Hydroxyacid oxidase 2 (HAO2) encodes peroxisomal proteins with 2-hydroxy acid oxidase activity, which participated in the production of reactive oxygen species and cellular breakdown22; HAO2 has already been shown downregulated in hepatocellular carcinoma (HCC) tissues and ccRCC, overexpression of which restrained HCC and RCC cells proliferation by eliminating lipid droplet accumulation23,24. This evidence concerns the gene HAO2 and renal cell carcinoma.