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IL7R gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

IL7R gene

The IL7R gene provides instructions for a protein subunit critical for immune cell development and survival, particularly for B and T cells.

Normal Function

The IL7R gene provides instructions for the interleukin 7 (IL-7) receptor alpha chain. This protein is a component of both the IL-7 receptor and the thymic stromal lymphopoietin (TSLP) receptor, which are found on the surface of immune cells such as B cells and T cells.

The IL-7 receptor interacts with the cytokine IL-7 to trigger signals that ensure the development, growth, and survival of B and T cells. Similarly, the TSLP receptor interacts with the cytokine TSLP to support the maturation and proliferation of various immune cells.

Health Conditions Related to Genetic Changes

Severe combined immunodeficiency (SCID)

Mutations in the IL7R gene can cause a form of severe combined immunodeficiency known as T-B+NK+ SCID. These mutations prevent the production of the IL-7 receptor alpha chain, impairing signaling and disrupting T cell development. This leaves individuals with few or no T cells, making them highly susceptible to recurrent and persistent infections.

Cancers of blood-forming cells

IL7R mutations are also associated with B-cell acute lymphoblastic leukemia (ALL) and T-cell ALL. In these cases, the mutations lead to an altered receptor that is "constitutively active," meaning signaling pathways are constantly turned on even without cytokine interaction. This constant signaling promotes the uncontrolled proliferation and survival of B or T cells, leading to leukemia.

Other Names for This Gene

  • CD127
  • CD127 antigen
  • CDW127
  • IL-7 receptor subunit alpha
  • IL-7R subunit alpha
  • IL-7R-alpha
  • IL-7RA
  • IL7RA
  • IL7RA_HUMAN
  • ILRA
  • interleukin 7 receptor alpha chain
  • interleukin 7 receptor isoform H5-6
  • interleukin-7 receptor subunit alpha
  • interleukin-7 receptor subunit alpha precursor

Frequently Asked Questions

Infants with IL7R-related SCID often appear healthy at birth but begin to show signs of immune failure within the first few months of life. Common early warning signs include persistent diarrhea, failure to thrive (poor weight gain), recurrent respiratory infections (such as pneumonia), and skin rashes or thrush that do not respond to standard treatment. Newborn screening is critical because it can detect low T-cell counts early, allowing for prompt diagnosis and intervention, such as hematopoietic stem cell transplantation, which significantly improves survival rates compared to treatment after severe infections have occurred.
T-B+NK+ SCID is characterized by a specific pattern of immune cell deficiency: patients have very low or absent T cells, but their B cells and Natural Killer (NK) cells are present in normal numbers. This differs from X-linked SCID (caused by IL2RG mutations) or JAK3 SCID, where B cell numbers may also be low or dysfunctional. The presence of B cells in IL7R-related SCID can sometimes lead to autoimmunity or B-cell lymphoproliferation, whereas the primary life-threatening risk remains the lack of T-cell mediated immunity, making patients highly susceptible to viral, fungal, and bacterial infections.
The same gene can cause opposite clinical outcomes depending on the nature of the mutation. Loss-of-function mutations prevent the IL-7 receptor from signaling, which halts T-cell development and leads to immunodeficiency (SCID). Conversely, gain-of-function or activating mutations keep the receptor in a "constitutively active" state, meaning it sends growth signals to B or T cells even without the presence of the IL-7 cytokine. This uncontrolled signaling drives the rapid, unregulated proliferation of these cells, leading to B-cell or T-cell acute lymphoblastic leukemia (ALL).
The IL7R protein, also known as CD127, serves as the alpha chain for two different receptor complexes. It pairs with a common beta chain (CD131) to form the IL-7 receptor, which is essential for the survival and proliferation of T cells and B cells. It also pairs with a different beta chain (OSMR) to form the TSLP receptor, which is involved in the maturation of dendritic cells and the regulation of allergic and inflammatory responses. This dual functionality means that mutations in IL7R can potentially affect not only T-cell development but also aspects of innate immunity and allergic inflammation, although the most severe clinical manifestations are typically related to the disruption of IL-7 signaling.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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