ACE2 and COVID-19: Considering the role of RAS in COVID-19 pathogenesis, the key mechanisms associated with lower COVID-19 severity and mortality in women are: I) Decreased ACE2 methylation in women, resulting in increased ACE2 expression; II) ACE2 is on the short arm of the X chromosome, where up to 30% of genes undergo X inactivation Escape; III) estrogen promotes ACE2 expression.