• Nathalie Fillon-Emery, Abalo Chango, Clotilde Mircher, Françoise Barbé, Henri Bléhaut, Bernard Herbeth, David S Rosenblatt, Marie-Odile Réthoré, Daniel Lambert, and Jean Pierre Nicolas.
• Faculté de Médecine, Laboratory of Medical Biochemistry, Vandoeuvre-Lès-Nancy, France.
• Am. J. Clin. Nutr. 2004 Dec 1;80(6):1551-7.

BackgroundThe effects of supplementation with B vitamins and of common polymorphisms in genes involved in homocysteine metabolism on plasma total homocysteine (tHcy) concentrations in trisomy 21 are unknown.ObjectivesWe aimed to determine the effects of orally administered folic acid and of folic acid combined with vitamin B-12, vitamin B-6, or both on tHcy in adults with trisomy 21. The study was also intended to analyze the possible influence of gene polymorphisms.DesignOne hundred sixty adults with trisomy 21 and 160 healthy, unrelated subjects aged 26 +/- 4 y were included. Plasma tHcy, red blood cell folate, serum folate, and vitamin B-12 were measured. Genotyping for the common methylenetetrahydrofolate reductase (MTHFR) 677C-->T, MTHFR 1298A-->C, cystathionine beta-synthase 844Ins68, methionine synthase 2756A-->C, methionine synthase reductase 66A-->G, and reduced folate carrier 80G-->A polymorphisms was carried out.ResultsThe mean tHcy concentration (9.8 +/- 0.7 micromol/L) of cases who did not use vitamins was not significantly different from that of controls (9.4 +/- 0.3 micromol/L). Plasma tHcy concentrations (7.6 +/- 0.3 mmol/L) in cases who used folic acid were significantly lower than in cases who did not. Folic acid combined with vitamin B-12 did not significantly change tHcy concentrations compared with those in cases who used only folic acid. Folic acid combined with vitamins B-6 and B-12 significantly lowered tHcy (6.5 +/- 0.5 micromol/L). The difference in tHcy according to MTHFR genotype was not significant. However, tHcy concentrations were slightly higher in TT homozygotes among the controls but not among the cases.ConclusionThis study provides information on the relation between several polymorphisms in genes involved in homocysteine and folate metabolism in adults with trisomy 21.

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