In particular, some conserved extended haplotypes of the major histocompatibility complex (MHC) and the presence of the killer cell immunoglobulin-like receptor (KIR) gene KIR2DS2 in combination with HLA-C alleles of the C1 group (HLA-C1) significantly counteract the risk of developing severe clinical manifestations in Sardinian COVID-19 patients (12, 22). The gene discussed is KIR3DL2; the disease is COVID-19.