Studies have also identified a Msp1 single nucleotide polymorphism in the CYP1A1 gene, a gene involved in estrogen metabolism and action, to be associated with breast cancer in AA but not in EA and the HSD17B1 312 Gly allele to be specifically associated with increased risk in AA for premenopausal breast cancer [28,29]. Here, CYP1A1 is linked to breast carcinoma.