无hMLH1/hMSH2生殖系突变的遗传性非息肉病性结直肠癌3家系报道

目的:考察遗传性非息肉病性结直肠癌(HNPCC)家系hMLH1/hMSH2生殖系突变的情况.方法:选择13个符合Amsterdam标准的HNPCC家系中的先证者,利用DNA 测序检测hMLH1/hMSH2基因突变情况.对其中不携带hMLH1/hMSH2生殖系突变的HNPCC 家系,利用免疫组化检测hMLH1/hMSH2基因表达、PCR-SSCP检测先证者肿瘤组织的微卫星不稳定性(MSI).结果:13个HNPCC家系的先证者中有3例检测不到hMLH1/hMSH2的生殖系突变.3例无hMLH1/hMSH2突变的先证者中,肿瘤组织的微卫星不稳定检测均为MSI-H,免疫组化检测hMLH1/hMSH2基因表达正常.结论:3个严格符合Amsterdam标准的HNPCC家系中未发现hMLH1/hMSH2基因系突变,提示可能存在其他基因突变导致该3个家系HNPCC肿瘤发生.     

国人HNPCC临床病理及错配修复基因突变特点

目的检测和分析中国人遗传性非息肉性大肠癌(hereditary non-polyposis colorectal cancer, HNPCC)hMSH2和hMLH1基因突变和临床病理特点,并探索高效的检测方法。方法收集31个国人HNPCC家系,采用PCR及变性高效液相色谱分忻(DHPLC)筛查hMSH2和hMLH1基因的突变,对DHPLC图形异常的样本用377DNA测序仪测序。结果31个国人HNPCC家系132个病人中共发现180例恶性肿瘤,其中胃癌19例(10．6％)；同时性癌少见,仅占所有结直肠癌(colorectal cancer,CRC)的3．0％。8个家系携带hMSH2或hMLH1基因序列改变,其中包括第一个带有hMSH2基因突变的蒙古族家系。结论国人中胃痛是发病率仪次于CRC的HNPCC相关肿瘤；DHPLC是一种非常有效的筛选hMSH2和hMLH1基因突变的方法；在中国hMLH1基因尤其是其前9个外显子的突变较hMSH2基因的突变更为常见。     

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

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。     

中国人HNPCC家系中hMSH2基因新突变及其功能分析

目的:报道1个在中国人遗传性非息肉病性结直肠癌(HNPCC)家系中发现的基因突变,并对其功能进行分析.方法:抽提1组符合Amsterdam标准的HNPCC家系先证者和其他家系成员的基因组DNA,PCR扩增先证者hMLH1 19个外显子和hMSH2 16个外显子,利用变性高效液相技术(dHPLC)筛查,对异常峰型利用DNA测序方法检测基因突变.发现先证者hMSH2基因存在错义突变后,对家系中其他成员和50名散发性大肠癌患者和100名正常成年人进行相同位点的检测,以判定是单核苷酸多态性位点(SNP)还是突变.利用5对微卫星标记对该家系中的2例肿瘤进行微卫星不稳定分析,免疫组化检测蛋白表达,利用同源建模方法对发现的突变位点进行功能分析,以研究突变的病理意义. 结果:在该家系的2例结肠癌患者中均发现hMSH2基因第13外显子2 108位出现C-A的错义突变,导致703位Ser变异为Tyr,即C.2 108C>A(p.Ser703Tyr),微卫星结果显示2例肿瘤均为微卫星高度不稳定(MSI-H),肿瘤免疫组化结果显示hMSH1基因表达正常而hMSH2基因不表达.同源建模发现该位点与目前报道的hMSH2基因突变不同,突变位于第Ⅳ结构域,Ser突变为Tyr后空间位阻增大,影响了蛋白的正常折叠和功能.结论:Ser703Tyr是中国人HNPCC的一个新的病理性突变.     

多重连接依赖的探针扩增技术检测中国人遗传性非息肉病性结直肠癌错配修复基因大片段缺失

目的了解中国人遗传性非息肉病性结直肠癌(HNPCC)家系hMSH2和hMLH1基因大片段缺失特点。方法采用多重连接依赖的探针扩增(MLPA)技术和GeneMapper分析技术检测17个HNPCC家系先证者hMSH2和hM-LH1基因种系大片段缺失。结果在3个家系中分别发现hMSH2基因第8外显子、1~6外显子和1~7外显子3种大片段缺失类型,未发现hMLH1基因大片段缺失。大片段缺失占hMSH2和hMLH1基因总种系病理性突变的19%。结论中国人HNPCC错配修复(MMR)基因大片段缺失发生率较高,hMSH2基因缺失可能更为常见。在分子遗传学检测中有必要开展MMR基因大片段缺失的检测。     

