We report herewith a male case of NK-cell type CAEBV with <i>SH2D1A</i> hypomorphic mutation (c.7G > T, p.Ala3Ser), two male cases of CAEBV/EBV-HLH with <i>XIAP</i> hypomorphic variant (c.1045_1047delGAG, p.Glu349del), and another female case of CD4<sup>+</sup>CAEBV with the same <i>XIAP</i> variant. The gene discussed is XIAP; the disease is hemophagocytic syndrome.