黑斑-息肉综合征染色体不稳定性及肿瘤易感基因位点的分析

Analysis of instability and deletion on chromosome 3p14 in Peutz-Jeghers Syndrome

目的通过对黑斑-息肉综合征（PJS）染色体不稳定性、基因缺失、点突变和重排的分析，确定与疾病易感的相关基因及变异方式。方法本研究经家系调查和利用患者外周血淋巴细胞比较分析了染色体脆性位点表达;采用聚合酶链反应（PCR）、PCR/SSCP分析、微卫星检测和DNA测序分析技术对染色体脆性位点（Fra）出现频率高的3p14的遗传标记进行检测。结果（1）4个家系共22例患者，其息肉性质均为腺瘤样息肉，死于结肠癌10例，占45.5％。（2）染色体比较分析PJS组检出脆性位点表达频率高的有8条染色体，频率最高的是3p14。（3）PCR结果表明在3p14-3p24区域变异频率较高的位点在D353340，有缺失、重排和点突变，显示患者该区域为纯合状态，缺失频率为42.9％;（4）同时有APC和k-ras等基因点突变。结论PJS患者大肠息肉为腺瘤样息肉，故有很高的结肠息肉癌变率，并且具有很强的染色体不稳定性，在3p14区域存在多种方式的基因变异，这一结果提示该区域可能存在与PJS发病或癌变的相关基因。

To determine the region where the tumor susceptible genes located, and to study chromosome instability, deletion and rearrangement of genes in Peutz-Jeghers Syndrome. Methods The method of induction was used to detect chromosome fragile sites of patients, Who were contrasted to familiar members and healthy individuals. DNA was extracted from leukocyte, polypus and tumor tissues, fresh or embedded in praffin.The highly frequent abnormality of chromosome 3p14 region was studied with PCR, PCR-SSCP, microsatellite analysis, and DNA sequencing. Results The highest frequency of fragile site was in chromosome 3p14 -3p24 region. The aberration frequency of D353340 is 21 .4%, and that of D3530 is 14.3%. Microsatellite analysis demonstrated LOH, of which the frequency is 42.9%; in addition APC、k-ras mutation alao occurred. The loss of guanylic acid was found in D3S1766. Conclusion PJS has high chromosome instability, with deletion, mutation and arrangement of genes in 3p14 region, suggesting that cancer susceptible genes would be harbed in 3p14 cloning.