The vast majority of canine inherited disease appears to be caused by a simple recessive mutation. Once the mutation is known genetic tests can be developed to detect the presence of the mutated gene. The test will be based on a small amount of DNA prepared from tissue taken from an individual dog. Ideally blood tissue but using tissue samples taken with less invasive techniques, for example scraping cells from the inside of the cheek, have also proved successful. The DNA sample will contain all the chromosomal material, and hence all of the genes, present in that individual. The DNA will be screened to see if it contains no copies, one copy or two copies of a particular mutant gene. For a disease known to result from a single recessive mutation, if no mutant copies are present, the animal is clear, if one copy is present the animal is a carrier and if two copies of the mutant gene are present it will be affected. A few diseases appear more complex involving more than one mutation. In this case one test is not sufficient to determine healthy, affected or carrier dogs.
What are the different types of DNA test?
What are the tests currently available on the market?