As bariatric surgery (Roux-en-Y gastric bypass) in grossly obese individuals is a way to decrease hepatic steatosis, inflammation, and fibrosis,2 we analysed the transcriptional profile of jejunal biopsies from obese patients before and 1 month after gastric bypass (GSE113819), observing a significant downregulation of PPARGC1A expression15 (Fig. S1A and B). The gene discussed is PPARGC1A; the disease is Hepatic steatosis.