The autosomal recessive disorder familial hemophagocytic lymphohistiocytosis (FHL) results from mutations in the various genes that regulate cytotoxic lymphocyte degranulation and their ability to kill virus-infected cells PRF1, UNC13D, STX11, and STXBP2 genes (1, 2). The gene discussed is STX11; the disease is hemophagocytic syndrome.