Hoffmeyer et al. found that a synonymous polymorphism 3435C > T was correlated with the level of P‐gp expression.5 Polymorphisms of ABCB1 may increase the efflux of chemotherapeutic drugs from cancer cells and thus increase their elimination from the body, resulting in a decrease of plasma concentrations, thereby affecting their therapeutic efficacy.18 The gene discussed is ABCB1; the disease is cancer.