AB0 blood group and risk of venous or arterial thrombosis in carriers of factor V Leiden or prothrombin G20210A polymorphisms

1 Centro Regional de Hemodonación, Universidad de Murcia 2 Centro de Investigación, Hospital Universitario La Fé, Valencia 3 Hematology Service, Hospital Clínico Universitario, Salamanca 4 Servicio de Hematología, Clínica Universitaria de Navarra, Pamplona 5 Unitat d’Hemostasia i Trombosi, Hospital de la Santa Creu i Sant Pau, Barcelona 6 Servicio de Hematología, Fundación Jiménez Díaz, Madrid and 7 Servicio de Cardiología, Hospital Virgen de la Arrixaca, Murcia, Spain Correspondence: Javier Corral, Centro Regional de Hemodonación, C/ Ronda de Garay s/n, Murcia 30003 Spain. E-mail: javier.corral{at}carm.es Background: Routine analyses for thrombophilia include determination of the presence of factor V Leiden and prothrombin 20210A polymorphisms. However, the usefulness of these determinations is controversial and the clinical benefit remains questioned because of the moderate risk of associated thrombosis in carriers. In the search for clusters of thrombotic risk factors to estimate individual risk better, we studied the effect of AB0 blood group, a highly prevalent factor with mild prothrombotic features, on the risk and severity of venous and arterial thromboses in carriers of these polymorphisms. Design and Methods: We genotyped the AB0 blood group in 981 carriers of factor V Leiden or prothrombin 20210A polymorphisms. In order to avoid the over-representation of a particular genotype and to suppress confounding factors, we included only non-related heterozygous carriers without additional genetic risk factors. We studied 609 patients with venous thromboembolism (287 with factor V Leiden, and 322 with prothrombin 20210A), 174 patients with myocardial infarction (78 with factor V Leiden, and 96 with prothrombin 20210A), and 198 controls (96 with factor V Leiden, and 102 with prothrombin 20210A). Results: Non-OO blood group did not increase the risk of myocardial infarction in carriers of factor V Leiden or prothrombin 20210A. However, non-OO blood group contributed significantly to the expression of venous thrombosis associated with both factor V Leiden (OR: 1.76; 95%CI: 1.06–2.91) and prothrombin 20210A (OR: 2.17; 95%CI: 1.33–3.53). Exclusion of A 2 A 2 and A 2 O from the non-00 blood group (because factor VIII-von Willebrand factor levels are similar in these and the 00 blood group) increased the thrombotic risk. Finally, non-OO blood group was associated with an earlier onset in symptomatic carriers of these polymorphisms. Conclusions: Our study sugge