Known hereditary thrombophilia (e.g. factor V Leiden/Prothrombin 2021a), and vWF promoter polymorphism haplotype 1 were reported to be used in the decision to start thromboprophylaxis by seven, and three centers, respectively, while non-0 blood group (BG) was not considered by any center. Here, F2 is linked to Rare hereditary thrombophilia.