A curly finding in canine genes

Professor Hannes Lohi’s research group has discovered a new gene variant underlying curly fur in the KRT71 keratin gene, also revealing an increasingly complex genetic structure behind dogs’ curly coats. In addition to breeding, the finding may benefit the treatment of certain diseases, as certain variants of the gene are also connected to hair growth disturbances and baldness.

Curly fur is fairly common among the animal kingdom, and it is also quite a prevalent trait of various dog breeds. Curly coats have been associated with the KRT71 gene and its different variants in several species. The range of KRT71 variants affect the production of a protein known as keratin by hair follicles in dog fur.  

“Curly fur in dogs has previously been linked with the KRT71 gene in certain breeds, but in conjunction with commercial tests it was observed that not all curly-coated breeds carried this particular gene variant. We started investigating the matter and identified a novel gene variant in the same gene, KRT71, in altogether six different breeds. However, our findings suggest that even these two KRT71 variants don’t entirely account for all aspects of dogs’ curly fur,” explains project participant Elina Salmela, PhD.

The new variant is also expressed in Curly-Coated Retrievers, all of which had the variant in question. Rarer occurrences of the variant were found in five other breeds: Spanish Water Dog, Irish Terrier, Bichon Frise, Lagotto Romagnolo and Chesapeake Bay Retriever.

“In light of these results, the genetics of curly fur is clearly more complex than previously understood. A gene test developed on the basis of our finding can help breeders of curly-coated dog breeds predict the fur type of their dogs more accurately than before,” says University Researcher Marjo Hytönen, PhD, who headed the project.

KRT71 variants of different breeds have also been linked with hair follicular dysplasia and alopecia, or baldness. Even though further research is needed, the finding gained in this study may also have clinical significance; various hair growth abnormalities that result in alopecia or sparse fur occur in more than 40% of Curly-Coated Retrievers.

“Together with other keratins, KRT71 forms a protein network in the hair follicle. Certain gene variants inhibit the normal development of the keratin network, leading to the sparse hair and fur, or baldness. The newly identified gene defect is in a structurally sensitive domain in terms of KRT71 functionality, which could explain why some dogs carrying this variant have hair growth disorders. However, this requires further investigation,” Hytönen explains.

The same gene variant was also independently discovered by a Swiss research group. The results of both groups were published in the Animal Genetics journal on Monday.

Professor Hannes Lohi’s research group conducts research at the Faculties of Veterinary Medicine and Medicine, University of Helsinki, as well as the Folkhälsan Research Centre. This study was supported, among others, by the Jenny and Antti Wihuri Foundation, the Ella and Georg Ehnrooth Foundation, the Academy of Finland, the Jane and Aatos Erkko Foundation and Wisdom Health (MARS Inc.).

Original article:

SalmelaE, Niskanen J, Arumilli M, Donner J, Lohi H, Hytönen MK.  A novel KRT71variant in curly-coated dogs, Animal Genetics, 50(1):101-104, 2018. doi: 10.1111/age.12746.