rs281865487

Variant names:

• chr16-66541919-G-A
• rs281865487
• ENST00000527800.6:c.-101C>T

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM2 PP3_Moderate PP5_Very_Strong

The NM_001272050.2(TK2):​c.-101C>T variant causes a 5 prime UTR premature start codon gain change. The variant allele was found at a frequency of 0.00000205 in 1,461,868 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TK2 NM_001272050.2 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 4.41
• Publications: 5 publications found

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: PanelApp Australia, Orphanet, Labcorp Genetics (formerly Invitae), G2P
• autosomal recessive progressive external ophthalmoplegia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.938
• PP5: Variant 16-66541919-G-A is Pathogenic according to our data. Variant chr16-66541919-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 38979.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001272050.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TK2	NM_004614.5	MANE Select	c.191C>T	p.Thr64Met	missense	Exon 3 of 10	NP_004605.4
	TK2	NM_001272050.2		c.-101C>T		5_prime_UTR_premature_start_codon_gain	Exon 3 of 10	NP_001258979.1	O00142-5
	TK2	NM_001172645.2		c.191C>T	p.Thr64Met	missense	Exon 3 of 9	NP_001166116.1	O00142-4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TK2	ENST00000527800.6	TSL:1	c.-101C>T		5_prime_UTR_premature_start_codon_gain	Exon 2 of 9	ENSP00000433770.1	O00142-5
	TK2	ENST00000544898.6	TSL:1 MANE Select	c.191C>T	p.Thr64Met	missense	Exon 3 of 10	ENSP00000440898.2	O00142-1
	TK2	ENST00000451102.7	TSL:1	c.98C>T	p.Thr33Met	missense	Exon 3 of 10	ENSP00000414334.4	O00142-2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000795 AC: 2 AN: 251476 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461868 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727228

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.0000187 AC: 1 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111998

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000295 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
3	-	-	not provided (3)
2	-	-	Mitochondrial DNA depletion syndrome, myopathic form;C4310734:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 3 (2)
1	-	-	Mitochondrial disease (1)
1	-	-	Mitochondrial DNA depletion syndrome (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	33
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.94
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H
PhyloP100		4.4
PrimateAI	Uncertain	0.64	T
PROVEAN	Pathogenic	-5.3	D
REVEL	Pathogenic	0.91
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.88
MutPred		0.80		Loss of methylation at K105 (P = 0.0303)
MVP		1.0
MPC		1.1
ClinPred		0.99	D
GERP RS		6.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.86
gMVP		0.90
Mutation Taster		=2/98	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
Splicevardb		2.0
SpliceAI score (max)		0.040		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: rs281865487; hg19: chr16-66575822;