Clinical outcome of preimplantation genetic diagnosis and screening using next generation sequencing

Association between frozen embryo transfer and childhood allergy: a retrospective cohort study

RESEARCH QUESTION

Does frozen embryo transfer (FET) increase the risk of allergic diseases in offspring?

DESIGN

This study followed up 653 singleton children: 166 born through FET and 487 born through natural conception. Demographic characteristics, perinatal information and allergic diseases of children and their parents were collected through clinical medical systems and questionnaires. Among these 653 children, allergen-specific immunoglobulin E (IgE) testing was performed using peripheral blood samples collected from 207 children: 145 in the FET group and 62 in the natural conception group. The prevalence of allergic diseases and positive rates of allergen-specific IgE testing were compared between the two groups with adjustments for confounding factors.

RESULTS

The prevalence of food allergy was significantly higher in children born through FET compared with children born through natural conception (adjusted OR = 3.154, 95% CI 1.895-5.250; P < 0.001). In addition, positive rates of food allergen sensitization were higher in children in the FET group compared with children in the natural conception group (adjusted OR = 5.769, 95% CI 2.859-11.751, P < 0.001). Children in the FET group had a higher positive sensitization rate to at least one allergen compared with children in the natural conception group (adjusted OR = 3.127, 95% CI 1.640-5.961, P < 0.001). No association was observed between FET and other allergic diseases, including asthma (P = 0.136), atopic dermatitis (P = 0.130) and allergic rhinitis (P = 0.922). Allergen sensitization IgE testing indicated no differences between the two groups in terms of positive sensitization rates of other common allergens, including animal and insect allergens (P = 0.627), inhaled outdoor allergens (P = 0.915) and inhaled outdoor allergens (P = 0.544).

CONCLUSION

This study suggests that children born through FET have increased risk of developing food allergy in early childhood.

Clinical outcomes in carriers of insertional translocation: a retrospective analysis of comprehensive chromosome screening results

Objective

To evaluate the clinical outcomes in the carriers of insertional translocation (IT).

Design

Retrospective case series.

Setting

University-affiliated reproductive medical center.

Patients

Twenty-three couples with ITs.

Intervention

No direct interventions were involved; however, this study included patients who underwent preimplantation genetic testing for structural chromosomal rearrangements (PGT-SR).

Main Outcome Measure

Outcome of preimplantation genetic testing for structural chromosomal rearrangements and percentage of blastocysts available for transfer.

Results

Among 23 IT carriers, 15 were simple interchromosome ITs (type A), 3 were intrachromosome IT carriers (type B), and 5 were interchromosome IT carriers combined with other translocations (type C). A total of 190 blastocysts from 30 cycles were biopsied, 187 embryos were tested successfully, and only 57 blastocysts (30.5%) from 21 patients were available for transfer (normal or balanced). The unbalanced rearrangement rate of type C was 79.2% (42/53), and the proportion of type A was 50.0% (57/114), which was significantly higher than that of type B (5%, 1/20). In type A, the probability of embryos harboring unbalanced rearrangement in female carriers was 56.0% (51/91), which was higher than that in male carriers (26.1%, 6/23). Furthermore, the haploid autosomal length value of the inserted fragment was correlated linearly with the incidence of abnormal embryos. In type A gametes, most gametes produced by 2:2 separation without crossover, and no 3:1 separation gamete was observed.

Conclusions

The chance of identifying normal or balanced and mosaic blastocysts per mature oocytes in patients with ITs are 16.6% (67/404). Greater IT complexity results in fewer transferable embryos. For simple interchromosome ITs, female carriers and those with higher haploid autosomal length values have a higher risk of producing embryos with unbalanced rearrangement.

Correlations between clinical parameters, blastocyst morphological classification and embryo euploidy

OBJECTIVE

The aim of the present study was to evaluate clinical and embryo parameters to predict embryo ploidy.

METHODS

In this retrospective analysis, we studied 838 biopsied day-5 blastocysts from 219 patients in the period from May 2021 to July 2022. All embryos were morphologically classified before biopsy and were divided into two groups according to genetic test results. Euploid embryos (299) were compared with aneuploid embryos (539) based on maternal age, anti-Mullerian hormone, antral follicle count, and embryo morphology.

