PGS/PGT-A genetic embryo diagnosis – success stories

Vladimiro Silva, PharmD
Scientific and Executive Director, Ferticentro

Genetics PGS / PGT-A, Success Stories

From this video you will find out:
  • What genetic testing can tell you about your embryo?
  • What is preimplantation genetic testing (PGT-A) (formerly PGS) and how can it help?
  • What are the clinical outcomes with and without PGT-A?
  • What information is required to perform PGT for a monogenic condition (PGT-M) or PGT for a structural rearrangement (PGT-SR)?

What are the pros and cons of preimplantation genetic testing (PGT-A/PGS)?

In this webinar, Vladimiro Silva, PharmD, Embryologist, Founder & IVF Lab Director at Ferticentro, Coimbra, Portugal, presented 3 real-life cases where embryo biopsy was necessary to achieve a pregnancy and a healthy baby.

First, Dr Silva started by stating that genetics starts with counselling and, roughly speaking, testing the embryos. Genetics is also about making informed decisions about your embryos. If you are a carrier of a genetic disease, you have to live with that, if you are a woman older than 39, your eggs will have a certain risk of being aneuploid or having genetic abnormalities, and we cannot do anything about it. However, we do know whether those problems exist or not, and we have the power to decide what can be done with that information.

IVF & genetics – what’s the purpose

What’s the point of performing genetic testing? IVF is very useful to prevent the transmission of genetic diseases, it is also used to screen for potential genetic issues, some of them are age-related, and some of them are not. We are born with them, and it is also used to find HLA compatible embryos in very special cases, for example, we’re talking about compatibility to do bone marrow transplantations, and IVF can also help us with that.

There are 3 types of genetic tests that we can do in IVF:

  • Preimplantation Genetic Test for Monogenic disease (PGT-M), if you are a carrier of a certain disease, such as Huntington’s disease, neurofibromatosis, or if your partner is also a carrier in the case of recessive diseases or if it is an autosomal dominant disease, this means that if you are a carrier, you will always have the disease you are at risk, and you can resource to IVF to avoid passing that disease to your child
  • Preimplantation Genetic Test for Aneuploidies (PGT-A)
  • Preimplantation Genetic Test for Structural Rearrangements (PGT-A), sometimes we are a carrier of a genetic abnormality in our karyotype in the number of chromosomes that we have, but that change is balanced, so we don’t have any disease, we live a completely normal life because we have all the DNA that we require to do that but when we are forming gametes, sperm, or eggs in the case of women there could be problems
  • Preimplantation Genetic Test for HLA compatibility

PGT-A (formerly PGS)

It is a genetic test that we do on embryos to screen for numerical chromosomal abnormalities. We all have 46 chromosomes, and sometimes either because of the egg or the sperm, embryos can have an extra chromosome or a missing chromosome, this is what we call an aneuploidy which means embryos with the wrong number of chromosomes. If we have embryos with the wrong number of chromosomes, those embryos will most likely fail to implant, and so we will have a negative result, or if they implant, they can lead to a miscarriage. However, in some situations, if implantation is successful, it can lead to the birth of a handicapped child or a child with a genetic condition. When we have a chromosomally normal embryo, we call it a euploid embryo, and we know, for a fact, that these embryos are more likely to lead to a successful pregnancy. PGT-A is done with The Next Generation Sequencing method (NGS), it’s used all over the world these days, and this allows us to analyse all 24 chromosomes because we have 23 pairs, so a total of 46. There are 24 different types of chromosomes, but only 23 pairs, so these chromosomal abnormalities are detected before embryo transfer. We get the eggs, we fertilize them in the lab, we create embryos, and we cultivate the embryos until day-5 or day-6, in some rare cases, we might even take them to day-7, and then we make a small hole in the embryo, we take some cells out, and we test those cells, we freeze the embryo, and we wait for the result of those tests.

This allows patients to make informed decisions about their treatment, this is not about making your embryos better, it’s about getting information and the capacity to select the best embryo. If, for example, none of your embryos is viable, you might think, or you might consider egg donation, or you won’t lose time transferring lots and lots of embryos.

