rs766143485

Positions:

• chr17-70175158-G-A
• chr17-70175158-G-C

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 3P and 6B. PM1 PP2 BP4_Moderate BS2

The NM_000891.3(KCNJ2):​c.119G>A​(p.Arg40Gln) variant causes a missense change. The variant allele was found at a frequency of 0.0000304 in 1,614,054 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000039 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: KCNJ2 NM_000891.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:8 B:1
• Conservation: PhyloP100: 6.84

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 Likely_benign. Variant got -3 ACMG points.

• PM1: In a topological_domain Cytoplasmic (size 79) in uniprot entity KCNJ2_HUMAN there are 15 pathogenic changes around while only 0 benign (100%) in NM_000891.3
• 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.
• BP4: Computational evidence support a benign effect (MetaRNN=0.25481462).
• BS2: High AC in GnomAd4 at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNJ2	NM_000891.3	c.119G>A	p.Arg40Gln	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.119G>A	p.Arg40Gln	missense_variant	2/2	1	NM_000891.3	ENSP00000243457	P1
KCNJ2	ENST00000535240.1	c.119G>A	p.Arg40Gln	missense_variant	2/2	1		ENSP00000441848	P1

Frequencies

GnomAD3 genomes AF: 0.0000394 AC: 6 AN: 152162 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000966

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251464 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135906

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000462

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000294 AC: 43 AN: 1461892 Hom.: 0 Cov.: 32 AF XY: 0.0000193 AC XY: 14 AN XY: 727246

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.0000351

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000394 AC: 6 AN: 152162 Hom.: 0 Cov.: 32 AF XY: 0.0000404 AC XY: 3 AN XY: 74338

Gnomad4 AFR AF: 0.0000966

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000340

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:8 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Nov 29, 2018	The R40Q variant of uncertain significance in the KCNJ2 gene has been reported as a likely benign variant in one patient with primary electrical disease who also harbors a loss of function variant in the PKP2 gene (Proost et al., 2017). This variant is observed in 6/277196 (0.002%) alleles from individuals of multiple ethnic backgrounds in large population cohorts (Lek et al., 2016). The R40Q variant is a semi-conservative amino acid substitution, which may impact secondary protein structure as these residues differ in some properties. Finally, in-silico analyses, including protein predictors and evolutionary conservation, support that this variant does not alter protein structure/function. Therefore, based on the currently available information, it is unclear whether this variant is pathogenic or rare benign. -
Uncertain significance, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Mar 08, 2022	The KCNJ2 c.119G>A; p.Arg40Gln variant (rs766143485) is reported in the literature in an individual affected with fetal thrombotic vasculopathy (Munroe 2018), and an individual affected with primary electrical disease who also carried a pathogenic PKP2 variant (Proost 2017). This variant is also reported in ClinVar (Variation ID: 324830), but is only observed on five alleles in the Genome Aggregation Database, indicating it is not a common polymorphism. The arginine at codon 40 is moderately conserved, and computational analyses are uncertain whether this variant is neutral or deleterious (REVEL: 0.201). In vitro functional analyses demonstrate reduced channel function (Munroe 2018). However, given the limited clinical and functional data, the significance of this variant is uncertain at this time. References: Munroe PB et al. Postmortem Genetic Testing for Cardiac Ion Channelopathies in Stillbirths. Circ Genom Precis Med. 2018 Jan;11(1):e001817. PMID: 29874177. Proost D et al. Targeted Next-Generation Sequencing of 51 Genes Involved in Primary Electrical Disease. J Mol Diagn. 2017 May;19(3):445-459. PMID: 28341588. -

Andersen Tawil syndrome;C1865018:Short QT syndrome type 3;C3151431:Atrial fibrillation, familial, 9 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Aug 31, 2021

- -

SUDDEN INFANT DEATH SYNDROME Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Robert's Program, Boston Children's Hospital

Oct 01, 2021

We classify this variant as a variant of uncertain significance using ACMG/AMP criteria. As this variant has functional evidence supporting pathogenicty, we suspect this variant is favoring pathogenic. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 29, 2024

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 40 of the KCNJ2 protein (p.Arg40Gln). This variant is present in population databases (rs766143485, gnomAD 0.008%). This missense change has been observed in individual(s) with primary electrical disease (PED), however this individual also had a pathogenic variant in another PED-related gene (PMID: 28341588, 29874177). ClinVar contains an entry for this variant (Variation ID: 324830). 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 not expected to disrupt KCNJ2 protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change affects KCNJ2 function (PMID: 29874177). 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. -

Atrial fibrillation, familial, 9 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Andersen Tawil syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Short QT syndrome type 3 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Cardiovascular phenotype Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 22, 2023

This alteration is classified as benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.26
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Benign	0.37	T;T
Eigen	Benign	0.077
Eigen_PC	Uncertain	0.26
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.90	.;D
M_CAP	Benign	0.023	T
MetaRNN	Benign	0.25	T;T
MetaSVM	Benign	-0.93	T
MutationAssessor	Benign	1.8	L;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.79	T
PROVEAN	Benign	-0.79	N;N
REVEL	Benign	0.20
Sift	Benign	0.059	T;T
Sift4G	Benign	0.093	T;T
Polyphen		0.18	B;B
Vest4		0.56
MutPred		0.72		Loss of MoRF binding (P = 0.0659);Loss of MoRF binding (P = 0.0659);
MVP		0.68
MPC		0.96
ClinPred		0.17	T
GERP RS		5.7
Varity_R		0.14
gMVP		0.89

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: rs766143485; hg19: chr17-68171299;