Clear, carrier, affected – what do test results mean?
- Clear or normal (also known as A) will never develop the disease •
- Carrier (also known as B) will never develop the disease but are silent carriers and there are implications for breeding
- Affected (also known as C) will develop disease – age of onset of symptoms will vary with each animal and each disease
Normal or Clear dogs can be mated to any dog and will never produce affected pups of the relevant disease – as an example, the genetically inheritable degenerative eye disorder, PRA-prcd.
A carrier can be used for breeding but should only be paired with a Clear dog. This will always avoid producing affected pups. As resulting pups will be a mix of both Clear and Carriers, breeders have the choice of DNA testing prior to selection of breeding stock to retain. This would allow the breeder to prevent further inheritance through retention of a Clear pup.
Alternatively, breeding stock could be selected prior to determining genotype and the breeder would then manage breeding strategies in accordance with DNA results. Retaining Carrier pups which would, in time, be mated only to Clear dogs allows the breeder to select superior stock based on other aspects: conformation, temperament and health aspects. Should the superior pup be a Carrier, the only issue is that Clear status is delayed for another generation or more if needed. Appropriate breeding strategies will prevent the production of disease-affected pups while maintaining genetic diversity and possibly better overall breeding quality puppies for the betterment of the future of our breed.
Affected dogs should only be bred to a Normal/Clear dog to avoid producing any Affected pups. All puppies produced from an Affected to Clear mating will have the Carrier genotype. These pups need to be bred according to the Carrier Breeding Strategies above.