PGT-A is related to maternal age, on the graphic shown, until above the age of 35, the probability of having abnormal embryos spikes, and it ends up at 76% at the age of 43 or 44 years old. This is why egg donation is such a good alternative for many patients because we know that egg donors are less than 35 years old, and so that’s when the risk of having a chromosomal abnormality is lower. It’s important to keep in mind that chromosomal abnormalities can also come from the sperm, but in statistical terms, this is more associated with the maternal age and the quality of the egg.

Some data from Igenomix show the results of IVF with PGT-A where the implantation rates are relatively steady across all age groups, this is the age lower than 35 below 42 years old, even though it goes a bit down, the differences are not that significant. However, if you look at IVF without PGT-A, you will see the natural pregnancy rate go down. It is because we also have to think about the uterus and the endometrium and those unselected embryos. PGT-A doesn’t improve your chance of getting a baby, it just helps us identify the most viable embryos. The delivery rates follow the same trend, and miscarriage rates follow the exact opposite trend. When we are doing PGT-A, we’re less likely to have a miscarriage because we identify embryos with genetic abnormalities, when we’re not doing it, we are risking the transfer of embryos with genetic abnormalities, so this is another reason to do it.

The risk is very age-related, for example, when we are talking about an egg donation case, since the donors all belong to this group, there is no difference. It doesn’t make sense to do PGT-A in egg donation cases.

PGT-M (formerly PGD)

It is used to avoid the chance of having a child with an inherited genetic disorder. The process looks the same as in PGT-A, we create the embryos in the lab, we analyse them before the embryo transfer, and we identified those who carry the alternate disease-causing gene. This is intended for patients who are known to carry serious genetic diseases (either autosomal dominant or recessive). It’s a custom-designed test for every patient. There are thousands or hundreds of variations for every disease, so in genetic diseases, it’s more or less the same. For example, for cystic fibrosis alone, there are more than 1 500 known mutations, so even though we have to identify those mutations, then there are still inter-patient differences that we have to identify to prepare for the test. All patients have to do an initial test this is what we call the pre-PGT test, this is used to prepare the test, then we create the embryos, we take the cells out of the embryo, we freeze the embryo, we wait for the PGT results, we send those cells to the genetics lab, and then they will tell us whether that embryo is a carrier, for example, of the Huntington’s disease, Neurofibromatosis, Cystic fibrosis, spinal muscular, atrophy, etc.

PGT-SR (formerly PGD)

It is intended for patients who are known to carry karyotype abnormalities such as lesions, duplications, and inversions. Sometimes a part of the chromosome is swiped with another chromosome, and so in the gametes that are being built, it causes an imbalance in forming the spermatozoa and eggs in the case of women. This can be inherited, or it may occur spontaneously. This is a karyotype abnormality that affects 1 in every 500 people, it doesn’t cause any problems to the person that carries this abnormality, they normally find it when they are trying to have a baby because they’re getting negative results, and they don’t know why so we do the karyotype test and we find that.

One of the examples is a translocation between chromosome 14 and chromosome 7. A part of the 14 chromosomes is on chromosome 7, and a part of the 7 is on chromosome 14. That person has all the DNA necessary to have a normal healthy life and doesn’t have any issues, however, when a woman is creating her eggs we’re only transmitting 1 chromosome from every pair, and so if we transfer the wrong chromosome to the egg, the only way to balance it is if the 14 has a part of the 7 is also transmitted. If she passes the 7 with the part of the 14 and the normal 14, then there is an imbalance because there will be too much of the 14 chromosomes. This can cause either miscarriages or negative pregnancy results, or maybe the birth of a child with genetic abnormalities.

Preimplantation Genetic Test for HLA compatibility

In some situations, for example, in children with some very severe diseases, the only way to find the only solution and treat them is by finding a compatible sibling, a compatible bone marrow donor, and sometimes a compatible bone donor is very hard to find. Quite often, the only solution is to have a genetically compatible sibling. These situations always have to be approved by the national IVF authorities, those are ethically complex cases but they allow us to save the lives of children that otherwise will have no chance of survival.

Genetic issues – real-life cases

The first case presented a 42-years-old single woman, she never tried for a pregnancy, she had a normal BMI, and she decided to have a child with an anonymous sperm number.

