Preimplantation genetic diagnosis for chromosomal rearrangements with the use of array comparative genomic hybridization at the blastocyst stage

Australasian Recurrent Pregnancy Loss Clinical Management Guideline 2024 Part I

Guidelines for the investigation and management of recurrent pregnancy loss (RPL) have been developed in Europe, USA and UK, but there is currently no Australasian guideline. The Australasian Certificate of Reproductive Endocrinology and Infertility Consensus Expert Panel on Trial Evidence group has prepared a two-part guideline to provide guidance on the management of RPL. In Part I chromosomal, anatomical, and endocrine factors are outlined along with relevant recommendations for clinical management, levels of evidence and grades of consensus. In Part II thrombophilia, autoimmune factors, infective, inflammatory, and endometrial causes, environmental and lifestyle factors, male factor and unexplained causes will be outlined.

Self-reported effects of perceived social support on marital quality in balanced translocation patients and their spouses undergoing preimplantation genetic testing in China: actor-partner interdependence model

This study aimed to analyse the relationship between perceived social support and marital quality in balanced translocation patients and their spouses undergoing a preimplantation genetic testing (PGT) treatment cycle in China. The authors assessed the actor and partner effects of perceived social support on marital quality in patient-spouse dyads using a dyadic analysis approach. In total, 59 couples were assessed using self-report questionnaires for marital quality and perceived social support. There were significant differences in marital quality between patients and their spouses (p=.0025) based on the APIM (actor-partner interdependence model) analyses. The perceived social support of both patients (p=.0076) and spouses (p<.001) had a significant effect on individual marital quality for actor effects. Partner effects showed that patients' perceived social support had a significant effect on spouses' marital quality (p=.0156) and the spouses' perceived social support had a significant effect on patients' marital quality (p=.0084). The findings indicate that the level of perceived social support affected both his/her own marital quality and that of his/her spouse.Impact StatementWhat is already known on this subject? Infertility and reproductive treatments affect both partners, that is, the couple as a unit and have a negative impact on an individual's marital satisfaction and social relationships.What do the results of this study add? There are significant differences in marital quality between balanced translocation patients and their spouses. Perceived social support significantly correlated with marital quality in both the actor and partner effects.What are the implications of these findings for clinical practice and/or further research? Health professionals should provide couple-based interventions involving both patients and spouses throughout the PGT treatment to improve perceived social support, thereby improving their marital quality.

Determining Mitochondrial 3243A>G Heteroplasmy Using an ARMS-ddPCR Strategy

OBJECTIVES

Determining mitochondrial DNA (mtDNA) A-to-G substitution at nucleotide 3243 (m.3243A>G) heteroplasmy is essential for both precision diagnosis of m.3243A>G-associated mitochondrial disease and genetic counseling. Precise determination of m.3243A>G heteroplasmy is challenging, however, without appropriate strategies to accommodate heteroplasmic levels ranging from 1% to 100% in samples carrying thousands to millions of mtDNA copies.

METHODS

We used a combined strategy of amplification-refractory mutation system-quantitative polymerase chain reaction (ARMS-qPCR) and droplet digital PCR (ddPCR) to determine m.3243A>G heteroplasmy. Primers were specifically designed and screened for both ARMS-qPCR and ddPCR to determine m.3243A>G heteroplasmy. An optimized ARMS-qPCR-ddPCR-based strategy was established using artificial standards, with different mixtures of m.3243A-containing and m.3243G-containing plasmids and further tested using clinical samples containing the m.3243A>G mutation.

RESULTS

One of 20 primer pairs designed in the study was omitted for ARMS-qPCR-ddPCR strategy application according to criteria of 85% to 110%, R2> 0.98 amplification efficiency, melt curve with a single clear peak, and specificity for m.3243A and m.3243G artificial standards (|CtWt-CtMut|max). Using plasmid standards with various m.3243A>G heteroplasmy (1%-100%) at low, mid, and high copy numbers (3,000, 104, and 105-107, respectively) and DNA from the blood of 20 patients carrying m.3243A>G with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, we found that ARMS-qPCR was reliable for determining m.3243A>G at 3% to 100% for low copy number and 1% to 100% for mid to high copy number samples. Meanwhile, ddPCR was reliable for determining m.3243A>G at 1% to 100% at low to mid copy number samples.

CONCLUSIONS

An ARMS-qPCR-ddPCR-based strategy was successfully established for precise determination of m.3243A>G heteroplasmy in complex clinical samples.

