先天性纤溶酶原激活物抑制剂-1缺乏症的诊断研究

目的　诊断 1例先天性纤溶酶原激活物抑制剂 1(PAI 1)缺乏症患者并研究其基因异常。方法　用发色底物法、酶联免疫吸附实验测定组织型纤溶酶原激活物 (tPA)、α2 纤溶酶抑制剂因子(α2 PI )与PAI 1的活性和 (或 )抗原 ,PCR法与DNA测序分析患者的基因异常 ,用限制性内切酶PshAⅠ对患者和 6 0名正常人PCR产物酶切以排除基因多态性。结果　患者优球蛋白溶解时间 (ELT) 70min ,血浆中加入生理浓度的PAI 1(5 0ng ml)后ELT延长至 12 0min ,PAI 1活性 0 .0 4AU ml,PAI 1抗原 5 .6ng ml,α2 PI活性、F活性及tPA抗原和活性均正常。PCR测序证实患者PAI 1基因外显子 2第 4 3位核苷酸G→A杂合性改变 ,导致信号肽第 15位的丙氨酸突变为苏氨酸。酶切鉴定排除了多态性。结论　报道国内首例PAI 1缺乏症患者 ,其基因改变可能为复合杂合子 ,其中之一为Ala15Thr,该突变为一种国际上尚未报道的新的基因突变。

Report of a case of congenital plasminogen activator inhibitor-1 deficiency

OBJECTIVE: To report a patient with congenital plasminogen activator inhibitor-1 (PAI-1) deficiency and explore its molecular mechanism. METHODS: The activities of tissue plasminogen activator (tPA), alpha(2) antiplasmin (alpha(2)AP) and PAI-1 were measured by the methods of chromogenic substrate, the antigens of tPA and PAI-1 were measured by ELISA. PAI-1 gene was studied by PCR product sequencing and restriction endonuclease ana-lysing. RESULTS: In the present patient, the euglobulin clot lysis time was 70 minutes and was corrected to normal range after added 50 ng/ml PAI-1 to his plasma. The activities of t-PA, alpha(2)AP, and factor were normal; the activity and antigen of PAI-1 in plasma were both significantly decreased. Nucleotide sequence analysis revealed that the patient had a heterozygous missense mutation in exon 2, a G to A transition at nucleotide 43. The possibility of gene polymorphism was excluded by restriction endonuclease analysing. CONCLUSIONS: It is the first patient with congenital PAI-1 deficiency reported in China. The PAI-1 deficiency in the patient may be caused by compound heterozygosity, one of which is the G to A transition at nt43, a new mutation in congenital PAI-1 deficiency.