Specifically, we aim to incorporate new markers such as TCRα signature (TCR Vα7.2) in V(D)J recombination defects, CD57 as a marker of senescent lymphocytes in APDS, gp91phox, p22phox, p47phox, and p67phox in CGD, as well as signaling lymphocyte activation molecule (SLAM)–associated protein (SAP) and X-linked inhibitor of apoptosis protein (XIAP) in X-linked lymphoproliferative diseases 1 and 2 (12, 66, 70, 71). The gene discussed is XIAP; the disease is X-linked lymphoproliferative disease.