TYMP (thymidine phosphorylase) is a cytosolic enzyme that catalyzes the reversible phosphorolysis of thymidine, producing molecules utilized for carbon and energy sources or pyrimidine base rescue for nucleotide synthesis 1. The enzyme functions as a homodimer and plays a critical role in maintaining balanced mitochondrial nucleotide pools essential for mtDNA synthesis 1. TYMP deficiency is the primary cause of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), a rare autosomal recessive mitochondrial DNA depletion syndrome 23. In MNGIE, TYMP mutations lead to thymidine phosphorylase deficiency, causing accumulation of thymidine and deoxyuridine that impairs mitochondrial DNA maintenance and integrity 2. The disease typically presents in the second decade with severe gastrointestinal dysmotility and peripheral neuropathy, with a mean age at death of 37 years 23. Beyond MNGIE, TYMP has emerged as a potential biomarker in multiple sclerosis, where higher plasma levels show protective effects 4, and in glioma metabolism, where it represents a key metabolic biomarker linked to nucleotide metabolism reprogramming 5. The protein also appears elevated in cerebrospinal fluid of multiple sclerosis patients and correlates with disability outcomes 6.