SH2D1A and X-linked lymphoproliferative disease: It has been suggested that in both X-linked lymphoproliferative syndrome and sporadic hemophagocytic lymphohistiocytosis, EBV LMP1 inhibits the expression of the SAP gene, causes the abnormal activation of T lymphocytes, upregulates Th1 cytokines (IFN-γ), and increases macrophage activation, which can lead to the development of hemophagocytosis [98].