CCND1 and brain neoplasm: Logistic regression analysis for SNP–SNP interactions among all four SNPs of RB1 and CCND1 genes showed positive significant correlation between s137853294 vs rs498136 (OR, 3.372; 95% CI, 0.520–21.872; P=0.02) and rs614367 vsrs498136 (OR, 3.083; 95% CI, 0.559–17.00; P=0.029) with increased risk of brain tumor as shown in Table 7.