Pregnancies and live births after trophectoderm biopsy and preimplantation genetic testing of human blastocysts

Preimplantation genetic testing for aneuploidy: predictive embryonic factors

PURPOSE

In a preimplantation genetic testing for aneuploidy (PGT-A) cycle, does the blastocyst quality before biopsy, or the day of biopsy, or the embryo hatching status have an impact on either euploidy or the rate of embryo survival after freezing?

METHODS

This was a retrospective study including 6130 biopsied blastocysts coming from 1849 PGT-A cycles performed in our center (2016-2022). Embryos were categorized according to the inner cell mass and trophectoderm quality, using Gardner's scoring (excellent: AA; good: AB, BA, BB; poor: AC, CA, BC, CB, CC); the day of biopsy (5 or 6); and their hatching status (fully hatched blastocysts [FHB] or non-fully hatched blastocysts [nFHB]). The independent relationship between each group and both euploidy and survival rate was assessed.

RESULTS

Excellent-quality embryos were more euploid than both good- and poor-quality embryos (52.69%, 39.69%, and 26.21%; p < 0.001), and day 5-biopsied embryos were more euploid than day 6-biopsied embryos (39.98% and 34.80%; p < 0.001). Survival rates of excellent-quality (92.26%) and good-quality (92.47%) embryos were higher than survival rates in the poor-quality group (84.61%) (p = 0.011 and p = 0.002). Day 5-biopsied embryos survived better than day 6-biopsied embryos (93.71% vs. 83.69%; p < 0.001) and FHB had poorer survival than nFHB (78.61% vs. 93.52%; p < 0.001).

CONCLUSIONS

Excellent-quality and day 5-biopsied embryos are more prone to be euploid than good and poor or day 6-biopsied embryos, respectively. Poor-quality, day 6-biopsied embryos, and FHB have significantly lower survival after biopsy and vitrification.

Preimplantation genetic testing for X-linked chronic granulomatous disease induced by a CYBB gene variant: A case report

INTRODUCTION

X-linked recessive chronic granulomatous disease (XR-CGD) is a severe primary immunodeficiency principally caused by a CYBB (OMIM: 300481) gene variant. Recurrent fatal bacterial or fungal infections are the main clinical manifestations of XR-CGD.

PATIENT CONCERNS

In the current case, in vitro fertilization (IVF) associated with preimplantation genetic testing for monogenic disorder (PGT-M) was applied for a Chinese couple who had given birth to a boy with XR-CGD.

DIAGNOSIS

Next-generation sequencing-based SNP haplotyping and Sanger-sequencing were used to detect the CYBB gene variant (c.804 + 2T>C, splicing) in this family.

INTERVENTIONS

The patient was treated with IVF and PGT-M successively.

OUTCOMES

In this IVF cycle, 7 embryos were obtained, and 2 of them were euploid and lacked the CYBB gene variant (c.804 + 2T>C). The PGT results were verified by prenatal diagnosis after successful pregnancy, and a healthy girl was eventually born.

CONCLUSION

PGT-M is an effective method for helping families with these fatal and rare inherited diseases to have healthy offspring. It can availably block the transmission of disease-causing loci to descendant.

Prenatal diagnosis and preimplantation genetics testing of 3M syndrome in a Chinese family with novel biallelic variants of CUL7

BACKGROUND

3M syndrome is a rare autosomal recessive developmental disorder characterized by pre and postnatal growth deficiency, dysmorphic facial features, and normal intelligence. 3M syndrome should be suspected in a proband with a combination of characteristic or recognizable dysmorphic features. The diagnosis of 3M syndrome could be confirmed by identifying biallelic variants in CUL7, OBSL1, or CCDC8.

METHODS

Whole-exome sequencing (WES) was performed to identify genetic causes. Reverse-transcription polymerase chain reaction (RT-PCR) was performed to detect aberrant splicing events. Haplotypes were constructed using multiplex PCR and sequencing. Variants of the parental haplotype and target likely pathogenic variants were detected by PCR and Sanger sequencing from the embryos. Copy number variant (CNV) detection was performed by next-generation sequencing.

RESULTS

We present the case of a nonconsanguineous Chinese couple with one abnormal pregnancy, where the fetus showed 3M phenotypes of shortened long bones. WES identified two novel heterozygous mutations in CUL7: NM_014780.5:c.354del (p.Gln119ArgfsTer52) and NM_014780.5:c.1373-15G>A. RT-PCR from RNA of the mother's peripheral blood leucocytes showed that c.1373-15G>A caused the insertion of a 13-bp extra intron sequence and encoded the mutant p.Leu459ProfsTer25. Both variants were classified as likely pathogenic according to ACMG/AMP guidelines and Clinical Genome Resource specifications. During genetic counseling, the options of prenatal diagnosis through chorionic villus sampling or amniocentesis, adoption, sperm donation, and electing not to reproduce, as well as preimplantation genetic testing for monogenic disorders (PGT-M), were discussed. The couple hopes to conceive a child of their own and refused to accept the 25% risk during the next pregnancy and opted for PGT-M. They finally successfully delivered a healthy baby through PGT-M.

CONCLUSION

This study expanded the mutation spectrum of CUL7, detected the aberrant splicing event of CUL7 via RT-PCR, constructed the haplotype for PGT-M, and demonstrated the successful delivery of a healthy baby using PGT-M.

Human-induced pluripotent stem cell-derived ovarian support cell co-culture improves oocyte maturation in vitro after abbreviated gonadotropin stimulation

STUDY QUESTION

Can in vitro maturation (IVM) and developmental competence of human oocytes be improved by co-culture with ovarian support cells (OSCs) derived from human-induced pluripotent stem cells (hiPSCs)?

SUMMARY ANSWER

OSC-IVM significantly improves the rates of metaphase II (MII) formation and euploid Day 5 or 6 blastocyst formation, when compared to a commercially available IVM system.

WHAT IS KNOWN ALREADY

IVM has historically shown highly variable performance in maturing oocytes and generating oocytes with strong developmental capacity, while limited studies have shown a positive benefit of primary granulosa cell co-culture for IVM. We recently reported the development of OSCs generated from hiPSCs that recapitulate dynamic ovarian function in vitro.

STUDY DESIGN, SIZE, DURATION

The study was designed as a basic science study, using randomized sibling oocyte specimen allocation. Using pilot study data, a prospective sample size of 20 donors or at least 65 oocytes per condition were used for subsequent experiments. A total of 67 oocyte donors were recruited to undergo abbreviated gonadotropin stimulation with or without hCG triggers and retrieved cumulus-oocyte complexes (COCs) were allocated between the OSC-IVM or control conditions (fetal-like OSC (FOSC)-IVM or media-only IVM) in three independent experimental design formats. The total study duration was 1 April 2022 to 1 July 2023.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oocyte donors between the ages of 19 and 37 years were recruited for retrieval after informed consent, with assessment of anti-Mullerian hormone, antral follicle count, age, BMI and ovarian pathology used for inclusion and exclusion criteria. In experiment 1, 27 oocyte donors were recruited, in experiment 2, 23 oocyte donors were recruited, and in experiment 3, 17 oocyte donors and 3 sperm donors were recruited. The OSC-IVM culture condition was composed of 100 000 OSCs in suspension culture with hCG, recombinant FSH, androstenedione, and doxycycline supplementation. IVM controls lacked OSCs and contained either the same supplementation, FSH and hCG only (a commercial IVM control), or FOSCs with the same supplementation (Media control). Experiment 1 compared OSC-IVM, FOSC-IVM, and a Media control, while experiments 2 and 3 compared OSC-IVM and a commercial IVM control. Primary endpoints in the first two experiments were the MII formation (i.e. maturation) rate and morphological quality assessment. In the third experiment, the fertilization and embryo formation rates were assessed with genetic testing for aneuploidy and epigenetic quality in blastocysts.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed a statistically significant improvement (∼1.5×) in maturation outcomes for oocytes that underwent IVM with OSCs compared to control Media-IVM and FOSC-IVM in experiment 1. More specifically, the OSC-IVM group yielded a MII formation rate of 68% ± 6.83% SEM versus 46% ± 8.51% SEM in the Media control (P = 0.02592, unpaired t-test). FOSC-IVM yielded a 51% ± 9.23% SEM MII formation rate which did not significantly differ from the media control (P = 0.77 unpaired t-test). Additionally, OSC-IVM yielded a statistically significant ∼1.6× higher average MII formation rate at 68% ± 6.74% when compared to 43% ± 7.90% in the commercially available IVM control condition (P = 0.0349, paired t-test) in experiment 2. Oocyte morphological quality between OSC-IVM and the controls did not significantly differ. In experiment 3, OSC-IVM oocytes demonstrated a statistically significant improvement in Day 5 or 6 euploid blastocyst formation per COC compared to the commercial IVM control (25% ± 7.47% vs 11% ± 3.82%, P = 0.0349 logistic regression). Also in experiment 3, the OSC-treated oocytes generated blastocysts with similar global and germline differentially methylated region epigenetic profiles compared commercial IVM controls or blastocysts after either conventional ovarian stimulation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

While the findings of this study are compelling, the cohort size remains limited and was powered on preliminary pilot studies, and the basic research nature of the study limits generalizability compared to randomized control trials. Additionally, use of hCG-triggered cycles results in a heterogenous oocyte cohort, and potential differences in the underlying maturation state of oocytes pre-IVM may limit or bias findings. Further research is needed to clarify and characterize the precise mechanism of action of the OSC-IVM system. Further research is also needed to establish whether these embryos are capable of implantation and further development, a key indication of their clinical utility.

