Animal and human studies reported that changes in gut microbiome composition, associated with markers of chronic GI inflammation (e.g., tumour necrosis factor-α, interferon-gamma, interleukin-6, and interleukin-1β), accelerate the pathogenesis of PD by promoting neuroinflammation leading to neurodegeneration [152,162,163,164,165,166,167,168,169]. The gene discussed is IL6; the disease is Parkinson disease.