Thiopurine methyltransferase polymorphisms in children with acute lymphoblastic leukemia.

Introduction: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. 6-mercaptopurine (6-MP) and methotrexate are backbone drugs for maintenance phase of treatment. Purine Analogs 6-MP/6-thioguanine/azathiopurine are metabolized to its inactive form by the enzyme thiopurine methyltransferase (TPMT).