典型Lynch综合征1例遗传家系分析

发布时间：2018-06-20 09:08

本文选题：Lynch综合征 + DNA错配修复基因　；参考：《昆明医科大学》2017年硕士论文

【摘要】：[目的]Lynch综合征是最常见的遗传性结直肠癌综合征之一。目前临床中用以诊断Lynch综合征的方法主要是对符合Amsterdam标准或Bethesda指南的患者行IHC检测其病理组织中的MMR蛋白表达或进行MSI检测,但这些方法无法避免一定的误诊及漏诊。本文从1个符合AmsterdamⅡ临床诊断标准的典型Lynch综合征先证者及其家系成员入手,对先证者进行MMR蛋白表达检测、MSI检测,并应用二代高通量测序对先证者进行遗传性结直肠癌相关致病基因检测,明确该家系致病突变基因及位点。从而评估各分子检测的一致性,并对家系成员进行致病突变基因及位点的筛查和健康指导,对临床进行Lynch综合征的诊断及家系健康管理进行探索。[方法]对临床诊疗时经CT及肠镜等检查发现多原发结肠癌且符合Amsterdam Ⅱ标准考虑为可疑Lynch综合征的患者进行临床评估后行结肠次全切除术。术后对切除标本行IHC检测明确MMR蛋白表达情况,并行MSI检测进一步明确患者微卫星状态,随后进行患者家系成员患病情况调查及回顾性调查追踪寻访,依据所掌握的资料绘制该家族的家系图,再采用目标区域捕获结合二代高通量测序技术,对先证者及家系内患者检测相关基因外显子及其附近±10bp内含子区变异(包括点突变,20bp以内的缺失插入突变)明确致病突变,并对家系内其他成员行验证实验,分析他们的患病危险程度以进行健康指导。[结果]先证者CT及肠镜检查确定为多原发结肠癌,后行根治性结肠次全切除术。术后病理检查提示:阑尾根部、降结肠高-中分化管状腺癌,部分为粘液腺癌(大小分别为6cm×4cm×4cm;2.5cm×2cm×1cm);肠系膜淋巴结(5/28)见癌转移。将病理标本行IHC染色提示MSH2及MSH6蛋白表达缺失,同时行MSI检测提示MSI-H即微卫星高度不稳定。根据对患者家族史的追溯完成家系图的绘制,发现先证者家系现在四代共有7名病理确证Lynch综合征相关肿瘤患者,先证者(27岁)现罹患多原发结肠癌,先证者母亲曾确诊为子宫内膜癌(52岁),已行手术治疗,规律复查未再发相关肿瘤。先证者外祖母为多系统多原发肿瘤患者,先后罹患子宫内膜癌(51岁)、乙状结肠癌(64岁)及直肠癌(72岁),并于同年去世。先证者外祖母的3个兄弟分别罹患直肠癌,先证者另有1位表妹因罹患病理未明确肿瘤去世。对患者家族中11位成员采血提取DNA行基因检测,证实家系内患者均于MSH2基因检出无义突变c.2038CT(p.Arg680Ter),导致MSH2基因编码蛋白在第680位发生截短,为该家系致病突变。而在表现型正常家族成员中,2人行基因检测确证为基因突变携带者,后行肠镜检查发现结直肠多发息肉,其余未发现携带该基因突变。[结论]本文所研究的Lynch综合征家系疾病史连续4代,是符合Amsterdam Ⅱ标准的典型Lynch综合征家系。先证者病理标本的IHC/MSI检测与基因检测结果一致,基因检测结果提示了该家系的致病基因为MSH2基因的一个已知致病突变位点c.2038CT(p.Arg680Ter)。基因检测有利于对Lynch综合征患者进行家系内筛查,并对进一步的遗传学咨询及家系健康管理提供了明确的依据。
[Abstract]:[Objective]Lynch syndrome is one of the most common hereditary colorectal cancer syndrome. At present, the main clinical use of the diagnosis of Lynch syndrome is to detect the expression of MMR protein in the pathological tissue of the patients with Amsterdam or Bethesda guidelines by IHC, or to perform MSI detection, but these methods can not avoid misdiagnosis and leakage. In this paper, we start with 1 typical Lynch syndromes and their family members, which conform to the Amsterdam II clinical diagnostic criteria, carry out MMR protein expression detection, MSI detection, and use two generation high-throughput sequencing to detect the hereditary colorectal cancer related genes and identify the gene and loci of the family. In order to evaluate the consistency of the various molecular detection, the screening and health guidance for the genes and loci of the family members, the diagnosis of Lynch syndrome and the health management of the family were explored. [Methods] multiple primary colon cancer was detected by CT and enteroscopy, and the Amsterdam II standard was considered for the clinical diagnosis and treatment. Patients with suspected Lynch syndrome underwent subtotal colectomy after clinical evaluation. After the operation, the expression of MMR protein was determined by IHC detection, and the microsatellite status of the patients was further confirmed by MSI detection. The family map, then the target region capture and two generation high-throughput sequencing technology, was used to detect the mutations in the exons of the related gene exons and their adjacent 10bp introns (including point mutations and 20bp deletion mutations) in the patients and their families, and to test the other members of the family and analyze them. [results] CT and colonoscopy were identified as multiple primary colon cancer, followed by radical colonic subtotal resection. Postoperative pathological examination suggested that O Nebe, high and middle differentiated tubular adenocarcinoma of the descending colon were mucous adenocarcinoma (6cm * 4cm x 4cm; 2.5cm * 2cm x 1cm); mesenteric lymph nodes. IHC staining showed that the expression of MSH2 and MSH6 protein was missing, and MSI was used to detect the high instability of the microsatellite. According to the family history of the patients, the family history of the patients had been traced, and the four generation of the first four generations of the patients were found to confirm the Lynch syndrome related tumor patients, the precursor (2). 7 years of age) suffered from multiple primary colon cancer. The first confirmed mother had been diagnosed with endometrial carcinoma (52 years old) and had undergone surgical treatment. The first syndrome was a multisystem, multiple primary tumor, with endometrial carcinoma (51 years old), sigmoid carcinoma (64 years old) and rectal cancer (72 years old), and died in the same year. The progenitor of the first syndrome was the progenitor of the precursor. The 3 brothers of the mother had rectal cancer respectively, and 1 other cousins died of a pathological undefined tumor. 11 members of the family had a DNA gene test, which confirmed that the MSH2 gene detected a nonsense mutation c.2038CT (p.Arg680Ter) in the family of the family, causing the MSH2 gene encoding protein to be truncated in 680th. Among the members of the normal family, 2 people were confirmed to be the carriers of the gene mutation, and the colonoscopy was used to detect multiple colorectal polyps, and the others were not found to carry the mutation. [Conclusion] the history of the family disease of Lynch syndrome was 4 generations, which was a typical Lynch ensemble in line with the standard of Amsterdam II. The IHC/MSI detection of the histopathological specimens of the first syndrome is consistent with the results of the gene detection. The gene detection results suggest that the pathogenic gene of the family is a known pathogenicity site c.2038CT (p.Arg680Ter) of the MSH2 gene. The gene detection is beneficial to the screening of the patients in the family of Lynch syndrome and the further genetic counseling. The family's health management provides a clear basis.
【学位授予单位】：昆明医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R735.3

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