9-135786406-C-T

Variant summary

Our verdict is Benign. Variant got -21 ACMG points: 0P and 21B. BP4_Strong BP6_Very_Strong BP7 BS1 BS2

The NM_020822.3(KCNT1):c.3387C>T(p.Ala1129=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000812 in 1,576,410 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts 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. A1129A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000075 (1 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:6
• Conservation: PhyloP100: -3.41

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 -21 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.72).
• BP6: Variant 9-135786406-C-T is Benign according to our data. Variant chr9-135786406-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 473389.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-3.41 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.000138 (21/152314) while in subpopulation EAS AF= 0.00271 (14/5172). AF 95% confidence interval is 0.00164. There are 0 homozygotes in gnomad4. There are 8 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High AC in GnomAd at 21 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.3387C>T	p.Ala1129=	synonymous_variant	29/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.3387C>T	p.Ala1129=	synonymous_variant	29/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152198 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000965

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00270

Gnomad SAS AF: 0.000621

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000268 AC: 47 AN: 175690 Hom.: 0 AF XY: 0.000247 AC XY: 24 AN XY: 97028

Gnomad AFR exome AF: 0.000114

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00270

Gnomad SAS exome AF: 0.000349

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000212

GnomAD4 exome AF: 0.0000751 AC: 107 AN: 1424096 Hom.: 1 Cov.: 36 AF XY: 0.0000836 AC XY: 59 AN XY: 705374

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00146

Gnomad4 SAS exome AF: 0.000436

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000366

Gnomad4 OTH exome AF: 0.000204

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152314 Hom.: 0 Cov.: 33 AF XY: 0.000107 AC XY: 8 AN XY: 74482

Gnomad4 AFR AF: 0.0000962

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00271

Gnomad4 SAS AF: 0.000621

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000756

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Benign:2

Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Dec 08, 2017	- -
Benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Jul 01, 2022	KCNT1: BS1, BS2 -

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

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Jan 10, 2024

- -

KCNT1-related disorder Benign:1

Benign, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Apr 26, 2019

This variant is classified as 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

Likely benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Mar 15, 2022

- -

Autosomal dominant nocturnal frontal lobe epilepsy 5 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Mar 15, 2022

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.72
Cadd	Benign	2.9
Dann	Benign	0.64

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: rs372410150; hg19: chr9-138678252; COSMIC: COSV53714717; COSMIC: COSV53714717;