Tao J, Arias-Salgado E G, González-Manchón C, Díaz-Cremades J, Ayuso M S, Parrilla R
Department of Pathophysiology and Human Molecular Genetics, Centro de Investigaciones Biológicas, Madrid, Spain.
Br J Haematol. 2000 Oct;111(1):96-103. doi: 10.1046/j.1365-2141.2000.02336.x.
This work reports the molecular genetic analysis of two patients who suffer mucocutaneous haemorrhages, prolonged bleeding time and failure of platelets to aggregate, either spontaneously or in response to agonists. The absence of platelet surface glycoprotein (GP)IIb-IIIa complexes confirmed the clinical diagnosis of Glanzmann's thrombasthenia (GT). Polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis of exon 2 of GPIIb showed polymorphic bands caused by the homozygous deletion of a cytosine at position 288 relative to the translation start site. causing a shifting of the reading frame and appearance of a premature termination codon. The heterozygous relatives showed a reduced platelet content of GPIIb-IIIa, and a correlation was found between the levels of GPIIb mRNA and surface expression of GPIIb-IIIa complexes. Unlike other mRNAs carrying a nonsense mutation, (288Cdel)GPIIb does not force alternative splicing of GPIIb mRNA. As expected, co-transfection of Chinese hamster ovary (CHO) cells with cDNAs encoding GPIIIa and (288delC)GPIIb failed to enhance the surface exposure of GPIIIa. It is concluded that the (288delC)GPIIb mutation is responsible for the thrombasthenic phenotype of the patients. In addition, it has also been determined that heterodimerization of GPIIb-IIIa requires the integrity of exons 2 and 3 of GPIIb.
这项研究报告了对两名患有皮肤黏膜出血、出血时间延长以及血小板自发或对激动剂无聚集反应的患者进行的分子遗传学分析。血小板表面糖蛋白（GP）IIb-IIIa复合物的缺失证实了临床诊断为Glanzmann血小板无力症（GT）。对GPIIb外显子2进行聚合酶链反应单链构象多态性（PCR-SSCP）分析，结果显示相对于翻译起始位点，第288位胞嘧啶纯合缺失导致了多态性条带的出现，从而导致阅读框移位并出现提前终止密码子。杂合亲属的血小板GPIIb-IIIa含量降低，并且发现GPIIb mRNA水平与GPIIb-IIIa复合物的表面表达之间存在相关性。与携带无义突变的其他mRNA不同，（288Cdel）GPIIb不会促使GPIIb mRNA发生可变剪接。正如预期的那样，将编码GPIIIa和（288delC）GPIIb的cDNA共转染到中国仓鼠卵巢（CHO）细胞中，未能增强GPIIIa的表面暴露。得出的结论是，（288delC）GPIIb突变是导致患者血小板无力症表型的原因。此外，还确定了GPIIb-IIIa的异二聚化需要GPIIb外显子2和3的完整性。
