In this study, we tried to sequence PRF1, UNC13D, STX11, STXBP2, SH2D1A, XIAP, and ITK genes, together with cytokine determination for HLH patients to test whether cytokine profile could be used as a tool to distinguish between primary HLH and secondary HLH patients. Here, STXBP2 is linked to hemophagocytic syndrome.