Altogether, the above genes coding for proteins belonging to the High Molecular Weight Kininogen/Prekallikrein/FXI/FXII contact system, have a key role in blood coagulation balance and their defects are not associated with bleeding but rather with venous or arterial thrombosis and recurrent pregnancy loss also affecting fetal-placental unit as demonstrated by previous GWAS and case-control studies [52,53,54]. This evidence concerns the gene F11 and Arterial thrombosis.