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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed August 2010

What is the official name of the XIAP gene?

The official name of this gene is “X-linked inhibitor of apoptosis.”

XIAP is the gene's official symbol. The XIAP gene is also known by other names, listed below.

What is the normal function of the XIAP gene?

The XIAP gene provides instructions for making a protein that is found in many types of cells, including immune cells. It helps protect these cells from self-destructing (undergoing apoptosis) by blocking (inhibiting) the action of certain enzymes called caspases, which are necessary for apoptosis. Specifically, the XIAP protein inhibits caspase enzymes 3, 7, and 9. The XIAP protein also plays a role in several other signaling pathways that are involved in various functions in the body.

Does the XIAP gene share characteristics with other genes?

The XIAP gene belongs to a family of genes called BIRC (baculoviral IAP repeat-containing genes).

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 XIAP gene related to health conditions?

X-linked lymphoproliferative disease - caused by mutations in the XIAP gene

XIAP gene mutations have been identified in some people with X-linked lymphoproliferative disease (XLP). These mutations reduce or eliminate production of the XIAP protein. It is unknown how a lack of XIAP protein results in the signs and symptoms of XLP, including a proliferation of lymphocytes that destroys blood-forming cells and damages the liver and other organs (hemophagocytic lymphohistiocytosis).

Where is the XIAP gene located?

Cytogenetic Location: Xq25

Molecular Location on the X chromosome: base pairs 123,859,812 to 123,913,979

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The XIAP gene is located on the long (q) arm of the X chromosome at position 25.

The XIAP gene is located on the long (q) arm of the X chromosome at position 25.

More precisely, the XIAP gene is located from base pair 123,859,812 to base pair 123,913,979 on the X chromosome.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about XIAP?

You and your healthcare professional may find the following resources about XIAP 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 XIAP gene or gene products?

  • API3
  • apoptosis inhibitor 3
  • baculoviral IAP repeat-containing protein 4
  • BIRC4
  • hILP
  • IAP-like protein, human
  • mammalian IAP homolog A
  • MIHA
  • X-linked inhibitor of apoptosis, E3 ubiquitin protein ligase
  • X-linked inhibitor of apoptosis protein

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding XIAP?

apoptosis ; caspase ; gene ; ligase ; proliferation ; protein ; ubiquitin

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Holcik M, Gibson H, Korneluk RG. XIAP: apoptotic brake and promising therapeutic target. Apoptosis. 2001 Aug;6(4):253-61. Review. (
  • Latour S. Natural killer T cells and X-linked lymphoproliferative syndrome. Curr Opin Allergy Clin Immunol. 2007 Dec;7(6):510-4. Review. (
  • Marsh RA, Madden L, Kitchen BJ, Mody R, McClimon B, Jordan MB, Bleesing JJ, Zhang K, Filipovich AH. XIAP deficiency: a unique primary immunodeficiency best classified as X-linked familial hemophagocytic lymphohistiocytosis and not as X-linked lymphoproliferative disease. Blood. 2010 Aug 19;116(7):1079-82. doi: 10.1182/blood-2010-01-256099. Epub 2010 May 20. (
  • Marsh RA, Villanueva J, Kim MO, Zhang K, Marmer D, Risma KA, Jordan MB, Bleesing JJ, Filipovich AH. Patients with X-linked lymphoproliferative disease due to BIRC4 mutation have normal invariant natural killer T-cell populations. Clin Immunol. 2009 Jul;132(1):116-23. doi: 10.1016/j.clim.2009.03.517. Epub 2009 Apr 23. (
  • NCBI Gene (
  • Rigaud S, Fondanèche MC, Lambert N, Pasquier B, Mateo V, Soulas P, Galicier L, Le Deist F, Rieux-Laucat F, Revy P, Fischer A, de Saint Basile G, Latour S. XIAP deficiency in humans causes an X-linked lymphoproliferative syndrome. Nature. 2006 Nov 2;444(7115):110-4. (


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.

Reviewed: August 2010
Published: February 8, 2016