CYP1A1 and breast cancer: Studying polymorphisms in genes involved in xenobiotic metabolism and oestrogen biosynthesis, CYP1A1, CYP1B1, COMT and CYP17, CYP19 and the BRCA1 founder mutation in relation to breast cancer risk, Ghisari et al. (164) found that the BRCA1 founder mutation and polymorphisms in CYP1A1 and CYP17 can increase breast cancer risk among Inuit women and that risk increases with higher serum levels of PFOS and PFOA.