The two studies reported to date regarding the association of GSTO polymorphism with the susceptibility of childhood ALL have not analyzed their impact on therapeutic outcome (15, 22), and in this regard, our study is the first to report the impact of GSTO1 (rs4925: C>A) and GSTO2 (rs156697: A>G) SNPs on the therapeutic outcome of ALL patients. The gene discussed is GSTO2; the disease is acute lymphoblastic leukemia.