Platelet PIA2 polymorphism and the risk for thrombosis in heparin-induced thrombocytopenia

Platelet glycoprotein (GP) IIb/IIIa has an important role in platelet aggregation. A polymorphism of platelet GPIIIa (pl(A2), also called HPA1b) has been associated with a higher risk of thrombosis, but its implication in heparin-induced thrombocytopenia (HIT) is unclear To investigate the hypothesis that the pl(A2) polymorphism influences the prothrombotic effects of HIT, we conducted a prospective study of 66 consecutive patients with a laboratory diagnosis of HIT The end point of the study was the diagnosis of a thrombus within 30 days of the positive HIT test result. The Diagnostica Stago (Asnieres, France) enzyme-linked immunosorbent assay was used to detect HIT antibodies, and a polymerase chain reaction assay was used to detect the pl(A2) polymorphism. Of the 66 patients, thrombotic complications developed in 2 7 (41%). Patients with the pl(A2) allele demonstrated a significantly higher thrombosis risk than did patients without (69% vs 32%; P =.0088; odds ratio, 4.68; 95% confidence interval, 1.39-15.72). The risk was stronger for arterial thrombosis and for patients 60 years or older There was a significant association between the Pl(A2) polymorphism of GPIIIa and the risk of thrombosis inpatients with HIT antibodies.