RAB27A and Griscelli disease type 2: Genetic defects in Rab27a and Munc13-4 lead to Griscelli syndrome type 2 and familial hemophagocytic lymphohistiocytosis type 3, respectively, both of which induce systemic inflammation due to defective lymphocyte cytotoxicity and resultant uncontrolled T-lymphocyte and macrophage activation (Feldmann et al., 2003; Ménasche et al., 2000).