RESUMO
BACKGROUND: Musladin-Lueke Syndrome (MLS) is a hereditary disorder affecting Beagle dogs that manifests with extensive fibrosis of the skin and joints. In this respect, it resembles human stiff skin syndrome and the Tight skin mouse, each of which is caused by gene defects affecting fibrillin-1, a major component of tissue microfibrils. The objective of this work was to determine the genetic basis of MLS and the molecular consequence of the identified mutation. METHODOLOGY AND PRINCIPAL FINDINGS: We mapped the locus for MLS by genome-wide association to a 3.05 Mb haplotype on canine chromosome 9 (CFA9 (50.11-54.26; p(raw) <10(-7))), which was homozygous and identical-by-descent among all affected dogs, consistent with recessive inheritance of a founder mutation. Sequence analysis of a candidate gene at this locus, ADAMTSL2, which is responsible for the human TGFß dysregulation syndrome, Geleophysic Dysplasia (GD), uncovered a mutation in exon 7 (c.660C>T; p.R221C) perfectly associated with MLS (p-value=10(-12)). Murine ADAMTSL2 containing the p.R221C mutation formed anomalous disulfide-bonded dimers when transiently expressed in COS-1, HEK293F and CHO cells, and was present in the medium of these cells at lower levels than wild-type ADAMTSL2 expressed in parallel. CONCLUSIONS/SIGNIFICANCE: The genetic basis of MLS is a founder mutation in ADAMTSL2, previously shown to interact with latent TGF-ß binding protein, which binds fibrillin-1. The molecular effect of the founder mutation on ADAMTSL2 is formation of disulfide-bonded dimers. Although caused by a distinct mutation, and having a milder phenotype than human GD, MLS nevertheless offers a new animal model for study of GD, and for prospective insights on mechanisms and pathways of skin fibrosis and joint contractures.
Assuntos
Doenças do Cão/congênito , Doenças do Cão/genética , Proteínas da Matriz Extracelular/genética , Artropatias/veterinária , Mutação de Sentido Incorreto , Anormalidades da Pele/veterinária , Animais , Sequência de Bases , Linhagem Celular , Mapeamento Cromossômico , Doenças do Cão/metabolismo , Doenças do Cão/fisiopatologia , Cães , Éxons , Proteínas da Matriz Extracelular/metabolismo , Humanos , Artropatias/genética , Artropatias/metabolismo , Artropatias/fisiopatologia , Camundongos , Dados de Sequência Molecular , Anormalidades da Pele/genética , Anormalidades da Pele/metabolismo , Anormalidades da Pele/fisiopatologiaRESUMO
Coat color and type are essential characteristics of domestic dog breeds. Although the genetic basis of coat color has been well characterized, relatively little is known about the genes influencing coat growth pattern, length, and curl. We performed genome-wide association studies of more than 1000 dogs from 80 domestic breeds to identify genes associated with canine fur phenotypes. Taking advantage of both inter- and intrabreed variability, we identified distinct mutations in three genes, RSPO2, FGF5, and KRT71 (encoding R-spondin-2, fibroblast growth factor-5, and keratin-71, respectively), that together account for most coat phenotypes in purebred dogs in the United States. Thus, an array of varied and seemingly complex phenotypes can be reduced to the combinatorial effects of only a few genes.
