T-B+ SCID due to JAK3 deficiency
Severe combined immunodeficiency (SCID) T-B+ due to JAK3 deficiency is a form of SCID (see this term) characterized by severe and recurrent infections, associated with diarrhea and failure to thrive.Annual incidence is between 1/100,000 and 1/1,000,000 live births depending on the population.The disease shares the same clinical picture as SCID due to gamma chain deficiency (see this term). Patients present in the first few months of life with the classical clinical features of SCID, i.e. chronic diarrhea, failure to thrive, recurrent respiratory infections and/or generalized infections due to opportunistic pathogens. Patients may present with skin rash, abnormalities of liver function, and pancytopenia. Materno-fetal transfusion-associated graft versus host disease is also associated with the disease. The disease is characterized by a lack of circulating T and NK (Natural Killer) cells and normal number of B lymphocytes.SCID due to JAK3 deficiency results from a defect in the JAK3 gene encoding an intracellular tyrosine kinase, the Janus activating kinase 3 required for cytokine-mediated signaling.Transmission is autosomal recessive.