The frequency of the dysfunctional allele A of ALDH2 SNP was significantly lower and the frequency of the dysfunctional allele G of ADH1B SNP was significantly higher in patients with lone AF than in control II (ALDH2 A allele frequency = 0.176 vs 0.235, OR = 1.3, P = 0.013, Fig. 3 and Table 3, ADH1B SNP G allele frequency = 0.286 vs 0.220, OR = 1.4, P = 0.0007, Fig. 4 and Table 4). The gene discussed is ALDH2; the disease is atrial fibrillation.