Thus, we focused on the role of the eNOS gene in the pathogenesis of NAFLD/NASH; NO, produced by various isoforms of NOS, is an ubiquitous signaling molecule involved in the regulation of metabolic homeostasis, and eNOS, which the endothelium produces as a vasoactive substance, has been shown to serve important functions, including the regulation of regional blood flow, insulin resistance, and energy production [6, 28]. This evidence concerns the gene NOS1 and metabolic dysfunction-associated steatotic liver disease.