title: DLA class II alleles are associated with risk for canine symmetrical lupoid onychodystrophy [corrected](SLO).
abstract: Symmetrical lupoid onychodystrophy (SLO) is an immune-mediated disease in dogs affecting the claws with a suggested autoimmune aethiology. Sequence-based genotyping of the polymorphic exon 2 from DLA-DRB1, -DQA1, and -DQB1 class II loci were performed in a total of 98 SLO Gordon setter cases and 98 healthy controls. A risk haplotype (DRB1*01801/DQA1*00101/DQB1*00802) was present in 53% of cases and 34% of controls and conferred an elevated risk of developing SLO with an odds ratio (OR) of 2.1. When dogs homozygous for the risk haplotype were compared to all dogs not carrying the haplotype the OR was 5.4. However, a stronger protective haplotype (DRB1*02001/DQA1*00401/DQB1*01303, OR = 0.03, 1/OR = 33) was present in 16.8% of controls, but only in a single case (0.5%). The effect of the protective haplotype was clearly stronger than the risk haplotype, since 11.2% of the controls were heterozygous for the risk and protective haplotypes, whereas this combination was absent from cases. When the dogs with the protective haplotype were excluded, an OR of 2.5 was obtained when dogs homozygous for the risk haplotype were compared to those heterozygous for the risk haplotype, suggesting a co-dominant effect of the risk haplotype. In smaller sample sizes of the bearded collie and giant schnauzer breeds we found the same or similar haplotypes, sharing the same DQA1 allele, over-represented among the cases suggesting that the risk is associated primarily with DLA-DQ. We obtained conclusive results that DLA class II is significantly associated with risk of developing SLO in Gordon setters, thus supporting that SLO is an immune-mediated disease. Further studies of SLO in dogs may provide important insight into immune privilege of the nail apparatus and also knowledge about a number of inflammatory disorders of the nail apparatus like lichen planus, psoriasis, alopecia areata and onycholysis.
authors.affiliation: Department of Animal Breeding and Genetics, Biomedical Centre, Swedish University of Agricultural Sciences SLU, Uppsala, Sweden. Maria.Wilbe@hgen.slu.se
authors.forename: Maria
authors.initials: M
authors.lastname: Wilbe
authors.forename: Martine Lund
authors.initials: ML
authors.lastname: Ziener
authors.forename: Anita
authors.initials: A
authors.lastname: Aronsson
authors.forename: Charlotte
authors.initials: C
authors.lastname: Harlos
authors.forename: Katarina
authors.initials: K
authors.lastname: Sundberg
authors.forename: Elin
authors.initials: E
authors.lastname: Norberg
authors.forename: Lisa
authors.initials: L
authors.lastname: Andersson
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lindblad-Toh
authors.forename: Ake
authors.initials: A
authors.lastname: Hedhammar
authors.forename: Göran
authors.initials: G
authors.lastname: Andersson
authors.forename: Frode
authors.initials: F
authors.lastname: Lingaas
mesh_terms: D000483:Alleles; D000818:Animals; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D007154:Immune System Diseases / Q000235:genetics / Q000662:veterinary*; D015810:Linkage Disequilibrium
chemical_list: D015395:Histocompatibility Antigens Class I; C039692:histocompatibility antigen DLA
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