目的对一个凝血因子X(FX)缺陷症家系进行FX基因突变的检测。方法用活化部分凝血活酶时间(APTT)、凝血酶原时间(PT)及FX促凝活性 (FX :C)测定进行表型诊断 ;用PCR法对先证者的FX基因8个外显子及其侧翼序列和5’端非翻译区 (5’UTR)序列进行扩增 ,PCR产物纯化后直接测序 ,检测其基因突变。家系成员DNA在先证者FX基因突变区域扩增后测序。结果先证者表型诊断为FX缺陷症 ;FX外显子区共发现3个与文献报道的FX基因序列不同的位点 ,其中位于第8外显子区的为纯合突变C1098T。家系分析表明先证者父、母、弟和妹均为C1098T杂合子。结论纯合错义突变C1098T引起的Thr318Met是导致本例遗传性FX缺陷症的原因。 Objective To detect the FX gene mutation in a pedigree of factor X (FX) deficiency. Methods Phenotypic diagnosis was performed with activated partial thromboplastin time (APTT), prothrombin time (PT) and FX procoagulant activity (FX: C). Eight exons of FX gene of probands And its flanking and 5 ’untranslated region (5’UTR) sequence amplification, PCR products were purified directly sequenced to detect the gene mutation. Family members of DNA in the proband FX gene mutation region amplified after sequencing. Results The phenotypes of probands were diagnosed as FX deficiency. Three FX loci were found in FX exon, which were different from those reported in the literature. Among them, homozygous mutation C1098T was located in exon 8. Pedigree analysis shows that the proband’s father, mother, brother and sister are C1098T heterozygotes. Conclusions Thr318Met caused by the homozygous missense mutation C1098T is responsible for the inherited FX deficiency in this case.