RESULTS

Maternal age (36.2±3.0) of euploid embryos was lower than maternal age (37.1±2.5) of aneuploid embryos (p<0.0001). AMH levels were higher (3.9±1.2) in the group of euploid embryos than in the group of aneuploid embryos (3.6±1.3, p<0.0001). However, the AFC was not different in the group of euploid embryos (15.3±6.0) compared to the group of aneuploid embryos (14.5±5.9, p=0.07). The presence of aneuploidy was negatively correlated with top embryo quality (embryos 4AA and 4AB). All euploid embryos (299) were top quality versus 331 of 539 (61.49%) aneuploid embryos (p<0.0001).

CONCLUSIONS

We found that euploid embryos were associated with lower maternal age, higher AMH levels, and higher quality embryos.

Chinese experts' consensus guideline on preimplantation genetic testing of monogenic disorders

Recent developments in molecular biological technologies and genetic diagnostic methods, accompanying with updates of relevant terminologies, have enabled the improvements of new strategies of preimplantation genetic testing for monogenic (single gene) disorders (PGT-M) to prevent the transmission of inherited diseases. However, there has been much in the way of published consensus on PGT-M. To properly regulate the application of PGT-M, Chinese experts in reproductive medicine and genetics have jointly developed this consensus statement. The consensus includes indications for patient selection, genetic and reproductive counseling, informed consent, diagnostic strategies, report generation, interpretation of results and patient follow-ups. This consensus statement serves to assist in establishment of evidence-based clinical and laboratory practices for PGT-M.

The effect of vitrification on blastocyst mitochondrial DNA dynamics and gene expression profiles

PURPOSE

Does vitrification/warming affect the mitochondrial DNA (mtDNA) content and the gene expression profile of blastocysts?

METHODS

Prospective cohort study in which 89 blastocysts were obtained from 50 patients between July 2017 and August 2018. mtDNA was measured in a total of 71 aneuploid blastocysts by means of real-time polymerase chain reaction (RT-PCR). Transcriptomic analysis was performed by RNA sequencing (RNA-seq) in an additional 8 aneuploid blastocysts cultured for 0 h after warming, and 10 aneuploid blastocysts cultured for 4-5 h after warming.

RESULTS

A significant decrease in mtDNA content just during the first hour after the warming process in blastocysts was found (P < 0.05). However, mtDNA content experimented a significantly increased along the later culture hours achieving the original mtDNA levels before vitrification after 4-5 h of culture (P < 0.05). Gene expression analysis and functional enrichment analysis revealed that such recovery was accompanied by upregulation of pathways associated with embryo developmental capacity and uterine embryo development. Interestingly, the significant increase in mtDNA content observed in blastocysts just after warming also coincided with the differential expression of several cellular stress response-related pathways, such as apoptosis, DNA damage, humoral immune responses, and cancer.

CONCLUSION

To our knowledge, this is the first study demonstrating in humans, a modulation in blastocysts mtDNA content in response to vitrification and warming. These results will be useful in understanding which pathways and mechanisms may be activated in human blastocysts following vitrification and warming before a transfer.

ESHRE good practice recommendations on recurrent implantation failure

STUDY QUESTION

How should recurrent implantation failure (RIF) in patients undergoing ART be defined and managed?

SUMMARY ANSWER

This is the first ESHRE good practice recommendations paper providing a definition for RIF together with recommendations on how to investigate causes and contributing factors, and how to improve the chances of a pregnancy.

WHAT IS KNOWN ALREADY

RIF is a challenge in the ART clinic, with a multitude of investigations and interventions offered and applied in clinical practice, often without biological rationale or with unequivocal evidence of benefit.

STUDY DESIGN SIZE DURATION

This document was developed according to a predefined methodology for ESHRE good practice recommendations. Recommendations are supported by data from the literature, if available, and the results of a previously published survey on clinical practice in RIF and the expertise of the working group. A literature search was performed in PubMed and Cochrane focussing on 'recurrent reproductive failure', 'recurrent implantation failure', and 'repeated implantation failure'.

PARTICIPANTS/MATERIALS SETTING METHODS

The ESHRE Working Group on Recurrent Implantation Failure included eight members representing the ESHRE Special Interest Groups for Implantation and Early Pregnancy, Reproductive Endocrinology, and Embryology, with an independent chair and an expert in statistics. The recommendations for clinical practice were formulated based on the expert opinion of the working group, while taking into consideration the published data and results of the survey on uptake in clinical practice. The draft document was then open to ESHRE members for online peer review and was revised in light of the comments received.

