Ectodermal Dysplasia Chesepeake Bay Retriever Type (ED-SFS)
Ectodermal Dysplasia Chesepeake Bay Retriever Type or Ectodermal Dysplasia-Skin Fragility Syndrome (ED/SFS) in Chesepeake Bay Retriever is an inherited skin disorder affecting the Chesepeake Bay Retrievers. It is associated with epidermal cell-cell separation, condition known as acantholosys. Congenital and hereditary disorders of skin adhesion are gathered in group of disorders known as epidermolysis bullosa (EB). ED/SFS is known to affects humans and dogs, and it was first time described in 1997 on a human patient as an inherited skin disorder, or genodermatosis. ED/SFS in Chesepeake Bay Retriever was a first hereditary epidermolysis bullosa described in animal species.
Mutations in the gene encoding protein plakophilin-1 (PKP1) have been associated with Ectodermal Dysplasia / Skin Fragility Syndrome. Protein plakophilin-1 interacts with protein desmoplakin, a component of desmosome which has an important role of maintaining the structural integrity of neighboring cells.
Characteristics and Symptoms
First clinical signs are noticed already at birth. Affected cubs exhibit fragile and pale skin and diffuse inflammatory skin disease, erythroderma. This signs appear at areas of friction or trauma. Common symptoms are also chronic perioral inflammation with cracking, known as cheilitis, and abnormal thickening of footpads, palmoplantar keratodermas, with fissures. Affected dogs exhibit hair abnormalities such as partial hypotrichosis, complete hairlessness and woolly hair as well as nail dystrophies. Growth delay is present.
Light microscopy examination reveals a widening of intercellular space with dissociation between epiderman cells in the superficial epidermal layers. This widening of intercellular space results in epithelial sloughing, or erosions. Epidermal cell-cell separation, or acantholosys, is associated with the aggregation of the keratin cytoskeleton, condition known as dyskeratosis. Acantholysis decreases with aging of the dog, but the epidermis becomes hyperplastic and hyperkeratotic. Transmission electron microscopy examination reveals a reduced number of hypoplastic desmosomes.
Ectodermal Dysplasia Chesepeake Bay Retriever Type (ED/SFS) is caused by a splice mutation of PKP1 gene encoding for protein plakophilin-1 (PKP1). The mutation causes a premature stop codon, resulting in truncated PKP1 protein. Such PKP1 results in incorrect recruitment of desmoplakin and consequentially dysfunctional desmosome formation and structure.
ED/SFS in Chesepeake Bay Retriever is inherited as an autosomal recessive disorder. Healthy parents of an affected puppy are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes have no symptoms. Dogs homozygous for the mutation will display the symptoms of the ED/SFS. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Olivry T, Linder KE, Wang P, Bizikova P, Bernstein JA, et al. (2012) Deficient Plakophilin-1 Expression Due to a Mutation in PKP1 Causes Ectodermal Dysplasia-Skin Fragility Syndrome in Chesapeake Bay Retriever Dogs. PLoS ONE 7(2): e32072. doi:10.1371/journal.pone.0032072