Leroy-Matheron C, Gouault-Heilmann M, Aiach M, Gandrille S
INSERM U.428, Paris, France.
Blood. 1998 Jun 15;91(12):4608-15.
The genomic analysis of a 70-year-old man with recurrent deep venous thrombosis having a protein S (PS)-deficient phenotype corresponding to both type III and type II evidenced two different mutations: a +5 g-->a mutation in the donor splice site of intron e (ivs e) and a ser 460 to Pro mutation. The propositus' son, who had a type II PS deficiency phenotype, only bore the ivs e +5 g-->a mutation. The study of platelet PS mRNA prepared from this subject showed that the ivs e, +5 g-->a mutation led to the generation of two abnormal transcripts, one lacking exon 5 and the other lacking exons 5 and 6. The presence of an additional PS band with a decreased molecular mass on immunoblots performed in reducing conditions suggested the presence of truncated PS lacking EGF1 (encoded by exon 5). Two monoclonal antibodies (MoAbs) were used to further characterize the nonfunctional plasma PS. Comparison of PS levels measured with each of these MoAbs and PS levels in conventional assays was consistent with the presence of an abnormal inactive protein in the plasma of both patients bearing the ivs e, +5 g-->a mutation, suggesting that variant PS lacking EGF1 is secreted but is devoid of activated protein C cofactor activity.
对一名70岁复发性深静脉血栓形成男性患者进行的基因组分析显示，其蛋白S（PS）缺陷表型同时符合III型和II型，发现了两种不同的突变：内含子e（ivs e）供体剪接位点的+5 g→a突变和ser 460突变为Pro。先证者的儿子具有II型PS缺乏表型，仅携带ivs e +5 g→a突变。对该受试者制备的血小板PS mRNA的研究表明，ivs e +5 g→a突变导致产生两种异常转录本，一种缺少外显子5，另一种缺少外显子5和6。在还原条件下进行的免疫印迹中出现分子量降低的额外PS条带，提示存在缺少EGF1（由外显子5编码）的截短型PS。使用两种单克隆抗体（MoAbs）进一步鉴定无功能的血浆PS。用这些MoAbs中的每一种测得的PS水平与传统检测中的PS水平比较，与携带ivs e +5 g→a突变的两名患者血浆中存在异常无活性蛋白一致，提示缺少EGF1的变异型PS被分泌，但缺乏活化蛋白C辅因子活性。
