As shown in Fig. 4, the Ecrg4-specific immunoreactive staining shown as brown color, with 200x magnification on the left side and 400x magnification on the right side of (A) and (B) respectively, was significantly less intense in the appendages of patients with persistent AF (A, left panel) than control patients with SR (B, right panel), suggesting that Ecrg4 may participate in the pathogenesis of AF. The gene discussed is ECRG4; the disease is atrial fibrillation.