ACE2 and obesity due to melanocortin 4 receptor deficiency: It has been recently proposed that the COVID-19 uses an angiotensin-converting enzyme 2 (ACE2)-dependent mechanism of cellular entry, similar to SARS-CoV and human respiratory coronavirus NL63. The interaction between the ACE2-RAS system, AT, and COVID-19 could explain the higher morbidity and mortality risk for COVID-19 patients with obesity. The role of ACE2-RAS in COVID-19 remains to be elucidated.