Missense mutations of the glycoprotein (GP) Ib beta gene impairing the GPIb alpha/beta disulfide linkage in a family with giant platelet disorder
Missense mutations of the glycoprotein (GP) Ib beta gene impairing the GPIb alpha/beta disulfide linkage in a family with giant platelet disorder
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DOI：
10.1182/blood.v89.7.2404
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发表时间：
1997-04-01
期刊：
影响因子：
20.3
通讯作者：
Naoe, T
中科院分区：
文献类型：
--
作者：
Kunishima, S;Lopez, JA;Naoe, T
我们在这里描述了一个孤立的遗传性巨血小板疾病（GPD）的分子基础，这是不伴有血小板减少症或白细胞夹杂物。在该患者中，使用利托那肽和肉毒素的血小板聚集几乎正常。流式细胞术分析表明，糖蛋白（GP）Ib/IX复合物在血小板膜上的表达水平下降。血小板GPIb α的量和血浆Glycocalicin浓度（GPIb α的水溶性胞外部分）也降低。抗GPIb α抗体共沉淀GPIb β和GPIX，尽管这些多肽与GPIb α的比率与正常血小板中的比率相比大大降低。非还原条件下的免疫印迹分析显示，患者血小板中的大多数GPIb α与GPIb β没有二硫键连接。DNA测序分析显示两个独立的单核苷酸取代的复合杂合性：在108例正常人的基因组DNA中未发现这些替换，这些突变可能导致GPIb/IX复合物的表达降低，并可能影响复合物与膜骨架的结合，从而损害正常的血小板形态。此外，由GPIb/IX复合物亚基突变引起的表型可以跨越从正常表型到孤立的GPD再到完全出血性疾病如Bernard-Soulier综合征的范围。(C)1997年，美国血液学会。
We describe here the molecular basis of an isolated hereditary giant platelet disorder (GPD) which is not accompanied with thrombocytopenia or leukocyte inclusion. Platelet aggregation with ristocetin and botrocetin was almost normal in this patient. Flow cytometric analysis showed that the glycoprotein (GP) Ib/IX complex was expressed on the platelet membranes at decreased levels. The amount of platelet GPIb alpha and the plasma glycocalicin concentration, the water-soluble extracellular portion of GPIb alpha, were also decreased. The anti-GPIb alpha antibody coprecipitated GPIb beta and GPIX, although the ratios of these polypeptides to GPIb alpha was greatly decreased compared with the ratio in normal platelets. Immunoblot analysis under nonreduced conditions showed that most of the GPIb alpha in the patient's platelets was not disulfide linked with GPIb beta. DNA sequencing analysis showed compound heterozygosity for two independent single nucleotide substitutions: from Tyr (TAG) to Cys (TGC) at residue 88, and from Ala (GCC) to Pro (CCC) at residue 108 in her GPIb beta gene, These substitutions were not found in genomic DNA samples from 108 normal individuals, These mutations might result in decreased expression of the GPIb/IX complex and may influence the association of the complex with the membrane skeleton, consequently impairing normal platelet morphology. Furthermore, the phenotype caused by mutations in the subunits of the GPIb/IX complex could span the spectrum from a normal phenotype, to isolated GPD, to a full-blown bleeding disorder, such as Bernard-Soulier syndrome. (C) 1997 by The American Society of Hematology.