In AF mice, all three populations of conventional TCRαβ+ (CD4+, CD8αβ+, and CD4+ CD8αα+) IELs were severely depleted while unconventional TCRαβ+ CD8αα+ IELs were partially reduced and unconventional TCRγδ+ IELs remain unaffected. This evidence concerns the gene CD4 and atrial fibrillation.