Genetic Variant KCNJ18:p.Ala200Pro (chr17-21703384-G-C) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PP3_Strong

The NM_001194958.2(KCNJ18):c.598G>C(p.Ala200Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,610,338 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAd4), which may indicate mosaicism or somatic mutations in the reference population data. In-silico tool predicts a pathogenic outcome for this variant. 9/15 in silico tools predict a damaging outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 49)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

KCNJ18
NM_001194958.2 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 8.25

Publications

4 publications found

Variant links:

Genes affected

KCNJ18 (HGNC:39080): (potassium inwardly rectifying channel subfamily J member 18) This gene encodes a member of the inwardly rectifying potassium channel family. Transcription of this locus is regulated by thyroid hormone, and the encoded protein plays a role in resting membrane potential maintenance. Mutations in this locus have been associated with thyrotoxic hypokalemic periodic paralysis. [provided by RefSeq, Jan 2013]

KCNJ18 Gene-Disease associations (from GenCC):

thyrotoxic periodic paralysis, susceptibility to, 2
Inheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics

KCNJ18 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.97

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNJ18	NM_001194958.2 link	c.598G>C	p.Ala200Pro	missense_variant	Exon 3 of 3	ENST00000567955.3	NP_001181887.2
KCNJ18	XM_005276919.4 link	c.904G>C	p.Ala302Pro	missense_variant	Exon 2 of 2		XP_005276976.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNJ18	ENST00000567955.3 link	c.598G>C	p.Ala200Pro	missense_variant	Exon 3 of 3	1	NM_001194958.2	ENSP00000457807.2

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152296

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000961

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.0000137

AC:

AN:

1457924

Hom.:

Cov.:

149

AF XY:

0.0000124

AC XY:

AN XY:

725168

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33408

American (AMR)

AF:

0.00

AC:

AN:

44532

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26080

East Asian (EAS)

AF:

0.000455

AC:

AN:

39600

South Asian (SAS)

AF:

0.00

AC:

AN:

85996

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51318

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1110916

Other (OTH)

AF:

0.0000332

AC:

AN:

60306

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.383

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000328

AC:

AN:

152414

Hom.:

Cov.:

AF XY:

0.0000537

AC XY:

AN XY:

74536

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

41598

American (AMR)

AF:

0.00

AC:

AN:

15314

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.000963

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10632

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68050

Other (OTH)

AF:

0.00

AC:

AN:

2116

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.285

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

ExAC

AF:

0.0000247

AC:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Pathogenic

0.54

BayesDel_noAF

Pathogenic

0.54

CADD

Pathogenic

(source)

DEOGEN2

Pathogenic

0.83

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.99

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.98

M_CAP

Uncertain

0.21

MetaRNN

Pathogenic

0.97

MetaSVM

Pathogenic

1.1

PhyloP100

8.3

PrimateAI

Pathogenic

0.85

PROVEAN

Pathogenic

-4.8

Sift

Uncertain

0.0010

Sift4G

Uncertain

0.0020

Vest4

0.72

MutPred

0.95

Loss of MoRF binding (P = 0.0508);

MVP

0.31

ClinPred

0.99

GERP RS

5.3

gMVP

0.94

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over