Gene
TK2
thymidine kinase 2
- HGNC 11831(opens in a new tab)
- Ensembl gene ENSG00000166548(opens in a new tab)
- NCBI Gene 7084(opens in a new tab)
Summary
- Cytogenetic location
- 16q21
- Coordinates
- Chromosome 16: 66,508,003–66,550,122 (GRCh38)
- Exons
- 10 exons across 42.1 kb
- Protein
- 265 amino acids
- Also known as
- SCA31
- MANE Select transcript
- ENST00000544898.6NM_004614.5
- Locus type
- gene with protein product
- Very high
- Confident
- Low
- Very low
Reference genomeGRCh38hg38
Positions on gene and variant pages follow this choice, in this browser.
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Primary Mitochondrial Disease
- Mitochondrial DNA Depletion Syndrome
Caused by variants in nuclear genes such as POLG, TWNK, TK2, DGUOK, MPV17, RRM2B and SUCLA2, which reduce the amount of mitochondrial DNA and can cause muscle, liver or brain disease.
- 3 GenCC submitters rate it definitive or strong
What knowing changes
Knowing is directly actionable: valproate must be avoided in POLG disease because of the risk of fatal liver failure, and TK2 deficiency has a nucleoside therapy.
How TK2 is laid out
- Coding sequence
- Untranslated region
- Intron
- Direction of transcription
- Known disease-causing sites
- Stretches short reads find hard
Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.
Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).
Nearby genes from Ensembl release 116, on GRCh38.
Exons make up 4.8 kb of the gene's 42.1 kb; 798 of those bases code for the protein.
How a genome test reads TK2
76
positions in TK2 where ClinVar classes a change as pathogenic or likely pathogenic
None of them falls in a region short reads find hard.
A whole genome covers all 42.1 kb of TK2, introns included, not only the 4.8 kb of exons.
Traits linked to TK2
The Human Phenotype Ontology lists these as features of the rare conditions TK2 can cause. Each trait's page lists the other genes linked to it.
Abnormality of the nervous system
- Difficulty articulating speech
- Peripheral neuropathy
- Pins and needles feeling
- Sensory axonal neuropathy
- Abnormal cerebral white matter morphology
- Abnormal cerebrospinal fluid morphology
- Action tremor
- Ataxia
Show 17 more traits
- Decreased reflex response
- Decreased sensation in extremities
- Degeneration of cerebellum
- Degeneration of cerebrum
- Depression
- Parkinsonism with favorable response to dopaminergic medication
- Shuffled walk
- Slow movements
- Stooped posture
- Cognitive impairment
- Abnormal basal ganglia morphology
- Delayed motor skills
- Epilepsy
- Inability to walk
- Intellectual disability
- Irritability
- Loss of ability to walk in early childhood
External links
Gene records
Transcript
Protein
Where this comes from
- HGNC: the gene's symbol, name, other symbols and location.
- MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
- GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
- The ACMG secondary findings list, SF v3.2.
- ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
- The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
- Data release 2026.10.16-c6eea6bf.
Cite this page
Dante Labs. (n.d.). TK2 gene: thymidine kinase 2. Retrieved 16 October 2026, from https://dantelabs.com/genes/tk2
Dante Labs. TK2 gene: thymidine kinase 2 [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/tk2
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