WIDER IMPLICATIONS OF THE FINDINGS

Together, these findings demonstrate a novel approach to IVM with broad applicability to modern ART practice. The controls used in this study are in line with and have produced similar to findings to those in the literature, and the outcome of this study supports findings from previous co-culture studies that found benefits of primary granulosa cells on IVM outcomes. The OSC-IVM system shows promise as a highly flexible IVM approach that can complement a broad range of stimulation styles and patient populations. Particularly for patients who cannot or prefer not to undergo conventional gonadotropin stimulation, OSC-IVM may present a viable path for obtaining developmentally competent, mature oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

A.D.N., A.B.F., A.G., B.P., C.A., C.C.K., F.B., G.R., K.S.P., K.W., M.M., P.C., S.P., and M.-J.F.-G. are shareholders in the for-profit biotechnology company Gameto Inc. P.R.J.F. declares paid consultancy for Gameto Inc. P.C. also declares paid consultancy for the Scientific Advisory Board for Gameto Inc. D.H.M. has received consulting services from Granata Bio, Sanford Fertility and Reproductive Medicine, Gameto, and Buffalo IVF, and travel support from the Upper Egypt Assisted Reproduction Society. C.C.K., S.P., M.M., A.G., B.P., K.S.P., G.R., and A.D.N. are listed on a patent covering the use of OSCs for IVM: U.S. Provisional Patent Application No. 63/492,210. Additionally, C.C.K. and K.W. are listed on three patents covering the use of OSCs for IVM: U.S. Patent Application No. 17/846,725, U.S Patent Application No. 17/846,845, and International Patent Application No.: PCT/US2023/026012. C.C.K., M.P.S., and P.C. additionally are listed on three patents for the transcription factor-directed production of granulosa-like cells from stem cells: International Patent Application No.: PCT/US2023/065140, U.S. Provisional Application No. 63/326,640, and U.S. Provisional Application No. 63/444,108. The remaining authors have no conflicts of interest to declare.

High sperm DNA fragmentation increased embryo aneuploidy rate in patients undergoing preimplantation genetic testing

RESEARCH QUESTION

Is high sperm DNA fragmentation (SDF) associated with a high embryonic aneuploidy rate in patients undergoing intracytoplasmic sperm injection (ICSI)-preimplantation genetic testing (PGT)?

DESIGN

This was a retrospective study of 426 couples with normal karyotypes undergoing ICSI-PGT at the authors' centre from March 2017 to March 2021. SDF was assessed using the sperm chromatin structure assay. The population was divided into low and high SDF groups according to cut-off values found by the receiver operating characteristic (ROC) curve. A 1:1 ratio propensity score matching (PSM) method was used to control for potential confounding factors, and a generalized linear mixed model was established to evaluate the relationship between SDF and the embryonic aneuploidy rate.

RESULTS

The ROC curve indicated a threshold of 30%. In total, 132 couples were included after PSM, and the high SDF group (>30%) had significantly higher SDF (40.74% ± 9.78% versus 15.54% ± 7.86%, P < 0.001) and a higher embryo aneuploidy rate (69.36% versus 53.96%, P < 0.001) compared with the low SDF group (≤30%). The two pronuclear fertilization rate, cleavage rate, rate of high-quality embryos at day 3 rate, blastocyst rate, biochemical pregnancy rate, clinical pregnancy rate, miscarriage rate, live birth rate, caesarean section rate, preterm birth rate, singleton rate and low birthweight rate were similar in both groups (P > 0.05). After PSM, SDF > 30% was significantly correlated with an increased embryo aneuploidy rate after adjusting for all confounding variables (adjusted odds ratio 1.70, 95% CI 1.00-2.88, P = 0.049).

CONCLUSIONS

SDF > 30% was associated with an increased embryo aneuploidy rate in couples with normal karyotypes undergoing PGT, but did not affect embryonic and clinical outcomes after transfer of euploid embryos.

The preimplantation genetic testing for monogenic disorders strategy for blocking the transmission of hereditary cancers through haplotype linkage analysis by karyomapping

PURPOSE

Providing feasible preimplantation genetic testing strategies for monogenic disorders (PGT-M) for prevention and control of genetic cancers.

METHODS

Inclusion of families with a specific pathogenic mutation or a clear family history of genetic cancers. Identification of the distribution of hereditary cancer-related mutations in families through genetic testing. After a series of assisted reproductive measures such as down-regulation, stimulation, egg retrieval, and in vitro fertilization, a biopsy of trophectoderm cells from a blastocyst was performed for single-cell level whole-genome amplification (WGA). Then, the detection of chromosomal aneuploidies was performed by karyomapping. Construction of a haplotype-based linkage analysis to determine whether the embryo carries the mutation. Meanwhile, we performed CNV testing. Finally, embryos can be selected for transfer, and the results will be verified in 18-22 weeks after pregnancy.

RESULTS

Six couples with a total of 7 cycles were included in our study. Except for cycle 1 of case 5 which did not result in a transferable embryo, the remaining 6 cycles produced transferable embryos and had a successful pregnancy. Four couples have had amniotic fluid tests to confirm that the fetus does not carry the mutation, while 1 couple was not tested due to insufficient pregnancy weeks. And the remaining couples had to induce labor due to fetal megacystis during pregnancy.

CONCLUSION

Our strategy has been proven to be feasible. It can effectively prevent transmission of hereditary cancer-related mutations to offspring during the prenatal stage.

Preimplantation Genetic Testing for Genetic Diseases: Limits and Review of Current Literature

Preimplantation genetic testing (PGT) has emerged as a revolutionary technique in the field of reproductive medicine, allowing for the selection and transfer of healthy embryos, thus reducing the risk of transmitting genetic diseases. However, despite remarkable advancements, the implementation of PGT faces a series of limitations and challenges that require careful consideration. This review aims to foster a comprehensive reflection on the constraints of preimplantation genetic diagnosis, encouraging a broader discussion about its utility and implications. The objective is to inform and guide medical professionals, patients, and society overall in the conscious and responsible adoption of this innovative technology, taking into account its potential benefits and the ethical and practical challenges that it presents.

Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis

BACKGROUND

A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'.

OBJECTIVE AND RATIONALE

Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts.

SEARCH METHODS

A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329).

OUTCOMES

We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%).

WIDER IMPLICATIONS

Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

Preimplantation genetic testing for Aicardi-Goutières syndrome induced by novel compound heterozygous mutations of TREX1: an unaffected live birth

BACKGROUND

Aicardi-Goutières syndrome (AGS) is a rare, autosomal recessive, hereditary neurodegenerative disorder. It is characterized mainly by early onset progressive encephalopathy, concomitant with an increase in interferon-α levels in the cerebrospinal fluid. Preimplantation genetic testing (PGT) is a procedure that could be used to choose unaffected embryos for transfer after analysis of biopsied cells, which prevents at-risk couples from facing the risk of pregnancy termination.

METHODS

Trio-based whole exome sequencing, karyotyping and chromosomal microarray analysis were used to determine the pathogenic mutations for the family. To block the inheritance of the disease, multiple annealing and looping-based amplification cycles was used for whole genome amplification of the biopsied trophectoderm cells. Sanger sequencing and next-generation sequencing (NGS)-based single nucleotide polymorphism (SNP) haplotyping were used to detect the state of the gene mutations. Copy number variation (CNV) analysis was also carried out to prevent embryonic chromosomal abnormalities. Prenatal diagnosis was preformed to verify the PGT outcomes.

RESULTS

A novel compound heterozygous mutation in TREX1 gene was found in the proband causing AGS. A total of 3 blastocysts formed after intracytoplasmic sperm injection were biopsied. After genetic analyses, an embryo harbored a heterozygous mutation in TREX1 and without CNV was transferred. A healthy baby was born at 38th weeks and prenatal diagnosis results confirmed the accuracy of PGT.

CONCLUSIONS

In this study, we identified two novel pathogenic mutations in TREX1, which has not been previously reported. Our study extends the mutation spectrum of TREX1 gene and contributes to the molecular diagnosis as well as genetic counseling for AGS. Our results demonstrated that combining NGS-based SNP haplotyping for PGT-M with invasive prenatal diagnosis is an effective approach to block the transmission of AGS and could be applied to prevent other monogenic diseases.

Day 5 versus day 3 embryo biopsy for preimplantation genetic testing for monogenic/single gene defects

BACKGROUND

Assisted reproductive technology (ART) has allowed couples with a family history of a monogenic genetic disease, or a disease-carrying gene, to reduce the chance of them having a child with the genetic disorder. This is achieved by genetically testing the embryos using an advanced process called preimplantation genetic testing for monogenic or single gene disorders (PGT-M), such as Huntington's disease or cystic fibrosis. This current terminology (PGT-M) has replaced the formerly-known preimplantation genetic diagnosis (PGD). During PGT-M, one or more embryo cells are biopsied and analysed for genetic or chromosomal anomalies before transferring the embryos to the endometrial cavity. Biopsy for PGT-M can be performed at day 3 of cleavage-stage embryo development when the embryo is at the six- to the eight-cell stage, with either one or two blastomeres being removed for analysis. Biopsy for PGT-M can also be performed on day 5 of the blastocyst stage of embryo development when the embryo has 80 to 100 cells, with five to six cells being removed for analysis. Day 5 biopsy has taken over from day 3 biopsy as the most widely-used biopsy technique; however, there is a lack of summarised evidence from randomised controlled trials (RCTs) that assesses the effectiveness and safety of day 5 biopsy compared to day 3 biopsy. Since biopsy is an invasive process, whether it is carried out at day 3 or day 5 of embryo development may have different impacts on further development, implantation, pregnancy, live birth and perinatal outcomes.

OBJECTIVES

To assess the benefits and harms of day 5 embryo biopsy, in comparison to day 3 biopsy, in PGT-M in women undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) cycles.

SEARCH METHODS

We searched the following electronic bibliographic databases in December 2021 to identify relevant RCTs: the Cochrane Gynaecology and Fertility Group (CGFG) Specialised Trials Register; CENTRAL, MEDLINE, Embase and PsycINFO. We also handsearched grey literature, such as trial registers, relevant journals, reference lists, Google Scholar, and published conference abstracts.

SELECTION CRITERIA

Eligible RCTs compared day 5 versus day 3 embryo biopsy for PGT-M.  DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. The primary review outcomes were live births and miscarriages. We calculated outcomes per woman/couple randomised and reported odds ratios (ORs) with 95% confidence intervals (CIs).

