MTHFR and breast cancer: López-Cortés et al. [103] did not find statistically significant differences between breast cancer subtypes but reported an association between the heterozygous C/T and homozygous mutant T/T genotypes for the c.665C>T (rs1801133) polymorphism, and a lower MTHFR messenger RNA (mRNA) expression in triple-negative breast cancer (TNBC) tumors.