蛋白C基因复合杂合突变导致的肺栓塞及家系研究

目的了解1例肺栓塞患者及其家系成员发生蛋白C缺陷症的分子发病学机制。方法收集先证者及其家系成员的枸橼酸钠抗凝血,采用发色底物法检测PC活性(PC∶A)、蛋白S活性(FPS∶A)和抗凝血酶活性(AT∶A),采用ELISA方法检测PC抗原(PC∶Ag)水平。采用PCR方法对先证者PC基因所有9个外显子及其侧翼序列进行扩增、测序,发现突变后,对先证者家系成员的PC基因有关外显子片段进行PCR扩增和测序。结果先证者及其父亲、母亲和妹妹均为Ⅱ型PC缺陷症患者。PC基因测序结果显示先证者的PC基因分别出现了位于3号外显子第5540位碱基的G→A的杂合突变和位于第7号外显子第10230位碱基C→T的杂合突变,导致PC E29K和R147W双杂合突变。先证者父亲携带PC E29K杂合突变,而先证者母亲和妹妹均为PCR147W杂合突变的携带者。结论先证者为PC E29K和R147W基因复合杂合突变携带者,且这两种突变分别遗传自其父母。其中,PC E29K错义点突变为目前国际上尚未见报道的新突变,而PC R147W是一种已报道的常见于遗传性易栓症患者的可导致Ⅱ型PC缺乏的错义点突变。

A pedigree analysis of pulmonary embolism caused by compound heterozygous mutations of protein C

Objective To study the molecular pathogenesis of protein C(PC) deficiency in a patient with pulmonary embolism and in his family members.Methods Anticoagulated blood samples were collected from the proband and his family members to detect PC,PS and AT activities.PC antigen level was measured using ELISA.The genomic DNA was extracted to amplify all the 9 exons and their flanking sequences of PC gene using PCR,and the PCR products were sequenced.The mutated exons identified were amplified and sequenced for the other family members.Results The proband and his parents and sister were identified as carriers of PC gene mutation,which led to type II PC deficiency.Sequencing of the proband’s PC gene showed two heterozygous point mutations in exon 3(G5540A) and exon 7(C10230T) to cause compound heterozygous mutations of PC E29K and PC R147W,which were inherited from his father and mother,respectively.His sister was a heterozygote of PC R147W.Conclusion The proband is a compourd heterozygous mutations carrier of PC E29K and PC147W.PC E29K is a novel PC mutation,and PC R147W is a reported PC gene mutation seen in patients with type II hereditary PC deficiency and recurrent thrombosis.