In this regard, studies have found that COVID-19 targets exclusively the angiotensin-converting enzyme 2 (ACE2) receptor as an entry receptor into ACE2-expressing cells (35) which have been identified as the surface receptor for the spike proteins of acute respiratory syndrome coronavirus (SARS-CoV) (36), a first and essential step of viral infections of host cells (37). The gene discussed is ACE2; the disease is viral infectious disease.