Severe Combined Immunodeficiency (SCID) - IL-2R γ-Chain Defect

Severe Combined Immunodeficiency (SCID) - IL-2R γ-Chain Defect is a rare genetic disorder that affects the body's immune system, which normally protects against infections. This condition involves a problem with a specific part of immune cells called the IL-2 receptor gamma chain, which is crucial for the development and function of T cells and natural killer (NK) cells. Because these immune cells are missing or not working properly, people with this disorder are highly vulnerable to severe and frequent infections caused by bacteria, viruses, and fungi. The disease usually appears in early infancy and can be life-threatening without treatment. The immune system's inability to fight infections leads to symptoms like persistent infections, failure to thrive, and chronic diarrhea.

Severe Combined Immunodeficiency (SCID) - IL-2R γ-Chain Defect is a form of SCID caused by mutations in the IL2RG gene encoding the common gamma chain of multiple interleukin receptors (IL-2, IL-4, IL-7, IL-9, IL-15, IL-21). This defect results in a profound deficiency of T cells and NK cells with normal or elevated B cells that are nonfunctional due to lack of T cell help. The condition is inherited in an X-linked recessive pattern and represents the most common form of SCID. The absence of functional T and NK cells leads to severe impairment of both cellular and humoral immunity, causing life-threatening opportunistic infections early in life. The hallmark is lymphopenia with absent or severely reduced T cell function and impaired cytokine signaling. Without intervention, affected infants typically die within the first year due to overwhelming infections.