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Paw Print Genetics is often asked if the same mutation always causes genetic disease, especially when the mutation is identified in a breed different from that originally investigated.  The answer is not simple.  For many of these types of genetic questions, I go back to my ‘human’ roots as a human geneticist.  Because more than 4,500 diseases and their genetic causes are known, human genetics can shed considerable light on problems just beginning to be investigated in dogs.

Currently, there are about 185 known mutations in dogs, with about 150 that cause disease and another 30 or so that cause traits such as coat color or coat length.  In dogs, these disease-causing mutations have been narrowly defined to certain breeds or certain clinical features (phenotypes), but is this always the case?

In human genetics, anything imaginable has been described. Certainly, there are diseases that are caused by single mutations; in this case, one mutation causes one disease.  But there are many examples of multiple mutations in one gene causing one disease and examples of multiple mutations in multiple genes causing one phenotype (one disease).  Likewise, there are many examples of the same exact mutation ...

Large, muscular dogs, Rhodesian ridgebacks trace their ancestry to southern Africa, and it includes hunting dogs, guard dogs and semi-domesticated tribal dogs. The ridgeback is notorious for two things: first, as an athletic lion-hunting dog that could chase down and keep lions at bay until hunters showed up to make the kill, and second for the ridge of hair on their back that runs counter to the rest of the dog’s hair.

With roots that begin in present-day South Africa and Rhodesia, the ridgeback descends from semi-domesticated hunting dogs of the Khoikhoi people. These dogs possessed a line of hair that ran against the direction of the rest of their hair, creating a “ridge” along their backs. These fierce dogs were noted for their guarding abilities. Dutch settlers eventually brought European dogs with them – including greyhounds, bloodhounds and great Danes – which were bred with these indigenous dogs of South Africa. This crossing resulted in the Boer hunting dog, which continued to possess the ridge of hair along its back, and which was eventually taken to neighboring Rhodesia, where it was bred with other hunting dogs. The results of these pairing established the foundation for the ridgebacks – athletic ...