Homozygosity at the C677T of the MTHFR gene is associated with increased breast cancer risk in the Turkish population.

BACKGROUND Folate deficiency is implicated in cancer development. Single nucleotide polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene can modulate the effect of folate. In this case-controlled study, a possible effect of the common MTHFR C677T (ala-->val) polymorphism on breast cancer susceptibility in Turkish patients was investigated. MATERIALS AND METHODS Polymorphism analysis was performed by melting curve analysis. RESULTS The variant allele valine (677T) was more frequent among the patients (30.1%) than in controls (23.9%). This difference was weakly significant (p = 0.046; OR = 1.37) and due to a significantly higher frequency of the valine homozygotes (677TT) among the patients (12.1% vs. 5.4%; p = 0.013, OR = 2.5). Among the patients diagnosed at more than 40 years of age, a more pronounced association of the valine homozygotes with breast cancer risk was observed (p = 0.009; OR = 3.3). CONCLUSION Homozygosity for the low-activity C677T genotype (TT) may represent a genetic determinant increasing breast cancer risk.