Low feasibility of in vitro matured oocytes originating from cumulus complexes found during ovarian tissue preparation at the moment of gender confirmation surgery and during testosterone treatment for fertility preservation in transgender men

OBJECTIVE

To study the feasibility of in vitro maturation of ovarian tissue oocytes for fertility preservation in transgender men on testosterone treatment.

DESIGN

Cross-sectional study SETTING: University hospital PATIENT(S): Eighty-three transgender men enrolled from November 2015 to January 2019 INTERVENTION(S): In vitro maturation of cumulus-oocyte complexes (COCs) harvested at the time of gender confirmation surgery, and fertilization through intracytoplasmic sperm injection.

MAIN OUTCOME MEASURE(S)

In vitro maturation, fertilization, and blastulation rates; comparison of morphokinetics with vitrified-warmed oocytes; and analysis of the genetic profiles of embryos.

SECONDARY OUTCOMES

association between serum hormone levels; COCs' morphologic characteristics, and vitrification rate.

RESULT(S)

All participants were on testosterone treatment for a median of 83 (64[Quartile 1]; 113.2[Quartile 2]) weeks. A total of 1,903 COCs (mean per participant, 23 ± 15.8) were collected. The in vitro maturation rate was 23.8%, vitrification rate was 21.5%, and survival rate after warming was 72.6% (n = 151). Intracytoplasmic sperm injection was performed in 139 oocytes. The rate of normal fertilized oocytes was 34.5%, and 25 (52.1%) embryos reached day 3. One blastocyst was achieved on day 5. Aberrant cleavage patterns and early embryo arrest were observed in 22 (45.8%) and 44 (91.7%) zygotes, respectively. Compared with vitrified-warmed donor oocytes, a delay was observed in pronuclei disappearance, t2 (time to reach 2 cell stage) timings, and CC1 (the duration of the 1st cell cycle) and SS3 (synchronization of cleavage pattern (calculated as t8-t5) time intervals. A normal genetic pattern was seen in 42% embryos. The proportion of vitrified oocytes was negatively associated with progesterone (odds ratio, 0.76) and positively associated with antimüllerian hormone serum levels (odds ratio, 1.23). The highest vitrification rate was achieved by the morphologic characteristic 344 at day 0 and by 433 at day 2.

CONCLUSION(S)

Ovarian tissue oocytes matured in vitro show low developmental capacity in transgender men, when collected under testosterone treatment.

A Rapid NGS-Based Preimplantation Genetic Testing for Chromosomal Abnormalities in Day-3 Blastomere Biopsy Allows Embryo Transfer Within the Same Treatment Cycle

Nowadays, most of the preimplantation genetic testing (PGT) is performed with a strategy of comprehensive chromosome screening and trophectoderm biopsy. Nevertheless, patients with ovarian insufficiency may not have competent blastocysts. In the present study, we aimed to establish the value of multiple annealing and looping-based amplification cycle (MALBAC)-based next-generation sequencing (NGS) for PGT in day-3 embryos. A total of 94.3% (1168/1239) of embryos yielded informative results, and the overall embryo euploid rate was 21.9% (256/1168). Overall, 225 embryos were transferred in 169 cycles with a clinical pregnancy rate of 49.1% (83/169). The live birth and implantation rates were 47.3% (80/169) and 44.4% (100/225), respectively. Double embryos transfer showed higher clinical pregnancy and live birth rates compared with single embryo transfer, but the implantation rates were similar (44.2% vs. 44.6%, P > 0.05). The euploid rate for reciprocal translocations (16.1%) was significantly lower than that for Robertsonian translocations (28.0%, P < 0.01) and inversions (28.0%, P < 0.01). However, higher percentages of embryos with de novo abnormalities were observed with Robertsonian translocations (23.3%, P < 0.01) and inversions (30.5%, P < 0.01) than with reciprocal translocations (11.6%). We demonstrated that NGS for PGT on day-3 embryos is an effective clinical application, particularly for patients with a diminished ovarian reserve and limited embryos.

Feasibility study of using unbalanced embryos as a reference to distinguish euploid carrier from noncarrier embryos by single nucleotide polymorphism array for reciprocal translocations

OBJECTIVES

To study the feasibility of using unbalanced embryos as a reference in distinguishing euploid carrier and noncarrier embryos by single nucleotide polymorphism (SNP) array-based preimplantation genetic testing (PGT) for reciprocal translocations.

