Haemophilia is a rare, X-linked congenital bleeding disorder, characterised by a deficiency of coagulation factor VIII (FVIII), known as haemophilia A, or factor IX (FIX), known as haemophilia B. These factor deficiencies are the result of pathogenic variants in the F8 and F9 clotting factor genes1. Here, F8 is linked to hemophilia.