Revised exon-intron structure of human JAK3 locus.

Jak3, a member of the Janus tyrosine kinase family is an intracellular kinase functionally coupled to cytokine receptors that share a common gamma chain (gamma c). Defects in the gamma c or Jak3 result in T-B + severe combined immunodeficiency (SCID). In order to clarify discrepancies between earlier reported genomic organisations of human JAK3, the present study was undertaken to redefine its whole exon-intron structure. The genomic structure of human JAK3 consists of 23 exons and 22 introns, and shows strong homology with the organisation of the murine JAK3 locus. The exon-intron sequences provided in this report can be used to facilitate the identification of new Jak3-deficient SCID patients, including prenatal diagnosis.