NM_000891.3:c.913A>G

Variant names:

• chr17-70175952-A-G
• rs199473387
• NM_000891.3:c.913A>G

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 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
• Publications: 12 publications found

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]

KCNJ2 Gene-Disease associations (from GenCC):

• Andersen-Tawil syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, G2P, Labcorp Genetics (formerly Invitae)
• short QT syndrome type 3

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• short QT syndrome

  Inheritance: AD Classification: MODERATE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• familial atrial fibrillation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• catecholaminergic polymorphic ventricular tachycardia

  Inheritance: AD Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Genomics England PanelApp
• long QT syndrome

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 uncertain in NM_000891.3
• 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 ClinVar as Pathogenic. ClinVar VariationId is 30120.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP2: Missense variant in the KCNJ2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 51 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 2.7459 (below the threshold of 3.09). Trascript score misZ: 3.9347 (above the threshold of 3.09). GenCC associations: The gene is linked to short QT syndrome type 3, short QT syndrome, Andersen-Tawil syndrome, familial atrial fibrillation, catecholaminergic polymorphic ventricular tachycardia, long QT syndrome.
• 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 VariationId is 67591.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNJ2	NM_000891.3	c.913A>G	p.Thr305Ala	missense_variant	Exon 2 of 2	ENST00000243457.4	NP_000882.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNJ2	ENST00000243457.4	c.913A>G	p.Thr305Ala	missense_variant	Exon 2 of 2	1	NM_000891.3	ENSP00000243457.2
KCNJ2	ENST00000535240.1	c.913A>G	p.Thr305Ala	missense_variant	Exon 2 of 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

Jun 04, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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). This variant is not present in population databases (gnomAD no frequency). 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).

Andersen Tawil syndrome Pathogenic:1

Aug 28, 2015

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

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

Cardiac arrhythmia Other:1

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

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

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
LIST_S2	Benign	0.0	.;D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	H;H
PhyloP100		9.3
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-4.8	D;D
Sift	Uncertain	0.0010	D;D
Sift4G	Uncertain	0.0020	D;D
Vest4		0.93
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.90
gMVP		0.92
Mutation Taster		=1/99	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs199473387; hg19: chr17-68172093;