ABCB1 and colorectal carcinoma: Homozygous carriers of the combination of the C-allele of MDR1 C3435T and the A-allele of MDR1 G-rs3789243-A were at 1.80 fold higher risk of CRC (95% CI: 1.06-3.05) than homozygous carriers of the combination of the T-allele of MDR1 C3435T and the G-allele of MDR1 G-rs3789243-A.