Why do Huskies have blue eyes?

Humans have been exercising selection in dogs since the domestication of the wolf. In the first instance we found a natural and quite gradual selection in the way in which the first dogs were domesticated; in second, an intense artificial selection during the formation of the most modern races.

An unintended consequence of this selection is that the canine genome now encodes a phenotypic diversity - characteristics that a gene, eg, blue eyes or brown eyes - can express dramatically high. This variety is susceptible to genetic analysis, and this is demonstrated by the latest study published recently in the journal PLOS Genetics by Adam Boyko and Aaron Sams, of the company Embark Veterinary Inc, and conducted in collaboration with the University of Veterinary Medicine of Cornell.

According to the authors, this represents the first consumer genomics study conducted in a non-human model and the largest study of the canine genome to date. It addresses the reason why huskies have blue eyes. In dogs, the blue eyes are iconic of the Siberian husky, a race of northern latitudes and although it is known that two genetic variants underlie the color of blue eyes in some dogs, these do not serve to explain the trait of the huskies.

To find out this last reason, Boyko and Sams who in his company had the sequenced genome of 6,070 dogs, made use of the information provided by the owners of the dogs and who, through online surveys and photographs, provided the scientists with data on the phenotype studied, in this case the eye color.

Thus, scientists discovered that chromosome 18 near the ALX4 gene, which plays an important role in mammalian eye development, was strongly associated with the variation in blue color for the eyes, mainly in Siberian huskies, but also in the Australian shepherds that do not show the merle mutation (which dilutes the color of melanin in dogs and mice). Thus, only one copy of the variant is sufficient to cause blue eyes or heterochromia - blue and brown eyes - in many of the individuals studied.

However, some dogs with the variant did not have blue eyes, so the researchers hypothesize that other genetic or environmental factors could be involved in the expression of this phenotype. Future studies on this mechanism may lead to the discovery of a new way in which blue eyes develop in mammals.

On the other hand, from a broader perspective, the results emphasize the power of knowledge based on the data provided by consumers. In words that Aaron J. Sams sends us via press release: "by using the genetic data of our clients' pets, combined with the colors of the eyes reported by them, we have discovered a genetic duplication that is strongly associated with the color of blue eyes In a single year, we gathered enough data to make the largest canine study of its kind, "he adds. "In addition, we are currently conducting similar research projects with respect to morphological or health-related characteristics, which benefit reproduction efforts and the welfare of dogs in the first place, but are valuable in the same way for studies. in humans, since dogs and humans exhibit many physical features, behaviors and analogous diseases in a shared environment, with this new methodology we hope to achieve great advances in the field of genetics and medicine ", concludes the researcher.