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Factor IX: Wikis


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Coagulation factor IX (plasma thromboplastic component, Christmas disease, hemophilia B)

PDB rendering based on 1cfh.
Available structures
1cfh, 1cfi, 1edm, 1ixa, 1j34, 1j35, 1mgx, 1nl0, 1rfn
Symbols F9; FIX; GLA domain; HEMB; MGC129641; MGC129642; PTC
External IDs OMIM306900 MGI88384 HomoloGene106 GeneCards: F9 Gene
RNA expression pattern
PBB GE F9 207218 at tn.png
More reference expression data
Species Human Mouse
Entrez 2158 14071
Ensembl ENSG00000101981 ENSMUSG00000031138
UniProt P00740 A0JLY3
RefSeq (mRNA) NM_000133 NM_007979
RefSeq (protein) NP_000124 NP_032005
Location (UCSC) Chr X:
138.44 - 138.47 Mb
Chr X:
56.35 - 56.38 Mb
PubMed search [1] [2]

Factor IX (or Christmas factor) is one of the serine proteases (EC of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes hemophilia B. It was discovered after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to hemophilia, in 1952.[1]



Factor IX is inactive unless activated by factor XIa (of the contact pathway) or factor VIIa (of the tissue factor pathway). When activated into factor IXa, in the presence of Ca2+, membrane phospholipids, and a Factor VIII cofactor, it hydrolyses one arginine-isoleucine bond in factor X to form factor Xa.


The gene for factor IX is located on the X chromosome (Xq27.1-q27.2). It was first cloned in 1982 by Kotoku Kurachi and Earl Davie.[2]

Polly, a transgenic cloned Poll Dorset sheep carrying the gene for factor IX, was produced by Dr Ian Wilmut at the Roslin Institute in 1997.[3]

Role in disease

Deficiency of factor IX causes Christmas disease (hemophilia B). Over 100 mutations of factor IX have been described; some cause no symptoms, but many lead to a significant bleeding disorder.

Some rare mutations of factor IX result in elevated clotting activity, and can result in clotting diseases, such as deep vein thrombosis.[4]


  1. ^ Biggs RA, Douglas AS, MacFarlane RG, Dacie JV, Pittney WR, Merskey C, O'Brien JR. Christmas disease: a condition previously mistaken for haemophilia. Br Med J 1952;2:1378-1382. PMID 12997790.
  2. ^ Kurachi K, Davie E (1982). "Isolation and characterization of a cDNA coding for human factor IX". Proc Natl Acad Sci USA 79 (21): 6461–4. doi:10.1073/pnas.79.21.6461. PMID 6959130.  
  3. ^ Nicholl D. (2002). An Introduction to Genetic Engineering Second Edition. Cambridge University Press. p. 257.  
  4. ^ Simioni P, Tormene D, Tognin G, Gavasso S, Bulato C, Iacobelli NP, Finn JD, Spiezia L, Radu C, Arruda VR (October 2009). "X-linked thrombophilia with a mutant factor IX (factor IX Padua)". N. Engl. J. Med. 361 (17): 1671–5. doi:10.1056/NEJMoa0904377. PMID 19846852.  

Further reading

  • Davie EW, Fujikawa K (1975). "Basic mechanisms in blood coagulation". Annu. Rev. Biochem. 44: 799–829. doi:10.1146/ PMID 237463.  
  • Sommer SS (1992). "Assessing the underlying pattern of human germline mutations: lessons from the factor IX gene". FASEB J. 6 (10): 2767–74. PMID 1634040.  
  • Lenting PJ, van Mourik JA, Mertens K (1999). "The life cycle of coagulation factor VIII in view of its structure and function". Blood 92 (11): 3983–96. PMID 9834200.  
  • Lowe GD (2002). "Factor IX and thrombosis". Br. J. Haematol. 115 (3): 507–13. doi:10.1046/j.1365-2141.2001.03186.x. PMID 11736930.  
  • O'Connell NM (2004). "Factor XI deficiency--from molecular genetics to clinical management". Blood Coagul. Fibrinolysis 14 Suppl 1: S59–64. PMID 14567539.  
  • Du X (2007). "Signaling and regulation of the platelet glycoprotein Ib-IX-V complex". Curr. Opin. Hematol. 14 (3): 262–9. doi:10.1097/MOH.0b013e3280dce51a. PMID 17414217.  


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