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TYMP gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TYMP gene

The TYMP gene provides instructions for an enzyme that regulates nucleoside levels and maintains mitochondrial DNA health.

Normal Function

The TYMP gene (previously known as ECGF1) provides instructions for making an enzyme called thymidine phosphorylase. This enzyme converts thymidine—a nucleoside used as a building block for DNA—into two smaller molecules: 2-deoxyribose 1-phosphate and thymine. By breaking down thymidine, this reaction helps regulate nucleoside levels in cells.

Thymidine phosphorylase is critical for maintaining appropriate thymidine levels in mitochondria. Mitochondria contain their own DNA, known as mitochondrial DNA (mtDNA), which requires nucleosides to build new molecules. Proper regulation of thymidine is essential for the maintenance and repair of mtDNA.

Health Conditions Related to Genetic Changes

Mitochondrial neurogastrointestinal encephalopathy disease

Approximately 50 variants in the TYMP gene have been identified in people with mitochondrial neurogastrointestinal encephalopathy (MNGIE) disease, a condition affecting the digestive and nervous systems.

  • Mechanism:TYMP variants reduce or eliminate thymidine phosphorylase activity, causing thymidine to build up to high levels in the body.
  • Impact: Excess thymidine damages mtDNA, disrupting maintenance and repair processes. This leads to mtDNA instability and potential mtDNA depletion, which impairs mitochondrial function.

Other Names for This Gene

  • ECGF1
  • endothelial cell growth factor 1 (platelet-derived)
  • gliostatin
  • hPD-ECGF
  • MNGIE
  • PD-ECGF
  • PDECGF
  • TdRPase
  • TP
  • TYPH_HUMAN

Frequently Asked Questions

Testing is usually done by targeted next‑generation sequencing or Sanger sequencing of the TYMP coding regions and exon‑intron boundaries. A peripheral blood sample (EDTA tube) provides DNA; in some labs, buccal swabs are acceptable. Results include identification of pathogenic variants, carrier status, or variants of uncertain significance.
MNGIE is inherited in an autosomal‑recessive manner. Both parents must carry one pathogenic TYMP allele; each subsequent child has a 25 % chance of being affected, a 50 % chance of being an asymptomatic carrier, and a 25 % chance of inheriting two normal alleles. Carrier testing of relatives and prenatal or pre‑implantation genetic diagnosis are available options for families.
Current strategies aim to lower plasma thymidine and deoxyuridine levels. Options include regular hemodialysis or peritoneal dialysis, enzyme replacement with allogeneic stem‑cell transplantation, and experimental gene‑therapy approaches delivering a functional TYMP copy. Dietary restriction of nucleosides has limited benefit, and treatment decisions are individualized based on disease severity and transplant eligibility.
Patients with chronic, progressive abdominal pain, severe constipation or pseudo‑obstruction, early‑onset weight loss, and episodes of vomiting—especially when accompanied by peripheral neuropathy, ophthalmoplegia, or leukoencephalopathy—should be evaluated for MNGIE. The combination of gut dysmotility and neurologic signs is a red flag that warrants TYMP sequencing or deletion analysis.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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