Single nucleotide polymorphisms in major histocompatibility class II haplotypes are associated with potential resistance to inflammatory bowel disease in German shepherd dogs

German shepherd dogs (GSD) in the UK are at increased risk of developing the Inflammatory Bowel Disaese (IBD). IBD is believed to be a multifactorial immune mediated disease affecting genetically predisposed dogs. The aim of the current study was to investigate whether susceptibility to IBD in GSD is associated with the major histocompatibility complex (MHC) class II locus (Dog Leukocyte Antigen, DLA). Sequence-based genotyping of the three polymorphic DLA genes DLA-DRB1, -DQA1 and -DQB1 was performed in 56 GSDs affected by IBD and in 50 breed-matched controls without any history of gastrointestinal signs. The haplotype DLA-DRB1*015:02-DQA1*006:01-DQB1*023:01 was found to be present only in the control population and was associated with a reduced risk of IBD (P<0.001). In contrast, the haplotype DLA-DRB1*015:01-DQA1*006:01-DQB1*003:01 was associated with IBD (Odds ratio [OR]=1.93, confidence interval [CI]=1.02-3.67, P=0.05). This study has identified an association between DLA-type and canine IBD, supporting the immunogenetic aetiology and immunopathogenesis of this disease.