Based on TPMT status, start with normal starting dose (e.g., 40-60 mg/m2/day) and adjust doses of thioguanine and of other myelosuppressive therapy without any special emphasis on thioguanine. Allow 2 weeks to reach steady-state after each dose adjustment (PMID 203542+J1301, 11037857). NUDT15 status could not be determined based on genotyping. If thiopurines are required and NUDT15 status is unknown, monitor closely for toxicity.