Gene and Protein Information
Species	TM	AA	Chromosomal Location	Gene Symbol	Gene Name	Reference
Human	-	461	Xq27.1	F9	coagulation factor IX
Mouse	-	471	X 33.5 cM	F9	coagulation factor IX
Rat	-	462	Xq36	F9	coagulation factor IX

Previous and Unofficial Names

hemophilia B | plasma thromboplastic component | Cf9 | FIX | factor IX | christmas factor

Database Links
Specialist databases
MEROPS	S01.214 (Hs)
Other databases
Alphafold	P00740 (Hs), P16294 (Mm), P16296 (Rn)
BRENDA	3.4.21.22
CATH/Gene3D	4.10.740.10
ChEMBL Target	CHEMBL2016 (Hs), CHEMBL4105734 (Rn)
DrugBank Target	P00740 (Hs)
Ensembl Gene	ENSG00000101981 (Hs), ENSMUSG00000031138 (Mm), ENSRNOG00000003430 (Rn)
Entrez Gene	2158 (Hs), 14071 (Mm), 24946 (Rn)
Human Protein Atlas	ENSG00000101981 (Hs)
KEGG Enzyme	3.4.21.22
KEGG Gene	hsa:2158 (Hs), mmu:14071 (Mm), rno:24946 (Rn)
OMIM	300746 (Hs)
Orphanet	ORPHA121683 (Hs)
Pharos	P00740 (Hs)
RefSeq Nucleotide	NM_000133 (Hs), NM_007979 (Mm), NM_031540 (Rn)
RefSeq Protein	NP_000124 (Hs), NP_032005 (Mm), NP_113728 (Rn)
UniProtKB	P00740 (Hs), P16294 (Mm), P16296 (Rn)
Wikipedia	F9 (Hs)

Enzyme Reaction
EC Number: 3.4.21.22

Download all structure-activity data for this target as a CSV file

Inhibitors
Key to terms and symbols	View all chemical structures	Click column headers to sort
Ligand Sp. Action Value Parameter Reference compound 57 [PMID: 20121197] Hs Inhibition 8.7 pIC50 6 ⤷ pIC50 8.7 (IC50 2x10-9 M) [6]

Antibodies
Key to terms and symbols		Click column headers to sort
Antibody Sp. Action Value Parameter Reference emicizumab Hs Binding 5.8 pKd 5 ⤷ pKd 5.8 (Kd 1.58x10-6 M) [5] Description: Determined by surface plasmon resonance analysis.

Clinically-Relevant Mutations and Pathophysiology
Disease:  Mild hemophilia B Synonyms: Hemophilia B; HEMB [OMIM: 306900] [Disease Ontology: DOID:12259] Disease Ontology: DOID:12259 OMIM: 306900 Orphanet: ORPHA169799
Disease:  Moderately severe hemophilia B Synonyms: Hemophilia B; HEMB [OMIM: 306900] [Disease Ontology: DOID:12259] Disease Ontology: DOID:12259 OMIM: 306900 Orphanet: ORPHA169796
Disease:  Severe hemophilia B Synonyms: Hemophilia B; HEMB [OMIM: 306900] [Disease Ontology: DOID:12259] Disease Ontology: DOID:12259 OMIM: 306900 Orphanet: ORPHA169793
Disease:  Symptomatic form of hemophilia B in female carriers Orphanet: ORPHA177929
Disease:  Thrombophilia, X-linked, due to factor IX defect Synonyms: Thrombophilia [Disease Ontology: DOID:2452] Disease Ontology: DOID:2452 OMIM: 300807

Gene Expression and Pathophysiology Comments

A gene therapy that delivers a factor IX gene for expression in the liver (etranacogene dezaparvovec-drlb; AMT-061; Hemgenix®) to treat hemophilia B first became available in 2022 (FDA approval). It has subsequently been approved by other national regulatory agencies.

General Comments

Factor IX deficiency causes hemophilia B [1]. It is inhibited by endogenous antithrombin (SERPINC1) [2]. Recombinant factor IX (Nonafact®) is used to treat hemophilia B, however it is very rapidly cleared from the circulation. Peptide factor IX mimetics with enhanced biological properties are being developed to improve the effectiveness of hemophilia B prophylaxis. One such potent and long-acting factor IX mimetic is CB 2679d (ISU304), which is being developed by Catalyst Biosciences for subcutaneous administration (see Phase 1 proof-of-concept clinical trial NCT03186677) [4]. CB 2679d has been granted EMA orphan medicinal product designation (July 2017) [3].