Several studies have found hypomethylation profiles within the interferon (IFN)-γ, IL-6, and TNF-α promoters, which was associated with increased IFN-γ, IL-6, and TNF-α transcription in gingival biopsies from patients with periodontitis (Zhang et al., 2010; Kobayashi et al., 2016). This evidence concerns the gene TNF and periodontitis.