When two DNA reports disagree
Sooner or later a breeder or a registry sees two reports for the same animal that don’t seem to agree. Often they don’t really disagree at all. Work through these checks in order before you decide which one to trust.
1. Check that they tested the same thing
A condition’s common name can cover more than one variant. Progressive retinal atrophy (PRA) in dogs is a good example: UC Davis’s Veterinary Genetics Laboratory describes prcd as one inherited form of PRA. A dog that’s clear for prcd-PRA can still carry a different form, so two reports that both say “PRA” may have tested different things.
Compare the exact test or variant name on each report, not just the condition’s name. If they tested different variants, both reports can be right.
2. Put both results in the same terms
Labs and health databases write results differently. UC Davis reports a genotype such
as N/PRCD. The Orthopedic Foundation for Animals (OFA) lists DNA results as Normal,
Carrier, or Affected/At-Risk. For a recessive condition, N/PRCD and “Carrier” say the
same thing.
Translate each result into one set of terms before you compare them. Our guide on how to read a genetic test result explains the notation.
3. Check it’s the same animal
If both reports tested the same variant and still disagree, check the animal. On each report, compare:
- the name the lab recorded;
- the registration number and microchip number, if there are any;
- the date the sample was taken or received.
A mismatch here usually means one sample came from a different animal, or was labelled wrongly.
4. Ask the labs
Send each lab both reports and ask how the difference could have happened, and whether they can retest. For a new test, a sample your vet collects and labels after scanning the microchip leaves little doubt about whose sample it is.
5. Keep both reports
Don’t delete the report you think is wrong. Keep both, with a note of what you found and how it was resolved. A registry or a future buyer may ask, and the explanation is part of the animal’s record.
Where AnimalTrace fits
AnimalTrace keeps each lab’s report on the animal’s record, exactly as the lab issued it, so both stay side by side when you need to compare them.
Sources
- UC Davis Veterinary Genetics Laboratory, PRA-prcd
- Orthopedic Foundation for Animals, Dilated cardiomyopathy DNA test results