Based on TPMT status, start with reduced starting doses (30%-80% of normal dose) if normal starting dose is 2-3 mg/kg/day (e.g., 0.6 – 2.4 mg/kg/day), and adjust doses of azathioprine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment (PMID 20354201, 11302950, 15606506, 16530532). NUDT15 phenotype could not be assigned based on genotyping. If thiopurines are required and NUDT15 status is unknown, monitor closely for toxicity.