DPP9 and COVID-19: The COVID-19 Host Genomics Initiative (HGI) has identified a number of additional variants and genes linked to the severity or susceptibility to infection, including loci involving innate immunity or inflammation, such as the tyrosine kinase 2 (TYK2) crucial for antiviral responses, the interferon alpha and beta receptor subunit 2 gene (IFNAR2), the inflammasome regulator Dipeptidyl peptidase 9 (DPP9), and the oligoadenylate synthetase OAS1/OAS2/OAS3 gene cluster encoding activators of antiviral restriction enzymes [10].