Based on NUDT15, 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 20354201, 11037857). However, TPMT phenotype could not be assigned based on genotyping performed. Consider evaluating TPMT erythrocyte activity to assess TPMT phenotype. If thiopurines are required and TPMT status is unknown, monitor closely for toxicity.