MAIN RESULTS AND THE ROLE OF CHANCE

The working group recommends considering RIF as a secondary phenomenon of ART, as it can only be observed in patients undergoing IVF, and that the following description of RIF be adopted: 'RIF describes the scenario in which the transfer of embryos considered to be viable has failed to result in a positive pregnancy test sufficiently often in a specific patient to warrant consideration of further investigations and/or interventions'. It was agreed that the recommended threshold for the cumulative predicted chance of implantation to identify RIF for the purposes of initiating further investigation is 60%. When a couple have not had a successful implantation by a certain number of embryo transfers and the cumulative predicted chance of implantation associated with that number is greater than 60%, then they should be counselled on further investigation and/or treatment options. This term defines clinical RIF for which further actions should be considered. Nineteen recommendations were formulated on investigations when RIF is suspected, and 13 on interventions. Recommendations were colour-coded based on whether the investigations/interventions were recommended (green), to be considered (orange), or not recommended, i.e. not to be offered routinely (red).

LIMITATIONS REASONS FOR CAUTION

While awaiting the results of further studies and trials, the ESHRE Working Group on Recurrent Implantation Failure recommends identifying RIF based on the chance of successful implantation for the individual patient or couple and to restrict investigations and treatments to those supported by a clear rationale and data indicating their likely benefit.

WIDER IMPLICATIONS OF THE FINDINGS

This article provides not only good practice advice but also highlights the investigations and interventions that need further research. This research, when well-conducted, will be key to making progress in the clinical management of RIF.

STUDY FUNDING/COMPETING INTERESTS

The meetings and technical support for this project were funded by ESHRE. N.M. declared consulting fees from ArtPRED (The Netherlands) and Freya Biosciences (Denmark); Honoraria for lectures from Gedeon Richter, Merck, Abbott, and IBSA; being co-founder of Verso Biosense. He is Co-Chief Editor of Reproductive Biomedicine Online (RBMO). D.C. declared being an Associate Editor of Human Reproduction Update, and declared honoraria for lectures from Merck, Organon, IBSA, and Fairtility; support for attending meetings from Cooper Surgical, Fujifilm Irvine Scientific. G.G. declared that he or his institution received financial or non-financial support for research, lectures, workshops, advisory roles, or travelling from Ferring, Merck, Gedeon-Richter, PregLem, Abbott, Vifor, Organon, MSD, Coopersurgical, ObsEVA, and ReprodWissen. He is an Editor of the journals Archives of Obstetrics and Gynecology and Reproductive Biomedicine Online, and Editor in Chief of Journal Gynäkologische Endokrinologie. He is involved in guideline developments and quality control on national and international level. G.L. declared he or his institution received honoraria for lectures from Merck, Ferring, Vianex/Organon, and MSD. He is an Associate Editor of Human Reproduction Update, immediate past Coordinator of Special Interest Group for Reproductive Endocrinology of ESHRE and has been involved in Guideline Development Groups of ESHRE and national fertility authorities. D.J.M. declared being an Associate Editor for Human Reproduction Open and statistical Advisor for Reproductive Biomedicine Online. B.T. declared being shareholder of Reprognostics and she or her institution received financial or non-financial support for research, clinical trials, lectures, workshops, advisory roles or travelling from support for attending meetings from Ferring, MSD, Exeltis, Merck Serono, Bayer, Teva, Theramex and Novartis, Astropharm, Ferring. The other authors had nothing to disclose.

DISCLAIMER

This Good Practice Recommendations (GPR) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation. ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results. They do not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type. Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

Effect of Frozen-Thawed Embryo Transfer on the Metabolism of Children in Early Childhood

Background: As a routine procedure in assisted reproductive technology (ART), it is crucial to assess the safety of frozen and thawed embryo transfer (FET). We aimed to investigate the metabolic profile of children conceived through FET in their early childhood. Method: A total of 147 children between the age of 1.5 and 4 years old, conceived through FET or naturally conceived (NC), were recruited. A total of 89 children, 65 in the FET group and 24 in the NC group (matched with the FET group based on children’s BMI) were included in the final statistical analysis of biochemical markers and metabolomics. Results: Children conceived through FET had a lower level of fasting insulin level and HORM-IR and a higher level of fasting glucose and APOE as compared to children naturally conceived. Metabolomics showed that there were 16 small differential metabolites, mainly including amino acids, carnitines, organic acids, butyric, and secondary bile acid between two groups, which enriched in Nitrogen metabolism, Butanoate metabolism, Phenylalanine metabolism, and D-Arginine and D-ornithine metabolism pathways. Conclusion: Although the FET group had a significantly higher level of APOE and fasting glucose, it cannot yet be considered that children in the FET group had an obvious disorder of glucose and lipid metabolism. However, the potentially more active intestinal flora and lower carnitine levels of children in the FET group suggested by metabolomics are worth further exploration.

