Editing Factor IX (section)

{{cs1 config|name-list-style=vanc}}
{{Short description|Protein involved in coagulation}}
{{Infobox_gene}}

'''Factor IX''' ({{EC number|3.4.21.22}}), also known as '''Christmas factor''', is one of the [[serine protease]]s involved in [[coagulation]]; it belongs to peptidase family S1. Deficiency of this protein causes [[haemophilia B]].

<!-- History, society and culture -->
It was discovered in 1952 after a young boy named [[Stephen Christmas]] was found to be lacking this exact factor, leading to [[haemophilia]].<ref name="PMD12997790">{{cite journal | vauthors = Biggs R, Douglas AS, Macfarlane RG, Dacie JV, Pitney WR | title = Christmas disease: a condition previously mistaken for haemophilia | journal = British Medical Journal | volume = 2 | issue = 4799 | pages = 1378–82 | date = Dec 1952 | pmid = 12997790 | pmc = 2022306 | doi = 10.1136/bmj.2.4799.1378 }}</ref> Coagulation factor IX is on the [[WHO Model List of Essential Medicines|World Health Organization's List of Essential Medicines]].<ref name="WHO21st">{{cite book | vauthors = ((World Health Organization)) | title = World Health Organization model list of essential medicines: 21st list 2019 | year = 2019 | hdl = 10665/325771 | author-link = World Health Organization | publisher = World Health Organization | location = Geneva | id = WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO | hdl-access=free }}</ref>