No significant differences were observed in the percentage of GFRA4-immunopositive cells between the early stage (AF: 50.6 ± 4.4%, NP: 48.8 ± 3.8%) and the advanced stage of degeneration (AF: 55.1 ± 4.0%, NP: 56.8 ± 5.5%, Figure 15a). This evidence concerns the gene GFRA4 and atrial fibrillation.