9-135772926-C-G

Variant names:

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_StrongBP6_Very_StrongBS1BS2

The NM_020822.3(KCNT1):c.2220C>G(p.Asp740Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000331 in 1,518,882 control chromosomes in the GnomAD database, including 10 homozygotes. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. D740D) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00030 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00033 ( 10 hom. )

Consequence

KCNT1
NM_020822.3 missense

Scores

Clinical Significance

Likely benign criteria provided, multiple submitters, no conflicts B:10

Conservation

PhyloP100: -4.50

Publications

6 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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -20 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.0068859756).

BP6

Variant 9-135772926-C-G is Benign according to our data. Variant chr9-135772926-C-G is described in ClinVar as Likely_benign. ClinVar VariationId is 473370.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population sas. GnomAd4 allele frequency = 0.000302 (46/152300) while in subpopulation SAS AF = 0.00456 (22/4822). AF 95% confidence interval is 0.00309. There are 0 homozygotes in GnomAd4. There are 36 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

BS2

High AC in GnomAd4 at 46 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNT1	NM_020822.3 link	c.2220C>G	p.Asp740Glu	missense_variant	Exon 19 of 31	ENST00000371757.7	NP_065873.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNT1	ENST00000371757.7 link	c.2220C>G	p.Asp740Glu	missense_variant	Exon 19 of 31	1	NM_020822.3	ENSP00000360822.2

Frequencies

GnomAD3 genomes

AF:

0.000315

AC:

AN:

152182

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000458

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00497

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00316

Gnomad NFE

AF:

0.000132

Gnomad OTH

AF:

0.00239

GnomAD2 exomes

AF:

0.000737

AC:

AN:

126108

AF XY:

0.000901

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000417

Gnomad ASJ exome

AF:

0.000344

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000252

Gnomad OTH exome

AF:

0.00115

GnomAD4 exome

AF:

0.000334

AC:

456

AN:

1366582

Hom.:

Cov.:

AF XY:

0.000451

AC XY:

303

AN XY:

672564

show subpopulations

African (AFR)

AF:

0.0000324

AC:

AN:

30840

American (AMR)

AF:

0.000326

AC:

AN:

30714

Ashkenazi Jewish (ASJ)

AF:

0.000305

AC:

AN:

22932

East Asian (EAS)

AF:

0.00

AC:

AN:

35610

South Asian (SAS)

AF:

0.00415

AC:

307

AN:

73922

European-Finnish (FIN)

AF:

0.000209

AC:

AN:

43098

Middle Eastern (MID)

AF:

0.00239

AC:

AN:

5446

European-Non Finnish (NFE)

AF:

0.0000768

AC:

AN:

1067474

Other (OTH)

AF:

0.000477

AC:

AN:

56546

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.492

Heterozygous variant carriers

104

130

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

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:

0.000302

AC:

AN:

152300

Hom.:

Cov.:

AF XY:

0.000484

AC XY:

AN XY:

74452

show subpopulations

African (AFR)

AF:

0.0000481

AC:

AN:

41572

American (AMR)

AF:

0.000457

AC:

AN:

15304

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5166

South Asian (SAS)

AF:

0.00456

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00340

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000132

AC:

AN:

68020

Other (OTH)

AF:

0.00237

AC:

AN:

2110

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.510

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:

0.000254

Hom.:

Bravo

AF:

0.000204

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000233

AC:

ExAC

AF:

0.000530

AC:

ClinVar

Significance: Likely benign

Submissions summary: Benign:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Benign:5

Sep 01, 2023

CeGaT Center for Human Genetics Tuebingen

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

KCNT1: BS1 -

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Genome Diagnostics Laboratory, University Medical Center Utrecht

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Breakthrough Genomics, Breakthrough Genomics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:not provided

- -

Oct 13, 2019

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is associated with the following publications: (PMID: 31780880) -

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

Benign:1

Feb 04, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Inborn genetic diseases

Benign:1

May 21, 2018

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. -

KCNT1-related disorder

Benign:1

Mar 09, 2020

PreventionGenetics, part of Exact Sciences

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Developmental and epileptic encephalopathy, 14

Benign:1

Mar 15, 2022

Genome-Nilou Lab

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal dominant nocturnal frontal lobe epilepsy 5

Benign:1

Mar 15, 2022

Genome-Nilou Lab

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.079

BayesDel_addAF

Benign

-0.51

BayesDel_noAF

Benign

-0.51

CADD

Benign

0.0020

(source)

DANN

Benign

0.47

DEOGEN2

Benign

0.043

.;.;.;.;.;.;.;.;T;.

Eigen

Benign

-1.6

Eigen_PC

Benign

-1.8

FATHMM_MKL

Benign

0.086

LIST_S2

Benign

0.72

T;T;T;T;T;T;T;T;T;T

M_CAP

Benign

0.023

MetaRNN

Benign

0.0069

T;T;T;T;T;T;T;T;T;T

MetaSVM

Benign

-1.0

MutationAssessor

Benign

1.5

.;.;.;.;.;.;.;.;L;.

PhyloP100

-4.5

PrimateAI

Uncertain

0.59

PROVEAN

Benign

-0.88

.;.;N;.;.;N;.;.;N;N

REVEL

Benign

0.22

Sift

Benign

0.72

.;.;T;.;.;D;.;.;T;T

Sift4G

Benign

0.50

T;T;T;T;T;T;T;T;T;T

Polyphen

0.0030

.;.;.;.;.;.;.;.;B;.

Vest4

0.27

MutPred

0.41

.;.;.;.;.;.;Gain of solvent accessibility (P = 0.0155);Gain of solvent accessibility (P = 0.0155);Gain of solvent accessibility (P = 0.0155);.;

MVP

0.66

MPC

0.59

ClinPred

0.012

GERP RS

-7.8

Varity_R

0.033

gMVP

0.40

Mutation Taster

=100/0

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.040

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over