ABCB1 and acute lymphoblastic leukemia: MDR1 (G2677T) rs2032582, IL18 (607C > A) rs1946518, and IL18 (-137G > C) rs187238 variants were genotyped in 100 childhood ALL (58 male and 42 female) cases and 100 healthy controls (49 male and 51 female) using the tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) technique.