The KEGG enrichment analysis revealed that the DEGs were mainly involved in metabolic pathways, PPAR signaling pathway, cholesterol metabolism, IL-17 signaling pathway and the PI3K/AKT signaling pathway, especially osteoclast-related pathways, including rheumatoid arthritis, osteoclast differentiation and the TNF signaling pathway (Fig. 3B). The gene discussed is PPARA; the disease is rheumatoid arthritis.