*3271C>T		non_coding_transcript_exon	Exon 32 of 32	ENSP00000418777.1
KCNT1	ENST00000460750.5	TSL:1	n.*3271C>T		3_prime_UTR	Exon 32 of 32	ENSP00000418777.1

Frequencies

GnomAD3 genomes

AF:

0.000145

AC:

AN:

152146

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000966

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000414

Gnomad FIN

AF:

0.000753

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000118

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000912

AC:

AN:

241308

AF XY:

0.000114

show subpopulations

Gnomad AFR exome

AF:

0.000125

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000546

Gnomad FIN exome

AF:

0.000468

Gnomad NFE exome

AF:

0.0000810

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000833

AC:

121

AN:

1451878

Hom.:

Cov.:

AF XY:

0.0000761

AC XY:

AN XY:

722768

show subpopulations

African (AFR)

AF:

0.0000896

AC:

AN:

33466

American (AMR)

AF:

0.0000224

AC:

AN:

44682

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26106

East Asian (EAS)

AF:

0.0000756

AC:

AN:

39684

South Asian (SAS)

AF:

0.0000928

AC:

AN:

86192

European-Finnish (FIN)

AF:

0.000205

AC:

AN:

43970

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5760

European-Non Finnish (NFE)

AF:

0.0000828

AC:

AN:

1111714

Other (OTH)

AF:

0.0000829

AC:

AN:

60304

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.479

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000144

AC:

AN:

152264

Hom.:

Cov.:

AF XY:

0.000202

AC XY:

AN XY:

74440

show subpopulations

African (AFR)

AF:

0.0000963

AC:

AN:

41548

American (AMR)

AF:

0.00

AC:

AN:

15300

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5162

South Asian (SAS)

AF:

0.000414

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.000753

AC:

AN:

10622

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000118

AC:

AN:

68012

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.486

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000284

Hom.:

Bravo

AF:

0.0000869

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000233

AC:

ExAC

AF:

0.000107

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Developmental and epileptic encephalopathy, 14;C3554306:Autosomal dominant nocturnal frontal lobe epilepsy 5

Uncertain:2

Jun 23, 2020

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:research

Dec 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 1200 of the KCNT1 protein (p.Arg1200Cys). This variant is present in population databases (rs372028322, gnomAD 0.04%), and has an allele count higher than expected for a pathogenic variant. This variant has not been reported in the literature in individuals affected with KCNT1-related conditions. ClinVar contains an entry for this variant (Variation ID: 279822). 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 KCNT1 protein function. 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.

not provided

Uncertain:1

Jul 19, 2016

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The R1200C variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The R1200C variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species and in silico analysis predicts this variant is probably damaging to the protein structure/function. However, missense variants in nearby residues have not been reported in the Human Gene Mutation Database in association with KCNT1-related disease (Stenson et al., 2014). Additionally, the R1200C variant was not observed with any significant frequency in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project; but the 1000 Genomes Project reports R1200C was observed in 2/206 (1.0%) alleles from individuals of Gujarati Indian background, indicating it may be a rare (benign) variant in this population. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant.

Developmental and epileptic encephalopathy, 14

Uncertain:1

Mar 15, 2022

Genome-Nilou Lab

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Autosomal dominant nocturnal frontal lobe epilepsy 5

Uncertain:1

Mar 15, 2022

Genome-Nilou Lab

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.71

BayesDel_addAF

Uncertain

0.076

BayesDel_noAF

Uncertain

0.11

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Benign

0.32

Eigen

Uncertain

0.63

Eigen_PC

Uncertain

0.58

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

1.0

M_CAP

Pathogenic

0.42

MetaRNN

Uncertain

0.65

MetaSVM

Benign

-0.34

MutationAssessor

Uncertain

2.3

PhyloP100

5.6

PrimateAI

Uncertain

0.70

PROVEAN

Pathogenic

-5.7

REVEL

Uncertain

0.48

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Vest4

0.92

MVP

0.67

MPC

0.56

ClinPred

0.83

GERP RS

4.9

Varity_R

0.71

gMVP

0.72

Mutation Taster

=10/90

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over