Particular single nucleotide polymorphisms (SNPs) in CTLA4 and collagen type IV alpha 4 chain (COL4A4) have been associated with AD in the Springer Spaniel, whereas SNPs in oxysterol binding protein like 9 (OSBPL9) and PTPN22 were implicated in the Cocker Spaniel, and SNPs in syntaxin-binding protein 5 (STXBP5) in the Labrador Retriever. This evidence concerns the gene PTPN22 and Alzheimer disease.