Molecular analysis of hereditary nonpolyposis colorectal cancer in the United States:: High mutation detection rate among clinically selected families and characterization of an American founder genomic deletion of the MSH2 gene
Molecular analysis of hereditary nonpolyposis colorectal cancer in the United States:: High mutation detection rate among clinically selected families and characterization of an American founder genomic deletion of the MSH2 gene
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DOI：
10.1086/373963
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发表时间：
2003-05-01
影响因子：
9.8
通讯作者：
Fodde, R
中科院分区：
文献类型：
--
作者：
Wagner, A;Barrows, A;Fodde, R
遗传异质性和临床变异性阻碍了HNPCC家系生殖系突变的鉴定。在以前的研究中，MSH 2和MLH 1突变被发现在大约三分之二的阿姆斯特丹标准阳性家庭和阿姆斯特丹标准阴性家庭的百分比低得多。因此，HNPCC的相当一部分似乎不是由主要错配修复（MMR）基因引起的。后者是由于突变检测技术缺乏敏感性，还是其他基因构成了其余病例的基础？在这项研究中，我们解决这些问题，通过彻底调查一个队列的临床选择的北美家庭HNPCC。我们分析了59例临床明确的U。S.有MSH 2、MLH 1和MSH 6突变的HNPCC家族。为了最大限度地检测突变，采用了不同的技术，包括变性梯度凝胶电泳，Southern分析，微卫星不稳定性，免疫组织化学和单等位基因表达分析。在45（92%）的49个阿姆斯特丹标准阳性的家庭和7（70%）的10个阿姆斯特丹标准阴性的家庭中，检测到突变的三个分析MMR基因之一。49个突变发生在MSH 2或MLH 1，只有3个发生在MSH 6。相当大比例（27%）的突变是基因组重排（MSH 2中12个，MLH 1中2个）。值得注意的是，在7个明显不相关的家庭（占总队列的12%）中检测到了包含MSH 2外显子1-6的缺失，随后被证明是创始人。筛选第二个U。S.来自俄亥俄州的HNPCC队列允许鉴定两个具有相同创始者缺失的额外激酶。在本研究中，我们表明，最佳的突变检测HNPCC是通过结合准确和专家的临床选择与广泛的突变检测策略。值得注意的是，我们发现了一个常见的北美MSH 2缺失，约占我们队列的10%。系谱学、分子和单倍型研究表明，这种缺失代表了一种可追溯到世纪的北美创始人突变。
The identification of germline mutations in families with HNPCC is hampered by genetic heterogeneity and clinical variability. In previous studies, MSH2 and MLH1 mutations were found in approximately two-thirds of the Amsterdam-criteria-positive families and in much lower percentages of the Amsterdam-criteria-negative families. Therefore, a considerable proportion of HNPCC seems not to be accounted for by the major mismatch repair (MMR) genes. Does the latter result from a lack of sensitivity of mutation detection techniques, or do additional genes underlie the remaining cases? In this study we address these questions by thoroughly investigating a cohort of clinically selected North American families with HNPCC. We analyzed 59 clinically well-defined U. S. families with HNPCC for MSH2, MLH1, and MSH6 mutations. To maximize mutation detection, different techniques were employed, including denaturing gradient gel electrophoresis, Southern analysis, microsatellite instability, immunohistochemistry, and monoallelic expression analysis. In 45 (92%) of the 49 Amsterdam-criteria-positive families and in 7 (70%) of the 10 Amsterdam-criteria-negative families, a mutation was detected in one of the three analyzed MMR genes. Forty-nine mutations were in MSH2 or MLH1, and only three were in MSH6. A considerable proportion (27%) of the mutations were genomic rearrangements ( 12 in MSH2 and 2 in MLH1). Notably, a deletion encompassing exons 1-6 of MSH2 was detected in seven apparently unrelated families (12% of the total cohort) and was subsequently proven to be a founder. Screening of a second U. S. cohort with HNPCC from Ohio allowed the identification of two additional kindreds with the identical founder deletion. In the present study, we show that optimal mutation detection in HNPCC is achieved by combining accurate and expert clinical selection with an extensive mutation detection strategy. Notably, we identified a common North American deletion in MSH2, accounting for similar to10% of our cohort. Genealogical, molecular, and haplotype studies showed that this deletion represents a North American founder mutation that could be traced back to the 19th century.