Human CYP19 gene, which encodes aromatase cytochrome P450 is another plausible candidate gene where some studies have suggested association of common variants with significant breast cancer risk (Haiman et al. 2003; Ralph et al. 2007), while other studies suggested no association of any SNPs in CYP19 with breast cancer risk (Healey et al. 2000). The gene discussed is CYP19A1; the disease is breast cancer.