BMS 460 Lecture Notes - Endothelin, Von Willebrand Factor, Thromboplastin
26 Apr 2014
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Document Summary
Folate deficiency during first two months of pregnancy may result in neural tube defects. Women with reduced activity of 5,10-methylene-tetrahydrofolate reductase exhibit elevated levels of homocysteine and are at risk for bearing children with neural tube and other birth defects, e. g. , spina bifida. Pharmacologic doses of folic acid have been shown to reduce the incidence of neural tube defects by lowering plasma levels of homocysteine. Methylenetetrahydrofolate reductase (mthfr) catalyzes the conversion of 5,10- methylenethf to 5-methylthf, a cosubstrate for homocysteine remethylation to methionine. Folate dihydrofolate tetrahydrofolate methylene-thf methyl-thf. Homocysteine is a teratogen for the cns and heart. Failure to recycle homocysteine into methionine or to convert it into cysteine results in elevated levels of homocysteine. Mutations in mthfr gene causes deficiency of this enzyme, the most prevalent inborn error of folate metabolism, and has variable clinical manifestations from asymptomatic to severe psychomotor retardation, microcephalus and seizure.