Ultra-low-coverage genome-wide association study-insights into gestational age using 17,844 embryo samples with preimplantation genetic testing

BACKGROUND

Very low-coverage (0.1 to 1×) whole genome sequencing (WGS) has become a promising and affordable approach to discover genomic variants of human populations for genome-wide association study (GWAS). To support genetic screening using preimplantation genetic testing (PGT) in a large population, the sequencing coverage goes below 0.1× to an ultra-low level. However, the feasibility and effectiveness of ultra-low-coverage WGS (ulcWGS) for GWAS remains undetermined.

METHODS

We built a pipeline to carry out analysis of ulcWGS data for GWAS. To examine its effectiveness, we benchmarked the accuracy of genotype imputation at the combination of different coverages below 0.1× and sample sizes from 2000 to 16,000, using 17,844 embryo PGT samples with approximately 0.04× average coverage and the standard Chinese sample HG005 with known genotypes. We then applied the imputed genotypes of 1744 transferred embryos who have gestational ages and complete follow-up records to GWAS.

RESULTS

The accuracy of genotype imputation under ultra-low coverage can be improved by increasing the sample size and applying a set of filters. From 1744 born embryos, we identified 11 genomic risk loci associated with gestational ages and 166 genes mapped to these loci according to positional, expression quantitative trait locus, and chromatin interaction strategies. Among these mapped genes, CRHBP, ICAM1, and OXTR were more frequently reported as preterm birth related. By joint analysis of gene expression data from previous studies, we constructed interrelationships of mainly CRHBP, ICAM1, PLAGL1, DNMT1, CNTLN, DKK1, and EGR2 with preterm birth, infant disease, and breast cancer.

CONCLUSIONS

This study not only demonstrates that ulcWGS could achieve relatively high accuracy of adequate genotype imputation and is capable of GWAS, but also provides insights into the associations between gestational age and genetic variations of the fetal embryos from Chinese population.

Segmental aneuploidies with 1 Mb resolution in human preimplantation blastocysts

PURPOSE

This study aimed to investigate the spectrum and characteristics of segmental aneuploidies (SAs) of <10 megabase (Mb) length in human preimplantation blastocysts.

METHODS

Preimplantation genetic testing for aneuploidy was performed in 15,411 blastocysts from 5171 patients using a validated 1 Mb resolution platform. The characteristics and spectrum of SAs, including the incidence, sizes, type, inheritance pattern, clinical significance, and embryo distribution, were studied.

RESULTS

In total, 6.4% of the 15,411 blastocysts carried SAs of >10 Mb, 4.9% of embryos had SAs ranging between 1 to 10 Mb, and 84.3% of 1 to 10 Mb SAs were <5 Mb in size. Inheritance pattern analysis indicated that approximately 63.8% of 1 to 10 Mb SAs were inherited and were predominantly 1 to 3 Mb in size. Furthermore, 18.4% of inherited SAs and 51.9% de novo 1 to 10 Mb SAs were pathogenic or likely pathogenic (P/LP). Different from whole-chromosome aneuploidies, reanalysis indicated that 50% of the de novo 1 to 10 Mb SAs and 70% of the >10 Mb SAs arose from mitotic errors.

CONCLUSION

Based on the established platform, 1 to 10 Mb SAs are common in blastocysts and include a subset of P/LP SAs. Inheritance pattern analysis and clinical interpretation based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines contributed to determine the P/LP SAs.

