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目的 研究亚甲基四氢叶酸还原酶(MTHFR)基因多态与结直肠癌(包括结肠癌、直肠癌)易感性的关系。方法 应用聚合酶链反应(PCR)和限制性片段长度多态性方法(RFLP),检测了126例结直肠癌患者和343名正常对照的MTHFR C677T和A1298C两个位点基因多态,并比较不同基因型单独、联合时与结直肠癌风险的关系,以及两个多态位点与饮酒的联合作用。结果MTHFR677T和1298C突变基因在对照组中的频率分别为39.7％和17.1％。1298C突变基因携带者与野生型相比,患结直肠癌的风险均降低;在携带677C和1298C等位基因组合个体中,结直肠癌的风险略有降低(OR=0.718,95％CI:0.367～1.407),同时含677T和1298A等位基因者,结直肠癌的风险降低1倍;同时含有677T和1298C等位基因者,结直肠癌的风险降低4倍,直肠癌的风险降低7倍(OR=0.304,95％CI:0.108～0.852)。在过去饮酒者中,1298A等位基因携带者结直肠癌风险性增加2倍(OR=3.307,95％CI:0.521～17.698)。结论 MTHFR C667T和A1298C位点多态性在结直肠癌发生过程中起着一定作用,携带MTHFR 1298AC基因多态型者过去饮酒是结直肠癌的危险因素。
Objective To investigate the relationship between the polymorphism of methylenetetrahydrofolate reductase (MTHFR) and the susceptibility to colorectal cancer (including colon cancer and rectal cancer). Methods The gene polymorphisms of MTHFR C677T and A1298C in 126 patients with colorectal cancer and 343 normal controls were detected by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) The association of different genotypes alone and in combination with the risk of colorectal cancer, as well as the combined effect of two polymorphic loci and alcohol consumption. Results The frequencies of MTHFR677T and 1298C mutation in the control group were 39.7% and 17.1% respectively. The risk of colorectal cancer was lower in carriers of the 1298C mutation than in the wild type; the risk of colorectal cancer was slightly lower in carriers of the 677C and 1298C alleles (OR = 0.718, 95% CI: 0.367 ~ 1.407), while those with 677T and 1298A alleles had a 1-fold reduced risk of colorectal cancer. Patients with both 677T and 1298C alleles had a 4-fold reduced risk of colorectal cancer and a 7-fold reduced risk of rectal cancer OR = 0.304, 95% CI: 0.108-0.852). In the past drinkers, 1298A allele carriers had a 2-fold increased risk of colorectal cancer (OR = 3.307, 95% CI: 0.521 to 17.698). Conclusion MTHFR C667T and A1298C loci polymorphisms play a role in the development of colorectal cancer. MTHFR 1298AC polymorphism was a risk factor for colorectal cancer in the past.