Since the acetate concentration is positively associated with ghrelin level and insulin resistance, while butyrate concentration is negatively correlated with inflammation [34,35], the change in Firmicutes and Bacteroidetes abundance in the gut affecting the levels of SCFAs may be another common path in the pathogenesis of psoriasis and obesity, which are often associated. The gene discussed is GHRL; the disease is obesity due to melanocortin 4 receptor deficiency.