The gut microbiota could induce inflammation in both gut and systemic circulation due to lipopolysaccharides (LPS) from pathogenic bacteria and synthesis of pro-inflammatory cytokines (Mulak and Bonaz, 2015) such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α that were elevated in the blood of PD patients (Dufek et al., 2009; Reale et al., 2009). The gene discussed is TNF; the disease is Parkinson disease.