It has been suggested that CYP19 variation may enhance breast cancer development in some women [19], and that the potentially functional CYP19_630 3 bp Del/Ins polymorphism and the CYP19_681 (TTTA)n polymorphism may play a low penetrance role in breast cancer susceptibility in an ethnic specific manner [20]. The gene discussed is CYP19A1; the disease is breast cancer.