ACE2 and COVID-19: Moreover, previous Genome-Wide Association Studies (GWAS) aimed at identifying novel quantitative trait loci regulating ACE1 activity and ACEi pharmacogenetics, recognized new variants in the ACE1 gene (rs4343) and in the ABO-blood group locus (rs495828 and rs8176746) [88], providing an explanation for the correlation of the ABO-locus/ACE1-ACE2 mutual levels/RAS-unbalancing/severe COVID-19.