修订Bethseda标准筛选遗传性非息肉病性结直肠癌患者的队列研究

目的研究修订Bethseda标准筛选遗传性非息肉病性结直肠癌（HNPCC）的价值及在结直肠癌中的构成比。方法对2004年8月至2005年12月进行手术治疗的连续110例患者建立队列、多重荧光聚合酶链反应方法检测肿瘤的微卫星不稳定（MSI）状态,对于MSI结直肠癌患者检测hMSH2、hMLH1和hMSH6基因种系突变。结果110例患者中共检出MSI结直肠癌患者23例（20．9％）。在23例MSI结直肠癌患者中,共发现病理性突变7个（30．4％）,占所有结直肠癌6．4％;其中hMSH6基因种系突变3个,hMSH2基因突变3个,hMLH1基因突变1个。结论以修订Bethesda标准,MSI结直肠癌检出率为20．9％,HNPCC检出率6．4％;在中国人错配修复基因种系突变中hMSH2和hMSH6错义突变比较多见。     

典型遗传性非息肉性大肠癌1例家系分析

目的 探讨遗传性非息肉性大肠癌(HNPCC)的临床特点、病理特点,提高早期诊断和治疗水平,提出HNPCC在临床和基因水平上的筛查策略.报道1例典型的HNPCC家族的临床资料.方法 提取肿瘤组织、正常组织DNA,进行微卫星不稳定性分析、免疫组织化学检测.检测1个家系3例HNPCC患者的肿瘤组织微卫星不稳定状态、错配修复基因hMSH2及hMLH1蛋白水平的表达变化.结果 3例先证者3个肿瘤组织均表现为高度微卫星不稳定性,3例均表现为hMSH2蛋白表达舁常.结论 典型的HNPCC病例中错配修复基因突变率较高,hMLH1、hMSH2蛋白免疫组化的检测可作为HNPCC可疑家系的临床筛选,以及DNA测序前的筛选手段.     

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

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hMLHl基因突变筛查结果。方法 共收集了28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hMLHl基因的突变，然后对DHPLC图形异常的样本进行测序。结果 126例患者共诊断170例次恶性肿瘤(23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45。9岁)，右侧癌多见。共在12个家系中发现8种hMSH2或hMLHl基因序列改变，其中hMSH2基因的第3个外显子的无义突变即G204X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hMLHl基因突变的方法。在我国hMLHl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。     

人类错配修复基因hMLH1和hMSH2错义突变真核表达载体的构建及表达

目的 构建人类错配修复基因hMLH1和hMSH2错义突变真核表达载体并检测它们在瞬时转染细胞中的蛋白表达.方法 重组pcDNA3.1-hMLH1-wt和pcDNA3.1-hMSH2-wt质粒为模板,用定点诱变的方法分别构建hMLH1基因和hMSH2基因错义突变真核表达载体,将诱变前后的重组质粒瞬时转染至HCT-116细胞(hMLh1基因缺陷型)或LoVo细胞(hMSH2基因缺陷型)中,免疫印迹法和免疫荧光法分别检测这两种基因在各自的转染细胞中的蛋白表达.结果 测序证实,定点突变成功,构建出hMLH1基因错义突变pcDNA3.1-hMLH1-T117M和pcDNA3.1-hMLH1-V384D真核表达载体以及hMSH2基因错义突变pcDNA3.1-hMSH2-L390F、pcDNA3.1-hMSH2-Q419K和pcDNA3.1-hMSH2-Q629R真核表达载体.结果 表明转染后,除hMLH1-T117M突变体蛋白表达缺失外,其余的野生型及突变型真核表达载体在转染细胞中均能表达相应的蛋白.结论 成功构建了在人的肿瘤细胞系中能有效表达的两种hMLH1基因错义突变和三种hMSH2基因错义突变的真核表达载体,为进一步研究这些错义突变的病因学作用和功能意义奠定了实验基础.     

