rs370085077

chr9-135786359-C-Gchr9-135786359-C-T

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BS2

The NM_020822.3(KCNT1):c.3340C>G(p.Arg1114Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000238 in 1,430,066 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1114W) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000024 (0 hom.)
• Consequence: KCNT1 NM_020822.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.79

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 -4 ACMG points.

• BS2: High AC in GnomAdExome at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.3340C>G	p.Arg1114Gly	missense_variant	29/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.3340C>G	p.Arg1114Gly	missense_variant	29/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000331 AC: 6 AN: 181208 Hom.: 0 AF XY: 0.0000200 AC XY: 2 AN XY: 99880

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000385

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000676

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000238 AC: 34 AN: 1430066 Hom.: 0 Cov.: 36 AF XY: 0.0000311 AC XY: 22 AN XY: 708426

Gnomad4 AFR exome AF: 0.0000304

Gnomad4 AMR exome AF: 0.0000254

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000362

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000255

Gnomad4 OTH exome AF: 0.0000169

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 11, 2022

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 1114 of the KCNT1 protein (p.Arg1114Gly). This variant is present in population databases (no rsID available, gnomAD 0.007%). This variant has not been reported in the literature in individuals affected with KCNT1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.28
BayesDel_addAF	Benign	-0.062	T
BayesDel_noAF	Benign	-0.14
Cadd	Benign	22
Dann	Uncertain	1.0
Eigen	Benign	0.084
Eigen_PC	Benign	0.052
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.17	D
MetaRNN	Uncertain	0.64	D;D;D;D;D;D;D;D;D;D
MetaSVM	Benign	-1.1	T
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.58	T
REVEL	Benign	0.25
Sift4G	Benign	0.26	T;T;T;T;T;T;T;T;T;T
Vest4		0.79
MVP		0.54
MPC		0.27
ClinPred		0.60	D
GERP RS		3.8
Varity_R		0.13
gMVP		0.45

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: rs370085077; hg19: chr9-138678205;