全外显子组测序技术检测一家系非综合征型唇腭裂基因突变

Identifi cation of a novel pathogenic mutation in a family with non-syndromic cleft lip and palate by Whole Exon Sequencing

目的通过全外显子组测序技术,检测非综合征型唇腭裂家系致病基因新型突变。为该家系产前诊断以及遗传咨询提供可靠的遗传学依据。方法经知情同意,对死胎接生术后的胎儿进行检测。分析整理孕妇家系资料并绘制系谱图,采用高通量测序技术(NGS)对引产胎儿进行全外显子组测序,找到死产胎儿的高度可疑致病突变位点,并用Sanger测序的方法对家系成员一一验证。结果该家系中共5人,1名患者为非综合征型轻微唇裂,已实施手术修复。2名已故患者,由家系成员自述均为孕20w左右,B超提示严重唇腭裂,行死胎接生术,引产胎儿外观均符合唇腭裂表型。采用高通量测序技术(NGS)对引产胎儿行全外显子组测序,检测到先证者CDON c.323G>C(p.Ser108Thr)的错义突变;Sanger测序证实该家系中现存1人携带CDON c.323G>C(p.Ser108Thr)错义突变,为非综合征型轻微唇裂,已实施手术修复。该位点变异导致第108号氨基酸由Ser变为Thr(p.Ser108Thr),该变异可能导致蛋白功能受到影响,经家系验证该位点突变源自胎儿姥姥。生物信息学分析预测这种新型突变会引发蛋白功能异常。结论研究筛选出先证者及家系成员CDON基因的新型突变,该家系中携带CDON c.323G>C突变的成员临床表型差异较大,CDON基因符合常染色体显性遗传方式,结合常染色体显性遗传的外显率不同以及该家系的检测结果,认为CDON c.323G>C突变有可能是本家系致病的分子基础。

Objective:To detect novel mutations in pathogenic genes of non-syndromic cleft lip and palate families by total exon group sequencing.It provides reliable genetic basis for prenatal diagnosis and genetic counseling of the family.Methods:Informed consent was used to detect the fetus after stillbirth.The pedigree data of pregnant women were analyzed and the pedigree map was drawn.The induced fetus was sequenced by high throughput sequencing(NGS)technique.The highly suspicious mutation sites of stillbirth fetus were found and verified by Sanger sequencing.Results:There were 5 persons in this family.One patient had mild non-syndromic cleft lip and had undergone surgical repair.Two deceased patients were reported by family members to be about 20 weeks pregnant.B-mode ultrasonography indicated severe cleft lip and palate.They underwent stillbirth.The appearance of induced fetus conformed to the phenotype of cleft lip and palate.High-throughput sequencing(NGS)was used to sequence all exons of induced abortion fetuses.Missense mutations in the proband CDON c.323G>C(p.Ser108Thr)were detected.Sanger sequencing confirmed that two of the family members carried CDON c.323G>C(p.Ser108Thr)missense mutations.One of them was a non-syndromic mild cleft lip and had been operated on.The mutation of this site resulted in the change of amino acid 108 from Ser to Thr(p.Ser108Thr),which may affect the function of protein.Families confirmed that the mutation originated from fetal grandmother.Bioinformatics analysis predicted that this new mutation would lead to abnormal protein function.Conclusion:A new mutation of CDON gene in proband and family members was screened out.The clinical phenotype of the members carrying CDON c.323G>C mutation in this family is quite different.CDON gene conforms to the autosomal dominant inheritance mode.Combining with the different autosomal dominant inheritance and the results of detection in this family,it is considered that CDON c.323G>C mutation may be the molecular basis of the pathogenesis of this family.