S100A9 and atrial fibrillation: In summary, through the gene differential expression analysis, functional enrichment analysis, and PPI analysis of DEGs in AF and NAFLD we have successfully provided deeper insight to the molecular changes in AF and NAFLD pathogenesis, and identified several potential candidate therapeutic changes, including CXCR2, PTPRC, CCR2, MNDA, NCF2, S100A9, S100A8, S100A12. These hub genes were mainly enriched in inflammation and immune related biological functions and pathways.