Evaluation of Angiotensin-converting Enzyme 2 (ACE2) in COVID-19: A Systematic Review on All Types of Studies for Epidemiologic, Diagnostic, and Therapeutic Purposes: Angiotensin-converting enzyme 2 (ACE2) in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses the angiotensin-converting enzyme 2 (ACE2) receptor of SARS-CoV for cell entry. We aimed to check the association between ACE2 and COVID-19 (coronavirus disease 2019) in a systematic review. Two databases (PubMed/Medline and Scopus) and bioRxiv were checked for retrieving all types of studies in relation to ACE2 and COVID-19 until March 18, 2020. Forty-one studies were entered to the systematic review. These studies included nineteen original, eight reviews, four letters to the editor, three research papers, one correspondence, one commentary, one mini review, two reports, one opinion, and one perspective. In summary, the results showed that the ACE2 receptor for COVID-19 is similar to that of SARS-CoV. However, its expression was different in various populations as well as in the two genders. ACE2 may be used as a therapeutic target. Patients who take ACE inhibitors may have benefit in severe disease outcomes. Finally, pangolins and snakes and turtles may act as the potential intermediate hosts transmitting disease to humans.