一个Gly341Arg纯合突变所致遗传性FⅫ缺陷症近亲婚配家系的分析  

Analysis of a consanguineous pedigree affected with hereditary coagulation factor Ⅻ deficiency caused by homozygous Gly341Arg mutation

作　　者：杨丽红[1] 金赛燕 季伟丹 程晓丽[1] 李小龙[1] 金艳慧[1] 王明山[1] 

机构地区：[1]温州医科大学附属第一医院医学检验中心,浙江325015

出　　处：《中华医学遗传学杂志》2018年第1期69-73,共5页Chinese Journal of Medical Genetics

基　　金：浙江省科技厅计划（2013C37046）

摘　　要：目的对一个姨表近亲婚配的遗传性凝血因子Ⅻ（coagulation factor FⅫ，Ⅻ）缺陷症家系进行实验室表型和F衄基因突变的分析，探讨其分子发病机制。方法检测先证者及9名家系成员活化部分凝血活酶时间（activated partial thromboplastin time,APTT）等凝血常规功能、FⅫ活性（FⅫactivity，FⅫ：c）和FⅫ抗原（FⅫantigen，FⅫ：Ag）含量，进行表型诊断；用DNA直接测序法分析先证者FⅫ基因所有14个外显子、侧翼、5’和3＇非翻译区及家系成员相应的突变位点区域，用反向测序证实突变。采用ClustalX-2．1-win软件分析突变氨基酸的保守性，并同时采用4个生物信息学评分软件（PolyPhen-2，PROVEAN，SIFT和Mutation Taster）分析突变对蛋白质功能的影响。结果先证者（IV2）和哥哥（Ⅳ1）APTT明显延长（分别为61．6s和68．6s），FⅫ：C和FⅫ：Ag分别降低为12％、10％和11％、10％；先证者祖母（Ⅱ2）、外祖母（Ⅱ3）、父亲（Ⅲz）、母亲（Ⅲ6）、大姑（Ⅲ1）和大姨（Ⅲ5）APTT正常，FⅫ：C和FⅫ：Ag均降低约为正常值的一半；先证者小姑（Ⅲ3）和大舅（Ⅲ4）各项指标及家系成员其它指标均正常。基因测序发现先证者（IV。）和其哥哥（Ⅳ1）FⅫ基因第10外显子存在c．1078G〉A（P．Gly341Arg）纯合错义突变；先证者祖母（Ⅱ2）、外祖母（Ⅲ3）、父亲（Ⅲ2）、母亲（Ⅲ6）、大姑（Ⅲ1）和大姨（Ⅲ5）均存在P．Gly341Arg杂合错义突变；先证者小姑（Ⅲ3）和大舅（Ⅲ4）为正常野生型。ClustalX-2．1-win软件保守性分析结果表明，Gly341在同源物种间高度保守。4个生物信息学软件对该突变的预测结果一致：PolyPhen-2评分（0．934分）、PROVEAN评分（-6．214分）均预示为有害突变；Mutation Taster评分（0．976分）预示可引起相应疾病；SIFT评分（0．01分）预示可影响蛋白质功能。结论Gly341Arg纯合错义�Objective To analyze the laboratory phenotype and FⅫ gene mutation in a consanguineous Chinese pedigree affected with factor Ⅻ （FⅫ） deficiency. Methods Activated partial thromboplastin time （APTT）, FⅫ activity （FⅫ：C） and FⅫ antigen （FⅫ：Ag） of the proband and her family members （10 individuals from 3 generations） were determined. Sanger sequencing was used to detect potential mutation within the 14 exons, their flanking regions and 5＇, 3＇-untranslated regions of the F~ gene. Suspected mutations were verified by backward sequencing. Conservation of the amino acids were analyzed with ClustalX-2. 1-win. Four online bioinformatics software （ PolyPhen-2, PROVEAN, SIFT and MutationTaster） were used to assess the impact of the mutations on the protein function. Results The APTT of the proband and her eider brother have prolonged to 61.6 s and 68.6 s,and their FⅫ：C and FⅫ ： Ag have decreased to 12%, 10% and 11%, 10%, respectively. The APTT of the paternal grandmother, maternal grandmother, father, mother, elder paternal aunt and elder maternal aunt were all normal, hut their FⅫ ：C and FⅫ：Ag have reduced to half of the normal value. Gene sequencing found that the proband and her elder brother have both carried a homozygous missense e. 1078G〉A（p. Gly341Arg）mutation in exon 10 of the FⅫ gene, for which the paternal grandmother, maternal grandmother, father, mother, elder paternal aunt and elder maternal aunt were heterozygous. Bioinformatic analysis suggested that the Gly341 is highly conserved, while p. Gly341Arg is a harmful mutation which may cause disease by affecting the function of FⅫ protein. Conclusion Homozygous p. Gly341Arg mutation, caused by consanguineous marriage,probably underlies the congenital FⅫ deficiency in this pedigree.

关 键 词：凝血因子Ⅻ 纯合子 突变 系谱 近亲 

分 类 号：R596[医药卫生—内科学]