MAIN RESULTS

We included one RCT involving 20 women. The evidence was of very low certainty; the main limitations of the study were serious risk of bias due to lack of blinding of study personnel, and imprecision. We are uncertain whether day 5 embryo biopsy compared to day 3 biopsy has an effect on live births (OR 1.50, 95% CI 0.26 to 8.82; 1 RCT, 20 women; very low-certainty evidence). The evidence suggests that if the chance of live birth following day 3 biopsy was assumed to be 40%, then the chance with day 5 biopsy is between 15% and 85%. It is also uncertain whether day 5 embryo biopsy compared to day 3 biopsy has an effect on miscarriages (OR 1.00, 95% CI 0.05 to 18.57; 1 RCT, 20 women; very low-certainty evidence).  We are uncertain whether day 5 embryo biopsy compared to day 3 biopsy has an effect on other secondary outcome measures, including viable intrauterine pregnancies (OR 2.25, 95% CI 0.38 to 13.47; 1 RCT, 20 women; very low-certainty evidence), ectopic pregnancies (OR 0.16, 95% CI 0.01 to 3.85; 1 RCT, 20 women; very low-certainty evidence), stillbirths (OR not estimable as no events in either group; 1 RCT, 20 women; very low-certainty evidence) or termination of pregnancies (OR 3.32, 95% CI 0.12 to 91.60; 1 RCT, 20 women; very low-certainty evidence). No studies reported on gestational age at birth, birthweight, neonatal mortality and major congenital anomaly.

AUTHORS' CONCLUSIONS

We are uncertain if there is a difference in live births and miscarriages, viable intrauterine pregnancies, ectopic pregnancies, stillbirths or termination of pregnancies between day 5 and day 3 embryo biopsy for PGT-M. There was insufficient evidence to draw any conclusions regarding other adverse outcomes. The results should be interpreted with caution, as the evidence was of very low certainty due to limited studies, high risk of bias in the included study, and an overall low level of precision.

Freeze all-first versus biopsy-first: A retrospective analysis of frozen blastocyst transfer cycles with preimplantation genetic testing for aneuploidy

Potential use of preimplantation genetic testing for aneuploidy (PGT-A) is increasing. Patients who have excess embryos cryopreserved at the blastocyst stage may desire PGT-A but there is little data available on options for these patients. We compared the efficacy and safety of the timing on the cryopreservation and trophectoderm(TE) biopsy for preimplantation genetic testing for aneuploidy (PGT-A) program associated with the better outcomes after frozen blastocyst transfer. Retrospective analysis of patients who underwent PGT-A cycles from January 2016 to December 2019 was carried out. 2684 blastocysts from cycles were subjected to TE biopsy for performing array comparative genomic hybridization test and Next-generation sequencing. All cycles were divided into two according to the timing of biopsy: biopsy-first (n = 211 cases/ 232 transfers) versus freeze all-first (n = 327 cases/ 415 transfers). In the biopsy-first group, embryos were cultured to expanded blastocyst and proceed to TE biopsy on day 5 or day 6 followed by cryopreservation. In the freeze all-first, blastocysts were vitrified and warmed before biopsy. Rates of clinical pregnancy (52.3% vs. 38.7%, P = 0.09) and ongoing pregnancy (44.3% vs. 34.5%, P = 0.07) in biopsy-first were significantly higher than those in freeze all-first. Biopsy-first showed comparable miscarriage rate with freeze all-first (15.2% (33/217) vs.11.1% (10/90), respectively). Rate ratio (RR) for clinical pregnancy was lower in freeze all-first group (adjusted RR = 0.78, 95% confidence interval: 0.65, 0.93). The RRs for miscarriage and live birth was also lower but it did not reach statistical significance. Our result supported performing TE biopsy of blastocyst for PGT-A before vitrification and warming. This finding would contribute to more evidence-based decision in PGT-A cycles.

PGT for structural chromosomal rearrangements in 300 couples reveals specific risk factors but an interchromosomal effect is unlikely

RESEARCH QUESTION

What factors affect the proportion of chromosomally balanced embryos in structural rearrangement carriers? Is there any evidence for an interchromosomal effect (ICE)?

DESIGN

Preimplantation genetic testing outcomes of 300 couples (198 reciprocal, 60 Robertsonian, 31 inversion and 11 complex structural rearrangement carriers) were assessed retrospectively. Blastocysts were analysed either by array-comparative genomic hybridization or next-generation sequencing techniques. ICE was investigated using a matched control group and sophisticated statistical measurement of effect size (φ).

RESULTS

300 couples underwent 443 cycles; 1835 embryos were analysed and 23.8% were diagnosed as both normal/balanced and euploid. The overall cumulative clinical pregnancy and live birth rates were 69.5% and 55.8%, respectively. Complex translocations and female age (≥35) were found to be risk factors associated with lower chance of having a transferable embryo (P < 0.001). Based on analysis of 5237 embryos, the cumulative de-novo aneuploidy rate was lower in carriers compared to controls (45.6% versus 53.4%, P < 0.001) but this was a 'negligible' association (φ < 0.1). A further assessment of 117,033 chromosomal pairs revealed a higher individual chromosome error rate in embryos of carriers compared to controls (5.3% versus 4.9%), which was also a 'negligible' association (φ < 0.1), despite a P-value of 0.007.

CONCLUSIONS

These findings suggest that rearrangement type, female age and sex of the carrier have significant impacts on the proportion of transferable embryos. Careful examination of structural rearrangement carriers and controls indicated little or no evidence for an ICE. This study helps to provide a statistical model for investigating ICE and an improved personalized reproductive genetics assessment for structural rearrangement carriers.

Case Report: Preimplantation Genetic Testing for X-Linked Severe Combined Immune Deficiency Caused by IL2RG Gene Variant

Preimplantation genetic testing (PGT) has been increasingly used to prevent rare inherited diseases. In this study, we report a case where PGT was used to prevent the transmission of disease-caused variant in a SCID-X1 (OMIM:300400) family. SCID-X1 is an X-linked recessive inherited disease whose major clinical manifestation of immune deficiency is the significant reduction in the number of T-cells and natural killer cells. This family gave birth to a boy who was a hemizygous proband whose IL2RG gene was mutated (c.315T > A, p(Tyr105*), NM_000206.3, CM962677). In this case, Sanger sequencing for mutated allele and linkage analysis based on single-nucleotide polymorphism (SNP) haplotype via next-generation sequencing were performed simultaneously. After PGT for monogenic disorder, we detected the aneuploidy and copy number variation (CNV) for normal and female carrier embryos. Four embryos (E02, E09, E10, and E11) were confirmed without CNVs and inherited variants at the IL2RG gene. Embryo E02 (ranking 4BB) has been transferred after considering the embryo growth rate, morphology, and PGT results. Prenatal genetic diagnosis was used to detect amniotic fluid cells, showing that this fetus did not carry the variant of the IL2RG gene (c.315T > A). Ultimately, a healthy girl who had not carried disease-causing variants of SCID-X1 confirmed by prenatal diagnosis was born, further verifying our successful application of PGT in preventing mutated allele transmission for this SCID family.

The impact of preimplantation genetic testing for aneuploidies (PGT-A) on clinical outcomes in high risk patients

PURPOSE

To investigate whether preimplantation genetic testing for aneuploidy (PGT-A) improves the clinical outcome in patients with advanced maternal age (AMA), recurrent miscarriages (RM), and recurrent implantation failure (RIF).

METHODS

Retrospective cohort study from a single IVF center and a single genetics laboratory. One hundred seventy-six patients undergoing PGT-A were assigned to three groups: an AMA group, an RM group, and a RIF group. Two hundred seventy-nine patients that did not undergo PGT-A were used as controls and subgrouped similarly to the PGT-A cohort. For the PGT-A groups, trophectoderm biopsy was performed and array comparative genomic hybridization was used for PGT-A. Clinical outcomes were compared with the control groups.

RESULTS

In the RM group, we observed a significant decrease of early pregnancy loss rates in the PGT-A group (18.1% vs 75%) and a significant increase in live birth rate per transfer (50% vs 12.5%) and live birth rate per patient (36% vs 12.5%). In the RIF group, a statistically significant increase in the implantation rate per transfer (69.5% vs 33.3%) as well as the live birth rate per embryo transfer (47.8% vs 19%) was observed. In the AMA group, a statistically significant reduction in biochemical pregnancy loss was observed (3.7% vs 31.5%); however, live birth rates per embryo transfer and per patient were not significantly higher than the control group.

CONCLUSION

Our results agree with recently published studies, which suggest caution in the universal application of PGT-A in women with infertility. Instead, a more personalized approach by choosing the right candidates for PGT-A intervention should be followed.

Rapid, accurate mapping of transgene integration in viable rhesus macaque embryos using enhanced-specificity tagmentation-assisted PCR

Genome engineering is a powerful tool for in vitro research and the creation of novel model organisms and has growing clinical applications. Randomly integrating vectors, such as lentivirus- or transposase-based methods, are simple and easy to use but carry risks arising from insertional mutagenesis. Here we present enhanced-specificity tagmentation-assisted PCR (esTag-PCR), a rapid and accurate method for mapping transgene integration and copy number. Using stably transfected HepG2 cells, we demonstrate that esTag-PCR has higher integration site detection accuracy and efficiency than alternative tagmentation-based methods. Next, we performed esTag-PCR on rhesus macaque embryos derived from zygotes injected with piggyBac transposase and transposon/transgene plasmid. Using low-input trophectoderm biopsies, we demonstrate that esTag-PCR accurately maps integration events while preserving blastocyst viability. We used these high-resolution data to evaluate the performance of piggyBac-mediated editing of rhesus macaque embryos, demonstrating that increased concentration of transposon/transgene plasmid can increase the fraction of embryos with stable integration; however, the number of integrations per embryo also increases, which may be problematic for some applications. Collectively, esTag-PCR represents an important improvement to the detection of transgene integration, provides a method to validate and screen edited embryos before implantation, and represents an important advance in the creation of transgenic animal models.

