The association between AD and KIR2DL5*001:01 was not found to be confounded by race, HLA-A*01:01, HLA-A*02:01, HLA-B*07:02, HLA-C*07:02, C2, Bw4 (an HLA ligand), B80T (an HLA variant associated with HLA-B position 80 coding for threonine), seasonal allergies or asthma. This evidence concerns the gene C2 and Alzheimer disease.