<p>This entry represents SH2 domain-containing protein 1A (SH2D1A). SH2D1A is an adaptor protein that appears to regulate B-cell differentiation via switching of SLAM (CD150)-mediated signalling pathways [<cite idref="PUB00042795"/>]. The SLAM receptor is expressed on activated T and B lymphocytes. SH2D1A inhibits SLAM self-association. SH2D1A acts by blocking the recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region [<cite idref="PUB00042796"/>]. </p><p>Defects in SH2D1A are a cause of lymphoproliferative syndrome X-linked type 1 (XLP1) (OMIM:308240), which is also known as X-linked lymphoproliferative disease (XLPD) or Duncan disease [<cite idref="PUB00042797"/>]. XLP is a rare immunodeficiency characterised by extreme susceptibility to infection with <taxon tax_id="10376">Epstein-Barr virus</taxon> (EBV) (HHV-4) (Human herpesvirus 4). Symptoms include severe or fatal mononucleosis, acquired hypogammaglobulinemia, pancytopenia and malignant lymphoma.</p> SH2 protein 1A