IFNG and ornithine translocase deficiency: Based on these observations, we hypothesized that the pathogenesis of HHH may be initiated by a series of cytokine storms including the release of inflammatory interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-10, and IL-18 cytokines, and IL-8 chemokine, as occurs in HPS [5, 6, 10].