Development of genetic tests
Detecting new mutations and developing genetic tests is one of the first steps in controlling hereditary diseases in a dog population. Genetic tests allow us to avoid hereditary diseases with planned mating and even eradicate them through their informed use.
The development of a genetic test is done in several stages. Cooperation of breeders, veterinarians and researchers is essential for the development of a genetic test. Dog breeders can best track whether a problem that occurs in the dog line is hereditary. Most genetic diseases discovered in dogs to date are inherited autosomal recessively, in which both copies of the same gene must be defective for the genetic disease to develop - a copy received from the mother and a copy received from the father. You can read more about the mode of inheritance of genetic diseases HERE. It is very important for breeders to work with veterinarians, who can accurately describe the symptoms, link them to certain conditions and publish them in scientific journals. Thus, it often happens that several articles with symptoms of a genetic disease have been published before the development of the genetic test. In addition to the mode of inheritance and symptoms, it is also very important to know when the first signs of a genetic disease appear. Is it a genetic disease that occurs during embryonic development, immediately after birth, in the first year of life, or is it a late-onset disease.
When it is clear from the scientific publications or observations of breeders that certain symptoms are present due to a genetic disease, researchers search the entire genome and try to find causative mutation with the help of the latest genetic techniques. Mutations are permanent inherited changes in the genome caused by various factors called mutagens. Under the term mutation we often imagine something that is harmful to the individual, but this is not the case. Mutations can also be beneficial as they can give some individuals a new trait that improves their quality of life. For example, a mutation in hair length allows some breeds of dogs to live a better-quality life in cold conditions. Mutations that are beneficial to an individual are often preserved in nature. In the case of genetic diseases, we are talking about mutations that are harmful therefore we try to avoid them by correct breeding plans.
Detecting mutations alone can be quite time consuming, as research can take years. Mutations are sought throughout the dog’s genome, which is about 2.5 billion bases long. Genetic diseases can be monogenic, where the mutation is present in only one gene, or they can be polygenic, where several genes are involved in the development of a genetic disease. At the time of writing, more than 300 mutations associated with genetic diseases and traits of dogs are known. Most of known genetic diseases are monogenic, as much more studies and knowledge of the function of individual genes are needed to understand the functioning of polygenetic diseases.
When a new mutation for a particular genetic disease is known and well described, an article in scientific journal is published. The publication of the article is followed by the development of a genetic test that will be available to the general public.