UGT1A7 and breast cancer: Specifically, it was reported that cytosine/cytosine homozygous genotype of cytochrome P450 XIB2 (CYP11B2) was associated with reduced breast cancer risk at younger age, but increased risk at older age (Ralph et al. 2007), and homozygous cytosine-guanine (CG/CG) genotype of uridine phosphorylase glycosyltransferase 1A7 (UGT1A7) was associated with increased breast cancer risk at younger ages but decreased risk at older ages (Ralph et al. 2007).