homocystinuria due to methylene tetrahydrofolate reductase deficiency

Methylenetetrahydrofolate reductase deficiency

Methylenetetrahydrofolate reductase deficiency is the most common genetic cause of elevated serum levels of homocysteine (hyperhomocysteinemia). It is caused by genetic defects in MTHFR, which is an important enzyme in the methyl cycle. Common variants of MTHFR deficiency are asymptomatic and have only minor effects on disease risk. Severe variants (from nonsense mutations) are rare.