GSTM1 and acute leukemia: The pooled OR of acute leukemia risks associated with GSTM1 null genotype, GSTP1 Val105 allele and GSTT1 null genotype, were 1.22 (95% CI 1.07–1.38), 1.07 (95% CI 1.00–1.13) and 1.19 (95% CI 1.00–1.41), respectively.