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Reviewed May 2008
What is the official name of the XK gene?
The official name of this gene is “X-linked Kx blood group.”
XK is the gene's official symbol. The XK 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 XK gene?
The XK gene provides instructions for producing a protein that is found in various tissues of the body, particularly the brain, muscle, and heart. This protein is also present on the surface of red blood cells and carries a molecule known as the Kx blood group antigen. Blood group antigens are found on the surface of red blood cells and determine a number of blood types. When blood cells with unfamiliar antigens enter the bloodstream, the body's immune system recognizes the cells as foreign and may trigger an immune reaction that destroys the foreign blood cells.
The function of the XK protein is unclear; researchers believe that it might play a role in transporting substances into and out of cells. On red blood cells, the XK protein attaches to another blood group protein, the Kell protein. The function of this blood group complex is unknown.
Does the XK gene share characteristics with other genes?
The XK gene belongs to a family of genes called blood group (blood group antigens).
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? in the Handbook.
How are changes in the XK gene related to health conditions?
Where is the XK gene located?
Cytogenetic Location: Xp21.1
Molecular Location on the X chromosome: base pairs 37,685,781 to 37,732,130
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The XK gene is located on the short (p) arm of the X chromosome at position 21.1.
More precisely, the XK gene is located from base pair 37,685,781 to base pair 37,732,130 on the X chromosome.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about XK?
You and your healthcare professional may find the following resources about XK 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 XK 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 XK?
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (6 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.