rs763578184

Positions:

• chr9-135784858-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PP3_Strong BS2

The NM_020822.3(KCNT1):​c.3125G>A​(p.Arg1042Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000151 in 1,460,422 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 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. R1042W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.000015 (0 hom.)
• Consequence: KCNT1 NM_020822.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.29

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 Uncertain_significance. Variant got 0 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982
• BS2: High AC in GnomAdExome4 at 22 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.3125G>A	p.Arg1042Gln	missense_variant	27/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.3125G>A	p.Arg1042Gln	missense_variant	27/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.0000120 AC: 3 AN: 249278 Hom.: 0 AF XY: 0.0000148 AC XY: 2 AN XY: 134996

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.0000999

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000179

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000151 AC: 22 AN: 1460422 Hom.: 0 Cov.: 34 AF XY: 0.0000110 AC XY: 8 AN XY: 726498

Gnomad4 AFR exome AF: 0.00

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: 0.0000180

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000370 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 14;C3554306:Autosomal dominant nocturnal frontal lobe epilepsy 5 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Oct 06, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Oct 31, 2017	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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with KCNT1-related disease. This variant is present in population databases (rs763578184, ExAC 0.003%). This sequence change replaces arginine with glutamine at codon 1042 of the KCNT1 protein (p.Arg1042Gln). The arginine residue is highly conserved and there is a small physicochemical difference between arginine and glutamine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.35
CADD	Uncertain	26
DANN	Pathogenic	1.0
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.57	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.58	T
REVEL	Pathogenic	0.92
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D;D;D
Polyphen		1.0	.;.;.;.;.;.;.;.;D;.
Vest4		0.91
MutPred		0.84		.;.;.;.;.;.;Loss of phosphorylation at S1026 (P = 0.0572);Loss of phosphorylation at S1026 (P = 0.0572);Loss of phosphorylation at S1026 (P = 0.0572);.;
MVP		0.90
MPC		1.7
ClinPred		0.95	D
GERP RS		4.2
Varity_R		0.60
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs763578184; hg19: chr9-138676704;