Hemophilia B is a form of hemophilia characterized by spontaneous or prolonged hemorrhages due to factor IX deficiency. The disease is MONDO_0010604 (hemophilia B). Also known as: Christmas disease, congenital factor IX deficiency, congenital factor IX disorder, deficiency, functional factor IX, factor IX deficiency, haemophilia b, X-linked recessive, haemophilia type B, hemophilia b, X-linked recessive.