Thota et al. used genomic DNA and polymerase chain reaction restriction fragment length polymorphism (PCR–RFLP) analysis to determine whether or not the prevalence of the four most prevalent polymorphs in the CYP2D6*4 (G1934A), CYP2D6*10 (C188T), CYP3A5*3, and CYP2C19*2 alleles have any relationship to breast cancer [56]. The gene discussed is CYP2D6; the disease is breast cancer.