According to the analysis of the literature describing the association of immunogenic characteristics and the expression of ACE-2 and related proteins with the development of severe COVID-19, we can propose the following genetic factors as biomarkers-predictors—genes, associated with immune response (HLA genotype, genes coding cytokines and proinflammatory mediators receptors) and specifics in ACE-2 expression, and its transporter system proteins (SLC6A20, TMPRSS2 genes). This evidence concerns the gene SLC6A20 and COVID-19.