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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. [1] Common variants of MTHFR deficiency are asymptomatic and have only minor effects on disease risk. [2]
Methylenetetrahydrofolate reductase (MTHFR) is the rate-limiting enzyme in the methyl cycle, and it is encoded by the MTHFR gene. [5] Methylenetetrahydrofolate reductase catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate , a cosubstrate for homocysteine remethylation to methionine .
Vitamin B 12 deficiency prevents the 5-methyltetrahydrofolate (5-MTHF) form of folate from being converted into THF due to the "methyl trap". [18] This disrupts the folate pathway and leads to an increase in homocysteine which damages cells (for example, damage to endothelial cells can result in increased risk of thrombosis).
In response to decreased tetrahydrofolate (THF), the cell begins to transcribe more DHF reductase, the enzyme that reduces DHF to THF. Because methotrexate is a competitive inhibitor of DHF reductase, increased concentrations of DHF reductase can overcome the drugs inhibition. Many new drugs are under development to reduce antifolate drug ...
For people with the FOLR1 mutation, even when the systemic deficiency is corrected by folate, the cerebral deficiency remains and must be treated with folinic acid. Success depends on early initiation of treatment and treatment for a long period of time. [9] [3] Fewer than 20 people with the FOLR1 defect have been described in the medical ...
Methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1 (MTHFD1) is a gene located in humans on chromosome 14 [4] that encodes a protein, C-1-tetrahydrofolate synthase, cytoplasmic also known as C1-THF synthase, with three distinct enzymatic activities.
Tetrahydrofolic acid is a cofactor in many reactions, especially in the synthesis (or anabolism) of amino acids and nucleic acids.In addition, it serves as a carrier molecule for single-carbon moieties, that is, groups containing one carbon atom e.g. methyl, methylene, methenyl, formyl, or formimino.
5,10-Methenyltetrahydrofolate synthetase deficiency (MTHFS deficiency) is a rare neurodevelopmental disorder caused by mutations affecting the MTHFS gene, which encodes the enzyme 5,10-Methenyltetrahydrofolate synthetase. [2] The disease starts at birth or in early infancy and presents with microcephaly, short stature, and developmental delay.