Summary
JAK3 (Janus Kinase 3) deficiency is an autosomal recessive form of severe combined immune deficiency (SCID). It is characterized by lack of circulating T and NK (Natural Killer) cells and normal number of B lymphocytes. The disease is due to mutations in the JAK3 gene encoding an intracellular tyrosine kinase that is physically and functionally coupled with several cytokine receptors. Identification of gene anomalies has allowed physicians to make the diagnosis (even prenatal), and may prompt novel forms of treatment based on gene therapy. Although a relatively low number of JAK3-deficient subjects have been diagnosed, JAK3 deficiency represents an important cause of autosomal recessive SCID in the United States and its prevalence in Europe appears to be even higher. However it is considered as a rare disease (incidence is between 1/100,000 and 1/1,000,000 live births). JAK3-deficient patients present with the classical clinical features of SCID in the first few months of life, i.e. chronic diarrhoea, failure to thrive, recurrent respiratory infection and/or generalized infections from opportunistic pathogens, or signs of graft-versus-host reaction (skin rash, abnormalities of liver function, pancytopenia) from transplacental acquired maternal T cells. The treatment of choice for JAK3 deficiency is allogeneic bone marrow transplantation.*Author: Pr Luigi D. Notarangelo (January 2005)*.
