ABO and Venous thrombosis: In the present study, we used only the five prothrombotic genotypes that were most strongly associated with the risk of a first venous thrombosis in literature and applied previously to the prediction of first thrombotic events [28] and we developed GRS based on these five SNPs (FVL rs6025, PTM rs1799963, ABO rs8176719, FGG rs2066865 and FXI rs2036914).