遗传性非息肉病性结直肠癌患者的临床特点及hMSH2与hMLH1种系突变的筛查

Clinical features and hMSH2/hMLH1 germline mutation screening of Chinese hereditary nonpolyposis colorectal cancer patients

目的 分析我国遗传性非息肉性结直肠癌 (HNPCC)患者的临床特点 ,报告hMSH2和hMLH1基因突变筛查结果。方法 共收集了 2 8个家系 ,其中 15个家系符合阿姆斯特丹Ⅰ标准 ,13个家系符合日本临床诊断标准。记录的数据包括患者性别 ,结直肠癌发生的部位 ,诊断年龄 ,是否具有同时和 /或异时结直肠癌及结肠外癌 ,肿瘤的组织病理特点等。通过PCR及变性高效液相色谱分析(DHPLC)筛查hMSH2和hMLH1基因的突变 ,然后对DHPLC图形异常的样本进行测序。结果 12 6例患者共诊断 170例次恶性肿瘤 (2 3例患有多原发癌 )。 98例 (77 8% )的患者患有结直肠癌 ,且发病年龄早 (平均 4 5 9岁 ) ,右侧癌多见。共在 12个家系中发现 8种hMSH2或hMLH1基因序列改变 ,其中hMSH2基因的第 3个外显子的无义突变即G2 0 4X是发现的首例我国蒙古族家系错配修复 (MMR)基因突变。结论 HNPCC患者是恶性肿瘤 (尤其是结直肠癌 )的高发人群。DHPLC是一种非常有效的筛选hMSH2和hMLH1基因突变的方法。在我国hMLH1基因尤其是其前九个外显子的突变较hMSH2基因的突变更常见。

Objective To analyze the clinical features of hereditary nonpolyposis colorectal cancer (HNPCC) among Chinese and report the results of screening of hMSH2 and hMLH1 gene mutations. Methods The data concerning sex,site of colorectal cancer (CRC),age of diagnosis,history of synchronous and/or metachronous colorectal cancer,instance of extracolonic cancers,and histopathology of tumors of 126 patients from 28 independent families of HNPCC in China were collected, of which 15 met the Amsterdam criteriaⅠ and 13 met the Japanese clinical diagnosis criteria. The genomic DNA was extracted from the peripheral lymphocytes. Polymerase chain reaction (PCR) and denaturing high-performance liquid chromatography (DHPLC) were used to screen the coding region of hMSH2 and hMLH1 genes. Samples showing abnormal DHPLC profiles were sequenced by a 377 DNA sequencer. Results One hundred and seventy malignant neoplasms were found in the 126 patients,in which 23 of multiple cancers were found. Ninety-eight of the 126 patients (77.8%) had colorectal cancers,with an average age of onset of 45.9 years and a right-sided predominance. Eight hMSH2 or hMLH1 gene sequence variations were found in 12 families,and a germline G204X nonsense mutation in the third exon of hMSH2 was found for the first time,the first mismatch repair gene (MMR) mutation ever found in Chinese Mongolian people. Conclusions HNPCC is a typical auto-dominant hereditary disease,characterized by early onset,proximal predominance of colorectal cancer,multiple synchronous and metachronous colorectal cancers,and an excess of extra-colonic cancers. Frequent gastric cancer occurrence and less synchronous colorectal cancers are notable features in Chinese HNPCC patients. DHPLC is a powerful tool in hMSH2 and hMLH1 gene mutation screening. Three novel mutations have been found. hMLH1 gene mutations,especially those of the first nine exons,are more common than hMSH2 gene mutations in Chinese patients.