rs142642528

Positions:

• chr9-135778784-G-A
• chr9-135778784-G-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.2691G>A​(p.Ala897=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000632 in 1,613,736 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00038 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00066 (2 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:5
• Conservation: PhyloP100: -2.27

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=-0.61).
• BP6: Variant 9-135778784-G-A is Benign according to our data. Variant chr9-135778784-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 383085.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-2.27 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.000381 (58/152286) while in subpopulation SAS AF= 0.000827 (4/4834). AF 95% confidence interval is 0.000495. There are 0 homozygotes in gnomad4. There are 20 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High AC in GnomAd4 at 58 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.2691G>A	p.Ala897=	synonymous_variant	23/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.2691G>A	p.Ala897=	synonymous_variant	23/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes AF: 0.000368 AC: 56 AN: 152168 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000966

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000770

Gnomad SAS AF: 0.000827

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000647

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000319 AC: 80 AN: 250948 Hom.: 0 AF XY: 0.000383 AC XY: 52 AN XY: 135762

Gnomad AFR exome AF: 0.0000616

Gnomad AMR exome AF: 0.0000579

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00131

Gnomad SAS exome AF: 0.000457

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000335

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.000658 AC: 962 AN: 1461450 Hom.: 2 Cov.: 33 AF XY: 0.000641 AC XY: 466 AN XY: 727058

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000157

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000605

Gnomad4 SAS exome AF: 0.000557

Gnomad4 FIN exome AF: 0.0000188

Gnomad4 NFE exome AF: 0.000721

Gnomad4 OTH exome AF: 0.00129

GnomAD4 genome AF: 0.000381 AC: 58 AN: 152286 Hom.: 0 Cov.: 33 AF XY: 0.000269 AC XY: 20 AN XY: 74462

Gnomad4 AFR AF: 0.000144

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000772

Gnomad4 SAS AF: 0.000827

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000647

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000458 Hom.: 0

Bravo AF: 0.000389

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.000763

EpiControl AF: 0.000356

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:5

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

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 24, 2024

- -

Inborn genetic diseases Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 30, 2017

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. -

Developmental and epileptic encephalopathy, 14 Benign:1

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

Oct 11, 2021

- -

Autosomal dominant nocturnal frontal lobe epilepsy 5 Benign:1

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	-0.61
CADD	Benign	9.1
DANN	Benign	0.86

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

LitVar

Other links and lift over

dbSNP: rs142642528; hg19: chr9-138670630; COSMIC: COSV99707145;