The reason for that is as follows: after infection with SARS-CoV-2, the ACE2 level was found to be reduced due to binding with the spike protein of SARS-CoV-2 [84], suggesting that SARS-CoV-2 may reduce the level of ACE2 in infected cells, resulting in an imbalance between ACE1 and ACE2. This evidence concerns the gene ACE2 and infection.