Influence of methylenetetrahydrofolate reductase genotype, age, vitamin B-12, and folate status on plasma homocysteine in children.

BACKGROUND Several studies have examined the association of the methylenetetrahydrofolate reductase (MTHFR) genotype with plasma homocysteine in adults, but few studies have been performed in children. OBJECTIVE We measured the concentrations of plasma total homocysteine, folate, and vitamin B-12 in a group of healthy fasting children and related these to MTHFR genotype. DESIGN After the subjects fasted, blood samples were collected into EDTA-containing tubes. Plasma, red blood cells, and the buffy coat were immediately stored at -80 degrees C for biochemical and molecular analyses. Plasma total homocysteine was determined by HPLC. Folate and vitamin B-12 were measured by a double-labeled radioimmunoassay, and the genotypic analysis was performed by polymerase chain reaction amplification of genomic DNA extracted from blood leukocytes. RESULTS Plasma homocysteine concentrations correlated negatively with folate and vitamin B-12(,) but positively with age (P: < 0. 0001). Whereas folate and vitamin B-12 accounted for 27% and 19% of the variation in homocysteine, respectively, age accounted for 48% of the variation. When the cohort was divided into older (>10 y) and younger (10 y. CONCLUSION Our data show that in a healthy pediatric population, MTHFR genotype played a significant role in determining homocysteine concentrations in older (>10 y), nutritionally stressed children.