Application of Two Blastocyst Biopsy Strategies in Preimplantation Genetic Testing Treatment and Assessment of Their Effects

BACKGROUND

Blastocyst biopsy has become the most mainstream biopsy method. Currently, there are two blastocyst biopsy strategies. Many studies have compared the advantages and disadvantages between blastomere and blastocyst biopsy, but fewer articles have compared the two blastocyst biopsy strategies. For the moment, no published studies have explored the entire set of information on embryo development, next-generation sequencing results, and clinical outcomes, including the baby's health status with the two blastocyst biopsy strategies.

METHODS

A total of 323 preimplantation genetic testing cycles from April 2018 to May 2020, including 178 cycles with Strategy A and 145 cycles with Strategy B. Strategy A was to create a laser-assisted zona pellucid opening for cleavage embryo on the third day after insemination, but Strategy B was not. Strategy A performed a biopsy for artificially assisted hatching blastocysts, while Strategy B performed a biopsy for expanded blastocysts on day 5 or 6. In this study, embryo development, next-generation sequencing results, pregnancy outcomes, and offspring health of the two strategies were compared and analyzed.

RESULTS

There were no statistical differences between the two groups in the rate of fertilization, blastocyst and abortion. The rate of cleavage from Strategy A was slightly higher than Strategy B, and the rate of high-quality cleavage embryo was lower than Strategy B, while the rate of high-quality blastocyst was higher than Strategy B. The rate of no-results blastocyst was significantly lower than Strategy B. In particular, the rate of biochemical pregnancy, clinical pregnancy, and live birth of Strategy A were significantly lower than those of Strategy B. The average Apgar scores of newborns were ≥8 in both groups, and there was no significant difference in average height and weight. In Strategy A, a baby was born with thumb syndactyly, and Strategy B had no congenital disabilities.

CONCLUSIONS

Blastocyst biopsy strategy without laser-assisted zona pellucid drilling on day 3 achieves better clinical treatment effects. Therefore, Strategy B is an optimal treatment regime for PGT.

Obstetric and neonatal outcomes of pregnancies resulting from preimplantation genetic testing: a systematic review and meta-analysis

BACKGROUND

Preimplantation genetic testing (PGT) includes methods that allow embryos to be tested for severe inherited diseases or chromosomal abnormalities. In addition to IVF/ICSI and repeated freezing and thawing of the embryos, PGT requires a biopsy to obtain embryonic genetic material for analysis. However, the potential effects of PGT on obstetric and neonatal outcomes are currently uncertain.

OBJECTIVE AND RATIONALE

This study aimed to investigate whether pregnancies conceived after PGT were associated with a higher risk of adverse obstetric and neonatal outcomes compared with spontaneously conceived (SC) pregnancies or pregnancies conceived after IVF/ICSI.

SEARCH METHODS

PubMed, EMBASE, MEDLINE, Web of Science and The Cochrane Library entries from January 1990 to January 2021 were searched. The primary outcomes in this study were low birth weight (LBW) and congenital malformations (CMs), and the secondary outcomes included gestational age, preterm delivery (PTD), very preterm delivery (VPTD), birth weight (BW), very low birth weight (VLBW), neonatal intensive care unit (NICU) admission, hypertensive disorders of pregnancy (HDP), gestational diabetes, placenta previa and preterm premature rupture of membranes (PROM). We further pooled the results of PGT singleton pregnancies. Subgroup analyses included preimplantation genetic diagnosis (PGD), preimplantation genetic screening (PGS), cleavage-stage biopsy combined with fresh embryo transfer (CB-ET) and blastocyst biopsy combined with frozen-thawed embryo transfer (BB-FET).

OUTCOMES

This meta-analysis included 15 studies involving 3682 babies born from PGT pregnancies, 127 719 babies born from IVF/ICSI pregnancies and 915 222 babies born from SC pregnancies. The relative risk (RR) of LBW was higher in PGT pregnancies compared with SC pregnancies (RR = 3.95, 95% confidence interval [CI]: 2.32-6.72), but the risk of CMs was not different between the two groups. The pooled results for the risks of LBW and CMs were similar in PGT and IVF/ICSI pregnancies. The risks of PTD (RR = 3.12, 95% CI: 2.67-3.64) and HDP (RR = 3.12, 95% CI: 2.18-4.47) were significantly higher in PGT pregnancies compared with SC pregnancies. Lower gestational age (mean difference [MD] = -0.76 weeks, 95% CI -1.17 to -0.34) and BW (MD = -163.80 g, 95% CI: -299.35 to -28.24) were also noted for PGT pregnancies compared with SC pregnancies. Nevertheless, compared with IVF/ICSI pregnancies, the risks of VPTD and VLBW in PGT pregnancies were significantly decreased by 41% and 30%, respectively, although the risk of HDP was still significantly increased by 50% in PGT pregnancies compared with IVF/ICSI pregnancies. The combined results of obstetric and neonatal outcomes of PGT and IVF/ICSI singleton pregnancies were consistent with the overall results. Further subgroup analyses indicated that both PGD and PGS pregnancies were associated with a higher risk of PTD and a lower gestational age compared with SC pregnancies.

WIDER IMPLICATIONS

This meta-analysis showed that PGT pregnancies may be associated with increased risks of LBW, PTD and HDP compared with SC pregnancies. The overall obstetric and neonatal outcomes of PGT pregnancies are favourable compared with those of IVF/ICSI pregnancies, although PGT pregnancies were associated with a higher risk of HDP. However, because the number of studies that could be included was limited, more randomised controlled trials and prospective cohort studies are needed to confirm these conclusions.

From Zygote to Blastocyst: Application of Ultrashort Lasers in the Field of Assisted Reproduction and Developmental Biology

Although the use of lasers in medical diagnosis and therapies, as well as in fundamental biomedical research is now almost routine, advanced laser sources and new laser-based methods continue to emerge. Due to the unique ability of ultrashort laser pulses to deposit energy into a microscopic volume in the bulk of a transparent material without disrupting the surrounding tissues, the ultrashort laser-based microsurgery of cells and subcellular components within structurally complex and fragile specimens such as embryos is becoming an important tool in developmental biology and reproductive medicine. In this review, we discuss the mechanisms of ultrashort laser pulse interaction with the matter, advantages of their application for oocyte and preimplantation embryo microsurgery (e.g., for oocyte/blastomere enucleation and embryonic cell fusion), as well as for nonlinear optical microscopy for studying the dynamics of embryonic development and embryo quality assessment. Moreover, we focus on ultrashort laser-based approaches and techniques that are increasingly being applied in the fundamental research and have the potential for successful translation into the IVF (in vitro fertilization) clinics, such as laser-mediated individual embryo labelling and controlled laser-assisted hatching.

Single blastocyst stage versus single cleavage stage embryo transfer following fresh transfer: A systematic review and meta-analysis

OBJECTIVES

To compare the available evidence of the effectiveness of single blastocyst stage transfer against the effectiveness of single cleavage stage embryo transfer.

STUDY DESIGN

A systematic research based on Pubmed, Embase and the Cochrane Library was performed until May 2, 2020 to identify all relevant studies. The Cochrane Collaboration's Review Manager (RevMan) 5.0.2 software was used for statistical analysis.

RESULTS

Five randomized controlled trials (RCTs) were included in analysis, involving 1784 patients in total, who were divided into 2 groups, which were the single blastocyst stage transfer (SBT) group of 932, and the single cleavage stage transfer (SCT) group of 852. Our meta-analysis concluded that SBT group had a significantly higher clinical pregnancy rate (RR 1.26; 95%CI: 1.14-1.39), ongoing pregnancy rate (RR 1.19; 95%CI: 1.05-1.35) and delivery rate (RR 1.4; 95%CI: 1.13-1.75) than SCT group during the fresh transfer. While miscarriage rate (RR 0.93; 95% CI: 0.66-1.33), multiple pregnancy rate (RR, 1.12; 95% CI, 0.51-2.45) and ectopic pregnancy rate (RR, 0.5; 95% CI: 0.13-1.90) between two groups showed no significant difference. However, the SCT group contained notably more cryopreserved embryos than the SBT group. (RR -0.68, 95% CI: -0.95 to -0.41).

CONCLUSIONS

Our results indicate that single blastocyst stage transfer is associated with higher ongoing pregnancy rate and delivery rate comparing to single cleavage stage transfer in the clinical practice. Due to the low quality of the evidence of the primary outcomes, other higher-quality lager RCTs are necessary before a fully informed decision is made.

Different Strategies of Preimplantation Genetic Testing for Aneuploidies in Women of Advanced Maternal Age: A Systematic Review and Meta-Analysis

Background: Preimplantation genetic testing for aneuploidies (PGT-A) is widely used in women of advanced maternal age (AMA). However, the effectiveness remains controversial. Method: We conducted a comprehensive literature review comparing outcomes of IVF with or without PGT-A in women of AMA in PubMed, Embase, and the Cochrane Central Register of Controlled Trials in January 2021. All included trials met the criteria that constituted a randomized controlled trial for PGT-A involving women of AMA (≥35 years). Reviews, conference abstracts, and observational studies were excluded. The primary outcome was the live birth rate in included random control trials (RCTs). Results: Nine randomized controlled trials met our inclusion criteria. For techniques of genetic analysis, three trials (270 events) performed with comprehensive chromosomal screening showed that the live birth rate was significantly higher in the women randomized to IVF/ICSI with PGT-A (RR = 1.30, 95% CI 1.03–1.65), which was not observed in six trials used with FISH as well as all nine trials. For different stages of embryo biopsy, only the subgroup of blastocyst biopsy showed a higher live birth rate in women with PGT-A (RR = 1.36, 95% CI 1.04–1.79). Conclusion: The application of comprehensive chromosome screening showed a beneficial effect of PGT-A in women of AMA compared with FISH. Moreover, blastocyst biopsy seemed to be associated with a better outcome than polar body biopsy and cleavage-stage biopsy.

