Preimplantation Genetic Testing (PGT): Guide to Your Options

PGT And Genetic Testing Of Embryos

The Last Decade Of IVF: Genetic Testing Of Embryos

Over the past decade we have learned that the single most important factor in having a successful pregnancy is the chromosomal normalcy of the embryo. The sequencing of the human genome (or DNA sequencing) is the process of determining the precise order of nucleotides within a DNA molecule. And the advent of rapid DNA sequencing methods has been instrumental in the field of assisted reproduction and significantly increased pregnancy rates where sequencing is used on embryos, beginning with an embryo biopsy.

At IRMS, we have several distinct ways to perform the embryo biopsy to identify the normal embryos we seek to transfer. A critical and unique aspect of the IRMS practice is an Embryology Team who work hand in glove with our Physician Team, in real time. Our Embryologists follow the development of your embryos from the point of fertilization and throughout their development, whether we elect to do a Day 3 transfer or Day 5 transfer. All of this information gained by continually observing your embryos is communicated to your IRMS physician to determine the ideal date of transfer. That is why the date of transfer of embryos can be different for different patients and may change for you during your treatment cycle.

Everyone’s journey through fertility treatment is unique and though we recognize that chromosomally normal embryos that have achieved the blastocyst stage of development are the gold standard, hundreds of thousands of babies have been born from Day 3 and Day 4 embryos. Because we recognize this truth, we individualize our care to you and your embryos to provide the highest possible chance at pregnancy.

Over just the past few years there have been such profound advancements in embryo testing capability that the work in the IVF Labs across the country has increased. As a result, in the
United States, there has been a shortage of truly senior embryologists but NOT at IRMS where we have a large Embryology Team with decades of experience.

The IRMS Lab provides our valued patients a team who have been at the forefront of the genetic testing of embryos; helping to advance and refine the techniques used today. We have the capability to do PGT or preimplantation genetic testing at any time and do not batch cycles, which can be a limiting factor for an IVF Clinic with a Lab of lesser capacity or experience.

Preimplantation Genetic Testing & Diagnosis

IRMS offers three types of PGT testing:

PGT-A also known as (PGS) preimplantation genetic screening is a test that examines the chromosomal material of an embryo. It can tell if the appropriate number of chromosomes are present (46), or if an abnormal number of chromosomes are present. We only want to transfer chromosomally normal embryos.

In the PGT-A process, IVF is performed and the resulting embryos are incubated. Once incubated anywhere from Day 5 to 7 of embryo development, an embryo biopsy is performed. The biopsy is when an embryologist carefully removes a small cell sample from each embryo and that sample is tested to determine if the embryo is normal. Then, only normal, healthy embryos are used for transfer back to the uterus. PGT-A can be seamlessly added to an IVF cycle to significantly increase the chances of success. Because our focus is on individualized care, your IRMS physician will counsel you as to whether PGT-A is the very best option in your unique case.

PGT-M formerly known as PGD is for couples that already know they are at increased risk for passing on a single gene disorder. PGT-M can be performed much like PGT-A but in this case, the test is unique to the specific disorder. Some examples of single gene disorders include:

Sickle cell anemia, cystic fibrosis, Tay-Sachs, hemophilia and Duchenne Muscular Dystrophy.

PGT-SR is used for structural rearrangements. Most commonly, balanced translocations when someone has all the right amounts of chromosomal material but part of one chromosome has switched places or translocated with another. This increases the risk of chromosomally abnormal or unbalanced eggs and sperm, which can increase the risk for infertility, miscarriages and birth defects.

PGT Analysis Using High Resolution Next Generation Sequencing (hr-NGS)

hrNGS is the most advanced form of PGT (Preimplantation Genetic Testing). hrNGS is used to screen embryos for chromosomal normalcy (euploidy) and can test the full set of 23 pairs of chromosomes.

What makes hrNGS unique is its capability to detect mosaic embryos. Mosaic embryos’ cells exhibit different genotypes. Next Generation DNA Sequencing through high throughput sequencing hrNGS determines if an embryo is mosaic and pinpoints which chromosome is affected.

Again, it is with this detailed chromosomal information that we can help you, our valued patients, make informed decisions about your overall care on your journey to having a healthy baby. At IRMS our Physicians and Embryologists are at the forefront of this technology.

Who are the ideal candidates for genetic testing of embryos?

  • Women over the age of 35
  • Patients with recurrent pregnancy loss
  • Patients with prior unsuccessful fertility treatments
  • Patients who require single embryo transfer for medical reasons or who strongly desire single embryo transfer
  • Any patient who wishes to maximize their success rate for pregnancy
  • Any patient with a large number of embryos to help select the best embryo first
  • Gender selection

What are the advantages of genetic testing of embryos?

  • Increased probability of live-birth with elective single embryo transfer (eSET)
  • Reduced rates of multiple pregnancy
  • Lower pregnancy loss rates
  • Reduction in unsuccessful embryo transfers and thus fewer fertility treatment procedures per live birth
  • Shorten the time interval from treatment start to ongoing pregnancy and live birth
  • Enhanced information about the potential for pregnancy in cryopreserved embryos