rs149452823

chr9-135777442-C-T

Variant summary

Our verdict is Benign. Variant got -15 ACMG points: 0P and 15B. BP4_Moderate BP6_Very_Strong BP7 BS2

The NM_020822.3(KCNT1):c.2454C>T(p.Ile818=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000558 in 1,613,952 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00017 (0 hom., cov: 34)
  • Exomes 𝑓: 0.000044 (0 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:6
• Conservation: PhyloP100: -2.20

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]

ACMG classification

Verdict is Benign. Variant got -15 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.41).
• BP6: Variant 9-135777442-C-T is Benign according to our data. Variant chr9-135777442-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 417221.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-2.2 with no splicing effect.
• BS2: High AC in GnomAd at 26 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.2454C>T	p.Ile818=	synonymous_variant	21/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.2454C>T	p.Ile818=	synonymous_variant	21/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes AF: 0.000171 AC: 26 AN: 152184 Hom.: 0 Cov.: 34

Gnomad AFR AF: 0.000531

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000677 AC: 17 AN: 251292 Hom.: 0 AF XY: 0.0000515 AC XY: 7 AN XY: 135852

Gnomad AFR exome AF: 0.000185

Gnomad AMR exome AF: 0.0000579

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000968

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000438 AC: 64 AN: 1461768 Hom.: 0 Cov.: 39 AF XY: 0.0000481 AC XY: 35 AN XY: 727216

Gnomad4 AFR exome AF: 0.000329

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000423

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.000171 AC: 26 AN: 152184 Hom.: 0 Cov.: 34 AF XY: 0.000175 AC XY: 13 AN XY: 74342

Gnomad4 AFR AF: 0.000531

Gnomad4 AMR AF: 0.000131

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000116 Hom.: 0

Bravo AF: 0.000121

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 14;C3554306:Autosomal dominant nocturnal frontal lobe epilepsy 5 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Dec 12, 2021

- -

Inborn genetic diseases Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 29, 2020

This alteration is classified as 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. -

Developmental and epileptic encephalopathy, 14 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Mar 15, 2022

- -

not provided Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

May 08, 2019

- -

Autosomal dominant nocturnal frontal lobe epilepsy 5 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Mar 15, 2022

- -

Epilepsy Benign:1

Likely benign, no assertion criteria provided

clinical testing

Clinical Molecular Genetics Laboratory, Johns Hopkins All Children's Hospital

Oct 13, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.41
Cadd	Benign	2.4
Dann	Benign	0.92

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: rs149452823; hg19: chr9-138669288; COSMIC: COSV53709326; COSMIC: COSV53709326;