应用外显子结合目标区域捕获测序芯片对一回族先天性白内障家系致病基因的检测

Detection of disease-causing gene in a Hui congential cataract pedigree by exon combined target region capture sequencing chip

背景 先天性白内障是造成儿童盲和弱视的重要原因,其中约50％的先天性白内障具有遗传性.目的 应用眼遗传病外显子结合目标区域捕获测序芯片检测一常染色体显性遗传先天性白内障家系的致病基因.方法 于2011年在宁夏眼科医院收集一回族常染色体显性遗传先天性白内障家系,采集家系中患者及表型正常成员的临床资料.对家系成员进行眼科检查,抽取患者、表型正常家系成员及300名正常对照者的外周静脉血各5 ml,提取DNA,利用眼遗传病外显子结合目标区域捕获测序芯片筛查和检测候选致病突变位点.采用PCR和直接测序法对家系成员和正常对照者进行突变位点验证,最终确定致病突变位点.结果 该家系共6代61名成员,均为回族,先天性白内障患者18例,为5代遗传,符合常染色体显性遗传特征.患者中合并眼球震颤和斜视者7例,合并高度近视者4例,来诊前均已实施白内障摘出术.利用眼遗传病外显子结合目标区域捕获测序芯片检测结合生物信息学方法筛查后共得到8个候选致病突变位点,其中5个在非编码区,3个在编码区,通过PCR和直接测序法验证确定CRYGD基因上的P24T突变是该家系的致病突变位点.该突变与家系内所有患者表型共分离,在家系表型正常者及300名正常对照者均未发现此突变.结论 外显子结合目标区域捕获测序技术快速检测CRYGD基因P24T突变为该先天性白内障家系致病突变,该技术为临床表型多样、致病基因众多的先天性白内障的致病基因检测提供新的手段.

Background Congenital cataract is an important cause of blindness and amblyopia in children,and about 50% of congenital cataract is hereditary.Objective The aim of this study was to determine the diseasecausing gene of one Hui congenital cataract pedigree by using exon combined target region capture sequencing chip of eye diseases.Methods This study was approved by Ethic Committee of Ningxia People＆#39;s Hospital and followed Declaration of Helsinki.One Hui congenital cataract pedigree was recruited in Ningxia Eye Hospital in 2011.All the disease history of the members in this family were collected and recorded,and the eye examinations were performed.The peripheral blood specimens were collected from family members and 300 healthy individuals for the extraction of DNA.Exon combined target region capture sequencing chip of eye diseases was used to screen the candidate diseasecausing mutations,then PCR and direct sequencing were used to confirm the disease-causing mutations.Results This H ui family included 61 members of 6 generations,and 18 patients were diagnosed in serial 5 passages,conforming to autosomal dominant inheritance pattern.Among 18 cataract patients,7 individuals were associated with nystagmus and strabismus,and 4 patients had high myopia.Eight candidate pathogenetic mutations were detected by exon combined target region capture sequencing chip of eye diseases and bioinformatics method,with 5 mutations in noncoding regions and 3 in coding regions.The mutation P24T of CYRGD gene was confirmed as pathogenic mutation of this pedigree by using PCR and direct sequencing methods.These mutations co-segregated with affected members of the family,and the mutations were not found in the unaffected family members and 300 unrelated controls.Conclusions P24T of CYRGD gene mutation is confirmed as pathogenic mutation of this pedigree.Exon combined target region capture sequencing chip provides a new approach to detect disease-causing mutations of congenital cataract with diversity clinical phenotypes.