17-70175952-A-G

Position:

• chr17-70175952-A-G

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_000891.3(KCNJ2):​c.913A>G​(p.Thr305Ala) 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 Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T305P) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCNJ2 NM_000891.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 9.32

Genes affected

KCNJ2 (HGNC:6263): (potassium inwardly rectifying channel subfamily J member 2) Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, probably participates in establishing action potential waveform and excitability of neuronal and muscle tissues. Mutations in this gene have been associated with Andersen syndrome, which is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-70175952-A-C is described in Lovd as [Pathogenic].
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KCNJ2. . Gene score misZ 2.7459 (greater than the threshold 3.09). Trascript score misZ 3.9347 (greater than threshold 3.09). GenCC has associacion of gene with long QT syndrome, short QT syndrome, Andersen-Tawil syndrome, familial atrial fibrillation, short QT syndrome type 3, catecholaminergic polymorphic ventricular tachycardia.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.994
• PP5: Variant 17-70175952-A-G is Pathogenic according to our data. Variant chr17-70175952-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 67591.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr17-70175952-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNJ2	NM_000891.3	c.913A>G	p.Thr305Ala	missense_variant	2/2	ENST00000243457.4	NP_000882.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNJ2	ENST00000243457.4	c.913A>G	p.Thr305Ala	missense_variant	2/2	1	NM_000891.3	ENSP00000243457.2
KCNJ2	ENST00000535240.1	c.913A>G	p.Thr305Ala	missense_variant	2/2	1		ENSP00000441848.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Andersen Tawil syndrome;C1865018:Short QT syndrome type 3 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 04, 2023

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Thr305 amino acid residue in KCNJ2. Other variant(s) that disrupt this residue have been observed in individuals with KCNJ2-related conditions (PMID: 17324964, 22589293, 24383070), which suggests that this may be a clinically significant amino acid residue. Experimental studies have shown that this missense change affects KCNJ2 function (PMID: 17341397). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt KCNJ2 protein function. ClinVar contains an entry for this variant (Variation ID: 67591). This missense change has been observed in individuals with catecholaminergic polymorphic ventricular tachycardia (CPVT) and Andersen-Tawil syndrome (PMID: 17341397, 27145478). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 305 of the KCNJ2 protein (p.Thr305Ala). -

Andersen Tawil syndrome Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Clinical Molecular Genetics Laboratory, Johns Hopkins All Children's Hospital

Aug 28, 2015

- -

Cardiac arrhythmia Other:1

not provided, no classification provided

literature only

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

-

This variant has been reported as associated with Arrhythmia in the following publications (PMID:17341397). This is a literature report, and does not necessarily reflect the clinical interpretation of the Imperial College / Royal Brompton Cardiovascular Genetics laboratory. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D;D
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	.;D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	H;H
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-4.8	D;D
REVEL	Pathogenic	0.98
Sift	Uncertain	0.0010	D;D
Sift4G	Uncertain	0.0020	D;D
Polyphen		1.0	D;D
Vest4		0.93
MutPred		0.98		Loss of glycosylation at T305 (P = 0.0577);Loss of glycosylation at T305 (P = 0.0577);
MVP		0.97
MPC		1.9
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.90
gMVP		0.92

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: rs199473387; hg19: chr17-68172093;