ACE2 and COVID-19: This could be explained by the higher expression of ACE-2 in the GIT than the lung, and also the increased occurrence of URTI or GIT symptoms in patients with OGDs than in asymptomatic patients may indicate the higher expression of ACE-2 in symptomatic patients than asymptomatic ones, or the presence of the ACE-2 polymorphism that may impact the course of COVID-19 [52,53].