Severe Combined Immunodeficiency (SCID) - RAG Gene Defect

Severe Combined Immunodeficiency (SCID) - RAG Gene Defect is a rare genetic disorder that affects the body's immune system, which normally protects against infections. This condition involves a problem with the RAG genes, which are essential for creating the diverse immune cells needed to fight germs. Because of this defect, people with this condition have very few or no functioning T cells and B cells, which are critical for immune defense. As a result, affected individuals are highly vulnerable to severe and frequent infections from bacteria, viruses, and fungi. The immune system's inability to respond properly makes even common infections potentially life-threatening. This disorder usually presents in early infancy with symptoms like persistent infections and failure to thrive.

Severe Combined Immunodeficiency (SCID) - RAG Gene Defect is a form of SCID caused by mutations in the RAG1 or RAG2 genes, which encode the recombination activating gene enzymes essential for V(D)J recombination during lymphocyte development. This defect leads to a failure in generating functional T cell receptors and B cell receptors, resulting in a profound deficiency of mature T and B lymphocytes. The hallmark of this condition is a T-B- NK+ immunophenotype, with absent or severely reduced T and B cells but normal or increased natural killer (NK) cells. Clinically, it manifests as severe, recurrent infections early in life, including opportunistic infections by organisms such as Pneumocystis jirovecii and Candida albicans. Without treatment, the condition is fatal due to overwhelming infections. The defect disrupts adaptive immunity, causing combined cellular and humoral immunodeficiency.