Because ACE2 can increase the activity of endothelial cells, in the absence of ACE2 in COVID-19 and aging, Ang II activation causes smooth muscle contraction, induce high expression of proinflammatory factors, promote vascular contraction and endothelial dysfunction, all of which contribute to increased vascular permeability and eventually become predisposing factors for DIC [28]. The gene discussed is ACE2; the disease is endothelial dysfunction.