GSTM1 and leukemia: Moreover, significantly increased leukemia risk was found for the GSTM1 null genotype among countries of East Asia (OR = 1.46, 95% CI: 1.27–1.67), North Africa (OR = 2.39, 95% CI: 1.28–4.47), South Asia (OR = 1.37, 95% CI: 1.01–1.87), and Southeast Asia (OR = 1.68, 95% CI: 1.24–2.27), as shown in Table 1.