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CAG solves IMM test problem

Dear CAG Customers,

As you may have read in social media, a problem has been discovered in the analysis of some sequencing results for IMM/MYH1 genetic tests.  A sample that was sent to two German laboratories, received two different results, and we were thankfully informed about this by a customer.

To determine the source of the issue, we did the following steps:

  1. We first did extensive testing of our primer sequences, and repeated tests that had already been carried out. We next used the published primer sequences.  Both analyses led to the same results.  We were therefore able to rule out an error in our laboratory.
  2. We next did an in-depth analysis of the MYH1 gene in which the IMM mutation is located. On the same chromosome (equine chromosome 11), we found a genetic sequence that is very similar to MYH1 (called a pseudogene). Some horses have a single base change in the pseudogene which makes it identical to the region of the IMM mutation. This can then lead to a false-positive result in those horses, as it looks like they have the mutation when they actually do not. This pseudogene problem was not previously known to us. A recent update of the equine genome has helped clarify the sequence in this region.
  3. After discovering the pseudogene issue, we contacted the second German laboratory. They were also not aware of the pseudogene problem and also had no solution for it.
  4. We therefore directly contacted the research group in the USA which published the test and holds the patent. We sent samples with suspect results to the laboratory in the USA at our own cost for further testing and analysis.
  5. We designed new laboratory and analysis protocols for the test. These protocols allow us to avoid the amplifying the pseudogene and the analysis will only detect the correct MYH1 We have now received the results from the laboratory in the USA and we have confirmed our hypothesis and new laboratory and analysis method. We are therefore again able to run all samples in-house.

We thank all of our customers for your patience.  Unfortunately, investigating such a situation and developing a solution is time consuming.  CAG holds the highest quality standards, and this is why we required this time.

Thank you for your trust in CAG.

July 22, 2019

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