PNPLA3 and metabolic disease: Although there are various possible reasons for people develop a fatty liver develop despite being non-obese, such as involvement of a genetic factor (i.e., PNPLA3 expression)27, it is generally considered non-obese subjects with fatty liver are in the state of insulin resistance and other metabolic disorder compared with non-obese subjects without fatty liver28, and it is also conceivable that insulin resistance may play an important role in the development and progression of RCC in these subjects.