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Reviewed May 2010
What is the official name of the F9 gene?
The official name of this gene is “coagulation factor IX.”
F9 is the gene's official symbol. The F9 gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the F9 gene?
The F9 gene provides instructions for making a protein called coagulation factor IX. Coagulation factors are a group of related proteins that are essential for the formation of blood clots. After an injury, clots protect the body by sealing off damaged blood vessels and preventing further blood loss.
Coagulation factor IX is made in the liver. This protein circulates in the bloodstream in an inactive form until an injury that damages blood vessels occurs. In response to injury, coagulation factor IX is activated by another coagulation factor called factor XIa. The active protein (sometimes written as coagulation factor IXa) interacts with coagulation factor VIII and other molecules. These interactions set off a chain of additional chemical reactions that form a blood clot.
How are changes in the F9 gene related to health conditions?
Genetics Home Reference provides information about warfarin sensitivity, which is also associated with changes in the F9 gene.
Where is the F9 gene located?
Cytogenetic Location: Xq27.1-q27.2
Molecular Location on the X chromosome: base pairs 139,530,734 to 139,563,464
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The F9 gene is located on the long (q) arm of the X chromosome between positions 27.1 and 27.2.
More precisely, the F9 gene is located from base pair 139,530,734 to base pair 139,563,464 on the X chromosome.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about F9?
You and your healthcare professional may find the following resources about F9 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
What other names do people use for the F9 gene or gene products?
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding F9?
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (11 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.