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目的检测中国食管癌高发区居民和高加索居民ＡＧＴ（Ｏ６ａｌｋｙｌｇｕａｎｉｎｅａｌｋｙｌｔｒａｓｆｅｒａｓｅ）的基因多态改变．方法采用ＰＣＲＳＳＣＰ和ＤＮＡ测序方法对河南食管癌高发区居民和高加索居民的癌组织和非癌组织进行基因多态分析．结果多态变异发生于第５外显子的１４３位密码子，并导致该位点的异亮氨酸（ＡＧＴ）被缬氨酸（ＧＴＣ）取代，且１４３位密码子与１７８位密码子的多态改变有一定联系．对９０例中国食管癌高发区居民的食管癌患者的检测发现，２例（２％）存在１４３／１７８密码子同时出现多态变异，同一地区的６０例正常居民中，无一例检测到该类型多态现象，但２８例高加索居民非癌患者中的６例（２１％）也携带有这种多态等位基因．此外，作者还证实河南食管癌高发区人群中存在第８４位密码子基因多态变异，最近在日本居民中也发现这种变化．这种多态变化导致亮氨酸（ＣＴＴ）变为苯丙氨酸（ＴＴＴ）．８４位密码子的多态变异在中国食管癌患者、中国和高加索非癌患者中的检出率分别为１６％，２０％和３６％，该多态改变与１４３／１７８密码子多态改变同时发生的现象只在１例高加索人ＤＮＡ中被检出．结论ＡＧＴ多态改变可能与食管癌的发生有关，其多态分布可?
Objective To detect polymorphism of AGT (O6-alkylguanine alkyltrasferase) gene in residents of high incidence area of esophageal cancer in China. Methods PCR-SSCP and DNA sequencing methods were used to analyze the polymorphisms of cancer tissues and non-cancer tissues in residents of high incidence areas of esophageal cancer in Henan Province and Caucasian residents. As a result, the polymorphic variation occurred in codon 143 of exon 5 and caused the isoleucine (AGT) at this site to be replaced by proline (GTC) and codon 143 and codon 178. Polymorphic changes have a certain connection. The detection of esophageal cancer in 90 patients with high prevalence of esophageal cancer in China revealed polymorphisms in 143/178 codons in 2 patients (2%). None of the 60 normal residents in the same region detected this type of esophageal cancer. Polymorphism, but 6 (21%) of 28 non-cancer patients in the Caucasian population also carry this polymorphic allele. In addition, the authors also confirmed the presence of a polymorphic polymorphism in the 84th codon in the high-incidence population in Henan, and this change was recently observed among Japanese residents. This polymorphic change causes leucine (CTT) to become phenylalanine (TTT). The polymorphisms of the 84 codons were detected in 16%, 20%, and 36% of patients with esophageal cancer, Chinese, and Caucasian non-cancer patients, respectively. This polymorphism was associated with polymorphism changes in 143/178 codons. What happened was only detected in one case of Caucasian DNA. Conclusion The polymorphism of AGT may be related to the occurrence of esophageal cancer.