The mechanism differs from other genetic disorders associated with HLH, such as XLP-1, in which the impaired cytotoxic responses by CD8+ lymphocytes and NK cells result in exaggerated amounts of IFNγ and the activation of macrophages, thus explaining the positive effect of the IFNγ blockade on the outcome of HLH15. Here, IFNG is linked to X-linked lymphoproliferative syndrome.