Skip navigation

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

URL of this page:

FAS gene

Fas cell surface death receptor

Normal Function

The FAS gene provides instructions for making a protein that is involved in cell signaling. Three FAS proteins group together to form a structure called a trimer, which then interacts with other molecules to perform its signaling function. This signaling initiates a process called a caspase cascade. The caspase cascade is a series of steps that results in the self-destruction of cells (apoptosis) when they are not needed.

Health Conditions Related to Genetic Changes

Autoimmune lymphoproliferative syndrome

At least 115 mutations in the FAS gene have been identified in people with a disorder of the immune system called autoimmune lymphoproliferative syndrome (ALPS). ALPS is characterized by the production of an abnormally large number of immune system cells (lymphocytes), resulting in enlargement of the lymph nodes (lymphadenopathy), the liver (hepatomegaly), and the spleen (splenomegaly). Autoimmune disorders, in which the immune system malfunctions and attacks the body's own tissues and organs, are also common in ALPS. People with ALPS have an increased risk of developing cancer of the immune system cells (lymphoma).

When the immune system is activated to fight an infection, large numbers of lymphocytes are produced. Normally, these lymphocytes undergo apoptosis when they are no longer required. FAS gene mutations lead to an abnormal trimer that interferes with the initiation of apoptosis. As a result, excess lymphocytes accumulate in the body's tissues and organs and often begin attacking them, leading to autoimmune disorders. Interference with apoptosis allows cells to multiply without control, leading to the lymphomas that occur in people with this disorder.

More About This Health Condition

Juvenile idiopathic arthritis

MedlinePlus Genetics provides information about Juvenile idiopathic arthritis

More About This Health Condition


Studies have associated certain FAS gene variations with increased risk of developing cancer, including cancers of the lung, breast, and esophagus. Researchers believe that these variations may affect the signaling that initiates apoptosis, increasing the risk that cells will multiply out of control and result in cancer.

Other Names for This Gene

  • APO-1
  • apo-1 antigen
  • APO-1 cell surface antigen
  • apoptosis antigen 1
  • apoptosis-mediating surface antigen FAS
  • APT1
  • CD95
  • CD95 antigen
  • Fas (TNF receptor superfamily, member 6)
  • Fas AMA
  • Fas antigen
  • FAS1
  • FASLG receptor
  • tumor necrosis factor receptor superfamily member 6

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Cao Y, Miao XP, Huang MY, Deng L, Lin DX, Zeng YX, Shao JY. Polymorphisms of death pathway genes FAS and FASL and risk of nasopharyngeal carcinoma. Mol Carcinog. 2010 Nov;49(11):944-50. doi: 10.1002/mc.20676. Citation on PubMed
  • Dowdell KC, Niemela JE, Price S, Davis J, Hornung RL, Oliveira JB, Puck JM, Jaffe ES, Pittaluga S, Cohen JI, Fleisher TA, Rao VK. Somatic FAS mutations are common in patients with genetically undefined autoimmune lymphoproliferative syndrome. Blood. 2010 Jun 24;115(25):5164-9. doi: 10.1182/blood-2010-01-263145. Epub 2010 Apr 1. Citation on PubMed or Free article on PubMed Central
  • Fleisher TA, Straus SE, Bleesing JJ. A genetic disorder of lymphocyte apoptosis involving the fas pathway: the autoimmune lymphoproliferative syndrome. Curr Allergy Asthma Rep. 2001 Nov;1(6):534-40. doi: 10.1007/s11882-001-0062-y. Citation on PubMed
  • Fleisher TA. The autoimmune lymphoproliferative syndrome: an experiment of nature involving lymphocyte apoptosis. Immunol Res. 2008;40(1):87-92. doi: 10.1007/s12026-007-8001-1. Citation on PubMed
  • Poppema S, Maggio E, van den Berg A. Development of lymphoma in Autoimmune Lymphoproliferative Syndrome (ALPS) and its relationship to Fas gene mutations. Leuk Lymphoma. 2004 Mar;45(3):423-31. doi: 10.1080/10428190310001593166. Citation on PubMed
  • Randhawa SR, Chahine BG, Lowery-Nordberg M, Cotelingam JD, Casillas AM. Underexpression and overexpression of Fas and Fas ligand: a double-edged sword. Ann Allergy Asthma Immunol. 2010 Apr;104(4):286-92. doi: 10.1016/j.anai.2010.01.021. Citation on PubMed
  • Rieux-Laucat F. Inherited and acquired death receptor defects in human Autoimmune Lymphoproliferative Syndrome. Curr Dir Autoimmun. 2006;9:18-36. doi: 10.1159/000090769. Citation on PubMed
  • Sun T, Miao X, Zhang X, Tan W, Xiong P, Lin D. Polymorphisms of death pathway genes FAS and FASL in esophageal squamous-cell carcinoma. J Natl Cancer Inst. 2004 Jul 7;96(13):1030-6. doi: 10.1093/jnci/djh187. Citation on PubMed
  • Teachey DT, Seif AE, Grupp SA. Advances in the management and understanding of autoimmune lymphoproliferative syndrome (ALPS). Br J Haematol. 2010 Jan;148(2):205-16. doi: 10.1111/j.1365-2141.2009.07991.x. Epub 2009 Nov 23. Citation on PubMed or Free article on PubMed Central
  • Turbyville JC, Rao VK. The autoimmune lymphoproliferative syndrome: A rare disorder providing clues about normal tolerance. Autoimmun Rev. 2010 May;9(7):488-93. doi: 10.1016/j.autrev.2010.02.007. Epub 2010 Feb 17. Citation on PubMed
  • Worth A, Thrasher AJ, Gaspar HB. Autoimmune lymphoproliferative syndrome: molecular basis of disease and clinical phenotype. Br J Haematol. 2006 Apr;133(2):124-40. doi: 10.1111/j.1365-2141.2006.05993.x. Citation on PubMed
  • Zhang B, Sun T, Xue L, Han X, Zhang B, Lu N, Shi Y, Tan W, Zhou Y, Zhao D, Zhang X, Guo Y, Lin D. Functional polymorphisms in FAS and FASL contribute to increased apoptosis of tumor infiltration lymphocytes and risk of breast cancer. Carcinogenesis. 2007 May;28(5):1067-73. doi: 10.1093/carcin/bgl250. Epub 2006 Dec 20. Citation on PubMed
  • Zhang X, Miao X, Sun T, Tan W, Qu S, Xiong P, Zhou Y, Lin D. Functional polymorphisms in cell death pathway genes FAS and FASL contribute to risk of lung cancer. J Med Genet. 2005 Jun;42(6):479-84. doi: 10.1136/jmg.2004.030106. Citation on PubMed or Free article on PubMed Central

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.