1-196235993-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_198503.5(KCNT2):c.3289G>A(p.Asp1097Asn) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNT2 NM_198503.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.33

Genes affected

KCNT2 (HGNC:18866): (potassium sodium-activated channel subfamily T member 2) Enables chloride-activated potassium channel activity. Involved in potassium ion export across plasma membrane. Located in plasma membrane. Implicated in developmental and epileptic encephalopathy 57. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.832

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT2	NM_198503.5	c.3289G>A	p.Asp1097Asn	missense_variant	27/28	ENST00000294725.14

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT2	ENST00000294725.14	c.3289G>A	p.Asp1097Asn	missense_variant	27/28	1	NM_198503.5	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1431532 Hom.: 0 Cov.: 25 AF XY: 0.00 AC XY: 0 AN XY: 714040

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Developmental and epileptic encephalopathy, 57 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Jun 11, 2020

Based on the classification scheme VCGS_Germline_v1.1.1, this variant is classified as 3C-VUS. Following criteria are met: 0103 - Both loss- and gain-of-function are known mechanisms of disease for this gene. Gain of function, loss of function, change of function, and the possibility of a dominant negative mechanism, have all been reported for pathogenic KCNT2 variants in patients with early-onset epileptic encephalopathies, including epilepsy of infancy with migrating focal seizures (PMID: 29069600, PMID: 29740868, PMID: 32038177). (N) 0107 - This gene is known to be associated with autosomal dominant disease. (N) 0200 - Variant is predicted to result in a missense amino acid change from aspartic acid to asparagine (exon 27). (N) 0251 - Variant is heterozygous. (N) 0301 - Variant is absent from gnomAD. (P) 0504 - Same amino acid change has been observed in mammals. (B) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (N) 0705 - No comparable variants have previous evidence for pathogenicity. (N) 0807 - Variant has not previously been reported in a clinical context. (N) 0905 - No segregation evidence has been identified for this variant. (N) 1007 - No published functional evidence has been identified for this variant. (N) 1208 - Inheritance information for this variant is not currently available. (N) Legend: (P) - Pathogenic, (N) - Neutral, (B) - Benign -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Benign	-0.053	T
BayesDel_noAF	Benign	-0.31
Cadd	Pathogenic	29
Dann	Pathogenic	1.0
Eigen	Pathogenic	0.84
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	1.0	D;D;D
M_CAP	Uncertain	0.24	D
MetaRNN	Pathogenic	0.83	D;D;D
MetaSVM	Uncertain	0.068	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-4.2	D;.;D
REVEL	Uncertain	0.48
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.82
MutPred		0.67		.;.;Loss of sheet (P = 0.0457);
MVP		0.32
MPC		1.2
ClinPred		1.0	D
GERP RS		5.7
Varity_R		0.76
gMVP		0.90

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr1-196205123; COSMIC: COSV54073872;