Objective: To observe the polymorphism of metabolizing enzyme N-actyltransferase 2 gene in populations with history of colorectal adenoma and polyp and to explore the relationship between NAT2 gene phenotype and colorectal cancer genetic susceptibility.
Methods: A cohort of 4,076 patients with history of colorectal adenoma or polyp was established Fifty-two cases were randomly selected from those with recurrence more than 2 times during the twenty years' follow-up. Fifty-two without recurrence were randomly selected as controls. DNA was isolated from the lymphocytes of peripheral blood of these 104 subjects. NAT2 polymorphism was detected by PCR-RFLP.
Results: The frequency of wild-type NAT2 (Wt/Wt) was significantly higher in control group (17/52, 32.7%) than in recurrence group (8/52, 15.4%) (P < 0.05). The frequency of heterogeneity type of NAT2 was significantly higher in recurrence group (40/52, 76.9%) than in control group (30/52, 57.7%) (P < 0.05). If OR of wild-type NAT2 (Wt/Wt) was 1, OR of Wt/M* genotype was 2.96 (95% CI: 1.091-8.009), and OR of M*/M* genotype was 2.125 (95% CI: 0.666-6.781). There was no difference of distribution between rapid enzyme type and slow enzyme type in the two groups.
Conclusion: The frequency of wild-type NAT2 gene (Wt/Wt) is significantly higher in patients without recurrence of adenoma or polyp than in patients with recurrence. The frequency of heterogeneity genotype of NAT2 is significantly higher in patients with recurrence of adenoma or polyp than in those without recurrence. Wild-genotype (Wt/Wt) may be a protection factor in recurrence of colorectal adenomas. No difference can be seen between the distribution of rapid and slow enzyme types in these two groups.