Department of Gynaecology and Obstetrics, Second Hospital of Jinlin University, Changchun 130041, PR China.
Beijing DnaLead Science and Technology Co., LTD, Beijing 102600, PR China.
Biochem Biophys Res Commun. 2014 May 9;447(3):503-7. doi: 10.1016/j.bbrc.2014.04.014. Epub 2014 Apr 13.
Inheritable colorectal cancers (CRC) accounted for about 20% of the CRC cases, such as hereditary nonpolyposis colorectal cancer (HNPCC), Gardner syndrome and familial adenomatous polyposis (FAP). A four-generation Han Chinese family was found affected with polyposis in colons. Inferred from the pedigree structure, the disease in this family showed an autosomal dominant inheritance model. To locate the causal mutations in this family, genomic DNAs were extracted and the next generation sequencing for 5 genes relating to colon cancer performed by Ion Torrent Personal Genome Machine with a 314 chip. The reads were aligned with human reference genome hg19 to call variants in the 5 genes. After analysis, 14 variants were detected in the sequenced sample and 13 been collected in dbSNP database and assigned with a rs identification number. In these variants, 9 were synonymous, 4 missense and 1 non-sense. In them, 2 rare variants (c.694C>T in APC and c.1690A>G in MSH2) might be the putative causal mutations for familial adenomatous polyposis (FAP) since the rarity of the mutated allele in normal controls. c.694C>T was detected in only affected members and generated a premature stop codon in APC. It should be a de novo germline mutation making APC containing this stop codon as targets for nonsense-mediated mRNA decay (NMD). c.1690A>G in MSH2 was not only detected in affected members, but also in normal ones in the family. Functional prediction revealed that the amino acid affected by this variant had no effect on the function of MSH2. Here, we report a de novo germline mutation of APC as the causal variant in a Chinese family with inheritable colon cancer by the next generation sequencing.
遗传性结直肠癌（CRC）约占 CRC 病例的 20%，例如遗传性非息肉病性结直肠癌（HNPCC）、Gardner 综合征和家族性腺瘤性息肉病（FAP）。一个四代汉族家庭被发现结肠有多发性息肉。根据家系结构推断，该家族的疾病表现为常染色体显性遗传模式。为了定位该家族的致病突变，提取基因组 DNA，使用 Ion Torrent Personal Genome Machine 进行与结肠癌相关的 5 个基因的下一代测序，该测序仪使用 314 芯片。将读取序列与人类参考基因组 hg19 进行比对，以在 5 个基因中调用变体。经过分析，在测序样本中检测到 14 个变体，并在 dbSNP 数据库中收集了 13 个变体，并分配了 rs 识别号。在这些变体中，9 个是同义的，4 个是错义的，1 个是无义的。其中，2 个罕见变体（APC 中的 c.694C>T 和 MSH2 中的 c.1690A>G）可能是家族性腺瘤性息肉病（FAP）的潜在致病突变，因为在正常对照中突变等位基因的罕见性。c.694C>T 仅在受影响的成员中检测到，并在 APC 中产生了一个提前终止密码子。这应该是一个从头发生的种系突变，使 APC 成为无意义介导的 mRNA 降解（NMD）的靶标。MSH2 中的 c.1690A>G 不仅在受影响的成员中检测到，而且在家族中的正常成员中也检测到。功能预测表明，受该变体影响的氨基酸对 MSH2 的功能没有影响。在这里，我们通过下一代测序报告了一个中国遗传性结直肠癌家庭中 APC 的从头发生种系突变作为致病变体。
