Disorders of folate metabolism

Vitamin B9 (folic acid)

• Folate (pteroylglutamic acid) is found in leafy vegetables, legumes, liver
• Pteroylglutamic acid consists of pteridine, p-aminobenzoic acid and glutamic acid
• Reduction to dihydrofolate (DHF) and tetrahydrofolate (THF) occurs in folate metabolism
• It serves as a transporter of single-carbon residues, which is essential for the endogenous formation of methionine, thymidylate (dTMP) and two intermediates in purine synthesis.

Hereditary folate malabsorption

• Severe megaloblastic anemia, progressive neurological disorders
• Folate deficiency syndrome in the brain with reduced levels of folate transporter in the brain
• Treatment with high doses of folate orally or lower parenterally

Glutamate formimino transferase deficiency

• Histidine catabolism is associated with the transfer of the formimino group to THF with the concomitant release of ammonia
• It has two catalytic activities as glutamate formiminotransferase and as formiminotetrahydrofolate cyclodeaminase
• Psychomotor retardation, megaloblastic anemia
• Hyperhistinemia and histidinuria develop

Methylenetetrahydrofolate reductase deficiency (MTHFR)

MTHFR metabolism

• Methyl-THF is a methyl donor for the conversion of homocysteine to methionine and the MTHFR deficiency results in an increase in total plasma homocysteine concentration and a decrease in methionine concentration leading to developmental delay, microcephaly, convulsions, hyperhomocysteinemia

Links

• Vitamin B9
• Disorders of cobalamin metabolism
• Disorders of sulfur amino acid metabolism

Source

• FERNANDES, John. Diagnostika a léčba dědičných metabolických poruch. 1. vydání. Praha : Triton, 2008. s. 576-580. ISBN 978-80-7387-096-6.

• MURRAY, Robert K., Daryl K. GRANNER a Peter A. MAYES, et al. Harperova biochemie. 4. vydání. Jinočany : H & H, 2002. 872 s. ISBN 80-7319-013-3.