title: Folate-responsive homocystinuria and "schizophrenia". A defect in methylation due to deficient 5,10-methylenetetrahydrofolate reductase activity.
abstract: Homocystinuria and homocystinemia without hypermthioninemia, but with reccurent episodes of folate responseive schizophrenic-like behavior, was documented in a mildly retarded adolescent girl who lacked the habitus associated with cystathionine synthase deficiency. Enzymes involved in homocysteine-methionine metabolism were demonstrated to be normal. A defect in the ability to reducte N-5-10--methylenetetrahydrofolate to 5-methyltetrahydrofolate was demonstrated. Methylenetetrahydrofolate reductase was 18 per cent of control values. Methyltetrahydrofolate is used for the methylation of homocysteine to methionine, and a deficiency of this compound could explain the homocystinemia and homocystinuria.
mesh_terms: D000293:Adolescent; D000429:Alcohol Oxidoreductases / Q000172:deficiency*; D003937:Diagnosis, Differential; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use*; D006710:Homocysteine / Q000378:metabolism; D006711:Homocystine / Q000097:blood / Q000652:urine; D006712:Homocystinuria / Q000175:diagnosis / Q000188:drug therapy / Q000201:enzymology*; D006801:Humans; D008715:Methionine / Q000097:blood / Q000378:metabolism; D008745:Methylation; D012559:Schizophrenia / Q000175:diagnosis / Q000201:enzymology* / Q000209:etiology; D013763:Tetrahydrofolates; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D013763:Tetrahydrofolates; D006710:Homocysteine; D006711:Homocystine; D005492:Folic Acid; D008715:Methionine; D000429:Alcohol Oxidoreductases; D014805:Vitamin B 12