  • a 42-year-old single woman, no previous pregnancy, high AMH level for her age, using an anonymous sperm donor

After evaluating her ovarian reserve, we got this astonishing value of 5.1 ng/mL, her FSH and LH were very well balanced, so her ovaries were working very well. We did an aggressive stimulation because we knew that from a normal point of view, we had everything we could dream of, however, there was the age factor, and it’s impossible to take the time to go backwards. We needed a lot of eggs, and the stimulation wasn’t that wonderful, we only got 9 eggs which are great in every age group, but from AMH of 5.1 ng/mL, we could expect 20 eggs or so. We got two day-6 blastocysts, we performed PGT-A, and we found that 1 of the embryos was aneuploid which means it had either an extra or a missing chromosome, another blastocyst was a mosaic embryo with 30% of the cells were abnormal.

We have to remember that when we do PGT-A, we’re only taking a group of cells from the embryo, normally 5 or 6 cells because we work with day-5 five or day-6 blastocysts. Sometimes they can or can’t be representative of the rest of the embryo, we can’t test all the cells of the embryo because otherwise, we would lose the embryo. The theory behind PGT-A is that those 5 or 6 cells are representative of the rest of the embryo. In this group of cells, 30% of them were abnormal, and 70% of them were normal. After discussing with the patient and talking to the genetician she decided to transfer that mosaic embryo, and luckily she got a healthy child, she did the amniocentesis, and the karyotype of the child and everything was okay. She now has a baby girl with a normal karyotype.

This is a typical case of a woman for whom PGT-A was very important because 1 of the embryos wasn’t viable. The fact that she did PGT-A led her to make an informed decision about mosaicism and also while doing the prenatal diagnosis procedure, the doctors knew that they had to do an amniocentesis because of the PGT-A result.

Another case presented a single woman in her 40s, her BMI was 25, so it was borderline normal, and she was a carrier of a genetic disease, it was an autosomal genetic disease, which means that she had a 50% risk of transmitting that disease to her child. We had to do the pre-PGT test, we had to test her and the sperm donor. We always keep DNA from our donors, we sent that DNA to the genetics lab to do the pre-PGT test.

  • a 40-year-old single woman, a carrier of genetic disease (ADPKD) – autosomal dominant: 50% risk of transmission

We started the stimulation with HMG of 375 UI a day, which is considered to be an aggressive protocol, and we got 5 eggs. From these 5 eggs, it was very likely that we wouldn’t have any viable embryos. Therefore, we did a second stimulation, we’ve frozen these eggs, and the result was different, we changed the protocol to the gonadotrophin, and the reaction was a lot better. We got 29 eggs, it was a completely amazing result for a 40-year-old patient. We’ve fertilized all of the 34 eggs, we warmed 5 that have been collected initially, and we got 22 developing embryos and 13 blastocysts. We did PGT-M, from those 13, 7 were not carriers of the genetic disease, and then we did PGT-A to test it because sometimes an embryo is not a carrier of the monogenic disease, but it can be, for example, trisomy 21. We did PGT-A on the 7 blastocysts that were not carriers of the genetic mutation, and 6 of them were euploid, which was also an amazing result. We transferred one of them, and there was a birth of a healthy child, and we still have 5 blastocysts frozen.

The last case presented a 25-year-old woman, with a normal BMI, she already had a child, and her child had a severe haematological disease according to the paediatrician’s team that was taking care of her daughter, the only solution to treat the existing child will be through a bone marrow transplant from a compatible donor. They were waiting for 3 years to find a compatible donor, but it didn’t happen. They knew that the theoretical probability of finding a compatible donor in a sibling was 20%, so they submitted an authorization request to the Portuguese IVF authority (CNPMA), which authorized treatment.

