STXBP2 and hemophagocytic syndrome: Mutations in PRF1, UNC13D, STX11, STXBP2, SH2D1A, XIAP, and ITK genes of all the 45 HLH cases accounted for 2/45 (4.4 %), 6/45 (13.3 %), 0/45 (0.0 %), 2/45 (4.4 %), 3/45 (6.7 %), 0/45 (0 %), and 0/45 (0.0 %), respectively.