A case of complex balanced chromosomal translocations associated with adverse pregnancy outcomes

Complex chromosomal rearrangements (CCR) are rare chromosomal structural abnormalities. The chromosomal structural variants in CCR carriers are one of the factors contributing to a history of adverse pregnancy and childbirth. In this study, we report a patient with a history of adverse pregnancy and childbirth who exhibited complex balanced chromosomal translocations. The female patient was phenotypically and intellectually normal; in her first pregnancy, the embryo was damaged, and a histological examination of the chromosomes of the embryos revealed a deletion of approximately 4.66 Mb at 1p32.3p32.2, a duplication of approximately 1.02 Mb at 1p22.2p22.1, a duplication of approximately 1.46 Mb at 6q27 and a deletion of approximately 7.78 Mb at 9p24.3p24.1. Chromosomal examinations of the patient revealed the karyotype to be 46,XX,(1;9)(p32; p34). In the second pregnancy, the foetus was diagnosed prenatally with three or more positive ultrasound soft indicators. The patient's karyotype was re-examined and further confirmed by fluorescence in situ hybridisation as 46,XX,t(1;9;6)(p31;p22;q27), revealing this patient was a carrier of complex balanced chromosomal translocations. Carriers of CCR have a higher risk of spontaneous abortion, and genetic counselling clinicians should consider the karyotype analyses of such patients in clinical practice and recheck their chromosomes if necessary.

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.

Logistic regression analyses of factors affecting the euploidy of blastocysts undergoing in vitro fertilization and preimplantation genetic testing

Embryo chromosomal abnormalities are considered as the main cause of low pregnancy rate for in vitro fertilization (IVF). Recently, a new metric of success in assisted reproductive technology, that is, the ability to achieve at least 1 euploid blastocyst for transfer, has been brought into focus among clinicians. Our study aimed to investigate the effects of different factors on the euploidy of blastocysts undergoing IVF and preimplantation genetic testing (PGT). This retrospective observational study included 493 cycles underwent IVF/intracytroplasmatic sperm injection intended to obtain trophectoderm biopsy for PGT from June 2016 to December 2019 at a single academic fertility center. Logistic regression was adopted to analyze the clinical characteristics and embryonic data related to the ability to achieve at least 1 euploid blastocyst for transfer. The study took 1471 blastocysts from 493 cycles as samples for PGT. Among them, 149 cycles (30.22%) had no euploid blastocyst and 344 cycles (69.78%) had at least 1 euploid blastocyst. A multivariate logistic analysis suggested that maternal age >36, abnormal parental karyotype, nonfirst cycles and blastocysts number per cycle <3 were the risk factors for no euploid blastocyst. The parental karyotype, maternal age, number of cycles, and number of blastocysts per cycle were the dominant factors affecting the ability to achieve at least 1 euploid blastocyst for transfer and therefore could be regarded as potential predictors for genetic counseling.

Blood CD4+CD25+ T regulatory cells constitute a potential predictive marker of subsequent miscarriage in unexplained recurrent pregnancy loss

The aim of this study was to investigate the relationship between pre-pregnancy blood immune status and unexplained recurrent pregnancy loss (URPL), and to evaluate the predictive value of pre-pregnancy blood Treg levels for subsequent miscarriage in patients with URPL. We retrospectively analyzed 76 women who had experienced two or more miscarriages before 24 weeks of gestation for no obvious reason, and 74 women who had achieved live births as controls. Flow-cytometric analysis of peripheral blood CD4 + T cells, CD8 + T cells, NK cells, NKT cells, B cells, NK cell subpopulations (including CD56^bright NK cells, CD56^dim NK cells, CD56^dimCD16⁺ NK cells, and CD56^brightCD16^- NK cells) was executed in the luteal phase of women in the URPL and control groups. When we reviewed and analyzed reproductive outcomes in URPL patients, we found that blood Tregs were significantly lower in the URPL group than in the controls (1.89% ± 0.61% vs. 2.15% ± 0.58%, P < 0.01) during the luteal phase pre-pregnancy. However, we discerned no differences among blood CD4⁺T cells, CD8⁺T cells, B cells, NKT cells, or NK cells, NK subpopulations (CD56^bright NKs, CD56^dim NKs, CD56^dimCD16⁺ NKs, or CD56^brightCD16^- NKs) between the two groups. By implementing receiver operating characteristic (ROC) curve analysis to determine whether Treg levels predicted subsequent miscarriages, we found that the area under the ROC curves was 0.714, and that the cutoff value was 1.35, with a sensitivity of 0.556 and specificity of 0.923. Based on the cutoff value, we divided pregnant URPL patients into two groups, demonstrating that the subsequent miscarriage rates in the low-Treg level group (<1.35%) were significantly higher than those in the normal-Treg level group (>1.35%) (71.43% vs. 14.29%, P < 0.01). CONCLUSION: The pre-pregnancy blood Treg level was a potential marker that predicted subsequent miscarriage in women with URPL.

