Disease-causing mutations in the genes encoding perforin (PRF1, FHL2), munc13-4 (UNC13D, FHL3), syntaxin 11 (STX11, FHL4), and munc18-2 (UNC18-2/STXBP2, FHL5) have been previously identified in Familial Hemophagocyic Lymphohistiocytosis (FHL), whereas mutation in RAB27A and LYST account for Griscelli syndome type 2 and Chediak-Higashi syndrome, respectively