SCID: CLINICAL FEATURES
These patients typically present in the first year of life with failure to thrive and recurrent infections caused by bacterial, viral, and fungal pathogens. Infections typically affect the respiratory and gastrointestinal systems. The infections may be caused by common pathogens (adenovirus, respiratory syncytial virus, parainfluenza virus), as well as by opportunistic organisms of low-grade virulence (Candida, Pneumocystis carinii, cytomegalovirus). Live vaccines such as BCG can lead to disseminated life-threatening infections. The persistent infections developing in SCID patients rapidly lead to malnutrition, growth impairement, and early death. Because of the patient’s inability to reject allogeneic cells, graft-versus-host diseases (GVHD) can be caused by transplacentally acquired maternal lymphocytes or by allogeneic cells following blood transfusion. GVHD manifest as skin rashes or hepatosplenomegaly and lymphadenopathy.