Association between MDR1 C3435T Gene Polymorphism and Acute Lymphoblastic Leukemia (ALL) in Iranian Population

P-glycoprotein (P-gp), an ATP-dependent efflux pump, is a membrane protein encoded by MDR1 gene. P-gp has an important role in protection of the cell against xenobiotics and toxic compounds. Recently, a silent C3435T polymorphism in exon 26 of MDR1 has been reported to be associated with a decreased expression of P-gp in TT genotypes carriers compared with CC genotypes carriers. To evaluate the distribution of allelic variants of C3435T MDR1 in a group of healthy population in Iran and find the association between MDR1 C3435T polymorphism and the incidence of ALL, 126 patients with ALL and 139 healthy controls were included in our study and their MDR1 polymorphisms were detected by PCRRFLP assay. 71.9% of the healthy people had 3435TC genotype, 15.8% had 3435TT genotype and 12.2% had 3435CC genotype. Also, the frequency of T allele was 51.8% and C allele 48.2%. The mutant homozygous TT and TC genotypes were found to be associated with the incidence of ALL (OR=1.96 for TT genotype and OR=0.53 for TC genotype). MDR1 C3435T polymorphism may contribute to the incidence of ALL. TT genotypes carriers are more at risk of developing ALL than other genotypes carriers.