ACE2 and COVID-19: Genetic predisposition, as in other inflammatory diseases, might be responsible for alterations in the clinical course of COVID-19 patients through polymorphisms in crucial genes such as ACE2 and MHC class I. Components of the immune response to the virus appear to be primarily related to disease severity, whereas genes related to the binding of the ACE2 cell surface—the entry point for SARS-CoV-2—during the early stages of infection appear to be largely responsible for the varying susceptibility to SARS-CoV-2.