  • a 25-year-old woman with a husband, and 1 child with severe haematological disease; tried to find a compatible donor without success

We did the treatment to search for HLA compatibility selection, so it’s kind of a specialized form of PGT-M. We did the first ovarian stimulation, and we’ve we had 23 eggs, from this 23, we were expecting 20%, theoretically speaking, we would have 4 eggs that could be compatible, but we have to play also with the pregnancy rate, even though the patient was 25 years old, we could aspirate to have 50-60% so it was narrow and we would depend on luck. We decided to freeze all of these eggs, and then we did a second ovarian stimulation, and we got 33 more eggs, so we ended up fertilizing 56 between the fresh and the frozen, at the end of everything, we had 14 blastocysts, and we did the PGT-M for HLA compatibility, we got 3 compatible blastocysts. From those 3, we did PGT-A to see if they had the right number of chromosomes, and they were all euploid which was amazing, then we did the first embryo transfer, and the result was negative. We got very worried because there could be something else, and we only had 2 additional embryos out of 56 eggs, and it was a lot for the patient. We studied her endometrium, and we ended up finding that her endometrium was only receptive at 14.5 hours of progesterone which is what we call a misplacement of the window of implantation, so we did the frozen embryo transfer respecting the indications from the ERA test and we had the birth of a healthy HLA compatible child, and so hopefully everything will go well for this family.

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- Questions and Answers

I’m 40, I just had a failed IVF cycle. Before attempting a second IVF want to try an IUI with my best friend’s sperm, he is 50 but leads a very healthy lifestyle. What do you think? My partner has low sperm motility and 1% sperm morphology. Before the IVF, I had a laparoscopy, and the surgeon found that I had narrow fallopian tubes. I had 2 pregnancies at the age of 35,36, but both were terminated. I know IUI has a much lower success rate than IVF, but I wanted to give it a try with different sperm.

I wouldn’t advise you to do IUI for 2 different reasons. The first one is that when you are 40, I don’t remember your AMH, but when you are 40, in theoretical terms, the chances of success of an IUI are quite low. Statistically speaking, it will be below 10% or possibly even lower depending on the AMH. On average, from ESHRE data, IUI has a global success rate of around 8 or 9%. For patients aged 40 and older, it will be lower than that depending on the AMH, and so on, it’s certainly below 10%, it might be below 5%, so the chances are already very low. On top of that, if you had problems with your tubes, if you had narrow tubes, I would need to take a look at the report, but it could even be impossible because if there is a tube blockage, there’s no way for an IUI to work. If the tubes are narrow, we would have to see it, but that’s certainly another factor against you. If you want to try with a different person, maybe it’s better to do IVF instead. If the tubes are okay, you can try, but I don’t know if that will make a difference because of the female age factor. It’s a hard call, but I would say it’s preferable to try IVF.

I’m 41, I have had just my 7th transfer failure with PGT-A normal embryo. I am already on steroids and blood thinners, intralipids, what more can I do? I have two more normal poor quality embryos left. I don’t want to waste them but not sure what else can be done. I have never been pregnant.

In the best-case scenario, we have a 60-70% of pregnancy rate in those cases. Why it’s not 100%? It’s because there is a part of the process that involves the lab and the clinic and the treatment protocol, but the endometrium also plays a very important role. Steroids, blood thinners, intralipids are things that are used to take care of immune and haematological issues that may keep the embryos from implanting in the uterus. I would advise doing 2 tests. One of them is the endometrial receptivity analysis, there are multiple tests on the market, at Ferticentro, we work with the ERA (Endometrial Receptivity Array), it’s because we know that in some patients the exposure to progesterone can have a very significant role. Sometimes, the endometrium only becomes receptive after being exposed to progesterone for 120 hours, some patients take longer, some patients take less. There is one significant thing about the ERA test, it has to be done correctly, and it is only valid for 9 months, so that could also be an explanation. Sometimes patients might have accidental mistakes without even knowing that they made a mistake while taking the progesterone, or for some reason, there was a problem in the absorption, and the ERA test results are wrong and misleading the clinic. There is also microbiome and chronic endometritis issues. Sometimes, there are local underlying infections in the uterus that are asymptomatic, so patients don’t feel anything, we can’t see anything on the ultrasound scan, but those infections are there, and they are keeping the embryos to implant. All women have bacteria inside their womb, but it has to be the right bacteria, it has to be at least 80% of lactobacillus, and sometimes there is an imbalance in those bacteria, and that can cause issues in the implantation process. Other times, there is chronic endometritis, we need to give probiotics, antibiotics or sometimes there are changes even in the endometrial factor or in the window of implantation itself. In some, even more, rare cases, there could be immune incompatibilities issues. People are talking a lot about the KIR/HLA compatibility because we would have to see if there is any incompatibility in terms of their immunity. Those cases where we have immunity incompatibility can be very hard to treat, and some protocols are designed for that, and we can use those, but we would have to take a look and maybe do further tests. I wouldn’t transfer those remaining embryos without further tests, many protocols can be used. You’ve mentioned the natural cycle as well, and it can be different from an artificial cycle, so it’s not a very easy situation otherwise, you would already be pregnant, but we would need more information.

