Severe Combined Immunodeficiency

Severe combined immunodeficiency (SCID), (also known as "Alymphocytosis," "Glanzmann–Riniker syndrome," "Severe mixed immunodeficiency syndrome," and "Thymic alymphoplasia") is a genetic disorder in which both "arms" (B cells and T cells) of the adaptive immune system are impaired due to a defect in one of several possible genes. SCID is a severe form of heritable immunodeficiency. It is also known as the bubble boy disease because its victims are extremely vulnerable to infectious diseases and some of them, such as David Vetter, become famous for living in a sterile environment. SCID is the result of an immune system so highly compromised that it is considered almost absent.

Chronic diarrhea, ear infections, recurrent Pneumocystis jirovecii (previously carinii) pneumonia, and profuse oral candidiasis commonly occur. These babies, if untreated, usually die within 1 year due to severe, recurrent infections unless they have undergone successful Hematopoietic stem cell transplantation.