ACE2 and COVID-19: We previously synthesized a high-resolution CRISPR library targeting 833 genes implicated in SARS-CoV-2 biology31 based on their identification in prior CRISPR screens of SARS-CoV-2 cytopathic effect19,20,22–26,32, human genome-wide association studies of COVID-19 susceptibility33, RNA-seq analysis of genes whose expression correlated with the SARS-CoV-2 receptor ACE234, and our own genome-wide CRISPR screen for modifiers of ACE2 abundance31.