During a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which gives rise to COVID-19, the angiotensin-converting-enzyme 2 (ACE2) receptor, expressed in many human tissues, including the lungs, the heart, the kidneys, the liver, and the nervous system, plays a crucial role in mediating viral entry (16). Here, ACE2 is linked to COVID-19.