However, the majority of the studies have indicated that COVID-19 development and/or severity are associated with polymorphisms in innate and adaptive immune genes, including killer-cell immunoglobulin-like receptors (KIR) and human leukocyte antigens (HLA) class I and II as well as genes involved in viral response pathways (LZTFL1, OAS gene family) (40–43). This evidence concerns the gene KIR3DL1 and COVID-19.