The frequencies of mutant allele (A) and genotype (GA+AA) of FUT3 (rs3745635) in patients with extensive colitis were significantly lower than in patients with distal colitis (P = 0.006, 95%CI: 0.553–0.845; P = 0.011, 95%CI: 0.621–0.900, respectively) (Table 5). Here, FUT3 is linked to distal colitis.