The C allele of rs55886062 is assigned a no function allele by CPIC. Patients with the AA genotype and cancer who are treated with capecitabine, a fluoropyrimidine-based chemotherapy, may have decreased, but not absent, risk of drug toxicity as compared to patients with the AC or CC genotype. However, conflicting evidence has been reported. Other genetic and clinical factors may also influence risk of drug toxicity.