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Background: The 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. Objectives: We 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. Design: One hundred sixty adults with trisomy 21 and 160 healthy, unrelated subjects aged 26 [+ or -] 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 [right arrow] T, MTHFR 1298A [right arrow] C, cystathionine [beta]-synthase 844Ins68, methionine synthase 2756A [right arrow] C, methionine synthase reductase 66A [right arrow] G, and reduced folate carrier 80G [right arrow] A polymorphisms was carried out. Results: The mean tHcy concentration (9.8 [+ or -] 0.7 [micro]mol/L) of cases who did not use vitamins was not significantly different from that of controls (9.4 [+ or -] 0.3 [micro]mol/L). Plasma tHcy concentrations (7.6 [+ or -] 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 [+ or -] 0.5 [micro]mol/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. Conclusion: This study provides information on the relation between several polymorphisms in genes involved in homocysteine and folate metabolism in adults with trisomy 21. KEY WORDS Down syndrome, trisomy 21, folate, homocysteine, polymorphism, CBS, MTR, MTRR, MTHFR, RFC, vitamin B-12, vitamin B-6

Background: An elevated plasma total homocysteine (tHcy) concentration seems to increase the risk of cardiovascular disease. Objective: We evaluated the determinants of tHcy in healthy French adults. Design: tHcy was measured by HPLC and fluorometric detection in 1.139 women and 931 men aged 35-60 y. Subjects were participants of the Supplementation with Antioxidant Vitamins and Minerals Study, which investigates the effects of antioxidant supplementation on chronic diseases. Red blood cell folate (RBCF), plasma vitamins B-6 and B-12, and cardiovascular disease risk factors were also measured. The habitual diet was assessed in 616 subjects. Cross-sectional analyses were adjusted for age, smoking, energy intake, and concentration or intake of folate and vitamin B-6, where appropriate. Results: The mean ([+ or -] SD) tHcy concentration was 8.74 [+ or -] 2.71 [micro]mol/L in women and 10.82 [+ or -] 3.49 [micro]mol/L in men. In women, tHcy was positively related to age (P = 0.001), apolipoprotein B (P < 0.01), serum triacylglycerol (P < 0.01), fasting glucose (P = 0.02), and coffee and alcohol consumption (both P < 0.01) and inversely related to RBCF (P = 0.11) and plasma vitamin B-12 (P = 0.08) and vitamin B-6 (P = 0.01) intakes. In men, tHcy was positively associated with body mass index (P = 0.03), blood pressure (P < 0.02), serum triacylglycerol (P < 0.01), fasting glucose (P = 0.01), and energy intake (P < 0.01) and inversely associated with physical activity (P = 0.04), RCBF (P = 0.02), plasma vitamin B-12 (P = 0.09), and dietary fiber (P < 0.01), folate (P = 0.03), and vitamin B-6 (P = 0.09) intakes. Conclusion: To control tHcy, decreasing coffee and alcohol consumption may be important in women, whereas increasing physical activity, dietary fiber, and folate intake may be important in men. KEY WORDS Homocysteine, habitual diet, folate, cardiovascular disease risk, men, women, coffee, Supplementation with Antioxident Vitamins and Minerals Study, France