Cellular and molecular pathogenesis of X-linked lymphoproliferative disease

In the past few years important advances have been made in the understanding of the molecular mechanisms leading to X-linked lymphoproliferative disease (XLP). It has been possible to identify the gene defective in XLP and to demonstrate that, in normal individuals, it encodes the Src homology 2 domain-containing protein 1 A (SH2D1A) that plays a crucial role in signaling via a number of surface molecules expressed by cells of the immune system. At present a variety of mutations have been identified that result in lack of defective SH2D1A molecules. Importantly, it has recently been demonstrated that lack of SH2D1A affects the function of surface molecules that are involved in the mechanism of natural killer-mediated recognition and killing of Epstein-Barr virus-infected B cells.