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. This evidence concerns the gene PNPLA3 and renal cell carcinoma.