Fertility and Sterility Published Research Yields Insight on Detection of Mosaicism Aiding in Embryo Selection, Resulting in Higher Implantation Rates and Lower Rates of Miscarriage
LIVINGSTON, NJ–(Marketwired – Apr 12, 2016) – Reprogenetics, the largest genetics laboratory in the United States specializing in Preimplantation Genetic Diagnosis (PGD), has published a clinical paper on the use of High-Resolution Next Generation Sequencing (HR-NGS) techniques for Preimplantation Genetic Diagnosis for Aneuploidy (PGD-A). This test detects mosaic embryos — those containing a mixture of abnormal and normal cells — as well as the discovery of abnormalities detectable with other techniques, which will improve the selection process during in vitro fertilization (IVF).
The paper showed clinical value of HR-NGS for detecting mosaicism and as a selection tool to assist in identifying embryos with the greatest likelihood of viability. The paper also establishes that mosaic embryos can be considered to represent a distinct category in terms of viability.
“Previous embryo selection methods had limited possibility of detecting mosaic embryos. Now with advanced HR-NGS techniques, including PGD-A, we can detect mosaic embryos, which miscarry more frequently and implant less frequently, allowing the most viable embryos to be prioritized for transfer,” said Dr. Santiago Munné, Co-Founder and CEO of Reprogenetics.
The clinical paper supports the use of HR-NGS to assist in the identification of healthy embryos and demonstrating that a major reason for the decrease in embryo implantation rates per transfer with advancing maternal age is aneuploidy. The study was published online in the journal Fertility and Sterility.
With HR-NGS, embryos can be prioritized for transfer, ideally in a single-embryo transfer. This results in higher implantation rates and lower rates of miscarriage. The paper showed the ability of HR-NGS to reduce misclassification of mosaic embryos, with normal and aneuploidy cell lines, adding a new dimension to HR-NGS and further improving its capability to differentiate individual embryos. In addition, the report showed a growing body of evidence suggesting the incidence of miscarriage is reduced during IVF cycles with the use of HR-NGS.
“At Reprogenetics, we believe improved techniques to assess the viability of embryos prior to transfer during IVF are greatly needed. We are encouraged and excited by the clinical validation of PGD-A offered by this analysis,” Dr. Munné added.
The report describes that at least three recent randomized clinical trials, several case-controlled prospective studies and two metanalyses have shown that PGD-A significantly improves implantation rates and ongoing pregnancy rates. A large multicenter randomized clinical trial is currently underway to assess the clinical utility of preimplantation aneuploidy testing.
About the Research
Reprogenetics has found that about 20% of blastocysts are mosaic at the blastocyst stage, a figure that has now been confirmed using modern HR-NGS. High Resolution NGS allows for detection of these mosaic embryos, while low resolution NGS testing, and other techniques currently utilized, do not detect mosaic embryos efficiently. In the case of these other techniques, the mosaic embryos could be wrongly classified as either normal or abnormal depending on the amount of normal cells in the biopsy, resulting in a potential miscarriage or lower likelihood of pregnancy.
Although almost one-third of blastocysts are mosaic, the increasing likelihood of meiotic (oocyte-derived) aneuploidy with increasing maternal age means that the proportion of embryos that are euploid/aneuploid mosaics decreases with age, from 26.6% in women < 35 years old to 10.5% in > 42 year olds. In addition, although miscarriage rates in PGD-A cycles are low (typically around 10% in cases using aCGH), they do sometimes occur. In a recent study, blastocyst biopsy specimens from 46 embryos that had miscarried, which had originally been classified as euploid after aCGH, were reanalyzed using HR-NGS. Remarkably, over 50% were shown to be mosaic. These data suggest that mosaicism, undetectable by most PGD-A techniques, plays an important role in pregnancy loss. From these results, it could be argued that miscarriage rates, already greatly reduced after aCGH, could be reduced further still in cycles where non-mosaic euploid embryos are available for transfer. Based on this evidence, the authors’ recommendation is to report all mosaic embryos detected as mosaic, irrespective of the percentage of abnormal cells. Artificially forcing mosaic embryos into euploid or aneuploidy categories carries a risk of misdiagnosis.
Fertility and Sterility is the official journal of the American Society of Reproductive Medicine (ASRM). For copies of the full Fertility and Sterility article titled, “Mosaicism: ‘survival of the fittest’ versus ‘no embryo left behind,” please contact Nicole Mascuch at Reprogenetics at email@example.com.
Acquired by The Cooper Companies in August of 2015 Reprogenetics, headquartered in Livingston, New Jersey, is the world’s largest genetics laboratory specializing in preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD). PGS, which tests for the correct number of chromosomes, and PGD, which tests embryos for specific inherited disorders, have the potential to increase implantation rates and establish a pregnancy unaffected by specific known genetic characteristics. Reprogenetics offers the latest technology in comprehensive chromosome screening, routinely investigates the accuracy of new protocols, and performs randomized clinical trials with the next generation of technology while offering personalized service to its referring fertility centers and their patients worldwide. More information about Reprogenetics can be found at www.reprogenetics.com.