Immunological aspects of immunodeficiency diseases part 55

Mutations in proteins required for normal functioning and signal transduction through the T-cell receptor (TCR) cause rare forms of SCID. Mutations of the tyrosine phosphatase, CD45, which helps to initiate signaling by the TCR, results in T-B+SCID in humans. Mutations of components of CD3-complex (CD3 γ, ε, δ) result in a SCID phenotype. During signal transduction via TCRs, the protein tyrosine kinases lck and ZAP70 are required for phosphorilation of ITAMs on the intracytoplasmic segment of the TCR. Deficiency of either of these kinases results in rare forms of SCID