The reproducibility of trophectoderm biopsies in euploid, aneuploid, and mosaic embryos using independently verified next-generation sequencing (NGS): a pilot study.

PURPOSE: To assess the accuracy and reliability of comprehensive chromosome screening by next-generation sequencing (NGS) of human trophectoderm (TE) biopsy specimens. METHODS: The reliability and accuracy of diagnoses made by preimplantation genetic testing for aneuploidy (PGT-A) from TE biopsy were tested. Repeat biopsies of TE and inner cell mass (ICM) samples were obtained from thawed blastocysts previously tested by NGS. To test for the reliability of the NGS assay, biopsy samples were compared with the original PGT-A results. Prior NGS testing classified the TE samples as euploid, aneuploid, or aneuploid-mosaic. The resulting re-biopsied samples underwent SurePlex whole genome amplification followed by NGS via the MiSeq platform, with copy number value (CNV) determined using BlueFuse Multi Software. The primary outcome measure was reliability, defined as concordance between initial TE result and the repeat biopsies. Accuracy was determined by concordance between the TE and ICM samples, and compared between three chromosome types (disomic, aneuploid, and mosaic). RESULTS: Re-biopsies were performed on 32 embryos with prior PGT-A showing euploidy (10 embryos), aneuploidy of one or two chromosomes (4 embryos), or aneuploid-mosaic with one aneuploid chromosome and one mosaic chromosome (18 embryos). One hundred twenty-nine biopsy samples completed NGS (90 TE and 39 ICM biopsies) and 105 biopsy results were included in the analysis. TE biopsies provide a highly accurate test of the future fetus, with the ICM disomic concordance rate of 97.6%. Clinical concordance rates indicate that TE biopsies provide a reliable test when the result is euploid (99.5%) or aneuploid (97.3%), but less reliable when the result is mosaic (35.2%). CONCLUSION: TE biopsies predict euploidy or aneuploidy in the ICM with a high degree of accuracy. PGT-A with NGS of TE biopsies is shown to be highly reliable, with clinically relevant concordance rates for aneuploidy and euploidy over 95%. TE biopsies indicating mosaicism were less reliable (35.2%), presumably because mitotic non-disjunction events are not uniformly distributed throughout the blastocyst. However, classification of TE biopsy of PGT-A with NGS results as either aneuploid or euploid provides a highly reliable test.

Paternal Age Is Not Associated With Pregnancy Outcomes After Single Thawed Euploid Blastocyst Transfer.

Although controversial, increasing paternal age has been shown to negatively affect assisted reproductive technology (ART) outcomes and success rates. Most studies investigating the effect of paternal age on ART outcomes use a donor oocyte model to minimize maternal aneuploidy contribution. This study sought to determine whether increasing paternal age is associated with adverse in vitro fertilization (IVF) outcomes when aneuploidy is minimized using preimplantation genetic screening. There were 573 single thawed euploid embryo transfers from 473 patients undergoing oocyte donor and autologous IVF cycles. Cycles were categorized according to paternal age at oocyte retrieval, and an age adjustment was performed for maternal age in order to evaluate for an isolated paternal age effect. Fertilization rate was found to decrease significantly with increasing paternal age ( P = .04). After controlling for oocyte age, there was no significant difference in pregnancy outcomes across all paternal age categories after euploid embryo transfer, including implantation rate ( P = .23), clinical pregnancy rate ( P = .51), and spontaneous abortion rate ( P = .55). Therefore, if a couple is able to produce and transfer a single thawed euploid embryo, no difference in IVF pregnancy outcomes is identified with increasing paternal age.

Diagnosis and clinical management of embryonic mosaicism.

Embryonic mosaicism occurs when two or more cell populations with different genotypes are present within the same embryo. New diagnostic techniques for preimplantation genetic screening (PGS), such as next-generation sequencing, have led to increased reporting of mosaicism. The interpretation of mosaicism is complicated because the transfer of some mosaic embryos has resulted in live births. Mosaic embryos may represent a third category between normal (euploidy) and abnormal (aneuploidy). This category of mosaic embryos may be characterized by decreased implantation and pregnancy potential as well as increased risk of genetic abnormalities and adverse pregnancy outcomes. Euploid embryos should be preferentially transferred over mosaic embryos. Genetic counseling is necessary before the transfer of a mosaic embryo is considered. Certain types of mosaic embryos should be preferentially transferred over others. Transfer of embryos with mosaic trisomies 2, 7, 13, 14, 15, 16, 18, and 21 may pose the most risk of having a child affected with a trisomy syndrome; however, the transfer of embryos with mosaic monosomies or other mosaic trisomies are not devoid of risk. Patients must be counseled about the risk of undetected monosomies or trisomies within a biopsy specimen as well as the risk of intrauterine fetal demise or uniparental disomy with the transfer of mosaic embryos. Until more data are available, patients should be encouraged to undergo another cycle to obtain euploid embryos, when possible, rather than transferring a mosaic embryo.

Delayed intracytoplasmic sperm injection (ICSI) with trophectoderm biopsy and preimplantation genetic screening (PGS) show increased aneuploidy rates but can lead to live births with single thawed euploid embryo transfer (STEET).

PURPOSE: The aim of this study was to report the results of IVF with trophectoderm biopsy and preimplantation genetic screening (PGS) following delayed intracytoplasmic sperm injection (ICSI). METHODS: Patients undergoing IVF with PGS and delayed ICSI were included in the study. Indications for delayed ICSI included absent or poor fertilization via standard insemination or more than 50 % immature oocytes, noted post-cumulus stripping for standard ICSI procedure. Delayed ICSI was performed the day after retrieval due to absent or poor fertilization. The immature oocytes were kept in extended culture, and if demonstrated maturity, ICSI was performed. Primary outcome included fertilization rate and blastocyst stage formation, defined by the number of blastocysts for biopsy. Secondary outcome included aneuploidy rate and pregnancy outcomes following single thawed euploid embryo transfers (STEET). RESULTS: Sixteen patients with delayed ICSI were included in the study. Twelve were due to poor fertilization and four secondary to immature oocytes. A total of 219 oocytes were retrieved; ten were frozen upon patient request, 168 had standard insemination, and 13 had routine ICSI on the day of retrieval. A total of 129 oocytes underwent delayed ICSI. Sixty-three (49 %) fertilized, 19 (14.7 %) reached blastocysts for biopsy; fivw of which were chromosomally normal (26.3 %). Three patients underwent STEET of a delayed ICSI embryo; all three resulted in live births, including one embryo biopsied on day 8 of development. CONCLUSION: Fertilization failure or an excessive proportion of immature oocytes in an IVF cycle, necessitating delayed ICSI, showed equivalent fertilization and blast formation rates. With the implementation of trophectoderm biopsy and PGS, these embryos can lead to healthy live born babies.