Of all the analyzed two-loci combinations, the one associated with the highest risk of malignant brain tumors turned out to be a double deletion of GSTM1-GSTT1 (27 people – 15.7% patients; p = 0.017, OR = 2.42, 95% confidence interval 1.18–4.95) (Figure). This evidence concerns the gene GSTM1 and brain neoplasm.