{"Azathioprine can be affected by a patient's TPMT and NUDT15 phenotype. Neither TPMT or NUDT15 phenotype could be assigned based on genotyping performed. Consider evaluating TPMT erythrocyte activity to assess TPMT phenotype. Erythrocyte TPMT activity test results can be falsely low at diagnosis of leukemia and is unreliable in the case of recent red blood cell transfusions. If thiopurines are required and either TPMT or NUDT15 status is unknown, monitor closely for toxicity. Please consult a clinical pharmacist for more information."}