What’s your opinion on day-3 biopsy and fresh embryo transfer? Is that different from a day-5 biopsy and frozen embryo transfer?

‘m completely against day-3 biopsy and transferring a fresh embryo for 2 reasons. First, it is relatively dangerous for the embryo. At day-3, the embryo has only about 8 cells, it’s the normal number, if we take 1 or 2 of them, we’re taking cells from a very early embryo, and some studies have shown that the probability of the embryo to start degenerating is higher if we do a biopsy on day-3. In 2007, there was a study comparing day-3 embryo tested with PGT-A and doing nothing, and they concluded that it was preferable to do nothing than to do PGT-A on day-3 embryo because a lot of embryos were degenerating and leading to implantation failures because of that. Day-3 biopsies have been generally abandoned because of that, these days we’re all doing day-5 biopsies. On top of that, embryo vitrification provides 98% survival rates, which is wonderful, it’s a very reliable way of testing the embryos because we get to take out more cells, so it’s more representative of the embryo. The embryos are stronger, they survive better the biopsy procedure, and the chances they survive vitrification are very high. At our clinic (Ferticentro), we don’t do day-3 biopsies, and we will never do it. When we’re doing PGT-A, we are evaluating the nucleus of the cells, and sometimes there are other things in the cells like the mitochondria that are also very important to give energy to the embryo to develop. There was a recent study, about 2 years ago, where they were getting the nucleus from, for example, a 38-year-old lady with a history of horrible embryos. They removed the nucleus from the egg donor, and they used the rest of the egg and put the nucleus in there. Why did they do that? It’s because then there were the mitochondria from the egg donor sustaining the nucleus from the patient, and the results were wonderful. It’s still a very experimental procedure, it’s not something that you can do daily, but it’s a very promising way. This fragility of the embryo also explains why in certain PGT-A cases, we’re not getting pregnancies even with genetically normal embryos and why sometimes those embryos don’t survive the freezing and thawing process, so it’s one of the possible justifications. When we do PGT-A at Ferticentro, we also do mitoscore, it’s a technique that allows us to have an idea of the mitochondria potential of the embryo. It’s still experimental, we’re still checking if it works or not, but it’s one more factor that helps us to decide which embryo to transfer.

What are your thoughts on Mitoscoring?

I’m in favour, sometimes it’s not just about the nucleus of the cells, it’s also about the mitochondria and so Mitoscoring. the research on that is still very preliminary, we cannot say definitively that it’s the holy grail of PGT-A, but I think it’s a promising way of investigation and I do hope that in a few years, we’ll all be doing that and getting good results from that. It can help us to understand the implementation potential of the embryo besides the genetic factor, it’s not all about genetics, other embryonic factors can make things go wrong.

Did you confirm your mosaic level by AI or not?

I don’t know what you mean by AI, but if it is artificial intelligence, we’ve not confirmed it because we rely on the results reported to us by the genetics lab. When the genetics lab analysed the embryos, they just indicated the percentage of mosaicism, we work based on that. Then, we do prenatal testing on the ongoing pregnancy to make sure that everything goes well. Normally, there is a cut-off on mosaic embryos that we can transfer or not. There is no consensus about this in the scientific community, but normally people say that above 40%, it’s relatively dangerous or at least there is a certain risk that the abnormal cell line overlaps the normal one. When patients only have that kind of embryos, they take the risk as long as they make informed decisions, this can work and if we get 1 extra pregnancy out of even 100 that makes it worth it. Mosaicism is a very complicated issue, there is a lot of debate going on nowadays, possibly with non-invasive pre-implantation genetic testing, this can be solved. However, there is still a lot of investigation yet to be done.

