SH2D1A and X-linked lymphoproliferative disease: Furthermore, X-linked lymphoproliferative diseases: XLP1 (caused by defects of SH2D1A (OMIM #300490), encoding SLAM-associated protein (SAP) [19]) and XLP2 (caused by changes in XIAP, which encodes the X-linked inhibitor of apoptosis (OMIM #300079) (Sieni et al. 2014) also frequently develop HLH.