RESUMO
Progressive retinal atrophy (PRA) is the collective name of a class of hereditary retinal dystrophies in the dog and is often described as the equivalent of retinitis pigmentosa in humans. PRA is characterized by visual impairment due to degeneration of the photoreceptors in the retina, usually leading to blindness. PRA has been reported in dogs from more than 100 breeds and can be genetically heterogeneous both between and within breeds. The disease can be subdivided by age at onset and rate of progression. Using genome-wide association with 15 Shetland Sheepdog (Sheltie) cases and 14 controls, we identified a novel PRA locus on CFA13 (Praw = 8.55 × 10(-7) , Pgenome = 1.7 × 10(-4) ). CNGA1, which is known to be involved in human cases of retinitis pigmentosa, was located within the associated region and was considered a likely candidate gene. Sequencing of this gene identified a 4-bp deletion in exon 9 (c.1752_1755delAACT), leading to a frameshift and a premature stop codon. The study indicated genetic heterogeneity as the mutation was present in all PRA-affected individuals in one large family of Shelties, whereas some other cases in the studied Sheltie population were not associated with this CNGA1 mutation. To our knowledge, this is the first report of a mutation in CNGA1 causing PRA in dogs.
Assuntos
Canais de Cátion Regulados por Nucleotídeos Cíclicos/genética , Doenças do Cão/genética , Cães/genética , Degeneração Retiniana/veterinária , Animais , Estudos de Casos e Controles , Códon sem Sentido , Análise Mutacional de DNA , Cães/classificação , Mutação da Fase de Leitura , Estudo de Associação Genômica Ampla , Genótipo , Polimorfismo de Nucleotídeo Único , Degeneração Retiniana/genética , Países Escandinavos e Nórdicos , Deleção de SequênciaRESUMO
Cone-rod dystrophy in the standard wire-haired dachshund (SWHD) is inherited as a simple autosomal recessive trait and the recently discovered mutation is widespread within the SWHD population in Norway and other Scandinavian countries. The gene frequency was estimated to be 4.8%. On the basis of the assumption that the size of the ancestral haplotype around a mutation is inversely correlated with the number of generations since the mutation arose, we have found that the mutation is of a relatively recent origin. The conserved haplotype was found to be 8 Mb in size and therefore we estimate that the mutation arose roughly eight generations (approximately 37 years) ago. This indicates that the mutation arose after breed separation.