Preimplantation Genetic Testing for Rare Inherited Disease of MMA-CblC: an Unaffected Live Birth

Methylmalonic acidemia combined with homocysteinemia and cobalamin C type (MMA-CblC, MIM # 277400) is a rare inherited disease with cobalamin metabolic disorder, which are caused by deficiency in the MMACHC gene. A couple with a proband child carried with compound heterozygous mutations of MMACHC (c.609G>A and c.567 dup T, NM_015506) sought for assisted reproductive technology to avoid the transmission of pathogenic genetic variants and unnecessary induction of labor. Thus, in vitro fertilization (IVF), preimplantation genetic testing (PGT), and prenatal genetic diagnosis were applied to fulfill this clinical demand. In this study, seven embryos were biopsied and carried out whole-genome amplification using multiple annealing and looping-based amplification cycle (MALBAC) method. Sanger sequencing together with copy number variation (CNV) analysis and single-nucleotide polymorphism (SNP) haplotyping was conducted to detect the mutated alleles and chromosomal abnormalities simultaneously. Three embryos (E07, E06, and E02) were confirmed without CNVs and inherited mutations at MMACHC gene. Embryo E07 with the best embryo ranking of 5BB was selected preferentially to transfer which led to a successful pregnancy and an unaffected live birth. Prenatal genetic diagnosing with amniotic fluid cells, Sanger sequencing with cord blood cells, and neonate MMA screening further verified our successful application of PGT in preventing mutated allele transmission for this rare inherited disease.

Vitrification yields higher cryo-survival rate than slow freezing in biopsied bovine in vitro produced blastocysts

Vitrification and slow freezing are the two commonly used embryo cryopreservation methods. In most studies, vitrification of intact embryos has proven superior in several respects, including cell and embryo survival and pregnancy rate. However, there is a lack of data for comparing these two methods in in vitro produced (IVP) bovine blastocysts, which have been subjected to the retrieval of trophectoderm (TE) biopsy. Day 7 IVP blastocysts were pooled and randomized into four groups: 1) non-biopsy (NB), 2) biopsy (B), 3) biopsy-vitrification (BV), 4) biopsy-slow freeze (BSF). The blastocysts in the B, BV, and BSF groups were subjected to TE biopsy. For the B group, this was followed by 5 hours (h) incubation and subsequent scoring of the biopsy-survival (re-expansion) rate before processing for further analyses. For the BV and BSF groups, the biopsy procedure was followed by 2 h incubation, allowing for a quick re-expansion, after which the blastocysts were subjected to vitrification and slow freezing, respectively. After warming and thawing, respectively, they were then incubated for 5 h followed by scoring the cryo-survival (re-expansion) rates before processing for further analyses. These included quantification of ICM and TE cells, cleaved caspase-3- and TUNEL-positive cells, quantitative PCR on cellular stress markers (SOD1 and PRDX1), and ultrastructural analysis. The biopsy-survival rate in the B group was 94% (307/326). The cryo-survival rate in BV (86%, 138/161) was higher than that in BSF (57%, 81/142; P < 0.001). No differences were noted between the average ICM, TE, and total cell numbers of the groups. The percentages of cleaved caspase-3-positive cells were higher in BV vs. NB (P < 0.05), in BSF vs. NB (P < 0.001), and in BSF vs. B (P < 0.001). The percentages of TUNEL-positive cells were higher in BV vs. NB (P < 0.05) and in BSF vs. NB (P < 0.001). The levels of mRNA abundance for SOD1 and PRDX1 in B, BV, and BSF were not different from that in NB. The ultrastructural analysis of blastocysts in the BV and BSF groups showed distension of extracellular spaces and appearance of intracellular vacuoles in the ICM, distension of mitochondria, and disorganization of mitochondrial cristae in both ICM and TE, and weakened tight junctions between adjacent TE cells. In summary, our findings demonstrate that vitrification yields a higher cryo-survival rate than slow freezing in biopsied bovine IVP blastocysts. However, biopsy-vitrification and biopsy-slow-freeze values are comparable in terms of ICM, TE, and total blastocyst cell numbers, as well as cleaved caspase-3- and TUNEL-positive cell rates. Moreover, biopsy and cryopreservation performed alone had no effect on ICM, TE, total blastocyst cell numbers, or TUNEL-positive cell rates. Biopsy and vitrification performed alone had no effect on the cleaved caspase-3 positive cell rates, whereas slow freezing resulted in an increased rate. Furthermore, double traumatization with a combination of biopsy and cryopreservation, either vitrification or slow freezing, resulted in increased rates of cleaved caspase-3- and TUNEL-positive cells.

Meta-analysis of the embryo freezing transfer interval

BACKGROUND

The decision of whether frozen embryo transfer (FET) should be performed in the cycle immediately after OPU or at least one cycle later is controversial. FET could improve pregnancy rates in IVF; however, how much time is needed for the endometrium to return to optimal receptivity after ovarian stimulation is not known.

METHODS

Electronic search in MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials to identify studies providing data on the influence of the interval between embryo freezing (or OPU) and FET in FET cycles published between January 1, 2007, and February 1, 2020.

MAIN FINDINGS

Data analyzed indicated that in the immediate FET cycles, there was a trend to an increased biochemical pregnancy rate (RR = 1.08; CI = 1.00-1.18), whereas the clinical pregnancy rate was somewhat higher, but without reaching statistical significance (RR = 1.07; CI = 0.99-1.15). The live birth rate was similar in the two groups (RR = 1.05; CI = 0.95-1.15), as was the implantation rate (RR = 0.98; CI = 0.83-1.16). Stratifying by embryo stage or FET type (freeze-all or FET after failed fresh transfer) showed no differences.

CONCLUSION

Systematically delaying FET does not offer benefits to IVF outcomes. In addition, immediate transfer is associated with a nonsignificant trend to better clinical pregnancy rate and it also avoids the psychological effects of prolonging the stress on prospective parents.

Trophectoderm biopsy protocols may impact the rate of mosaic blastocysts in cycles with pre-implantation genetic testing for aneuploidy

Purpose

This study aimed to analyze the impact of different biopsy protocols on the rate of mosaic blastocysts.

Methods

This is a retrospective cohort study which included 115 cycles with pre-implantation genetic testing for aneuploidy (PGT-A). Two groups were allocated based on the biopsy protocols: method 1 group, the zona pellucida (ZP) was drilled on day 3 embryos followed by trophectoderm (TE) biopsy; and method 2 group, the ZP was opened on day 5 or 6 blastocysts followed by TE biopsy. All biopsy samples were assessed using next-generation sequencing (NGS) at a single reference laboratory. The euploid, aneuploid, and mosaic blastocyst rates and clinical outcomes were compared.

Results

The mosaicism rate in the method 1 group was 19.58%, significantly higher than the method 2 group (8.12%; P < 0.05). No statistically significant difference was observed in euploid, aneuploid blastocyst rates, and clinical pregnancy rates between the two groups. Logistic regression analysis indicated that the biopsy protocols were independently associated with the mosaicism rates among all the variables.

Conclusions

The present study showed that different biopsy protocols may have an impact on the mosaic blastocyst rate. ZP opening on day 3 combined with TE biopsy might increase the incidence of mosaic blastocysts.

Cell-free DNA in spent culture medium effectively reflects the chromosomal status of embryos following culturing beyond implantation compared to trophectoderm biopsy

This prospective study evaluated the accuracy of non-invasive preimplantation genetic testing for aneuploidy (niPGT-A) using cell-free DNA in spent culture medium, as well as that of preimplantation genetic testing for aneuploidy (PGT-A) using trophectoderm (TE) biopsy after culturing beyond implantation. Twenty frozen blastocysts donated by 12 patients who underwent IVF at our institution were investigated. Of these, 10 were frozen on day 5 and 10 on day 6. Spent culture medium and TE cells were collected from each blastocyst after thawing, and the embryos were cultured in vitro for up to 10 days. The outgrowths after culturing beyond implantation were sampled and subjected to chromosome analysis using next-generation sequencing. Chromosomal concordance rate, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false-positive rate (FPR), and false-negative rate (FNR) of niPGT-A and PGT-A against each outgrowth were analyzed. The concordance rate between the niPGT-A and outgrowth samples was 9/16 (56.3%), and the concordance rate between the PGT-A and outgrowth samples was 7/16 (43.8%). NiPGT-A exhibited 100% sensitivity, 87.5% specificity, 88.9% PPV, 100% NPV, 12.5% FPR, and 0% FNR. PGT-A exhibited 87.5% sensitivity, 77.8% specificity, 87.5% PPV, 75% NPV, 14.3% FPR, and 22.2% FNR. NiPGT-A may be more accurate than PGT-A in terms of ploidy diagnostic accuracy in outgrowths.

The dawn of the future: 30 years from the first biopsy of a human embryo. The detailed history of an ongoing revolution

Following early studies showing no adverse effects, cleavage stage biopsy by zona drilling using acid Tyrode's solution, and removal of single blastomeres for preimplantation genetic testing (PGT) and identification of sex in couples at risk of X-linked disease, was performed by Handyside and colleagues in late 1989, and pregnancies reported in 1990. This method was later used for specific diagnosis of monogenic conditions, and a few years later also for chromosomal structural and/or numerical impairments, thereby establishing a valuable alternative option to prenatal diagnosis. This revolutionary approach in clinical embryology spread worldwide, and several other embryo biopsy strategies developed over three decades in a process that is still ongoing. The rationale of this narrative review is to outline the different biopsy approaches implemented across the years in the workflow of the IVF clinics that provided PGT: their establishment, the first clinical experiences, their downsides, evolution, improvement and standardization. The history ends with a glimpse of the future: minimally/non-invasive PGT and experimental embryo micromanipulation protocols. This grand theme review outlines a timeline of the evolution of embryo biopsy protocols, whose implementation is increasing worldwide together with the increasing application of PGT techniques in IVF. It represents a vade mecum especially for the past, present and upcoming operators and experts in this field to (re)live this history from its dawn to its most likely future.

[Pre-implantation genetic testing: Comparison between cleavage stage and blastocyst biopsy]

OBJECTIVES

Preimplantation genetic testing (PGT) refers to the set of techniques for testing whether embryos obtained through in vitro fertilization have genetic defect. There is a lack of global standardization regarding practices between countries or even from one center to another. In ours, biopsies are preferably performed on day 3 embryos, but also at the blastocyst stage on day 5. The blastocyst biopsy often requires systematic freezing of the embryos before obtaining the genetic results, whereas day 3 biopsy allows fresh embryo transfer of the healthy or balanced embryo after getting the genetic results. We wanted to compare the chances of success for couples performing PGT in our center according to the day of the biopsy.