METHODS

After comprehensive chromosome screening (CCS), euploid embryos were identified as normal or carriers using a family member as a reference. Next, unbalanced embryos were used as a reference, and the results were compared with the previous ones. Karyotypes of transferred embryos were validated by prenatal diagnosis.

RESULTS

Of 995 embryos from 110 couples, 288 were found to be euploid. Using a family member as a reference, 142 and 144 embryos were tested to be euploid noncarrier and carrier respectively, and the remaining 2 embryos were undetermined. When unbalanced embryos were selected as references, all the results were consistent with the previous ones. A total of 107 embryos were transferred, resulting in 66 clinical pregnancies. Karyotypes of prenatal diagnosis were all in accordance with the results of tested embryos.

CONCLUSIONS

SNP array-based haplotyping is a rapid and effective way to distinguish between euploid carrier and noncarrier embryos. In case no family member is available as a reference, unbalanced embryos can be used for identification of euploid carrier and noncarrier embryos.

[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.

The Valuable Reference of Live Birth Rate in the Single Vitrified-Warmed BB/BC/CB Blastocyst Transfer: The Cleavage-Stage Embryo Quality and Embryo Development Speed

Background

It is unclear whether we should focus attention on cleavage-stage embryo quality and embryo development speed when transferring single particular grade vitrified-warmed blastocysts, especially poor-quality blastocysts (grade “C”).

Method

This retrospective study considered 3386 single vitrified-warmed blastocyst transfer cycles from January 2010 to December 2017. They were divided into group 1 (AA/AB/BA, n = 374), group 2 (BB, n = 1789), group 3 (BC, n = 901), and group 4 (CB, n = 322). The effects of cleavage-stage embryo quality and embryo development speed were measured in terms of clinical pregnancy and live birth rates in each group.

Results

Pregnancy outcomes showed a worsening trend from groups 1 to 4; the proportion of embryos with better cleavage-stage quality and faster development speed decreased. In group 1, only the blastocyst expansion degree 3 was a negative factor in the clinical pregnancy rate (odds ratio (OR) [95% confidence interval (CI)]: 0.233 [0.091–0.595]) and live birth rate (0.280 [0.093–0.884]). In the other groups (BB, BC, and CB), blastocysts frozen on day 5 had significantly better clinical pregnancy outcomes than those frozen on day 6: 1.373 [1.095–1.722] for group 2, 1.523 [1.055–2.197] for group 3, and 3.627 [1.715–7.671] for group 4. The live birth rate was 1.342 [1.060–1.700] for group 2, 1.544 [1.058–2.253] in group 3, and 3.202 [1.509–6.795] in group 4, all Ps < 0.05). The degree of blastocoel expansion three for clinical pregnancy rate in group 2 (0.350 [0.135–0.906], P < 0.05) and day 3 blastomere number (>7) for live birth rate in group 4 (2.455 [1.190–5.063], P < 0.05) were two important factors.

Conclusion

We should consider choosing BB/BC/CB grade blastocysts frozen on day 5, CB grade blastocysts with day 3 blastomere numbers (>7), and AA/AB/BA grade blastocysts with degrees of expansion (≥4) to obtain better pregnancy outcomes.

Application of improved single blastomere fixation technique in preimplantation genetic diagnosis

To modify a fixation method improving the intensity and clarity of the single blastomeric signal detection by fluorescence in situ hybridization (FISH) in preimplantation genetic diagnosis. 333 cycles of assisted reproduction with preimplantation genetic diagnosis FISH (PGD-FISH) performed in our hospital were analyzed and a total of 3452 single blastomeres were obtained. For the conventional fixation method, the blastomeres were kept in 0.1% sodium citrate with 0.2 mg/ml bovine serum albumin (BSA) for 2-5 min. FISH was performed and the internal relationship between embryo quality and fixed rate, signal detection rate, and signal determination rate was explored. With the modified method, 91.54% of blastomeres were fixed, while 88.30% were fixed with the conventional method. The signal detection rate was significantly increased for the modified group than for the conventional group (compared 98.53% with 94.78%, P < 0.001). Especially, the signal determination rate also showed a significant difference between the two methods (compared 90.51% with 74.17%, P < 0.001). After the development of the fixation method, the fixation efficiency and the signal determination rate were greatly improved, providing more definite diagnosis for the patient. It will hopefully allow more assisted reproduction programs to offer their patients preimplantation genetic diagnosis with FISH.