主要DNA错配修复基因在大肠癌中的临床意义

研究较多的与大肠癌有关的DNA错配修复基因是hMSH2、hMLHl和hMSH6,前两个基因在HNPCC家系中突变较hMSH6常见,而在大肠癌散发病例中较少见。携带hMSH2和hMLH。突变的大肠癌患者发病年龄较携带hMSH6突变者早;携带hMSH2和hMLHl突变的大肠癌患者好发部位是右半结肠,而后者是左半结肠。     

可疑遗传性非息肉病性结直肠癌的hMLH1和hMSH2基因突变研究

目的比较分析符合国际诊断标准的遗传性非息肉病性结直肠癌（ＩＣＧＨＮＰＣＣ）家系和提出的可疑ＨＮＰＣＣ家系的分子特征的异同,建立可疑ＨＮＰＣＣ诊断标准并评价其应用价值。方法根据ＡｍｓｔｅｒｄａｍＨＮＰＣＣ诊断标准和作者提出的可疑ＨＮＰＣＣ诊断标准,分别收集得到２９个ＩＣＧ家系和３４个可疑家系。提取先证者的外周血基因组ＤＮＡ,应用ＰＣＲＳＳＣＰ和ＤＮＡ测序的方法进行ｈＭＬＨ１和ｈＭＳＨ２基因的突变筛选。结果２９个ＩＣＧ家系中有９个家系被检出含有ｈＭＬＨ１基因的种系突变,突变率为３１０％;３４个可疑家系中有１０个家系被检出含有ｈＭＬＨ１或ｈＭＳＨ２基因的突变,两个基因的突变率分别为２３５％和５９％。ＩＣＧ组和可疑组中两个基因总突变率之间差异无显著意义（Ｐ＞００５）。ｈＭＬＨ１基因同是两组家系中的主要相关基因。两组家系中,突变均较一致地分布于基因的后半部分,突变类型也极为相似,均以导致短缩蛋白的突变最为常见。结论ＩＣＧ组和可疑组在遗传背景上有着相似之处,对ＨＮＰＣＣ诊断标准有一定的临床应用价值,有助于ＨＮＰＣＣ家系的临床诊断。     

Clinical features and hMSH2/hMLH1 germ-line mutations in Chinese patients with hereditary nonpolyposis colorectal cancer

Background At least five mismatch repair （MMR） genes, including hMSH2, hMLH1, hPMS, hPMS2, and hMSH6/GTBP, are associated with hereditary nonpolyposis colorectal cancer （HNPCC）. More than 90% of families with HNPCC harbor the hMSH2and hMLH1 gene mutations. We have analyzed the clinical features of HNPCC among Chinese patients and report the results of screening for mutations in the hMSH2 and hMLH1 genes.
Methods The data concerning gender, site of colorectal cancer （CRC）, age at diagnosis, history of synchronous and/or metachronous colorectal cancer, instance of extracolonic cancers, and histopathology of tumors for 126 patients from 28 independent families with HNPCC were collected. Fifteen of the families met the Amsterdam I criteria, and 13 met the Japanese clinical criteria for diagnosis. 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 the hMSH2 and hMLH1 genes. Samples showing abnormal DHPLC profiles were sequenced.
Results One hundred and seventy malignant neoplasms were found in the 126 patients, of whom 23 had multiple cancers. Ninety-eight of the patients （77.8%） had colorectal cancers, with an average age at onset of 45.9 years and a right-sided predominance. Eight hMSH2 or hMLH1 gene sequence variations were found in 12 families, and a germ-line G204X nonsense mutation in the third exon of hMSH2 was found, representing the first mutation in an MMR gene ever found in people of Chinese Mongolian ethnicity.
Conclusions HNPCC is a typical autosomally dominant hereditary disease, characterized by early onset, a predominance of proximal colorectal cancer, and multiple synchronous and metachronous colorectal cancers. DHPLC is a powerful tool for detecting mutations in the hMSH2 and hMLH1 genes, Mutations in the first nine exons of the hMLH1 gene were more common in Chinese patients.     

Novel hMLH1 and hMSH2 germline mutations in African Americans with colorectal cancer.