Risk Factors Affecting Alternate Segregation in Blastocysts From Preimplantation Genetic Testing Cycles of Autosomal Reciprocal Translocations

Reciprocal translocations are the most common structural chromosome rearrangements and may be associated with reproductive problems. Therefore, the objective of this study was to analyze factors that can influence meiotic segregation patterns in blastocysts for reciprocal translocation carriers. Segregation patterns of quadrivalents in 10,846 blastocysts from 2,871 preimplantation genetic testing cycles of reciprocal translocation carriers were analyzed. The percentage of normal/balanced blastocysts was 34.3%, and 2:2 segregation was observed in 90.0% of the blastocysts. Increased TAR1 (ratio of translocated segment 1 over the chromosome arm) emerged as an independent protective factor associated with an increase in alternate segregation (p = 0.004). Female sex and involvement of an acrocentric chromosome (Acr-ch) were independent risk factors that reduced alternate segregation proportions (p < 0.001). Notably, a higher TAR1 reduced the proportion of adjacent-1 segregation (p < 0.001); a longer translocated segment and female sex increased the risk of adjacent-2 segregation (p = 0.009 and p < 0.001, respectively). Female sex and involvement of an Acr-ch enhanced the ratio of 3:1 segregation (p < 0.001 and p = 0.012, respectively). In conclusion, autosomal reciprocal translocation carriers have reduced proportions of alternate segregation in blastocysts upon the involvement of an Acr-ch, female sex, and lower TAR1. These results may facilitate more appropriate genetic counseling for couples with autosomal reciprocal translocation regarding their chances of producing normal/balanced blastocysts.

Preimplantation genetic testing for aneuploidy (PGT-A)-a single-center experience

PURPOSE

The aim of this study was to determine the prevalence and nature of human embryonic aneuploidy based on the preimplantation genetic testing for aneuploidy (PGT-A), the distribution of aneuploidy across the individual chromosomes, and their relationship to maternal age.

METHODS

This is a retrospective cohort study conducted at a single center. The study includes subjects who opted for PGT-A in their in vitro fertilization (IVF) cycle from 2016 to 2020. PGT-A was performed on 1501 embryos from 488 patients in 535 cycles. PGT-A was performed using NGS-based technique on Ion Torrent PGM (Life Technologies). Analysis was performed to determine the (i) frequency of the aneuploidy, (ii) the chromosome most commonly affected, (iii) relationship between maternal age and the rate of aneuploidy, and (iv) incidence of segmental aneuploidy.

RESULTS

The overall frequency of aneuploidy was observed to be 46.8%. The incidence of aneuploidy rate was ~ 28% at maternal age < 30 years which steadily increased to ~ 67% in women above 40 years. High frequency of aneuploidy was observed in chromosomes 16, 22, 21, and 15. Segmental abnormalities, involving loss or gain of chromosomal fragments, were observed at a frequency of 5.3%, and highest incidence of segmental gain was observed on the q-arm of chromosome 9.

CONCLUSION

The study provides important information regarding the frequency of the aneuploidy in IVF cohort and the most frequent chromosomal abnormality. The study further emphasizes the relationship between maternal age and aneuploidy. This study has important implications which help clinicians and genetic counselors in providing information in patient counseling.

RNA splicing analysis contributes to reclassifying variants of uncertain significance and improves the diagnosis of monogenic disorders

BACKGROUND

Numerous variants of uncertain significance (VUSs) have been identified by whole exome sequencing in clinical practice. However, VUSs are not currently considered medically actionable.

OBJECTIVE

To assess the splicing patterns of 49 VUSs in 48 families identified clinically to improve genetic counselling and family planning.

METHODS

Forty-nine participants with 49 VUSs were recruited from the Reproductive and Genetic Hospital of CITIC-Xiangya. Bioinformatic analysis was performed to preliminarily predict the splicing effects of these VUSs. RT-PCR and minigene analysis were used to assess the splicing patterns of the VUSs. According to the results obtained, couples opted for different methods of reproductive interventions to conceive a child, including prenatal diagnosis and preimplantation genetic testing (PGT).

