{"Thioguanine can be affected by a patient's TPMT and NUDT15 phenotype. This patient is predicted to be a NUDT15 poor metabolizer and is at high risk for life threatening myelosuppression with normal doses of thioguanine and should receive drastically reduced doses. Reduce daily dose by 10-fold (~90% dose reduction) and reduce frequency to 3 times per week instead of daily. During therapy, adjust thioguanine doses based on degree of myelosuppression and disease-specific guidelines. It usually takes at least 4-6 weeks of stable dosing to reach steady state after each dose adjustment. If myelosuppression occurs, emphasis should be on reducing thioguanine over other agents. TPMT phenotype could not 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 thioguanine is required and TPMT status is unknown, monitor closely for toxicity. Please consult a clinical pharmacist for more information."}