MTHFR and breast cancer: Other risk factors reported for breast cancer include mutations in the p53-inducible protein phosphatase PPM1D (protein phosphatase, Mg2+/Mn2+ dependent, 1D) [41], MTHFR (methylene­tetrahydrofolate reductase), Ala222Val gene polymorphisms [42], and APOBEC3B (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3B) overexpression [43].