CONTEXT: Germline mutations of the DNA mismatch repair (MMR) genes hMLH1 and hMSH2 have been shown to cosegregate with the colorectal cancer phenotype in multiple hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. However, the frequency of these mutations among African American patients with colorectal cancer is unknown. OBJECTIVE: To investigate the frequency of germline alterations of the DNA MMR genes hMLH1 and hMSH2 among African Americans affected by HNPCC and early-age onset colorectal cancer. DESIGN, SETTING, AND PATIENTS: Forty unrelated African American HNPCC and early-age onset colorectal cancer patients (8 women, 3 men) were identified from the cancer registry at a National Cancer Institute-designated referral center, 11 of whom were available for and agreed to study participation from January 1997 to February 1998. The mean age of the subjects was 44 years. An additional 50 age- and sex-matched African Americans without personal or family history of colorectal, endometrial, ovarian, urinary tract, or upper gastrointestinal tract malignancy were also studied as a polymorphism control population. In all subjects, genomic DNA was amplified by polymerase chain reaction for all hMLH1 and hMSH2 exons and screened using single-strand conformation polymorphism (SSCP) analysis. Samples demonstrating significant SSCP shifts underwent automated nucleotide sequencing analysis. MAIN OUTCOME MEASURE: Frequency of hMLH1 and hMSH2 germline alterations in the affected and control subjects. RESULTS: Germline hMLH1 and hMSH2 mutations were detected in 3 (27%) of the African American colorectal cancer probands studied. Each mutation was novel. Two hMLH1 (an A-->T transversion at codon 26 and a GG-->AT substitution across codons 177 and 178) mutations and 1 hMSH2 mutation (a C-->T transition at codon 389) were identified in 3 female study subjects. Six other hMLH1 and hMSH2 alterations were detected but were presumed to be polymorphisms. Neither missense mutation (at codons 26 and 389) was detected in the control population. CONCLUSIONS: The results of our analysis support an association between the 3 mutations reported and predisposition to colorectal cancer. Further studies are needed to define DNA MMR gene-associated colorectal cancer in African Americans, an understudied population at increased risk of fatal colorectal cancer.     

青年大肠癌微卫星不稳定和hMLH1/hMSH2表达缺失在遗传性非息肉病性大肠癌初筛中的应用

目的 探讨青年大肠癌中微卫星不稳定发生率和hMLH1/hMSH2表达缺失率及其在遗传性非息肉病性大肠癌初步筛查中的作用.方法 对73例中国南方青年大肠癌患者(年龄≤40岁)进行微卫星不稳定和hMLH1/hMSH2蛋白免疫组化检测.结果 微卫星不稳定性发生率为56.16%,hMLH1和/或hMSH2表达缺失率为49.32%,二者皆随患者发病年龄的降低而迅速增加;二者对阳性病例的检出率相似.结论 中国人青年大肠癌DNA错配修复基因缺陷为频发事件,运用微卫星不稳定分析和hMLH1/hMSH2蛋白免疫组化检测可在青年大肠癌有效地进行HNPCC患者及家系的初步筛查.     

Hereditary non-polyposis colorectal cancer (HNPCC): new germline mutation (190-191 del AA) in the human MLH1 gene and review of clinical guidelines for surveillance of affected families

Hereditary non-polyposis colorectal cancer (HNPCC) is one of the most common genetic diseases comprising at least 5-6% of all colorectal cancers. It is characterized by early onset and mostly right-sided tumors (proximal to the splenic flexure). Molecular analyses are useful methods for diagnosis in index patients and for the detection of risk persons in affected families. A 37-year-old female patient whose family history fulfilled the criteria for hereditary non-polyposis colorectal cancer (HNPCC) was studied using PCR and DNA sequencing for the detection of mutations in the mismatch repair genes hMSH2 and hMLH1. Additionally, literature was reviewed (MEDLINE research until 2000) concerning clinical guidelines for surveillance in HNPCC families. A new deletion of two adenosine nucleotides (190-191 del AA) at codon 64 in exon 2 of the hMLH1 gene was found. The frameshift led to a stop codon at amino acid position 75. This mutation is considered to be disease causing in the development of the colorectal cancer of this family. Six publications with detailed recommendations for the surveillance of risk persons were found in the literature. Following their guidelines, colonoscopy is recommended from 20-30 years on for members of a family who fulfills either the Amsterdam criteria or the Bethesda criteria in combination with a detection of microsatellite instability. Female risk persons should be investigated gynecologically, including a transvaginal ultrasound examination, from 25-35 years on for the early detection of endometrial or ovarian cancer. Recommendations for gastroscopy, abdominal ultrasound examination and urine analysis are not given in all publications. Genetic counseling is recommended from 18 years on for all members of affected families.     

基因hMSH2、hMLH1与p53突变型在散发性大肠癌患者的表达

目的:探讨错配修复基因hMSH2、hMLH1与p53突变型在散发性大肠癌发生中的作用。方法:用聚合酶链反应和单链DNA多态性分析(PCR-SSCP)对45例散发性大肠癌患者肿瘤组织及正常组织基因hMSH2、hMLH1、p53进行检测。结果:45例散发性大肠癌患者中,发生hMSH2、hMLH1、p53基因突变分别为2、6、22例,分别占4.44%、13.33%和48.89%。hMLH1、hMSH2基因在突变型p53患者中的突变率为27.27%明显高于在p53未发生突变的患者中的突变率8.69%(P<0.05)。结论:一定比例的散发性大肠癌患者中存在MMR基因缺陷,其中hMLH1所起的作用大于hMSH2,散发性大肠癌中MMR基因突变与p53突变密切相关。