In a study by Okumura et al., Baseline serum MMP-2, carboxylterminal telopeptide of collagen type I (ICTP), and Brain natriuretic peptide (BNP) levels were significantly higher in patients who experienced AF recurrence than in those who did not (860.3 ± 120.8 ng/mL vs. 687.0 ± 122.5 ng/mL; 3.2 ± 1.1 ng/mL vs. 2.7 ± 0.6 ng/mL; 105.0 [38.5–133.0] pg/mL vs. 38.9 [20.8–72.9] pg/mL, p < 0.05 for all) [40]. The gene discussed is NPPB; the disease is atrial fibrillation.