Background: MDR1, one of the most important drug-transporter genes, encodes P- glycoprotein (P-gp)-atransporter involved in protecting against xenobiotics and multi-drug resistance. The significance of the geneticbackground in childhood acute lymphoblastic leukemia (ALL) is not well understood. Materials and
Methods:To evaluate whether C3435T and C1236T MDR1 polymorphisms are associated with the occurrence and outcomeof ALL, 208 children with ALL (median age 5.0 yr) and 101 healthy Thai children were studied by polymerasechain reaction-restriction fragment-length polymorphism (PCR-RFLP) assay.
Results: C3435T and C1236TMDR1 polymorphism are significantly associated with the high-risk group (OR= 2.6, 95%CI =1.164-5.808; P=0.028 and OR= 2.231, 95%CI =1.068-4.659; p=0.047, respectively), indicating that both may be candidates formolecular markers in the high-risk group of ALL.