摘要背景 基因突变是导致遗传性先天性白内障的主要原因,全外显子组测序技术是目前研究致病基因突变较为理想的检测手段. 目的 应用高通量测序技术对中国汉族常染色体显性遗传先天性白内障(ADCC)一家系的3例患者进行全外显子组测序,筛选该ADCC家系的致病基因. 方法 采用横断面研究方法,收集中国汉族先天性白内障一家系,共有4代48人家系成员,其中Ⅰ1和Ⅰ2已去世.在Ⅱ、Ⅲ、Ⅳ代中各取1例患者的静脉血8 ～ 10 ml,采用全外显子捕获和新一代测序技术进行高通量测序,测序结果与人类HA PMAP8、dbSNP130和1000 Genome Project数据库进行比对,过滤已报道的常见变异后,再过滤掉同义突变,最后通过Sanger法测序排除外显子测序的假阳性结果,筛选出候选基因,并对其进行突变筛查.结果 该家系的所有成员中共11例患病者,且各代均有患病者,男女发病比例相当,符合ADCC的遗传规律,所有患者均为核性白内障.全外显子组测序发现,在各候选基因中,主要内源性蛋白(MIP)基因是ADCC的已知基因,故采用Sanger法首先对MIP基因进行验证并确定杂合突变(chr12:56845250 C＞T)为该家系的致病突变.该突变位于剪切位点上,造成由第4外显子编码的61个氨基酸被亮氨酸-组氨酸-丝氨酸所替代,导致异常截短蛋白的产生.结论 MIP基因剪切位点的杂合突变是导致该ADCC家系致病的分子发病机制.

abstractsBackground Genetic mutation remains to be the most common cause of congenital cataract.Whole exon sequencing technology is an ideal method to detect the pathogenic gene mutations.Objective This study was to identify the pathogenic gene in a Chinese autosomal dominant congenital cataract (ADCC) family by whole-exome sequencing.Methods This study complied with Helsinki Declaration and the protocol was approved by Ethic Committee of Peking University Third Hospital.Informed consent was obtained from each subject before any medical examination.A cross-sectional study was designed.A Chinese ADCC family with 4 generations and 48 members were enrolled in Peking University Third Hospital,of which Ⅰ1 and Ⅰ2 died.The periphery blood of 8-10 ml was collected from each member of Ⅱ,Ⅲ and Ⅳ generations for the high throughput sequencing of genes using whole exon trapping and new sequencing technology,and the sequencing results were compared with the data of human HA PMAP8,dbSNP130 and 1000 Genome Project database.The synonymous mutation was filtered after reported common variants,and the false positive results of explicit sequencing were finally excluded by Sanger sequencing and then the candidate genes were identified.The mutation genes were screened to determine the pathogenic gene of this ADCC family.Results Eleven ADCC patients were found in this family,and the patients distributed in each generation with an equal chance for involvement in male and female subjects,which conformed to an autosomal dominant inheritance pattern.All the patients were nuclear cataract.Genome-wide whole-exome sequencing found that major intrinsic protein (MIP) gene was known genes of ADCC in initially identified candidate genes,so the Sanger was used to verify the MIP gene.The heterozygous mutation of MIP gene (chr12:56845250 C ＞ T) appeared to be the pathogenic cause of this ADCC family.The mutation occurred in the splice sites of the gene,resulting in the fourth exon coded-61 amino acids are replaced by leucine,histidine and serine,which lead to the abnormal truncated proteins.Conclusions The heterozygous mutation of MIP gene is the molecular pathogenesis of this Chinese ADCC family.