METHODS

For this, we carried out a retrospective monocentric study including all PGT cycles performed between 2016 and 2019 divided into two groups: day 3 or day 5 biopsy.

RESULTS

There was no significant difference in terms of live birth rate (P=0.7375) after fresh embryo transfers, as well for pregnancy rates, clinical pregnancy rates, implantation rates and miscarriage rates. On the other hand, we observed higher live birth rates after frozen-thawed embryo transfer when the biopsy was performed on day 5 rather on day 3 (P=0.0001). We also wanted to assess what was the most efficient biopsy strategy in our laboratory. Our rates of useful embryos were similar regardless of the day of the biopsy (34% in D3 and 37.7% in D5, P=0.244). No statistical difference was found in the number of unnecessarily biopsied embryos in the two groups. But still, the percentage of embryos biopsied on D5 and immediately frozen was 42.8% (118 blastocysts), while no embryo biopsied on D3 led to this case.

CONCLUSION

Therefore, our results are in favor of generalization of the D5 biopsy as the international standard. However, the organizational, financial and logistical implications that this technic would impose make it unsystematic in our center.

Controlled hatching at the prescribed site using femtosecond laser for zona pellucida drilling at the early blastocyst stage

PURPOSE

To study whether the application of femtosecond laser pulses for zona pellucida (ZP) drilling of blastocysts at the embryonic or abembryonic poles can promote hatching to start immediately through the hole formed and ensure high hatching rates and embryo viability.

METHODS

Mouse blastocyst (E3.5) ZP were microdissected with femtosecond laser pulses (514-nm wavelength, 280-fs pulse duration, 2.5-kHz repetition rate) close to the trophoblast or inner cell mass (ICM). The sizes of the holes formed were in the range of 4.5-8.5 μm. Additional longitudinal incisions (5-7-μm long) on either side of the hole were created to determine whether hatching had started at the correct position. Embryos post-laser-assisted ZP drilling and intact embryos were cultured under standard conditions for 2 days; embryo quality was assessed twice daily. The hatching rates and in vitro and in vivo implantation rates (only for embryos with ZP dissected close to the ICM) were estimated.

RESULTS

Femtosecond laser-assisted ZP drilling at the early blastocyst stage facilitated embryo hatching to start at the artificial opening with probability approaching 100%. Despite the artificial opening's small size, no embryo trapping during hatching was observed. Both experimental groups had higher hatching rates than the control groups (93.3-94.7% vs. 83.3-85.7%, respectively). The in vitro implantation rate was comparable with that of the control group (92.3% vs. 95.4%). No statistically significant differences were obtained in the in vivo implantation rates between the experimental and control groups.

CONCLUSIONS

Blastocyst-stage femtosecond laser microsurgery of ZP is fast and delicate and enables the hatching process to be initiated in a controlled manner through a relatively small opening, with no embryo trapping.

Preimplantation genetic testing to reduce preterm births in assisted reproductive technology

The 10% rate of preterm birth rate worldwide has not been proved amenable to reduction. Avoiding multiple embryo transfer in assisted reproductive technologies (ART) using in vitro fertilization is one unassailable method. Preimplantation genetic testing (PGT) to select only a single euploid embryo for transfer is one unequivocal way, maintaining 50%-60% pregnancy rates while avoiding twins. Contemporary methodology entails trophectoderm biopsy of a 5-6-day blastocyst, and cryopreservation of biopsied embryos while awaiting analysis by next generation sequencing. Embryo biopsy is safe, analytic validity for chromosomal analysis high, and global access to PGT high.

The unknown human trophectoderm: implication for biopsy at the blastocyst stage

Trophectoderm biopsy is increasingly performed for pre-implantation genetic testing of aneuploidies and considered a safe procedure on short-term clinical outcome, without strong assessment of long-term consequences. Poor biological information on human trophectoderm is available due to ethical restrictions. Therefore, most studies have been conducted in vitro (choriocarcinoma cell lines, embryonic and pluripotent stem cells) and on murine models that nevertheless poorly reflect the human counterpart. Polarization, compaction, and blastomere differentiation (e.g., the basis to ascertain trophectoderm origin) are poorly known in humans. In addition, the trophectoderm function is poorly known from a biological point of view, although a panoply of questionable and controversial microarray studies suggest that important genes overexpressed in trophectoderm are involved in pluripotency, metabolism, cell cycle, endocrine function, and implantation. The intercellular communication system between the trophectoderm cells and the inner cell mass, modulated by cell junctions and filopodia in the murine model, is obscure in humans. For the purpose of this paper, data mainly on primary cells from human and murine embryos has been reviewed. This review suggests that the trophectoderm origin and functions have been insufficiently ascertained in humans so far. Therefore, trophectoderm biopsy should be considered an experimental procedure to be undertaken only under approved rigorous experimental protocols in academic contexts.

Trophectoderm biopsy for preimplantation genetic test and technical tips: A review

BACKGROUND

Recently, the Japan Society of Obstetrics and Gynecology initiated a clinical study of preimplantation genetic test for aneuploidy. There will be a great need for a standardized embryo biopsy technique in Japan. However, the gold standard trophectoderm (TE) biopsy procedure has not been established, and this review outlines the clinical use of TE biopsy.

METHODS

Based on literature, the method and associated techniques for TE biopsy, a dissection method of TE cells from blastocysts, were investigated.

MAIN FINDINGS

Two TE biopsy methods are used, namely assisted hatching (herniating) and non-assisted hatching (direct suction); however, it is not clear which of these methods is superior. It is critical to understand whether the flicking or pulling method is beneficial.

CONCLUSION

Non-assisted hatching biopsy method may cause blastocyst collapse with a higher probability, and it may extend the biopsy time. The biopsy procedure should be performed within 3 minutes, and thus direct TE suction may have greater disadvantages. It is a fact that pulling method of TE dissection with laser pulse is simple; however, excess laser shots may induce a higher frequency of mosaicism. It is important to understand that each technique of TE biopsy has benefits and disadvantages.

Preimplantation Genetic Testing: Where We Are Today

Background: Preimplantation genetic testing (PGT) is widely used today in in-vitro fertilization (IVF) centers over the world for selecting euploid embryos for transfer and to improve clinical outcomes in terms of embryo implantation, clinical pregnancy, and live birth rates. Methods: We report the current knowledge concerning these procedures and the results from different clinical indications in which PGT is commonly applied. Results: This paper illustrates different molecular techniques used for this purpose and the clinical significance of the different oocyte and embryo stage (polar bodies, cleavage embryo, and blastocyst) at which it is possible to perform sampling biopsies for PGT. Finally, genetic origin and clinical significance of embryo mosaicism are illustrated. Conclusions: The preimplantation genetic testing is a valid technique to evaluated embryo euploidy and mosaicism before transfer.

Preimplantation Genetic Testing for Chromosomal Abnormalities: Aneuploidy, Mosaicism, and Structural Rearrangements

There is a high incidence of chromosomal abnormalities in early human embryos, whether they are generated by natural conception or by assisted reproductive technologies (ART). Cells with chromosomal copy number deviations or chromosome structural rearrangements can compromise the viability of embryos; much of the naturally low human fecundity as well as low success rates of ART can be ascribed to these cytogenetic defects. Chromosomal anomalies are also responsible for a large proportion of miscarriages and congenital disorders. There is therefore tremendous value in methods that identify embryos containing chromosomal abnormalities before intrauterine transfer to a patient being treated for infertility—the goal being the exclusion of affected embryos in order to improve clinical outcomes. This is the rationale behind preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (-SR). Contemporary methods are capable of much more than detecting whole chromosome abnormalities (e.g., monosomy/trisomy). Technical enhancements and increased resolution and sensitivity permit the identification of chromosomal mosaicism (embryos containing a mix of normal and abnormal cells), as well as the detection of sub-chromosomal abnormalities such as segmental deletions and duplications. Earlier approaches to screening for chromosomal abnormalities yielded a binary result of normal versus abnormal, but the new refinements in the system call for new categories, each with specific clinical outcomes and nuances for clinical management. This review intends to give an overview of PGT-A and -SR, emphasizing recent advances and areas of active development.

Time of morulation and trophectoderm quality are predictors of a live birth after euploid blastocyst transfer: a multicenter study

OBJECTIVE

To investigate whether the morphodynamic characterization of a euploid blastocyst's development allows a higher prediction of a live birth after single-embryo-transfer (SET).

DESIGN

Observational cohort study conducted in two phases: training and validation.

SETTING

Private in vitro fertilization centers.

PATIENT(S)

Euploid blastocysts: 511 and 319 first vitrified-warmed SETs from 868 and 546 patients undergoing preimplantation genetic testing for aneuploidies (PGT-A) in the training and validation phase, respectively.

INTERVENTION(S)

Data collected from time of polar body extrusion to time of starting blastulation, and trophectoderm and inner-cell-mass static morphology in all embryos cultured in a specific time-lapse incubator with a continuous medium. Logistic regressions conducted to outline the variables showing a statistically significant association with live birth. In the validation phase, these variables were tested in an independent data set.

MAIN OUTCOME MEASURE(S)

Live births per SET.

RESULT(S)

The average live birth rate (LBR) in the training set was 40% (N = 207/511). Only time of morulation (tM) and trophectoderm quality were outlined as putative predictors of live birth at two IVF centers. In the validation set, the euploid blastocysts characterized by tM <80 hours and high-quality trophectoderm resulted in a LBR of 55.2% (n = 37/67), while those with tM ≥ 80 hours and a low-quality trophectoderm resulted in a LBR of 25.5% (N = 13/51).

CONCLUSION(S)

Time of morulation and trophectoderm quality are better predictors of a euploid blastocyst's reproductive competence. Our evidence was reproducible across different centers under specific culture conditions. These data support the crucial role of morulation for embryo development, a stage that involves massive morphologic, cellular, and molecular changes and deserves more investigation.

