Severe combined immune deficiency

Abstract Severe combined immune deficiency, also known by its acronym, SCID, was once inevitably fatal in infancy. In the 1970s, our understanding was limited to a description of thymic dysplasia and lymphopenia with no immunoglobulins. Although the first bone marrow transplant was done in 1958, there was little understanding of the variables impacting success and the next ten years saw advances in HLA typing and general understanding of the hematopoietic system, leading to the first transplant for SCID in 1968. Today, hematopoietic stem cell transplants are successful for SCID >90% of the time when the patient is identified through newborn screening. In parallel with treatment advances have been a wealth of diagnostic advances. This chapter will cover the individual types of SCID.