中国人HNPCC家系的临床特征及M3胆碱能受体基因(A)8区突变检测

目的:分析中国人遗传性非息肉病性大肠癌(HNPCC)家系的临床特征并检测这些家系中M3胆碱能受体基因(A)8区的突变情况.方法:根据2003年4月杭州会议制定的中国人HNPCC家系标准收集HNPCC家系共15个,分析其临床特征;提取先证者的外周血基因组DNA,PCR扩增M3胆碱能受体基因第8外显子中一段长153 bp,包含有微卫星位点(A)8的基因片段,直接进行DNA测序.结果:15个家系共有恶性肿瘤患者55例,其中大肠癌患者41例,平均每个家系发生大肠癌2.73例,73%的大肠癌患者发病年龄<50岁,51%的病灶位于近端结肠,40%发生在直肠肛门,同时和异时多原发大肠癌总发生率为12%,2/3的家系属于Lynch Ⅱ型,共发生肠外恶性肿瘤14例(18个),其中胃癌最常见.15例先证者外周血中无1例检测到M3胆碱能受体基因(A)8区的突变.结论:M3胆碱能受体基因与中国人群中HPNCC的发病可能无密切关系.中国人HNPCC家系标准应在临床工作中推广应用,并进一步验证其合理性和科学性.

Clinical features and mutation analysis of a poly-(A)8 tract in M3 cholinergic receptor gene in Chinese HNPCC families

OBJECTIVE: To characterize the clinical features of Chinese HNPCC families and to screen the mutations of a poly-(A)8 tract in M3 cholinergic receptor gene in these families. METHODS: The clinical features of 15 Chinese HNPCC families were characterized. Genomic DNAs from 15 probands were prepared. PCR and direct DNA sequencing analysis were employed to examine the mutations of a poly-(A)8 tract in exon 8 of M3 cholinergic receptor gene. RESULTS: Total 55 cancer patients were found in 15 families including 41 cases of colorectal carcinoma with an average of 2.73 colorectal carcinomas developed per family. Thirty out of forty-one (73%) patients were diagnosed before age of 50 years. Proximal colon was involved in 51% of patients, while anus and rectum were 40 %. Synchronous and metachronous multiple colorectal cancers developed in 5 patients (12%). Two thirds of families belonged to Lynch II syndrome, and total 18 extracolonic malignancies in 14 patients were identified. Gastric carcinoma was the most common extracolonic types. In 15 HNPCC probands, no mutation was detected in the poly-(A)8 tract of exon 8 of M3 cholinergic receptor gene. CONCLUSION: M3 cholinergic receptor gene might have little relation with HNPCC in Chinese population. The criteria for Chinese HNPCC are useful and practical in clinical application.