XIAP and X-linked lymphoproliferative syndrome: Other monogenic diseases that produce HLH are Chédiak-Higashi syndrome (LYST), Griscelli syndrome type 2 (RAB27A), Hermansky-Pudlak syndrome (AP3B1), X-linked lymphoproliferative syndrome (XLP)-1 (SH2D1A), and XLP-2 (XIAP) (19).