Mutations in UNC13D have been linked to familial hemophagocytic lymphohistiocytosis (FHL), thereby highlighting its role in regulating immune responses [8]; moreover, associated mutations can lead to defective cytotoxic granule exocytosis in natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), contributing to the dysregulated immune responses seen in FHL [9]. Here, UNC13D is linked to hemophagocytic syndrome.