9-135772736-A-G

Position:

• chr9-135772736-A-G

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP6 BS2

The NM_020822.3(KCNT1):​c.2030A>G​(p.Gln677Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000551 in 1,269,320 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: KCNT1 NM_020822.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:2
• Conservation: PhyloP100: 7.18

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 Likely_benign. Variant got -5 ACMG points.

• BP6: Variant 9-135772736-A-G is Benign according to our data. Variant chr9-135772736-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 417209.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=2, Uncertain_significance=2}. Variant chr9-135772736-A-G is described in Lovd as [Likely_benign].
• BS2: High AC in GnomAdExome4 at 7 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.2030A>G	p.Gln677Arg	missense_variant	19/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.2030A>G	p.Gln677Arg	missense_variant	19/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000551 AC: 7 AN: 1269320 Hom.: 0 Cov.: 31 AF XY: 0.0000114 AC XY: 7 AN XY: 613670

Gnomad4 AFR exome AF: 0.000113

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000767

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Nov 13, 2017	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Oct 01, 2022	KCNT1: PM2 -

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 03, 2017

The p.Q677R variant (also known as c.2030A>G), located in coding exon 19 of the KCNT1 gene, results from an A to G substitution at nucleotide position 2030. The glutamine at codon 677 is replaced by arginine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

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

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 11, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.098	T
BayesDel_noAF	Benign	-0.38
CADD	Benign	18
DANN	Benign	0.79
DEOGEN2	Benign	0.072	.;.;.;.;.;.;.;.;T;.
Eigen	Benign	-0.42
Eigen_PC	Benign	-0.42
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.94	D;D;D;D;D;D;D;D;D;D
M_CAP	Benign	0.077	D
MetaRNN	Uncertain	0.52	D;D;D;D;D;D;D;D;D;D
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.7	.;.;.;.;.;.;.;.;M;.
MutationTaster	Benign	0.99	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-2.1	.;.;N;.;.;.;.;.;N;N
REVEL	Benign	0.17
Sift	Benign	0.21	.;.;T;.;.;.;.;.;T;T
Sift4G	Benign	0.11	T;T;T;T;T;T;T;T;T;T
Polyphen		0.35	.;.;.;.;.;.;.;.;B;.
Vest4		0.70
MutPred		0.22		.;.;.;.;.;.;Loss of catalytic residue at M655 (P = 0.0337);Loss of catalytic residue at M655 (P = 0.0337);Loss of catalytic residue at M655 (P = 0.0337);.;
MVP		0.42
MPC		0.69
ClinPred		0.26	T
GERP RS		2.8
Varity_R		0.075
gMVP		0.53

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: rs1060505000; hg19: chr9-138664582;