In the VVS group, the serum ACE2 levels [2.38 ± 1.30 ± 1.47 vs. 1.27 (1.45) pg/ml] and POTS group serum ACE2 levels [2.38 ± 1.30 vs. 1.93 (2.78) pg/ml] were both significantly decreased compared to the control group, with statistically significant differences (P < 0.05). This evidence concerns the gene ACE2 and postural orthostatic tachycardia syndrome.