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 ...