A systematic review on concurrent aneuploidy screening and preimplantation genetic testing for hereditary disorders: What is the prevalence of aneuploidy and is there a clinical effect from aneuploidy screening?

INTRODUCTION

In assisted reproductive technology, aneuploidy is considered a primary cause of failed embryo implantation. This has led to the implementation of preimplantation genetic testing for aneuploidy in some clinics. The prevalence of aneuploidy and the use of aneuploidy screening during preimplantation genetic testing for inherited disorders has not previously been reviewed. Here, we systematically review the literature to investigate the prevalence of aneuploidy in blastocysts derived from patients carrying or affected by an inherited disorder, and whether screening for aneuploidy improves clinical outcomes.

MATERIAL AND METHODS

PubMed and Embase were searched for articles describing preimplantation genetic testing for monogenic disorders and/or structural rearrangements in combination with preimplantation genetic testing for aneuploidy. Original articles reporting aneuploidy rates at the blastocyst stage and/or clinical outcomes (positive human chorionic gonadotropin, gestational sacs/implantation rate, fetal heartbeat/clinical pregnancy, ongoing pregnancy, miscarriage, or live birth/delivery rate on a per transfer basis) were included. Case studies were excluded.

RESULTS

Of the 26 identified studies, none were randomized controlled trials, three were historical cohort studies with a reference group not receiving aneuploidy screening, and the remaining were case series. In weighted analysis, 34.1% of 7749 blastocysts were aneuploid. Screening for aneuploidy reduced the proportion of embryos suitable for transfer, thereby increasing the risk of experiencing a cycle without transferable embryos. In pooled analysis the percentage of embryos suitable for transfer was reduced from 57.5% to 37.2% following screening for aneuploidy. Among historical cohort studies, one reported significantly improved pregnancy and birth rates but did not control for confounding, one did not report any statistically significant difference between groups, and one properly designed study concluded that preimplantation genetic testing for aneuploidy enhanced the chance of achieving a pregnancy while simultaneously reducing the chance of miscarriage following single embryo transfer.

CONCLUSIONS

On average, aneuploidy is detected in 34% of embryos when performing a single blastocyst biopsy derived from patients carrying or affected by an inherited disorder. Accordingly, when screening for aneuploidy, the risk of experiencing a cycle with no transferable embryos increases. Current available data on the clinical effect of preimplantation genetic testing for aneuploidy performed concurrently with preimplantation genetic testing for inherited disorders are sparse, rendering the clinical effect from preimplantation genetic testing for aneuploidy difficult to access.

Preserving Genome Integrity During the Early Embryonic DNA Replication Cycles

During the very early stages of embryonic development chromosome replication occurs under rather challenging conditions, including a very short cell cycle, absence of transcription, a relaxed DNA damage response and, in certain animal species, a highly contracted S-phase. This raises the puzzling question of how the genome can be faithfully replicated in such a peculiar metabolic context. Recent studies have provided new insights into this issue, and unveiled that embryos are prone to accumulate genetic and genomic alterations, most likely due to restricted cellular functions, in particular reduced DNA synthesis quality control. These findings may explain the low rate of successful development in mammals and the occurrence of diseases, such as abnormal developmental features and cancer. In this review, we will discuss recent findings in this field and put forward perspectives to further study this fascinating question.

Chromosomal mosaicism in human blastocysts: the ultimate challenge of preimplantation genetic testing?

STUDY QUESTION

To what extent does a trophectoderm (TE) biopsy reliably reflect the chromosomal constitution of the inner cell mass (ICM) in human blastocysts?

SUMMARY ANSWER

Concordance between TE and ICM was established in 62.1% of the embryos analysed.

WHAT IS KNOWN ALREADY

Next generation sequencing (NGS) platforms have recently been optimised for preimplantation genetic testing for aneuploidies (PGT-A). However, higher sensitivity has led to an increase in reports of chromosomal mosaicism within a single TE biopsy. This has raised substantial controversy surrounding the prevalence of mosaicism in human blastocysts and the clinical implications of heterogeneity between the TE and ICM.

