In view of the coming winter storm that may produce power outages, we want to reassure our patients that your embryos are stored in tanks of liquid nitrogen which do not require any electricity to maintain their temperatures. Severe winter weather should have no effect on their storage.
Our team sat down and talked to one of our fertility doctors, Dr. Joseph Bird III, to discuss PGT. Watch the video below to see the full interview or read our transcript to learn more.
PGT is an acronym for pre-implantation genetic testing. What that means is, if someone goes through the IVF process and we make an embryo, what we can do is biopsy that embryo, primarily pulling from what will become the placenta, and send that off for specific genetic information.
There are sort of three categories of PGT testing. Probably the most common done at any infertility clinic is what we call PGT-A. The A stands for annuployy, which means that we are looking at major chromosomal additions or deletions. Something like an extra copy of the 21 chromosome, which would lead to something like Down Syndrome or a trisomy 21. Or the absence of an X or Y chromosome that leads to XO, which is Turner Syndrome. Those are things that are commonly seen or talked about, and that’s sort of what we are trying to test.
Our goal during that testing is to eliminate one of the causes as best as we can of miscarriages. Probably the number one cause of miscarriage, especially spontaneously, is do the chromosomes come together normally. And if they don’t, then that’s less than likely to be a fully functioning embryo, more than likely to end in miscarriage.
And so our ultimate goal with PGT-A testing when we have embryos, is to know what embryos give you the best chance of success. Our goal is to limit the number of transfers that we have to do to get that successful pregnancy. We have decent evidence to say that if I used up all the embryos and didn’t do genetic testing, I’d probably still arrive at the same pregnancy rate. But the biggest issue is how many transfers did I have to do to get to that? And so it is one of the ways that we can navigate that.
That becomes particularly important in our patients that are over the age of 35 because we do know that you are at increased risk in having that issue in combining chromosomes. So it can help us tease that out as a mechanism fairly well.
There are two other forms of PGT. One of them is PGT-M, which looks at a monogenic condition, meaning if you went through the IVF workup and got recessive genetic carrier screening, meaning we’re looking at your body and the likelihood that you have one copy of a gene that’s normal and another copy that is abnormal, and your body is using the normal copy so you don’t have any symptoms. But if you and your partner match up for that condition, you now have a one-in-four chance of passing that one.
Common symptoms that people know about, and probably the more severe ones, are cystic fibrosis, spinal muscular atrophy, and fragile X. These are things that can affect the life of the child and have pretty significant health outcomes. If we know we are dealing with that situation and we want to try and avoid that, then I can use this specific type of pre-implantation genetic testing to implant the embryos that are not affected by that condition or maybe that are carriers for the condition but not affected by that condition, so that we can eliminate the health complications that come with that condition, and hopefully potentially reduce the likelihood that that passes on generationally.
The other type of testing is particularly concentrated in my patients who struggle with what we call recurrent miscarriages due to an issue with chromosomes being mismatched or misplaced. We call that PGT-SR. And my goal in that is to identify whether the chromosome been switched in that particular embryo, and is that impacting the likelihood that it survives. It’s very rare that we have to use that type of PGT testing, but it is available and can be helpful for patients who struggle with recurrent miscarriages. And so that is a form of PGT testing as well.
Overall, we see a lot of benefit of doing that in our clinic, and it has helped a lot of our patients conceive more efficiently. So we routinely recommend PGT testing in our clinic on pretty much anyone going through the IVF process