In the last issue of Down to the Genes we defined the genetic conditions tracked in the American Simmental Association’s TraitTrac, and walked readers through using a Punnett Square to assess the likelihood of affected or carrier progeny from carrier parents. This month, we focus on what to do when an animal has a genetic hold, how to order genetic conditions testing, and how to interpret test results.
If a sire or donor dam contains one-eighth of a suspect breed population and carries a designation of population risk or carrier in lineage for genetic defects, they will need to be tested for each of the defects displaying PR/CL under TraitTrac to prevent progeny holds. Regardless of the results of the testing, i.e., the animal tests as a carrier, the record will be updated, progeny will be able to be registered, and certificates will be issued.
While on “genetic hold,” the ASA will not issue or release registration certificates, transfers, or updated performance data or other similar information. To remove the hold, members need to supply test results on the genetic condition. If DNA is not available on a sire or donor dam in question, their progeny must be tested before registration certificates and EPDs are released. The “genetic hold” will be automatically removed upon completion of condition testing or proof from another breed association of testing to clear the pedigree.
For natural calves (not ET) with a genetic hold, the defect risk is always tracked from the sire’s side and can be cleared by testing as far back in that sire’s pedigree as possible. For an ET calf, the hold can be generated from the sire or donor dam so make sure to check the TraitTrac display of both parents to view the defect testing needed.
Genetic Conditions DNA Testing:
There are two options for testing genetic conditions through the ASA. The first option is a stand-alone test for a genetic condition. If the only testing is for genetic conditions, members can submit DNA on the animal in question and pay $25/condition. The second option applies when members are completing a genomics panel on the same animal. With the GGP-LD or GGP-HD, members can pay the same price as the standalone test ($25) and receive all seven genetic condition results (AM, NH, CA, DD, OS, PHA, and TH). The genetic conditions panel is only available when ordering the GGP-LD or HD panel. If members decide they would like to test for genetic conditions after they have ordered the genomics panel, they will be charged the stand-alone price ($25/defect test).
Members can submit official genetic conditions test results from accredited genotyping laboratories and the ASA will update Herdbook with those results.
Members are automatically emailed results when the results are uploaded onto Herdbook. The email ASA uses is the email on the account that paid for the testing. If you do not have an email on file (or the wrong email on file), please update to receive automatic results letters in your inbox. In the case when ASA does not have an email for an account, the ASA mails the results letters to the member.
Possible results include:
Tested free – This animal does not carry the genetic condition and will not pass the condition onto their offspring.
Tested carrier – Animal has one copy of the genetic mutation and one copy of the normal gene. Half of their progeny will inherit the genetic condition gene. For recessive conditions, an animal needs two copies of the gene to display the phenotype.
Tested homozygous carrier – Extremely rare with genetic conditions (more common with traits). A homozygous carrier means the animal carries two copies of the genetic condition mutation. Homozygous carriers are possible in non-lethal conditions like Developmental Duplication (DD) or Contractural Arachnodactyly CA. Homozygous carriers will always pass on the mutation to their offspring.
- Published: 15 March 2019