Genetic basis - This phenotype is caused by a specific genetic variant in the KRT71 gene, namely c.1266_1273delinsACA in exon 7 that causes a frameshift mutation resulting in p.Ser422ArgfsTer alteration of the KRT71 protein. This mutation is fixed in Curly Coated Retrievers and found at lower frequencies in other breeds with curly or wavy coats such as Lagotto Romagnolo, Bichon Frise, Spanish Water Dog, Chesapeake Bay Retriever, and Irish Terrier. It is a second variant distinct from the originally known p.Arg151Trp mutation in KRT71 that also causes curly coats in other breeds. KRT71 encodes keratin 71, a structural protein important for hair follicle morphology and coat texture.
Pathophysiology - The frameshift mutation likely disrupts the keratin structure and function, altering hair follicle shape and hair curl. Some KRT71 variants are known to cause follicular dysplasia (abnormal hair follicle development) in dogs. The mutation changes the protein's C-terminus, which may impact hair strength and elasticity. Dogs heterozygous for the mutation often have wavy coats; homozygous dogs exhibit full curly coats (incomplete dominance inheritance).
Complications - Potential link to follicular dysplasia, which may affect coat health. No specific complications like skin disease have been definitively associated with this particular KRT71 mutation in the literature. Knowledge from other species shows some KRT71 mutations cause alopecia, suggesting a risk of hair loss or texture changes.
Why This Matters to Breeders and Vets - Testing for this mutation helps breeders understand and manage coat type traits in affected breeds to maintain desired breed standards. Identification of carriers prevents unintentional breeding of two carriers, reducing the risk of dogs with possible coat health issues. For vets, awareness can aid in diagnosing coat texture abnormalities and potential associated follicular problems.