title: Genome-wide analysis in German shepherd dogs reveals association of a locus on CFA 27 with atopic dermatitis.
abstract: Humans and dogs are both affected by the allergic skin disease atopic dermatitis (AD), caused by an interaction between genetic and environmental factors. The German shepherd dog (GSD) is a high-risk breed for canine AD (CAD). In this study, we used a Swedish cohort of GSDs as a model for human AD. Serum IgA levels are known to be lower in GSDs compared to other breeds. We detected significantly lower IgA levels in the CAD cases compared to controls (p = 1.1 × 10(-5)) in our study population. We also detected a separation within the GSD cohort, where dogs could be grouped into two different subpopulations. Disease prevalence differed significantly between the subpopulations contributing to population stratification (λ = 1.3), which was successfully corrected for using a mixed model approach. A genome-wide association analysis of CAD was performed (n cases = 91, n controls = 88). IgA levels were included in the model, due to the high correlation between CAD and low IgA levels. In addition, we detected a correlation between IgA levels and the age at the time of sampling (corr = 0.42, p = 3.0 × 10(-9)), thus age was included in the model. A genome-wide significant association was detected on chromosome 27 (praw = 3.1 × 10(-7), pgenome = 0.03). The total associated region was defined as a ~1.5-Mb-long haplotype including eight genes. Through targeted re-sequencing and additional genotyping of a subset of identified SNPs, we defined 11 smaller haplotype blocks within the associated region. Two blocks showed the strongest association to CAD. The ~209-kb region, defined by the two blocks, harbors only the PKP2 gene, encoding Plakophilin 2 expressed in the desmosomes and important for skin structure. Our results may yield further insight into the genetics behind both canine and human AD.
authors.affiliation: Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden. katarina.tengvall@imbim.uu.se
authors.forename: Katarina
authors.initials: K
authors.lastname: Tengvall
authors.forename: Marcin
authors.initials: M
authors.lastname: Kierczak
authors.forename: Kerstin
authors.initials: K
authors.lastname: Bergvall
authors.forename: Mia
authors.initials: M
authors.lastname: Olsson
authors.forename: Marcel
authors.initials: M
authors.lastname: Frankowiack
authors.forename: Fabiana H G
authors.initials: FH
authors.lastname: Farias
authors.forename: Gerli
authors.initials: G
authors.lastname: Pielberg
authors.forename: Örjan
authors.initials: Ö
authors.lastname: Carlborg
authors.forename: Tosso
authors.initials: T
authors.lastname: Leeb
authors.forename: Göran
authors.initials: G
authors.lastname: Andersson
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.forename: Åke
authors.initials: Å
authors.lastname: Hedhammar
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lindblad-Toh
mesh_terms: D000818:Animals; D003876:Dermatitis, Atopic / Q000235:genetics* / Q000662:veterinary; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006239:Haplotypes; D006801:Humans; D007070:Immunoglobulin A / Q000235:genetics; D051191:Plakophilins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
chemical_list: D007070:Immunoglobulin A; D051191:Plakophilins