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  1. lalaucb
  2. PGD
  3. Wednesday, 20 May 2015
  4.  Subscribe via email
I am desperate for some information and advice. I have no fertility issues (3 successful pregnancies and no miscarriages) and back in 2011 did 24-chromosome screening with single gene testing for a genetic recessive disease with GSN. We used day 3 biopsies. The first round of IVF I got pregnant with my son. This time we did a FET with a perfect looking "normal" embryo. I had 2 bhcg of 91 and 760 at 8dpt and 12dpt respectively. On day 15 I miscarried. I know there are other metabolic and genetic factors, so I'm trying not to think too much about why this embryo didn't work. My question is related to another embryo we have that is labeled for transfer, with "lesser" confidence ratings. Specifically, there is an 80% confidence call on chromosome 21 and 80% on sex-chromosome (with two other chromosomes at 90% and one at 85%). With what you know, how do you feel about the ratings on this embryo? Does it appear that for this embryo the cell that was received had lower quality DNA or the DNA amplified itself less, and that it is actually a good embryo to use? If there was any chance of aneuploidy on 21 or the sex chromosome, would that have been reported separately? We went through enormous cost and heartache to get where we are, so of course we want to take an educated next step. I sincerely thank you in advance for your help.
Accepted Answer
DrNorian Accepted Answer Pending Moderation
Thank you for your post, and I'll do my best to answer some questions raised. The 'Lesser Confidence Ratings' are difficult for me to understand. It may have to do with the embryo being screening on Day 3 or because the probes that they developed for the single gene testing, may have been less reliable in 2011 than they are now. Typically when we and reproductive genetics laboratories do PGD for single genes, several overlapping probes are developed in order to give more reliability for the final result.

I suspect that the 80% or 90% confidence calls have more to do with the accuracy of the single gene testing rather than with lower quality DNA or testing for aneuploidy (ie., incorrect number of chromosomes such as in the case of Trisomy 21 (Down Syndrome)). I'm not aware of confidence calls for aneuploidy; however, I would call GSN (now called Natera) directly and speak with a genetic counselor about this specific question.

One last thing to comment on has to do with genetic testing of Day 3 embryos. The current platforms typically require biopsy of at least 3 to 5 cells of the trophectoderm (aka the outside of the embryo that will develop into the placenta, not the part that develops into the fetus (or the ICM)). This helps to add accuracy to the testing. Whereas with Day 3 biopsies, only 1 cell (blastomere) can be screened.

I hope that this helps to answer some of your questions. Best of luck!
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  2. PGD
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