Recently, I was messaging with Dr. C. (hooray for communication!), and we were discussing genetic testing. I asked if it was possible the two embryos with chromosomal abnormalities directly related to Nick’s translocations could theoretically be normal and just have the same issue as Nick.
She wasn’t 100% sure but asked her nurse manager and embryologists. They all thought it was a possibility they could be normal.
This also prompted her to go back and look at notes from our first try. She immediately wrote back and let me know those embryos likely wouldn’t have the right amount of chromosomal material, and that the testing company had written back to the clinic when they’d been asked about that in 2022. She provided me with the full message.
______
Samples 1 and 3 from accession 81024 are aneuploid. There is evidence that they have the unbalanced translocation, meaning there is a loss/gain of DNA resulting from the translocation carried by the partner. This couple is unique in that the partner has both an unbalanced reciprocal translocation between chromosomes 8 and 11, but also a Robertsonian translocation. When someone is a carrier of a balanced reciprocal translocation, their offspring can be:
1) normal/euploid
2) balanced carriers of translocation, or
3) unbalanced/aneuploid
A hallmark of an unbalanced translocation is the presence of segmental aneuploidies, which are partial chromosome abnormalities (versus an abnormality of the entire chromosome). A Robertsonian translocation behaves similarly to a reciprocal one in that the same 3 outcomes are possible, but the key difference is that unbalanced offspring in this scenario result in full chromosome trisomies/monosomies, not segmental ones. PGT-SR and PGT-A cannot differentiate between outcomes 1 and 2. In a balanced situation, there is no loss/gain of DNA. Thus, a balanced carrier is indistinguishable from a true normal euploid embryo. PGT-SR is designed to detect outcome 3 – unbalanced structural rearrangements are associated with poor clinical outcomes like implantation failure, miscarriage, or in some cases live birth to a child with a genetic condition.
The reason we would not require additional testing on this patient’s 3 embryos previously tested for PGT-A is that they were already identified to all have chromosome abnormalities. PGT-SR would not change these results. In a future cycle/test however, we would be able to run PGT-SR to identify unbalanced abnormalities. I would highly recommend this couple speak with one of our genetic counselors to help understand all these technical aspects and limitations of PGT-SR. We’re happy to refer her to a GC session free of charge to the patient. Let us know if you’d like us to facilitate that.
______
This was the first time I’d seen this message, and I was so grateful Dr. C. sent it to me. After we got our horrible results from our first try, we were offered a genetic consult appointment from the testing company, and we did meet with them.
I never discussed it here, because it wasn’t all that helpful. Since we never saw the above message, we didn’t even have a clue what the consult was about. Our best guess was that Dr. G. wanted to know what our chances of success were in a second cycle. So that’s what we asked about.
Unsurprisingly, the counselor couldn’t be too helpful. The conversation lasted maybe 15-20 minutes, and that was it.
We’ve scheduled another genetic counseling session with them to discuss PGT-SR vs. PGT-A testing.
And now that I know what to ask, I’m prepared with questions:
1) In our case, what is the advantage of PGT-SR over PGT-A?
2) What is the cost difference between the two? 3) Is the PGT-SR necessary?
4) Could we simply have any future children’s karyotypes tested at a later date?
5) Are there any major medical implications of not knowing about a translocation?
I’ll share more about what we found out in next week’s blog.
If you’d like to help us on this journey–whether through monetary donations; sharing our fundraising efforts; or sending prayers, thoughts, or good vibes–please visit our GoFundMe page or reach out to ivfthat@gmail.com.
IVF That 