Factor IX ELISA Kit

Factor IX ELISA Kit

The VisuLize FIX Antigen Kit is intended to quantitatively measure factor IX (F9) antigen in human plasma and factor concentrates. The biological importance of Factor IX (F9) is demonstrated in Hemophilia B (Christmas disease), an X-linked congenital bleeding disease resulting from a quantitative (low activity and low antigen) or qualitative (low activity and normal antigen) defect in Factor IX function. The congenital deficiency of Factor IX (F9) may be classified as severe (1% Factor IX activity), moderate (between 1 and 5% Factor IX activity) or mild (between 5 and 40% Factor IX activity). The laboratory diagnosis of Factor IX deficiency typically involves quantitative determinations of procoagulant levels i.e., functional activity of Factor IX.¹ An ELISA for Factor IX antigen may be used in conjuction with functional assays in the area of gene therapy, assessment of Factor IX concentrates, determination of carrier status as well as distinguishing those patients with cross-reactive material (i.e., low functional activity but near normal antigen levels of Factor IX).

This product is cleared for in vitro Diagnostic use by FDA, Health Canada and CE marked.  Available for sale in the United States, Canada and select European countries.

Product Code: FIX-AG


  • Rapid sandwich ELISA to measure FIX antigen (FIX:Ag)
  • 70 minutes total incubation time!
  • FIX:Ag reported as International Units/ml traceable to WHO standard for FIX activity
  • Detection limit to 0.005 IU/ml FIX:Ag (0.5%)
  • Includes normal and low controls


  • Quantification of FIX in plasma and therapeutic concentrates
  • Diagnosis and characterization of Hemophilia B
  • Carrier testing for Hemophilia B
  • Thrombophilia screening

Product Datasheet: Factor IX F9 FIX ELISA Kit

References: 1. White GC, Roendaal, F. Aledort LM, Lusher JM, Rothschild C, Ingersley J. Definitions in Hemophilia, Recommendation of the Scientific Subcomittee on Factor VIII and Factor IX of the Scientific and Standardization Committee of the International Society on Thrombosis and Hemostasis, Thrombosis and Hemostasis, 2001, 85, p. 560.

Description of Factor IX (FIX)

Factor IX (FIX, Christmas Factor) is a vitamin K-dependent glycoprotein produced in the liver. Plasma concentration of FIX is normally around 5 μg/ml (87 nM) in plasma. The biological importance of FIX is demonstrated in Haemophilia B (Christmas disease), an X-linked congenital bleeding disease resulting from a quantitative (low activity and low antigen) or qualitative (low activity, normal antigen) defect in FIX function.

In its proenzyme or zymogen form FIX is a single chain molecule of 55,000 daltons. It contains two EGF-like domains and an amino-terminal domain containing 12 γ-carboxy-glutamic acid (Gla) residues. These Gla residues allow FIX to bind divalent metal ions and participate in calcium-dependent binding interactions. The activation of F.IX occurs by limited proteolysis in the presence of calcium by activated factor XI (FXIa) and/or by a complex of VIIa/tissue factor/phospholipid and activated Factor X between residues Arg146-Ala147 and between Arg180-Val181. The terminal activated product in either case is FIXaβ, a two-chain enzyme consisting of a heavy chain (28,000 daltons), a light chain (18,000 daltons) and an activation peptide product of 11,000 daltons. FIX can also be cleaved into inactive products by thrombin and by elastase.

The activity of FIXaβ in plasma is inhibited by antithrombin and this inhibition is accelerated 1000-fold in the presence of optimal concentrations of heparin 1-3.

References and Reviews

  1. Lawson, JH, Mann KG; Cooperative Activation of Human F.IX by the Human Extrinsic Pathway of Coagulation; JBC 266 pp11317-11327, 10991.
  2. Enfield DL, Thompson AR; Cleavage and Activation of Factor IX by Serine Proteases; Blood 64, pp 821-831, 1984.
  3. Limentani SA, Furie BC, Furie B, in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp. 94-108, J.B. Lippincott Co., Philadelphia PA, USA, 1994.

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