ABCD1 and atrial fibrillation: In the comparison between the high AF risk and control genotypes of the AF risk related ACE2 SNPs, there were significant differences on serum concentration of RAAS activation as follows: ACE [rs4646188 (P = 0.017 and 0.037)], Ang I [rs4240157 (both P < 0.001) and rs4646188 (P = 0.002 and 0.001)], Ang II [rs2074192 (both P < 0.001), rs4240157 (both P < 0.001), rs4646188 (both P < 0.001)], and ALD [rs2074192 (both P < 0.001) and rs4646188 (P = 0.005 and 0.011)], as shown in Table 6.