In terms of the coding region, CYP2B6*2 (c.64C > T) and CYP2B6*4 (c.785A > G) mutations increased enzyme activity, which significantly increased the risk of ADR (hemorrhagic cystitis and oral mucositis, respectively) for people with these allele mutations (Rocha et al., 2009). The gene discussed is CYP2B6; the disease is oral mucositis.