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The official name of this gene is “interleukin 7 receptor.”
IL7R is the gene's official symbol. The IL7R gene is also known by other names, listed below.
The IL7R gene provides instructions for making a protein called interleukin 7 (IL-7) receptor alpha chain. This protein is one piece of both the IL-7 receptor and the thymic stromal lymphopoietin (TSLP) receptor. These receptors are embedded in the cell membrane of immune system cells. The IL-7 receptor is found in B cells and T cells as well as the early blood-forming cells that give rise to them. The TSLP receptor is found in several types of immune cells, including B cells, T cells, monocytes, and dendritic cells. These cells identify foreign substances and defend the body against infection and disease.
At the cell surface, the IL-7 receptor interacts with a protein called IL-7. IL-7 is a cytokine, which is a protein that regulates the activity of immune system cells. The receptor and cytokine fit together like a lock and its key, triggering a series of chemical signals inside the cell. In early blood-forming cells, signaling through the IL-7 receptor ensures the development of mature B cells and T cells. IL-7 receptor signaling also stimulates the later growth and division (proliferation) and survival of these cells.
Similarly, the TSLP receptor interacts with the cytokine TSLP. Attachment of TSLP to its receptor triggers a set of signals that support proliferation and maturation of a variety of immune system cells.
The IL7R gene belongs to a family of genes called CD (CD molecules). It also belongs to a family of genes called fibronectin type III domain containing (fibronectin type III domain containing). It also belongs to a family of genes called IL (interleukins and interleukin receptors).
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? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
A common variation of the IL-7R gene increases the risk of developing multiple sclerosis. This condition affects the brain and spinal cord (central nervous system), causing muscle weakness, poor coordination, numbness, and a variety of other health problems. The genetic variation involved in multiple sclerosis affects a single protein building block (amino acid) in the IL-7 receptor alpha chain, specifying the amino acid isoleucine at position 244 instead of the amino acid threonine (written as Thr244Ile). The IL-7 receptor that contains this version of the alpha chain is not embedded in the cell surface but is instead found inside the cell. It is not clear if this alpha chain variant affects the TSLP receptor.
Because the IL7R gene is involved in regulation of the immune system, changes in it might be involved in the autoimmune response and inflammation that damage nerves and the protective coating surrounding them (the myelin sheath), leading to the signs and symptoms of multiple sclerosis. (Autoimmunity occurs when the immune system malfunctions and attacks the body's own tissues and organs, in this case tissues of the nervous system.) However, it is unclear exactly what role the IL-7R gene variant plays in development of multiple sclerosis. It is likely that a combination of genetic and environmental factors is involved.
Mutations in the IL7R gene can cause a form of severe combined immunodeficiency (SCID), in which affected individuals have decreased immune function and are prone to recurrent and persistent infections. Affected individuals with IL7R gene mutations have few or no T cells but normal numbers of B cells and another type of immune cell called NK cells. This form of the condition is called T-B+NK+ SCID. Many IL7R gene mutations that cause SCID prevent the production of the IL-7 receptor alpha chain, which impairs IL-7 receptor and TSLP receptor signaling. Without this signaling, development of T cells is disrupted. A lack of T cells reduces the immune system's ability to fight infections, leading to recurrent infections in people with T-B+NK+ SCID.
Mutations in the IL7R gene can also cause cancers of blood-forming cells, specifically B-cell acute lymphoblastic leukemia (ALL), which is characterized by elevated numbers of B cells in the blood, and T-cell ALL, characterized by elevated numbers of T cells. The mutations associated with these cancers lead to an altered IL-7 receptor alpha chain. With this alteration, signaling pathways like those triggered by the IL-7 receptor or the TSLP receptor are constantly turned on (constitutively active) even without cytokine interaction. Constant signaling increases proliferation and survival of B cells or T cells, leading to ALL.
Cytogenetic Location: 5p13
Molecular Location on chromosome 5: base pairs 35,856,874 to 35,879,602
The IL7R gene is located on the short (p) arm of chromosome 5 at position 13.
More precisely, the IL7R gene is located from base pair 35,856,874 to base pair 35,879,602 on chromosome 5.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about IL7R helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
acute ; acute lymphoblastic leukemia ; amino acid ; autoimmune ; autoimmunity ; cell ; cell membrane ; central nervous system ; cytokine ; gene ; genetic variation ; immune system ; immunodeficiency ; infection ; inflammation ; isoleucine ; leukemia ; myelin sheath ; nervous system ; NK cells ; precursor ; proliferation ; protein ; receptor ; sclerosis ; subunit ; threonine
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.