In the literature, increased levels of interferon-γ (IFN-γ) [18] and tumor necrosis factor-α (TNF-α) [19] have been reported in HT, and elevated levels of interleukin-4 (IL-4) [20] and interleukin-6 (IL-6) [21] also have been shown in GD. The gene discussed is IL6; the disease is hematocrit.