However, we should also note that IL-1ra, IL-6, and interferon-γ levels in gingival crevicular fluids were significantly correlated to serum levels, whereas TNF-α and IL-8 were not identified in the serum of periodontitis patients with normal renal function, [74]; however, similar analyses have not been performed in HD patients to date. The gene discussed is TNF; the disease is periodontitis.