Summary
The platelet membrane glycoprotein (GP) Ibα plays a key role in the initial formation
of thrombi. Polymorphisms (VNTR and HPA-2) in this receptor are associated with increased
risk of coronary heart disease (CHD) and cerebral vascular disease (CVD). We investigated
whether a recently described polymorphism (S/R), due to a single base change (T →
C) five nucleotides upstream the initiator codon of GPIbα, might influence the expression
of the protein, and be implicated in the development of arterial thrombosis.
One hundred and thirty nine healthy individuals provided blood samples for DNA analysis
of platelet GPIbα polymorphisms, and for flow cytometric analysis of the surface expression
of the receptor. A group of 20 S/R normal individuals and an identical number of S/S
participants, age and sex matched, was investigated for the analysis of the density
of various platelet receptors. The distribution of the S/R polymorphism was also analyzed
in two case/control studies including 104 CVD patients, 101 CHD patients, and one
control age, sex, and environmental risk factors matched for each case patient. Surface
density of GPIbα showed no wide variations between individuals, was not influenced
by the presence of S or R alleles, nor associated with the VNTR or HPA-2 polymorphisms.
The prevalence of the S/R genotype among CVD and CHD patients was not distinct from
that in the control groups. We conclude that the S/R polymorphism of GPIbα, flanking
the initiator codon of the receptor, does not seem to be associated with surface levels
of the protein, and is not an independent risk factor for arterial thrombosis.
Keywords
GPIbα - polymorphism - risk factor - arterial thrombosis - platelet