RESULTS

Eleven variants were found to alter pre-mRNA splicing and one variant caused nonsense-mediated mRNA decay, which resulted in the reclassification of these VUSs as likely pathogenic. One couple chose to undergo in vitro fertilisation with PGT treatment; a healthy embryo was transferred and the pregnancy is ongoing. Three couples opted for natural pregnancy with prenatal diagnosis. One couple terminated the pregnancy because the fetus was affected by short-rib thoracic dysplasia and harboured the related variant. The infants of the other two couples were born and were healthy at their last recorded follow-up.

CONCLUSION

RNA splicing analysis is an important method to assess the impact of sequence variants on splicing in clinical practice and can contribute to the reclassification of a significant proportion of VUSs. RNA splicing analysis should be considered for genetic disease diagnostics.

Identifying Balanced Chromosomal Translocations in Human Embryos by Oxford Nanopore Sequencing and Breakpoints Region Analysis

Background: Balanced chromosomal aberrations, especially balanced translocations, can cause infertility, recurrent miscarriage or having chromosomally defective offspring. Preimplantation genetic testing for structural rearrangement (PGT-SR) has been widely implemented to improve the clinical outcomes by selecting euploid embryos for transfer, whereas embryos with balanced translocation karyotype were difficult to be distinguished by routine genetic techniques from those with a normal karyotype.

Method: In this present study, we developed a clinically applicable method for reciprocal translocation carriers to reduce the risk of pregnancy loss. In the preclinical phase, we identified reciprocal translocation breakpoints in blood of translocation carriers by long-read Oxford Nanopore sequencing, followed by junction-spanning polymerase chain reaction (PCR) and Sanger sequencing. In the clinical phase of embryo diagnosis, aneuploidies and unbalanced translocations were screened by comprehensive chromosomal screening (CCS) with single nucleotide polymorphism (SNP) microarray, carrier embryos were diagnosed by junction-spanning PCR and family haplotype linkage analysis of the breakpoints region. Amniocentesis and cytogenetic analysis of fetuses in the second trimester were performed after embryo transfer to conform the results diagnosed by the presented method.

Results: All the accurate reciprocal translocation breakpoints were effectively identified by Nanopore sequencing and confirmed by Sanger sequencing. Twelve embryos were biopsied and detected, the results of junction-spanning PCR and haplotype linkage analysis were consistent. In total, 12 biopsied blastocysts diagnosed to be euploid, in which 6 were aneuploid or unbalanced, three blastocysts were identified to be balanced translocation carriers and three to be normal karyotypes. Two euploid embryos were subsequently transferred back to patients and late prenatal karyotype analysis of amniotic fluid cells was performed. The outcomes diagnosed by the current approach were totally consistent with the fetal karyotypes.

Conclusions: In summary, these investigations in our study illustrated that chromosomal reciprocal translocations in embryos can be accurately diagnosed. Long-read Nanopore sequencing and breakpoint analysis contributes to precisely evaluate the genetic risk of disrupted genes, and provides a way of selecting embryos with normal karyotype, especially for couples those without a reference.

The inconsistency between two major aneuploidy-screening platforms-single-nucleotide polymorphism array and next-generation sequencing-in the detection of embryo mosaicism

BACKGROUND

In preimplantation genetic testing for aneuploidy (PGT-A), appropriate evaluation of mosaic embryos is important because of the adverse implications of transferring embryos with high-level mosaicism or discarding those with low-level mosaicism. Despite the availability of multiple reliable techniques for PGT-A, data comparing the detection of mosaicism using these techniques are scarce. To address this gap in the literature, we compared the detection ability of the two most commonly used PGT-A platforms, next-generation sequencing (NGS) and the single-nucleotide polymorphism (SNP) array, for mosaic embryos.

RESULTS

We retrospectively reviewed the data of PGT-A or preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR) conducted at our center from January 2018 to October 2020, and selected blastocysts that underwent aneuploidy screening with both an SNP array and NGS. Trophectoderm biopsy, multiple displacement amplification (MDA), and aneuploidy screening with an SNP array were conducted on the enrolled blastocysts. When the SNP array indicated mosaicism, NGS was performed on the corresponding MDA product for verification. Among the 105 blastocysts diagnosed with mosaicism with the SNP array, 80 (76.19%) showed mosaicism in NGS, with complete and partial concordance rates of 47.62% (50/105) and 18.10% (19/105), respectively. The complete discordance rate of the two platforms was 34.29% (36/105). That is, 10.48% (11/105) of the blastocysts were diagnosed with completely different types of mosaicism with the two platforms, while 13.33% (14/105) and 10.48% (11/105) of the embryos diagnosed as showing mosaicism with SNP were detected as showing aneuploidy and euploidy with NGS, respectively.

