Previous studies have uncovered associations between immune-response genes (such as PD-L1, CD73, MHC-I, and IRF8) and human heart diseases including cardiomyopathy, atrial fibrillation, and atherosclerosis (Fig 1A) (Hennecke & Wiley, 2001; St Hilaire et al, 2011; Leonard et al, 2013; Meder et al, 2014; Johnson et al, 2016; Esfahani et al, 2019; Bracamonte-Baran et al, 2021). This evidence concerns the gene IRF8 and atrial fibrillation.