Hormonal Effects in Reproductive Technology with Focus on Diminished Ovarian Reserve

Modern use of reproductive technologies has revolutionized the treatment of infertile couples. Strategies to improve ovarian function in cases of diminished ovarian reserve are perhaps the least understood area in this field and will be the chief focus of this chapter.

Trophectoderm biopsy protocols can affect clinical outcomes: time to focus on the blastocyst biopsy technique

OBJECTIVE

To compare two different blastocyst biopsy protocols.

DESIGN

Retrospective single-center cohort study.

SETTINGS

Private in vitro fertilization center.

PATIENT(S)

The study included 1,670 frozen-thawed embryo transfers (FETs) with preimplantation genetic testing for aneuploidy (PGT-A).

INTERVENTION

None.

MAIN OUTCOME MEASURE(S)

Survival rate (SR) after thawing, clinical pregnancy rate (CPR), ongoing implantation rate (IR), and live birth rate (LBR).

RESULT(S)

Eight hundred thirty-five FETs with PGT-A cycles including only embryos biopsied in the sequential blastocyst hatching and biopsy protocol paired with the ablation of one-fourth of the zona pellucida (ZP) were matched with 835 FETs with PGT-A cycles including only embryos biopsied in the day 3 prehatching protocol by female age (±1 year), number of embryos transferred, use of gestational carrier or egg donor, and day of blastocyst transfer. Only FETs with euploid blastocysts graded no lower than 4BB were included, and cycles with fewer than five oocytes were excluded. SR after thawing, CPR, ongoing IR, and LBR were significantly higher in the FET cycles with the embryos biopsied in the sequential hatching and biopsy protocol. Four cases of monozygotic twin pregnancies were reported with the day 3 prehatching protocol and none with the sequential hatching and biopsy protocol.

CONCLUSION(S)

Our results show, for the first time, that using different blastocyst biopsy protocols can affect clinical outcomes. Because the study was retrospective, our findings should be validated in a prospective trial.

Quality of Blastocysts Created by Embryo Splitting: A Time-Lapse Monitoring and Chromosomal Aneuploidy Study

Objective

The aim of this study was to screen the potential of human embryos to develop into expanding blastocysts following in vitro embryo splitting and then assess the quality of the generated blastocysts based on chromosomal characteristics and using morphokinetics.

Materials and Methods

In this experimental study, a total of 82 good quality cleavage-stage donated embryos (8- 14 cells) were used (24 embryos were cultured to the blastocyst stage as controls and 58 embryos underwent in vitro splitting). After in vitro splitting, the blastomere donor and blastomere recipient embryos were named twin A and twin B, respectively. Morphokinetics and morphological parameters were evaluated using a time-lapse system in the blastocysts developed from twin embryos. Aneuploidy of chromosomes 13, 15, 16, 18, 21, 22, X and Y were analyzed in the twin blastocysts.

Results

Following in vitro splitting, of the 116 resulting twin embryos, 80 (69%) developed to the expanded blastocyst (EBL) stage compared to 21 (87.5%) embryos in the control group (P>0.05). The morphokinetics analysis suggested that the developmental time-points were influenced by the in vitro splitting. Moreover, the blastocysts developed from A and B twins had impaired morphology compared to controls. Regarding chromosome abnormalities, there was no significant difference in the rate of aneuploidy or mosaicism between the different groups.

Conclusion

This study showed that while no chromosomal abnormalities were seen, in vitro embryo splitting may affect the embryo morphokinetics.

Preimplantation Genetic Testing for Breast Cancer

Breast cancer (BC), a malignant tumor characterized mainly by a lump in the breast and a change in breast shape, has plagued many women of childbearing age in Nigeria today. This has thus propelled many to find both prophylactic and curative agents to combat BC in affected persons. This article extensively reviews a method of preventing BC in the offspring of affected parents, known as preimplantation genetic testing (PGT) – an assisted reproductive technique that selects genetically unaffected embryo(s) to be transferred to the uterus of a mother upon in vitro fertilization and standard genetic analysis. The present study also seeks to present the techniques involved in PGT that have been reported to prevent the inheritance of BC, its benefits and risks, related case studies in Africa and other continents, and ethical issues surrounding the application of assisted reproduction for BC testing. To achieve these, a thorough search was conducted in reputable scientific journals of reproduction and cancer, and expert knowledge was consulted with regard to these aspects of health and reproduction. Upon reviewing this very important subject, it was confirmed that the beneficial role of assisted reproduction in the field of science and the homes of many cannot be overestimated. This review of the role of PGT in BC prevention will enlighten the understanding of many – creating awareness that with PGT, BC-affected women can have not only children, but also healthy and genetically unaffected children.

Increased pregnancy outcome after day 5 versus day 6 transfers of human vitrified-warmed blastocysts

Vitrification is a highly efficient technique for the cryopreservation of the human embryo. The effect of delayed blastulation may be responsible for implantation failures and negatively affects in vitro fertilization (IVF) outcomes. The current literature displays discordant results; some studies have announced higher pregnancy rates after day 5 (D5) transfer compared with day 6 (D6) transfer, while others have shown equivalent outcomes. In the present study an investigation into the clinical implications of delayed blastulation (D5 versus D6) was carried out. We performed a retrospective study comparing clinical pregnancies and implantation rates following warmed single blastocyst transfer (WSBT). All patients coming for a programmed warmed transfer at Edinburgh Assisted Conception Programme, EFREC, Royal Infirmary of Edinburgh, were included in this study and divided in two groups according to the day of blastocyst vitrification: D5 (n = 1563) and D6 (n = 517). The overall survival rate was 95.0% (1976/2080) with no significant difference between the D5 and D6 groups: 95.3% (1489/1563) and 94.2% (487/517) respectively. WSBT of D6 blastocysts resulted in a lower implantation and clinical pregnancy compared with D5 embryos. The implantation rate (IPR) and clinical pregnancy rate (CPR) were respectively 49.4% and 42.6% for the D5 and 37.4% and 32.2% for the D6 embryos, which was statistically significant. The multiple pregnancy rate was 1.32% (1.14% for D5 vs 1.84% for D6). Although the transfer of D6 vitrified-warmed blastocyst remains a reasonable option, priority to a D5 embryo would reduce the time to successful pregnancy.

Overview of Preimplantation Genetic Diagnosis (PGD): Historical Perspective and Future Direction

Preimplantation genetic diagnosis (PGD) can be considered the earliest form of prenatal testing. It was first used in humans over 26 years ago. At its inception, PGD could only be performed for a limited number of genetic disorders. Technological advances in molecular biology and cytogenomics have been utilized in the field of PGD to greatly expand the spectrum of genetic disorders that can now be detected in early human embryos.

Live birth rate is associated with oocyte yield and number of biopsied and suitable blastocysts to transfer in preimplantation genetic testing (PGT) cycles for monogenic disorders and chromosomal structural rearrangements

Objectives

To investigate whether live birth (LB) is associated with oocyte yield and number of biopsied and suitable blastocyst to transfer following preimplantation genetic testing (PGT) for monogenic disorders (PGT-M) and chromosomal structural rearrangements (PGT-SR).

Study design

All couples underwent controlled ovarian stimulation, blastocyst biopsy, vitrification and transfer of suitable embryo(s) in a frozen embryo transfer (FET) cycle.

Results

Of 175 couples who underwent PGT treatment, 249 oocytes retrievals were carried out and 230 FET were subsequently undertaken. 122/230 (53%, 95% CI 47-59) FET resulted in a LB and 16/230 (7%, 95% CI 4-11) have resulted in ongoing pregnancies. 21/230 (9%, 95% CI 6-14) FET resulted in miscarriage and 69/230 (30%, 95% CI 24-36) concluded with failed implantation. Two (1%, 95% CI 0-3) transfers underwent termination for congenital malformation, with no evidence of misdiagnosis by prenatal testing. The relationship between number of oocytes retrieved and number of blastocysts biopsied and suitable embryos to transfer were significant (p = 0.00; Incidence rate ratio (IRR) 1.05; 95% 1.04-1.06; p = 0.00; IRR 1.04; 95%, 1.03-1.06), respectively. The number of oocytes collected (p = 0.007; OR 1.06; 95% CI 1.01-1.10), the number of blastocysts biopsied (p = 0.001; OR 1.14; 95% 95% CI 1.06-1.23) and the number of suitable embryos to transfer (p = 0.00; OR 1.38; 95% CI 1.17-1.64) were all significantly associated with the odds of achieving a LB. There is a 14% and 38% increased chance of a LB per additional blastocyst biopsied and suitable embryo to transfer, respectively.

Conclusions

PGT-M and PGT-SR outcomes are significantly associated with egg yield, number of blastocysts to biopsy and suitable embryos to transfer.

Preimplantation genetic testing for aneuploidy by microarray analysis of polar bodies in advanced maternal age: a randomized clinical trial

STUDY QUESTION

Does preimplantation genetic testing for aneuploidy (PGT-A) by comprehensive chromosome screening (CCS) of the first and second polar body to select embryos for transfer increase the likelihood of a live birth within 1 year in advanced maternal age women aged 36-40 years planning an ICSI cycle, compared to ICSI without chromosome analysis?

SUMMARY ANSWER

PGT-A by CCS in the first and second polar body to select euploid embryos for transfer does not substantially increase the live birth rate in women aged 36-40 years.

WHAT IS KNOWN ALREADY

PGT-A has been used widely to select embryos for transfer in ICSI treatment, with the aim of improving treatment effectiveness. Whether PGT-A improves ICSI outcomes and is beneficial to the patients has remained controversial.

