F12基因p.Gly175Cys和p.Gly542Ser复合杂合突变导致的遗传性凝血因子Ⅻ缺陷症的家系分析

Pedigree Analysis of Hereditary Coagulation Factor XII Deficiency Caused by Compound Heterozygous Mutation p.Gly175Cys and p.Gly542Ser of F12 Gene

目的:分析1例遗传性凝血因子Ⅻ(FⅫ)缺陷症家系的临床表型和基因突变情况,并探讨其分子致病机制。方法:凝固法检测活化部分凝血活酶时间和FⅫ活性;ELISA方法检测FⅫ抗原;Sanger测序法测定F12基因所有外显子及侧翼序列;ClustalX-2.1-win、PROVEAN及Swiss-Pdb Viewer软件分析突变位点氨基酸的保守性、突变氨基酸是否为有害突变及该位点发生突变后对蛋白质结构的影响。结果:先证者活化部分凝血活酶时间延长为71.3 s,FⅫ活性和FⅫ抗原分别降低为5%和6%;其F12基因第7和14外显子分别存在c.580G>T和c.1681G>A杂合错义突变,导致p.Gly175Cys和p.Gly542Ser;先证者父亲携带p.Gly175Cys杂合错义突变;先证者母亲、弟弟和女儿携带p.Gly542Ser杂合错义突变。软件分析结果表明Gly175和Gly542均保守,p.Gly175Cys和p.Gly542Ser为有害突变,突变发生后相应位点会对蛋白质局部结构产生影响。结论:p.Gly175Cys和p.Gly542Ser复合杂合突变是先证者家系遗传性FⅫ缺陷症的分子发病机制,其中p.Gly175Cys为国际上首次发现的新突变。

Objective:To analyze the clinical phenotype and gene mutation of a genetic coagulation factor XII(FXII)deficiency pedigree and explore the molecular pathogenesis.Methods:The activated partial thromboplastin time(APTT)and FXII activity(FXII:C)were detected by clotting method.The FXII antigen(FXII:Ag)was tested with ELISA.All exons and flanks of F12 gene were determined by Sanger sequencing.ClustalX-2.1-win,PROVEAN and Swiss-Pdb Viewer software were used to analyze the conservatism of amino acids at the mutant site,forecast whether the mutant amino acids were harmful and confirm the influence of the mutation on protein structure.Results:The APTT of the proband prolonged to 71.3 s.The FXII:C and FXII:Ag were decreased to 5%and 6%,respectively.There were two heterozygous missense mutations c.580G>T and c.1681G>A detected in exon 7 and exon 14 of F12 gene,resulting in p.Gly175Cys and p.Gly542Ser,severally.Proband’s father carried the p.Gly175Cys heterozygous mutation,while mother,brother and daughter had the p.Gly542Ser heterozygous mutation.Software analysis showed that both Gly175 and Gly542 were conserved,the two mutations were harmful and when mutations had occurred,the corresponding sites affected the protein local structure.Conclusion:The p.Gly175Cys and p.Gly542Ser compound heterozygous mutations are the molecular pathogenesis of the hereditary coagulation FXII deficiency pedigree.The p.Gly175Cys mutation has been detected for the first time in the world.