Embark scientists, working in collaboration with its citizen scientist customers, made the unique genetic discovery that the uniquely patterned coat of Cattle Dogs, Pointers, and other breeds known as “roaning” is strongly associated with a genomic region on chromosome 38 and likely regulated by the usherin gene (USH2A). Embark’s study R-locus for roaned coat is associated with a tandem duplication in an intronic region of USH2A in dogs and also contributes to Dalmatian spotting was recently published in the peer-reviewed journal PLOS One.
The study included nearly 1,000 dogs, out of hundreds of thousands of dogs, from Embark’s database. One of those dogs, Bogey the Australian Cattle Dog, a breed known for its roaning pattern, became the key to unlocking this genetic discovery because of his non-roan coat trait. Because his owner chose to be a citizen scientist and include Bogey’s genotype in Embark research, as well as his phenotype by providing photographs of him, this discovery was made possible. This recent tandem duplication discovery for roaning, just like the blue-eyed husky discovery, shows Embark is leading the way in canine genomic research.
Breeders can benefit from testing for roaning. The USH2A gene, along with the S Locus, regulates whether a dog will have roaning. Dogs with at least one copy of R will likely have roaning on otherwise uniformly unpigmented white areas created by the S Locus. Roan may not be visible if white spotting is limited to small areas, such as the paws, chest, face, or tail.
For those interested in testing for roan, such as for natural camouflage for their hunting dog in the field, an Embark roan test can be added to your tool kit when making breeding decisions. Breeds that could benefit include the German Shorthaired Pointer, Australian Cattle Dog, English Cocker Spaniel, Brittanys, Field Spaniels, English Setters, and Wirehaired Pointing Griffons, among others.
The results of this study may also shed light on the genetic origin of the Dalmatian’s unique spots. While historically, the spots on Dalmatians have been considered to have a different genetic mechanism from roaning patterns, all Dalmatians in the Embark study carried the duplication associated with roaning. It is possible that additional, not yet identified genes play a role and interact with the R locus to cause the characteristic Dalmatian spots, however, more research is needed.
While dogs can’t have roaning without the white spotting pattern caused by the S Locus (MITF gene), the white spotting (specifically piebald an extreme white) does come with some associated health risks, like deafness. Pigment-associated deafness has been observed in many breeds but the exact genetic mechanism is unclear and suggested to be complex.