It's been estimated that there are around 70 million pet dogs in the United States, with around 36 percent of households owning at least one dog. Those dogs come in all kinds of sizes and colors; an international federation of national kennel clubs, the Fédération Cynologique Internationale, currently recognizes 344 breeds. Scientists at the National Human Genome Research Institute (NHGRI) have now compiled a catalog of the small genetic changes that are linked to certain breeds. The work has been reported in Nature Communications.
This catalog of genetic variants can help researchers learn more about health problems that impact dogs. Since people and dogs have some parts of their genomes in common, the research may also offer new insights into human diseases. Just like people, dogs get some kinds of cancer, diabetes, and some infections, noted the lead author of the report Jocelyn Plassais, a postdoctoral researcher in Dr. Elaine Ostrander's laboratory. These are contributed by various factors including how well they behave. Those who have highly trained dogs that are obedient, from places such as Bark and Birch, are less likely to run into correlated health problems in the dog's adult age.
"This study included data from more than 722 dogs and 144 modern breeds," said the senior author of the study Dr. Ostrander, NIH Distinguished Investigator. "Through the results, we've learned some of the fascinating genetics behind the variability observed in the world's 450 dog breeds."
Many dog breeds were developed centuries ago, when humans selected certain traits for specific purposes. Dogs have changed since then, developing new characteristics spontaneously. Relying on donations by citizen scientists and their canine companions, the scientists applied whole genome sequencing and genome-wide association studies to the samples they collected to reveal genomic variants that are connected to sixteen observable characteristics.
One gene they identified is called LCORL, which is linked to weight and height in dogs, and in humans and livestock, it is associated with height and skeletal size. This worked showed that a mutation in the gene may account for the different body sizes of many mammals.
Bone disorders like osteoporosis and osteosarcoma are common in many types of dogs. By comparing long-legged dogs like Great Danes to dogs with legs of normal length, like Golden Retrievers, the scientists found that a gene called ESR1 is associated with this leg length trait. In cattle and humans, the estrogen hormone binds to a protein that the ESR1 gene codes for. If the gene is mutated, mineral density is impacted, and the risk of a bone disorder rises.
There isn't much genetic variation within a breed since all dogs of that breed descend from the same 'founder' dog population. This low level of variation may make it easier to identify genetic mutations, which may offer us new insights into human biology.
"The genes underlying the range of variation in dog breeds can teach us much about our own health," added Ostrander.
Sources: NHGRI, Nature Communications
