Genetic variability of platelet glycoprotein Ibalpha gene

Platelet GPIbalpha, GPIV and vWF polymorphisms and fatal pre-hospital MI among middle-aged men

BACKGROUND

The binding of platelet glycoprotein (GP) Ib-IX-V receptor complex to subendothelial collagen via von Willebrand factor is the initial step of the formation of platelet thrombi following atherosclerotic plaque rupture. Platelet GPIV binds to collagen and/or thrombospondin and further activates platelets. Genetic variation in these proteins could associate with platelet aggregability and the risk of myocardial infarction (MI).

METHODS AND RESULTS

We studied the associations of polymorphisms of GPIbalpha, GPIV and von Willebrand factor with the extent of coronary atherosclerosis, coronary narrowing, and fatal MI in an autopsy series of 300 middle-aged, Caucasian Finnish men who had suffered sudden out-of-hospital death. 31% of men with MI under the age of 50 carried the GPIbalpha HPA-2 ThrThr/Kozak TT haplotype as opposed to 62% of control men (OR 0.27, 95% CI 0.08-0.93, P = 0.03). In addition, 7% of men with MI under the age of 50 carried the GPIV AA genotype versus 29% of control men (OR 0.16, 95% CI 0.03-0.98, P < 0.05). These associations were not due to any effects of these gene variants on the coronary atherosclerotic changes. The G/A polymorphism of the von Willebrand factor gene failed to show any association with MI or coronary atherosclerosis in this series of men.

CONCLUSIONS

The combined ThrThr/TT haplotype of GPIbalpha as well as the AA genotype of GPIV seem to decrease the risk of fatal MI among men during early middle-age.

Gene polymorphism of platelet glycoprotein I balpha in Chinese patients with large- and small-artery subtypes of ischemic stroke

The platelet surface glycoprotein (GP) I balpha, an important part of the GP I b-IX-V complex, participates in the formation of thrombosis by initially mediating platelet adhesion under high shear stress. The purpose of present study was to investigate the association between gene polymorphism of GP I balpha (human platelet antigen 2, HPA2) and ischemic stroke in a matched case-control study. One hundred patients and 100 matched controls were enrolled in the study. The cases were divided into large- and small-vessel subtypes of ischemic stroke according to Trial of Org10172 in Acute Stroke Treatment criteria. Genotyping for GP I balpha polymorphism was documented by polymerase chain reaction amplification and restriction enzyme analysis. There were no statistically significant differences in the GP I balpha HPA2 genotype distribution between ischemic stroke group, large-vessel subtype group, small-vessel subtype group and corresponding control groups. The heterozygote genotype of GP I balpha HPA2 was more frequent in the large-vessel subtype group (16.1%) than in the small-vessel subtype group (10.1%), but the difference was not statistically significant. Ourresults suggest that the polymorphism of the GP I balpha HPA2 genotype might not be a genetic risk factor of ischemic stroke.