RESUMO
BACKGROUND: Several studies have examined the association between the methylenetetrahydrofolate reductase (MTHFR) genotype and plasma homocysteine concentrations in adults but few studies have been performed in children. OBJECTIVE: To determine plasma concentrations of total homocysteine, folate, vitamin B12, and red cell folate in a group of healthy children and to determine their possible relationship with the MTHFR genotype. SUBJECTS AND METHODS: Eighty-three subjects (45 boys and 38 girls), aged between 1 week and 18 years, were included in the study. Plasma and whole blood samples were stored at 80 C for biochemical and molecular analysis. Plasma total homocysteine was determined by fluorescence polarization immunoassay. Serum concentrations of folate, vitamin B12, and red cell folate were measured by electrochemiluminescence immunoassay. Genotypic analysis was performed by polymerase chain reaction amplification of genomic DNA extracted from blood leukocytes. RESULTS: Plasma homocysteine concentrations were negatively correlated with folate, vitamin B12, and red cell folate but were positively correlated with age (p < 0.005). There was an association between age-MTHFR genotype and folic acid, vitamin B12, and red cell folate, but not with homocysteine concentrations. CONCLUSIONS: Our results suggest that in a healthy pediatric population, homocysteine concentrations are determined by biochemical factors, such as folic acid, more than by genetic factors.