Monarch Disease Ontology entry MONDO_0010432 (thrombophilia, X-linked, due to factor 9 defect) is a hemostatic disorder characterized by a tendency to thrombosis that has X-linked recessive inheritance, and can be caused by a gain-of-function mutation in the gene encoding factor IX (F9). Also known as: deep venous thrombosis, protection against, X-linked recessive, thrombophilia 8, X-linked, due to factor IX defect, X-linked recessive, thrombophilia, X-linked, due to factor IX defect.