Genetic Disorders Policy

THIS ARTICLE IS ONLY A DRAFT AND HAS NOT BEEN APPROVED FOR INCLUSION IN THE GUIDELINES

Research indicates that genetic mutations, including those that cause abnormalities, occur in nature and more of these will be identified in the future as technology advances. It is important to understand that carrier animals of recessive genetic abnormalities often have other genetic attributes that are desired by the industry. With genomic tools, management of deleterious alleles is possible to avoid undesirable abnormalities and reduce the allele frequency in the population over time. Therefore, efforts to eradicate or eliminate animals based on being a carrier of recessive genetic abnormalities are not recommended.

Recommendation

BIF recommends the following strategic approach to diagnose, set policy, and manage recessive genetic abnormalities. More aggressive approaches may be necessary for lethal or dominant deleterious abnormalities.

Determining if a Genetic Abnormality Exists

Protocol to determine if an abnormality has an underlying genetic cause:

• Take pictures and/or video of the affected animal
• Collect tissues (i.e., tissue, whole blood) of the affected animal. Preserving the whole body of the affected animal is recommended.
• Capture DNA samples on the sire and dam of the affected animal.
• Have a veterinarian evaluate the affected animal and prepare a written report of their observations
• Provide as much pedigree and breed composition information as possible
• Work with the breed association, genetics provider &/or university personnel to determine the appropriate entity to further analyze the situation.

Policies for Reporting and Testing Genetic Abnormalities

Once a genetic abnormality has been identified, it is recommended that a pro-active approach for reporting and testing be taken. All breed associations should identify tested genetic carriers and potential carriers on their registration certificate, the organization herdbook and website. Animals that are carriers of known genetic abnormalities should be registerable. Test as many potential carriers as is economically feasible starting with the most widely used animals in that population.

Breeding Management for Genetic Abnormalities

Once carrier animals have been identified then the abnormality can be managed through both tactical and strategic approaches as part of the breeding program:

• The simplest strategy is to avoid mating potential carriers of the recessive abnormality to potential carriers of that same genetic disorder. However, care must be taken to identify what effect this approach will have on overall genetic improvement given that this strategy may sacrifice genetic improvement at the expense of avoidance of generating carriers
• A more comprehensive approach would incorporate a mate selection framework. Mate selection is the simultaneous choice of selection candidates and their pattern of mate allocation, i.e., a mating list. Mate selection applications can manage genetic defects while simultaneously controlling for changes in inbreeding and genetic improvement of the breeding program.

Attribution

This article was derived from a report by a BIF ad hoc committee and further developed by several authors including User:Dbullock, User:Mspangler, User:Bgolden, and User:Snewman.