STUDY DESIGN, SIZE, DURATION

To define the distribution and rate of mosaicism in human blastocysts, we assessed chromosomal profiles of the ICM and multiple TE portions obtained from the same embryo. We evaluated donated embryos with an unknown chromosomal profile (n = 34), as well as PGT-A blastocysts, previously diagnosed as abnormal or mosaic (n = 24). Our intra-embryo comparison included a total of 232 samples, obtained from 58 embryos.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Four embryo samples, including the ICM and three distinct TE portions, were acquired from good quality blastocysts by micromanipulation. Whole genome amplification (WGA), followed by NGS was performed on all embryo segments. Profiles were compared between samples from the same embryo, while the results from pretested blastocysts were further correlated to the original report. The embryos investigated in our untested group were obtained from good prognosis patients (n = 25), with maternal age ranging from 23 to 39 years. For the pretested embryo group, maternal age ranged from 23 to 40 years (n = 18).

MAIN RESULTS AND THE ROLE OF CHANCE

We uncover chromosomal mosaicism, involving both numerical and structural aberrations, in up to 37.9% of the blastocysts analysed. Within the untested group, the overall concordance between the ICM and all TE portions was 55.9%. A normal ICM was detected in 20.6% of blastocysts for which at least one TE portion showed a chromosomal aberration. Conversely, 17.6% of embryos presented with mosaic or uniform abnormalities within the ICM, while showing normal or mosaic TE profiles. For the pretested blastocysts, the overall concordance between the ICM and all TE samples was 70.8%. However, 50% of embryos previously diagnosed with mosaicism did not confirm the original diagnosis. Notably, 31.3% of embryos with a mosaic aberration reported in the original TE biopsy, revealed a euploid profile in the ICM and all three TE samples. Taken together, concordance between the ICM and all TE portions was established in 62.1% of blastocysts, across both embryo groups. Finally, we could not observe a significant effect of age on embryo mosaicism (P = 0.101 untested group; P = 0.7309 pretested group). Similarly, ICM and TE quality were not found to affect the occurrence of chromosomal mosaicism (P = 0.718 and P = 0.462 untested group; P = 1.000 and P = 0.2885 pretested group).

LARGE SCALE DATA

All data that support the findings of this study are available online in Vivar (http://cmgg.be/vivar) upon request.

LIMITATIONS, REASONS FOR CAUTION

Evaluating biological variation in some instances remains challenging. The technological limitations of sampling mitotic errors that lead to mosaicism, as well as WGA artefacts, warrant careful interpretation.

WIDER IMPLICATIONS OF THE FINDINGS

Our results highlight the complex nature of genetic (in)stability during early ontogenesis and indicate that blastocysts harbour a higher rate of chromosomal mosaicism than may have been anticipated. Moreover, our findings reveal an overall high diagnostic sensitivity and relatively low specificity in the context of PGT-A. This suggests that a considerable proportion of embryos are potentially being classified as clinically unsuitable. Ultimately, more precise quantification will benefit the clinical management of embryo mosaicism.

STUDY FUNDING/COMPETING INTEREST(S)

M.P. is supported by the Special Research Fund, Bijzonder Onderzoeksfonds (BOF01D08114). J.T. and L.D. are supported by the agency for innovation through science (131673, 141441). B.H. and this research are supported by the Special Research Fund, Bijzonder Onderzoeksfonds (BOF15/GOA/011). The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Reproductive outcome following pre-implantation genetic diagnosis (PGD) in the UK

In 2013, the National Health Service Commissioning board centralized the funding in England for up to three cycles of pre-implantation genetic diagnosis (PGD) for couples who have, or are carriers of, a specific genetic disorder. This study presents the historical data of PGD cycles and their clinical outcomes in UK as extrapolated from the national data registry. Retrospective analysis of outcome of cycles undergoing pre-implantation genetic diagnosis in the UK over the past 20 years was performed from the Human Fertilisation and Embryology Authority database (n = 2974). Binary logistic regression was used to determine trends over time and adjusted for maternal age. Briefly, the number of PGD cycles has risen 127-fold from 1991 to 2012 with 3.6-fold increase (360% rise) from 2004 to 2012. A total of one in four embryos following pre-implantation genetic diagnosis did not reach embryo transfer and 92% of these were due to a failure to survive. The live birth rate has risen over 20 years and there has been a steady decline in reported incidence of congenital abnormalities (p < 0.07). PGD has thus emerged as a safe and effective alternative to prenatal diagnosis but with ever evolving technological advances, a robust system of data collection that incorporates techniques used and reporting of mutation-specific clinical outcomes is suggested.