As for the PPAR pathway, 11 genes related to lipid metabolism, including 6 representative genes (apolipoprotein A1, APOA1; fatty acid-binding 3, FABP3; fatty acid-binding 7, FABP7; retinoid X receptor-gamma, RXRG; stearoyl-CoA desaturase, SCD; fatty acid desaturase 2, FADS2), were specifically associated with the PPAR signaling pathway (Additional File 5: Figure S1), and the mRNA levels of these genes changed significantly (P < 0.05 or P < 0.01) in the capons compared with controls (Fig. 4b), suggesting that caponization induces gene expression changes that regulate AF deposition. This evidence concerns the gene APOA1 and atrial fibrillation.