title: Analysis of DLA-DQB1 and polymorphisms in CTLA4 in Cocker spaniels affected with immune-mediated haemolytic anaemia.
abstract: BACKGROUND
  Cocker spaniels are predisposed to immune-mediated haemolytic anaemia (IMHA), suggesting that genetic factors influence disease susceptibility. Dog leukocyte antigen (DLA) class II genes encode major histocompatibility complex (MHC) molecules that are involved in antigen presentation to CD4(+) T cells. Several DLA haplotypes have been associated with autoimmune disease, including IMHA, in dogs, and breed specific differences have been identified. Cytotoxic T lymphocyte antigen 4 (CTLA4) is a critical molecule involved in the regulation of T-cell responses. Single nucleotide polymorphisms (SNPs) in the CTLA4 promoter have been shown to be associated with several autoimmune diseases in humans and more recently with diabetes mellitus and hypoadrenocorticism in dogs. The aim of the present study was to investigate whether DLA-DQB1 alleles or CTLA4 promoter variability are associated with risk of IMHA in Cocker spaniels.
  
  
  RESULTS
  There were a restricted number of DLA-DQB1 alleles identified, with a high prevalence of DLA-DQB1*007:01 in both groups. A high prevalence of DLA-DQB1 homozygosity was identified, although there was no significant difference between IMHA cases and controls. CTLA4 promoter haplotype diversity was limited in Cocker spaniels, with all dogs expressing at least one copy of haplotype 8. There was no significant difference comparing haplotypes in the IMHA affected group versus control group (p = 0.23). Homozygosity for haplotype 8 was common in Cocker spaniels with IMHA (27/29; 93 %) and in controls (52/63; 83 %), with no statistically significant difference in prevalence between the two groups (p = 0.22).
  
  
  CONCLUSIONS
  DLA-DQB1 allele and CTLA4 promoter haplotype were not found to be significantly associated with IMHA in Cocker spaniels. Homozygosity for DLA-DQB1*007:01 and the presence of CTLA4 haplotype 8 in Cocker spaniels might increase overall susceptibility to IMHA in this breed, with other genetic and environmental factors involved in disease expression and progression.
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hatfield, AL9 7TA Hertfordshire UK.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Threlfall
authors.affiliation: The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG UK.
authors.forename: Alisdair M
authors.initials: AM
authors.lastname: Boag
authors.affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, North Mymms, Hatfield, AL9 7TA Hertfordshire UK.
authors.forename: Francesca
authors.initials: F
authors.lastname: Soutter
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hatfield, AL9 7TA Hertfordshire UK.
authors.forename: Barbara
authors.initials: B
authors.lastname: Glanemann
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, North Mymms, Hatfield, AL9 7TA Hertfordshire UK.
authors.forename: Harriet M
authors.initials: HM
authors.lastname: Syme
authors.affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, North Mymms, Hatfield, AL9 7TA Hertfordshire UK.
authors.forename: Brian
authors.initials: B
authors.lastname: Catchpole
keywords: Cocker spaniel; Cytotoxic-T-Lymphocyte-Antigen-4 (CTLA4); Dog Leukocyte Antigen (DLA); Immune Mediated Haemolytic Anaemia (IMHA)