dbSNP rs281865492: TK2:p.Arg130Pro (chr16-66529054-C-G) – ACMG Classification: Likely_pathogenic (8 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1PM2PM5PP3_Moderate

The NM_004614.5(TK2):c.389G>C(p.Arg130Pro) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,744 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R130Q) has been classified as Likely pathogenic.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TK2
NM_004614.5 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 4.44

Publications

0 publications found

Variant links:

Genes affected

TK2 (HGNC:11831): (thymidine kinase 2) This gene encodes a deoxyribonucleoside kinase that specifically phosphorylates thymidine, deoxycytidine, and deoxyuridine. The encoded enzyme localizes to the mitochondria and is required for mitochondrial DNA synthesis. Mutations in this gene are associated with a myopathic form of mitochondrial DNA depletion syndrome. Alternate splicing results in multiple transcript variants encoding distinct isoforms, some of which lack transit peptide, so are not localized to mitochondria. [provided by RefSeq, Dec 2012]

TK2 Gene-Disease associations (from GenCC):

mitochondrial disease
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
mitochondrial DNA depletion syndrome, myopathic form
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae)
autosomal recessive progressive external ophthalmoplegia
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

TK2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PM1

In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 uncertain in NM_004614.5

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr16-66529054-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 38989.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.879

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TK2	NM_004614.5 link	c.389G>C	p.Arg130Pro	missense_variant	Exon 6 of 10	ENST00000544898.6	NP_004605.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TK2	ENST00000544898.6 link	c.389G>C	p.Arg130Pro	missense_variant	Exon 6 of 10	1	NM_004614.5	ENSP00000440898.2

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461744

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727170

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:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39696

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53290

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111998

Other (OTH)

AF:

0.00

AC:

AN:

60396

⚠️ 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: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.97

BayesDel_addAF

Pathogenic

0.48

BayesDel_noAF

Pathogenic

0.45

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.93

D;.;D;.;.;.;.;D;.;.;.;D;D

Eigen

Pathogenic

0.78

Eigen_PC

Pathogenic

0.74

FATHMM_MKL

Uncertain

0.97

LIST_S2

Uncertain

0.96

D;D;.;D;.;D;D;D;.;D;D;D;D

M_CAP

Uncertain

0.25

MetaRNN

Pathogenic

0.88

D;D;D;D;D;D;D;D;D;D;D;D;D

MetaSVM

Pathogenic

0.92

MutationAssessor

Pathogenic

3.1

M;.;M;.;.;.;.;.;.;.;.;.;.

PhyloP100

4.4

PrimateAI

Uncertain

0.50

PROVEAN

Benign

0.0

.;.;.;.;D;D;D;D;D;.;.;.;.

REVEL

Pathogenic

0.86

Sift

Pathogenic

0.0

.;.;.;.;D;D;D;D;D;.;.;.;.

Sift4G

Uncertain

0.013

D;D;D;D;D;D;D;D;D;D;D;.;.

Vest4

0.94

ClinPred

1.0

GERP RS

5.6

Varity_R

0.96

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over