Advances in the Molecular Etiology of Severe Combined Immunodeficiency and Its Screening

Severe combined immunodeficiency (SCID) is the most severe heterogeneous group of inherited disorders characterized by profound abnormalities such as humoral and cell-mediated immunity defects and hindered natural killer cell development and function. The knowledge of the molecular basis of SCID is essential for precise diagnosis and early treatment. In recent years, new genetic defects that cause SCID have been discovered, and the molecular and immunological mechanisms of SCID have been better understood. SCID symptoms include candidiasis, chronic diarrhea, failure to grow, and oral thrush. Hematopoietic stem cell transplantation, enzyme replacement therapy, and gene therapy are used to treat SCID. The prevalence of SCID varies worldwide. More than 80% of SCID infants have no family history of the condition. However, the development of a newborn screening test has enabled SCID detection before symptoms appear, ensuring that affected infants receive life-saving treatments. Countries that organize newborn screening programs for SCID can detect patients in their early stages of life and treat them accordingly. This review will serve as a source of up-to-date information on the identification of various genetic disorders that cause SCID, as well as their clinical characteristics, treatments, and diagnosis options, potentially saving the lives of many infants before pathogenic infections occur.