MTHFD1A gene on chromosome 14q24 that encodes an enzyme that has three distinct enzymatic activities:
• 5,10-methylenetetrahydrofolate dehydrogenase (E.C. 126.96.36.199);
• 5,10-methenyltetrahydrofolate cyclohydrolase (E.C. 188.8.131.52); and
• 10-formyltetrahydrofolate synthetase (E.C. 184.108.40.206).
These activities interconvert methyl (1-carbon) derivatives of tetrahydrofolate, which serve as substrates for methionine, thymidylate and de novo purine synthesis.
Defects in MTHFD1 may increase susceptibility to folate-sensitive neural tube defects and colorectal cancer.