STUDY DESIGN, SIZE, DURATION

This is a multinational, multicentre, pragmatic, randomized clinical trial with intention-to-treat analysis. Of 396 women enroled between June 2012 and December 2016, 205 were allocated to CCS of the first and second polar body (study group) as part of their ICSI treatment cycle and 191 were allocated to ICSI treatment without chromosome screening (control group). Block randomization was performed stratified for centre and age group. Participants and clinicians were blinded at the time of enrolment until the day after intervention.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Infertile couples in which the female partner was 36-40 years old and who were scheduled to undergo ICSI treatment were eligible. In those assigned to PGT-A, array comparative genomic hybridization (aCGH) analysis of the first and second polar bodies of the fertilized oocytes was performed using the 24sure array of Illumina. If in the first treatment cycle all oocytes were aneuploid, a second treatment with PB array CGH was offered. Participants in the control arm were planned for ICSI without PGT-A. Main exclusion criteria were three or more previous unsuccessful IVF or ICSI cycles, three or more clinical miscarriages, poor response or low ovarian reserve. The primary outcome was the cumulative live birth rate after fresh or frozen embryo transfer recorded over 1 year after the start of the intervention.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 205 participants in the chromosome screening group, 50 (24%) had a live birth with intervention within 1 year, compared to 45 of the 191 in the group without intervention (24%), a difference of 0.83% (95% CI: -7.60 to 9.18%). There were significantly fewer participants in the chromosome screening group with a transfer (relative risk (RR) = 0.81; 95% CI: 0.74-0.89) and fewer with a miscarriage (RR = 0.48; 95% CI: 0.26-0.90).

LIMITATIONS, REASONS FOR CAUTION

The targeted sample size was not reached because of suboptimal recruitment; however, the included sample allowed a 90% power to detect the targeted increase. Cumulative outcome data were limited to 1 year. Only 11 patients out of 32 with exclusively aneuploid results underwent a second treatment cycle in the chromosome screening group.

WIDER IMPLICATIONS OF THE FINDINGS

The observation that the similarity in birth rates was achieved with fewer transfers, less cryopreservation and fewer miscarriages points to a clinical benefit of PGT-A, and this form of embryo selection may, therefore, be considered to minimize the number of interventions while producing comparable outcomes. Whether these benefits outweigh drawbacks such as the cost for the patient, the higher workload for the IVF lab and the potential effect on the children born after prolonged culture and/or cryopreservation remains to be shown.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the European Society of Human Reproduction and Embryology. Illumina provided microarrays and other consumables necessary for aCGH testing of polar bodies. M.B.'s institution (UZBrussel) has received educational grants from IBSA, Ferring, Organon, Schering-Plough, Merck and Merck Belgium. M.B. has received consultancy and speakers' fees from Organon, Serono Symposia and Merck. G.G. has received personal fees and non-financial support from MSD, Ferring, Merck-Serono, Finox, TEVA, IBSA, Glycotope, Abbott and Gedeon-Richter as well as personal fees from VitroLife, NMC Healthcare, ReprodWissen, BioSilu and ZIVA. W.V., C.S., P.M.B., V.G., G.A., M.D., T.E.G., L.G., G.Ka., G.Ko., J.L., M.C.M., M.P., A.S., M.T., K.V., J.G. and K.S. declare no conflict of interest.

TRIAL REGISTRATION NUMBER

NCT01532284.

TRIAL REGISTRATION DATE

7 February 2012.

DATE OF FIRST PATIENT’S ENROLMENT

25 June 2012.

Preimplantation genetic testing for monogenic diseases: a Brazilian IVF centre experience

OBJECTIVE

To describe the cases of preimplantation genetic testing for monogenic diseases (PGT-M) in fertile couples who had undergone intracytoplasmic sperm injection (ICSI) cycles in a Brazilian in vitro fertilisation (IVF) centre and determine whether these cases were different from those reported from the European Society of Human Reproduction and Embryology (ESHRE).

METHODS

This retrospective collection included data obtained from ICSI-PGT-M cycles between 2011 and 2016. The disease indication, number of biopsied embryos, biopsy stage, diagnosed and affected embryos, and cycles with embryo to transfer as well as implantation, pregnancy and miscarriage rates were analysed and compared to cycles without genetic diagnosis (PGT) and with ESHRE PGD Consortium collection XIV-XV.

RESULTS

From 5,070 cycles performed, 72 had indications for PGT-M. The most common time for biopsy was cleavage-stage; 93% of the embryos had a diagnostic result, 59.4% of which were genetically transferable, resulting in 68% of the cycles with transferred embryos, a 22.1% implantation rate, and a 28.6% pregnancy rate. No differences in clinical outcomes of cycles with PGT-M or without PGT were observed. The day of biopsy and diagnostic success as well as implantation, pregnancy and miscarriage rates were similar to ESHRE collection.

CONCLUSIONS

Although the proportion of cases with PGT-M was low, its efficacy was similar to what was reported in the European collection and represents a viable alternative for families at risk of transmitting a genetic disorder to their offspring. The main difference between our and ESHRE collection were the disease indications, which reflected the admixed, multi-ethnic Brazilian population.

Day 7 blastocyst euploidy supports routine implementation for cycles using preimplantation genetic testing

Objective:

To determine if Day 7 blastocysts merit biopsy, vitrification and transfer consideration by contrasting their aneuploidy and implantation rates to Day 5 and 6 blastocysts.

Methods:

A total of 1,925 blastocysts were biopsied from 402 PGT-A cycles over a 12 to 16 month interval. All embryos were cultured under tri-gas, humidified conditions (37ºC) for up to 7 days (168 hours post-insemination). Biopsied blastocysts were vitrified and trophectoderm samples analyzed using NextGen sequencing. Single euploid embryo transfers were performed (n=254) using either a Day 5 (n=145), Day 6 (n=92) or a Day 7 blastocyst (n=16) post-warming. Euploidy rates and pregnancy outcomes were subsequently assessed and differences determined by day of development and blastocyst quality grade.

Results:

No differences were observed in implantation, pregnancy loss or ongoing pregnancy rates between Day 5 and Day 6 blastocysts. Development to Day 7 accounted for 6.6% of all blastocysts. Euploidy rates were higher in Day 5 blastocysts (53.5%; p<0.05) compared to Day 6 (40.4%) and Day 7 (35.9%). High implantation potential (56.3% to 79.3%) of vitrified-warmed euploid blastocyst occurred independent to the day of development. However, miscarriage/loss rates increased (22.2% vs. 2%; p<0.05) with Day 7 blastocysts, resulting in lower (p<0.05) live birth rates (43.8% vs. 67.4-77.2%).

Conclusion:

Culturing blastocysts to Day 7 has proven beneficial by achieving viable euploid embryos that would have otherwise been discarded. An extra Day of embryo growth allows select patients additional opportunities for in vitro development and possible healthy term live births.

Chromosomal analysis in IVF: just how useful is it?

Designed to minimize chances of genetically abnormal embryos, preimplantation genetic diagnosis (PGD) involves in vitro fertilization (IVF), embryo biopsy, diagnosis and selective embryo transfer. Preimplantation genetic testing for aneuploidy (PGT-A) aims to avoid miscarriage and live born trisomic offspring and to improve IVF success. Diagnostic approaches include fluorescence in situ hybridization (FISH) and more contemporary comprehensive chromosome screening (CCS) including array comparative genomic hybridization (aCGH), quantitative polymerase chain reaction (PCR), next-generation sequencing (NGS) and karyomapping. NGS has an improved dynamic range, and karyomapping can detect chromosomal and monogenic disorders simultaneously. Mosaicism (commonplace in human embryos) can arise by several mechanisms; those arising initially meiotically (but with a subsequent post-zygotic 'trisomy rescue' event) usually lead to adverse outcomes, whereas the extent to which mosaics that are initially chromosomally normal (but then arise purely post-zygotically) can lead to unaffected live births is uncertain. Polar body (PB) biopsy is the least common sampling method, having drawbacks including cost and inability to detect any paternal contribution. Historically, cleavage-stage (blastomere) biopsy has been the most popular; however, higher abnormality levels, mosaicism and potential for embryo damage have led to it being superseded by blastocyst (trophectoderm - TE) biopsy, which provides more cells for analysis. Improved biopsy, diagnosis and freeze-all strategies collectively have the potential to revolutionize PGT-A, and there is increasing evidence of their combined efficacy. Nonetheless, PGT-A continues to attract criticism, prompting questions of when we consider the evidence base sufficient to justify routine PGT-A? Basic biological research is essential to address unanswered questions concerning the chromosome complement of human embryos, and we thus entreat companies, governments and charities to fund more. This will benefit both IVF patients and prospective parents at risk of aneuploid offspring following natural conception. The aim of this review is to appraise the 'state of the art' in terms of PGT-A, including the controversial areas, and to suggest a practical 'way forward' in terms of future diagnosis and applied research.

Targeting Alzheimer's disease with gene and cell therapies

Alzheimer's disease (AD) causes dementia in both young and old people affecting more than 40 million people worldwide. The two neuropathological hallmarks of the disease, amyloid beta (Aβ) plaques and neurofibrillary tangles consisting of protein tau are considered the major contributors to the disease. However, a more complete picture reveals significant neurodegeneration and decreased cell survival, neuroinflammation, changes in protein and energy homeostasis and alterations in lipid and cholesterol metabolism. In addition, gene and cell therapies for severe neurodegenerative disorders have recently improved technically in terms of safety and efficiency and have translated to the clinic showing encouraging results. Here, we review broadly current data within the field for potential targets that could modify AD through gene and cell therapy strategies. We envision that not only Aβ will be targeted in a disease-modifying treatment strategy but rather that a combination of treatments, possibly at different intervention times may prove beneficial in curing this devastating disease. These include decreased tau pathology, neuronal growth factors to support neurons and modulation of neuroinflammation for an appropriate immune response. Furthermore, cell based therapies may represent potential strategies in the future.

Preimplantation genetic testing in assisted reproductive technology

Preimplantation genetic testing is a methodology aimed at the assessment of the genetic composition of an embryo. This diagnostic approach has been used in assisted reproduction for almost thirty years. During these years, the technologies used for embryo's genetic analysis have been continuously improved allowing the development of more precise, comprehensive and robust strategies that are clinically employed nowadays. In this review, the main diagnostic approaches used for embryo genetic and chromosomal assessment are described and discussed both from an embryological and genetic standpoint.