摘要
目的探讨1个ECEL1基因复合杂合变异所致的远端关节挛缩5D型(DA5D)家系的临床表型及遗传学特征。方法选择2022年7月因"四肢多关节活动受限"于河南省儿童医院康复科就诊的1例DA5D患儿(先证者)及其家系成员(先证者父母与胞姐)作为研究对象。收集先证者的临床资料, 并采集先证者及其家系成员的外周血各3 mL, 应用家系全基因组测序(trio-WGS)对先证者及其家系成员进行遗传变异检测。应用基因组聚合数据库(gnomAD)等数据库对检出的先证者候选致病基因变异位点进行筛选和分析, 并应用在线人类孟德尔遗传数据库(OMIM)进行临床表型注释, 应用PROVEAN等生物信息学软件对候选致病变异进行有害性预测。根据美国医学遗传学与基因组学学会(ACMG)相关指南, 对变异位点进行致病性评级。应用Sanger测序法对trio-WGS检测出的先证者相关变异位点于其家系成员中进行验证。应用MEGA-X、PyMOL软件对ECEL1蛋白分别进行物种间氨基酸保守性分析和变异结构预测。本研究遵循的研究程序经过河南省儿童医院伦理委员会的审查(批准号:2023-H-H01), 并与先证者监护人签署临床研究知情同意书。结果本研究先证者存在手足与膝、踝关节等肢体远端多关节挛缩, 以及右侧眼睑下垂、下颌发育不良、耳廓位置偏低、鼻孔形态前倾等特殊面容, 先证者父母及胞姐表型正常。家系trio-WGS检测和Sanger测序检测结果显示, 先证者ECEL1基因存在父源c.1742c.1743insT移码变异和母源c.2314T>G错义变异构成的复合杂合变异, 这2个变异位点均未见报道。先证者父亲及其胞姐均为c.1742c.1743insT移码杂合变异携带者, 先证者母亲为c.2314T>G杂合错义变异携带者。依据ACMG指南, c.1742c.1743insT变异被评定为可能致病变异(PSV1+PM2Supporting), c.2314T>G被评定为意义不明确变异(PM2Supporting +PM3+PP3)。根据先证者临床表现与基因检测结果, 先证者被诊断为DA5D患儿。ECEL1蛋白氨基酸残基序列保守性分析结果显示, 先证者ECEL1基因c.2314T>G(p.Cys772Gly)错义变异所在位点在人类及小家鼠、褐家鼠、原鸡、家犬、非洲象、非洲爪蟾、猕猴物种中高度保守。ECEL1蛋白变异结构预测结果显示, 先证者ECEL1基因c.1742c.1743insT移码变异导致ECEL1蛋白截短, c.2314T>G错义变异导致该蛋白的1个二硫键不能形成。结论 ECEL1基因复合杂合变异可能是导致本研究先证者DA5D发病的遗传学病因。本研究丰富了ECEL1基因的变异谱系, 为DA5D家系的遗传咨询提供了重要依据。
Objective To explore the clinical phenotypes and genetic characteristics of a pedigree with Distal arthrogryposis type 5D(DA5D)caused by compound heterozygous variants in the ECEL1 gene.Methods A child(proband)diagnosed with DA5D and his family members(proband's parents and sister)who was admitted to the Department of Rehabilitation Medicine of Henan Children's Hospital in July 2022 due to"multiplex distal arthrogryposis"were enrolled into this study.Clinical data of the proband were collected and peripheral blood samples were obtained from the proband and members of his family about 3 mL.Trio-whole genome sequencing(trio-WGS)was carried out to detected the genetic variations of the proband and his family members.The candidate's pathogenic gene variants were screened and analyzed by Genome Aggregation Database(gnomAD)and other databases.The screened variants wer annotated for clinical phenotypes using databases like the Online Mendelian Inheritance in Man(OMIM).The pathogenicity of the candidate variants was predicted by bioinformatics tools such as Provean.Based on the guidelines of the American College of Medical Genetics and Genomics(ACMG),pathogenicity ratings were conducted for variant sites.The protein conservation and mutation structure prediction of ECEL1 protein among species were carried out though MEGA-X and PyMOL.The research protocol of this study was reviewed by the Ethics Committee of Henan Provincial Children's Hospital(Approval No.2023-H-H01),and informed consent for clinical research was obtained from the guardians of the probands.Results The proband had multiplex distal arthrogryposis involving hands,feet,knees,and ankles,and had right ptosis,micrognathia,low auricular position,and upturned nose.The parents and sister both had normal phenotypes.Trio-WGS and Sanger sequencing revealed that the child had compound heterozygous variants of paternal c.1742_c.1743insT and maternal c.2314T>G,for which the father and sister were carriers of the c.1742_c.1743insT heterozygous variant and the mother was carrier of c.2314T>A.Neither mutation site has been reported.According to guidelines of ACMG,the c.1742_c.1743insT variant was classified as likely pathogenic(PSV1+PM2_Supporting),and c.2314T>G was classified as uncertain(PM2 Supporting+PM3+PP3).The results of conserved analysis of amino acid residue sequences of ECEL1 protein showed that the missense mutation of the maternal c.2314T>G(p.Cys772Gly)was highly conserved among humans and other seven species.The protein structure prediction revealed that the c.1742_c.1743insT frameshift mutation led to the protein truncation,and the c.2314T>G missense mutation resulted in the failure of forming 1 disulfide bond.Conclusion The compound heterozygous variants of ECEL1 gene were considered to be pathogenic for this DA5D patient,which have expanded the mutational spectrum of the ECELl gene and provided a reference for clinical diagnosis as well as genetic counseling for this family.
作者
胡韦毓
陈白云
高杨
王潇娜
李雨珂
李倩影
张会春
高超
Hu Weiyu;Chen Baiyun;Gao Yang;Wang Xiaona;Li Yuke;Li Qianying;Zhang Huichun;Gao Chao(Department of Rehabilitation Medicine,Children's Hospital Affiliated to Zhengzhou University,Henan Children's Hospital Zhengzhou Children's Hospital,Zhengzhou,Henan 450018,China;Information Center,Children's Hospital Affiliated to Zhengzhou University,Henan Children's Hospital Zhengzhou Children's Hospital,Zhengzhou,Henan 450018,China;Henan Provincial Key Laboratory of Children's Genetics and Metabolic Diseases,Children's Hospital Affiliated to Zhengzhou University,Henan Children's Hospital Zhengzhou Children's Hospital,Zhengzhou,Henan 450018,China;Department of Intensive Care Unit,Children's Hospital Affiliated to Zhengzhou University,Henan Children's Hospital Zhengzhou Children's Hospital,Zhengzhou,Henan,450018 China;Henan Clinical Medical Research Center for Pediatric Diseases,Zhengzhou,Henan 450018,China)
出处
《中华医学遗传学杂志》
2025年第3期322-329,共8页
Chinese Journal of Medical Genetics
基金
河南省科技攻关计划(222102310674、232102520024)
河南省儿科疾病临床医学研究中心开放课题(YJZX202205)
河南省医学科技攻关计划联合共建项目(LHGJ20220773、LHGJ20230606)。
