描述
Methylenetetrahydrofolate reductase deficiency (MTHFRD; Homocystinuria due to defect of n(5,10)-methylene THF deficiency) is caused by a defect in the MTHFR gene which codes for methylenetetrahydrofolate reductase. Methylenetetrahydrofolate reductase catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. A defect in this enzyme results in accumulation of homocysteine and methionine in both plasma and urine. Some of the symptoms and signs include mental retardation, withdrawal, hallucinations, delusions, muscle weakness. Some patients remain asymptomatic until adulthood.