Increased breast cancer risk at high plasma folate concentrations among women with the MTHFR 677T allele.
BACKGROUND: Folate is involved in DNA synthesis and methylation and may thereby influence carcinogenesis. OBJECTIVES: We examined plasma folate (P-folate) concentration in relation to genotypes of the folate-metabolizing enzyme methylenetetrahydrofolate reductase [MTHFR 677C<--T (rs1801133) and 1298A<--C (rs1801131)]. We also explored whether P-folate was associated with risk of postmenopausal bre
