chr9-135758462-C-G

Position:

• chr9-135758462-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP3 PP5_Moderate

The NM_020822.3(KCNT1):​c.808C>G​(p.Gln270Glu) variant causes a missense change involving the alteration of a conserved nucleotide. 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 Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q270K) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: KCNT1 NM_020822.3 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.58

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_pathogenic. Variant got 9 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_020822.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-135758462-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2114585.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.827
• PP5: Variant 9-135758462-C-G is Pathogenic according to our data. Variant chr9-135758462-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 445339.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNT1	NM_020822.3	c.808C>G	p.Gln270Glu	missense_variant	10/31	ENST00000371757.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNT1	ENST00000371757.7	c.808C>G	p.Gln270Glu	missense_variant	10/31	1	NM_020822.3	A2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Center for Pediatric Genomic Medicine, Children's Mercy Hospital and Clinics

Sep 11, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Benign	0.30	.;.;.;.;.;.;.;.;.;T;.
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.65	D
MetaRNN	Pathogenic	0.83	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.6	.;.;.;.;.;.;.;.;.;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-2.8	.;.;D;D;D;.;.;.;.;D;D
REVEL	Uncertain	0.38
Sift	Uncertain	0.0030	.;.;D;D;D;.;.;.;.;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D;D;D;D;D;D;D
Polyphen		0.22	.;.;.;.;.;.;.;.;.;B;.
Vest4		0.98
MutPred		0.64		.;.;.;.;.;.;.;Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);Gain of helix (P = 0.2294);
MVP		0.92
MPC		1.1
ClinPred		0.98	D
GERP RS		4.9
Varity_R		0.74
gMVP		0.97

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: rs1554771476; hg19: chr9-138650308;