Mutation screening of MSH2 and MLH1 mRNA in hereditary non-polyposis colon cancer syndrome
Mutation screening of MSH2 and MLH1 mRNA in hereditary non-polyposis colon cancer syndrome
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DOI：
10.1136/jmg.33.9.726
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发表时间：
1996-09-01
影响因子：
4
通讯作者：
Maher, ER
中科院分区：
文献类型：
--
作者：
Froggatt, NJ;Brassett, C;Maher, ER
人类错配修复基因（MSH 2、MLH 1、PMS 1和PMS 2）的种系突变已被报道可引起遗传性非息肉病性结肠癌综合征（HNPCC）。HNPCC激酶中种系突变的鉴定允许精确的诊断和准确的预测性测试。为了进一步研究HNPCC的遗传流行病学以及这种疾病中生殖系突变的性质和频率，我们研究了17例英国HNPCC患者的MSH 2和MLH 1生殖系突变。以前的遗传连锁研究表明，大多数英国HNPCC家庭将在这些基因之一突变。突变分析在三步过程中进行。(1)分析从淋巴母细胞系提取的mRNA的总体重排，（2）然后进行体外转录-翻译（IVTT）测定以检测蛋白质截短突变，和（3）在与MSH 2或MLH 1连锁但没有可检测突变的家族（n=6）中进行MSH 2或MLH 1的部分cDNA测序。在8/17例（47%）激酶（5例在MSH 2中，3例在MLH 1中）中鉴定出7种不同的种系突变。在3例病例中，MSH 2 mRNA中的单个外显子缺失，3个突变导致截短的蛋白产物，通过直接测序鉴定出2个错义突变。六个突变是新的。尽管MSH 2错义突变（Thr 905 Arg）与多发性结直肠息肉的易感性相关，但基因型和表型之间没有精确的相关性。MSH 2和MLH 1突变的结直肠癌和子宫癌的年龄相关风险相似。
Germline mutations in four human mismatch repair genes (MSH2, MLH1, PMS1, and PMS2) have been reported to cause hereditary non-polyposis colon cancer syndrome (HNPCC). The identification of germline mutations in HNPCC kindreds allows precise diagnosis and accurate predictive testing. To investigate further the genetic epidemiology of HNPCC and the nature and frequency of germline mutations in this disorder, we studied 17 English HNPCC kindreds for germline mutations in MSH2 and MLH1. A previous genetic linkage study had suggested that most English HNPCC families will have mutations in one of these genes. Mutation analysis was performed in a three step process. (1) mRNA extracted from lymphoblastoid cell lines was analysed for gross rearrangements, (2) the in vitro transcription-translation (IVTT) assay was then performed to detect protein truncating mutations, and (3) partial cDNA sequencing of MSH2 or MLH1 was undertaken in families (n=6) linked to MSH2 or MLH1 but without a detectable mutation. Seven different germline mutations were identified in eight of 17 (47%) kindreds (five in MSH2 and three in MLH1). In three cases there was a deletion of a single exon in MSH2 mRNA, three mutations resulted in a truncated protein product, and two missense mutations were identified by direct sequencing. Six mutations were novel. No precise correlation between genotype and phenotype was observed, although a MSH2 missense (Thr905Arg) mutation was associated with a susceptibility to multiple colorectal polyps. Age related risks for colorectal and uterine cancer were similar for MSH2 and MLH1 mutations.