Based on NUDT15, reduce starting doses to 25% of normal dose and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 4-6 weeks to reach steady-state after each dose adjustment. In setting of myelosuppression, emphasis should be on reducing thioguanine over other agents. For non-malignant conditions, consider alternative non-thiopurine immunosuppressant therapy (PMID 20354201). 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.