ACE2 and infection: The expression of ACE2 and TMPRSS2 is heterogeneously expressed in different organs (6) and tissues with more than 1% ACE2 expression proportion are considered at higher risk of infection, including lower respiratory tract (2%), lung (> 1%), heart (> 7.5%), ileum (3%), esophagus (> 1%), kidney (4%), and bladder (2.4%) (7).