Have you ever done a biopsy pre- and post-FET (frozen embryo transfer)? I would also like to see data following egg banking and PGT-A, PGT-M, etc.?

The answer is yes, we’ve done it many times. The example is the case that I withdraw from the list because I thought it could be boring. However, here we are, it was a patient with a lot of embryos, it was either 8 or 10 embryos, and then we started doing embryo transfers and getting negative results. The embryos were all frozen, we warmed them up, biopsied them, frozen them again, we got the results, two of them were viable, and we’ve transferred 1 of them. Those embryos were created, frozen, then warmed up, biopsied, they have been frozen again and warmed up again, and they were transferred, and that worked. Therefore, we can do this if we have a good vitrification program, which is a very difficult learning curve to have good results in vitrification. We have to do it every day, many times a day, 365 days a year. Regarding egg banking, it’s more or less the same. When we freeze eggs, we have a 90% of survival rate. When we freeze embryos, we have 98%, so there is a small difference. On the other hand, if we freeze eggs, we are saving an ICSI procedure, an additional biopsy procedure, so if we are freezing embryos instead of eggs, we are doubling a lot of expenses to the patients and a lot of procedures. We also have to think about cost-effectiveness to get98 of survival instead of 90, maybe it’s preferable to use the eggs. Even from an ethical point of view, it is easier to have eggs frozen than to have embryos for the patients. It has a different meaning in emotional terms, and so this is why we generally favour oocyte banking instead of embryo banking when we are doing multiple cycles before PGT, regardless of the type of PGT.

Why did you not transfer both embryos in the 1st case without PGT-A? Do you repeat ERA every 9 months?

The first case was with the 42-year-old lady and when we have a patient above the age of 39, we always recommend PGT-A, it was an informed decision of the patient. I always tell patients (it’s kind of a bold statement), that PGT-A is useless. It will not increase your pregnancy chances, however, at the same time, it is not useless. It will give you more information about your embryos. If you need that information to decide on what to do next, if this works or not, you should do PGT-A. If you say that you’ll never consider egg donation and you just want to keep trying with your own eggs, then it’s pointless to do PGT-A because we should let nature do its role. In this particular case, this patient was 42 years old, so above 39, she never tried, but she didn’t close the door to egg donation, so she needed to know whether her embryos would be viable or not before moving on with egg donation. This is why we ended up doing PGT-A, and so it was the patient who required that information, and so like I said, given the risks, we always talk about this possibility, but it’s not something compulsory for the patients, it’s something that we discuss with the patients. Ultimately, it’s the patient’s decision, it’s their life. Regarding the ERA test, we will have to go on a patient to patient basis, we do hope not to have patients having negative results for 9 months, but if we have an ERA test older than 9 months and we are getting negative results, we repeat it, and we’ve found not many but a few cases where the window of implantation changed after more than 9 months, so I advise patients to do that.
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Vladimiro Silva, PharmD

Vladimiro Silva, PharmD

Vladimiro Silva, PharmD, embryologist, Scientific and Executive Director at Ferticentro and Procriar, two of the leading IVF centres in Portugal. Doctor of Pharmacy, Faculty of Pharmacy, University of Coimbra. MSc in Health Economics, Faculty of Economy, University of Coimbra. Post-graduated in Health Services Management, Faculty of Economy, University of Porto. Post-graduated in Clinical Analysis, Faculty of Pharmacy, University of Porto. Author of hundreds of lectures, oral communications, posters and scientific articles in Portugal and abroad. Vladimiro Silva speaks: English, French, Spanish, Italian and Portuguese.
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Caroline Kulczycka

Caroline Kulczycka

Caroline Kulczycka is managing MyIVFAnswers.com and has been hosting IVFWEBINARS dedicated to patients struggling with infertility since 2020. She's highly motivated and believes that educating patients so that they can make informed decisions is essential in their IVF journey. In the past, she has been working as an International Patient Coordinator, where she was helping and directing patients on their right path. She also worked in the tourism industry, and dealt with international customers on a daily basis, including working abroad. In her free time, you’ll find her travelling, biking, learning new things, or spending time outdoors.
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