Combined KIR/HLA genotypes, specifically KIR3DL1 in combination with HLA-Bw4, co-carriage of KIR3DL1-high and KIR3DL1-low alleles with HLA-B*57 and HLA-B*27, and the synergistic effect of activating KIR3DS1 together with HLA-Bw4-80I (encoding for isoleucine at position 80) were associated with slower time to the onset of acquired immunodeficiency syndrome (AIDS) [36], and lowered the risk of certain opportunistic infections [38]. This evidence concerns the gene KIR3DL1 and AIDS.