CONCLUSIONS

The consistency of NGS and the SNP array in the diagnosis of embryo mosaicism is extremely low, indicating the need for larger and well-designed studies to determine which platform is more accurate in detecting mosaic embryos.

Analysis of clinical outcomes and meiotic segregation modes following preimplantation genetic testing for structural rearrangements using aCGH/NGS in couples with balanced chromosome rearrangement

Purpose

To retrospectively evaluate the effectiveness of PGT-SR by array comparative genomic hybridization (aCGH) or next-generation sequencing (NGS) in preventing recurrent miscarriages.

Methods

Thirty one couples with balanced translocation who underwent 68 PGT-SR cycles between 2012 and 2020 were evaluated. A total of 242 blastocysts were biopsied for aCGH or NGS. The genetically transferable blastocysts were transferred in the subsequent frozen-thawed single embryo transfer cycle.

Results

The genetically transferable blastocyst rate was 21.2% (51/241). Thirty five genetically transferable blastocysts were transferred into the uterine cavity. The clinical pregnancy rate was 57.1% (20/35), and the ongoing pregnancy rate was 100.0% (20/20). The incidence of interchromosomal effect (ICE) was influenced by ovarian stimulation protocol, female age, and carrier's gender, but dependent on the types of balanced translocation carriers. Furthermore, there was no significant difference in meiotic segregation modes in ovarian stimulation protocols and carrier's gender. Interestingly, the incidence of adjacent-1 segregation in ≧40 years group increased significantly compared with <35 years group.

Conclusions

For the first time in Japan, we show the effectiveness of PGT-SR using aCGH or NGS, which enables comprehensive analysis of chromosomes, in the prevention of recurrent miscarriages. Furthermore, our results may support better genetic counseling of balanced translocation carriers for PGT-SR cycles.

Whole-Genome Sequencing Reveals Exonic Variation of ASIC5 Gene Results in Recurrent Pregnancy Loss

Family trio next-generation sequencing-based variant analysis was done to identify the genomic reason on unexplained recurrent pregnancy loss (RPL). A family (dead fetus and parents) from Saudi Arabia with an earlier history of three unexplained RPLs at the ninth week of pregnancy was included in the study. Whole-genome sequencing (WGS) of a dead fetus and the parents was done to identify the pathogenic variation and confirmed through Sanger sequencing. WGS of dead fetus identifies a novel homozygous exonic variation (NM_017419.3:c.680G>T) in ASIC5 (acid-sensing ion channel subunit family member 5) gene; the parents are heterozygous. Newly designed ARMS PCR followed by direct sequencing confirms the presence of heterozygous in one subject and absence of homozygous novel mutation among randomly selected healthy Saudis. The second family with heterozygous was confirmed with three unexplained RPLs. Pathogenicity analysis of R227I amino acid substitution in ASIC5 protein through molecular docking and interaction analysis revealed that the mutations are highly pathogenic, decrease the stability of the protein, and prevent binding of amiloride, which is an activator to open the acid-sensing ion channel of ASIC5. The identified rare and novel autosomal recessive mutation, c.680G>T:p.R227I (ASIC5Saudi), in two families confirm the ASIC5 gene association with RPL and can be fatal to the fetus.

A mathematical model for predicting the number of transferable blastocysts in next-generation sequencing-based preimplantation genetic testing

PURPOSE

To investigate the clinical factors that could be used predict the number of transferable blastocysts in preimplantation genetic testing (PGT) cycles based on next-generation sequencing (NGS) and formed form a mathematical model to predict the chance likelihood of obtaining one transferable blastocyst, which is helpful for genetic counseling.

METHODS

This retrospective study enrolled couples undergoing PGT cycles for chromosomal structural rearrangement (PGT-SR, n = 363, 202 with reciprocal translocation carriers, 131 with Robertsonian translocation carriers, 30 with inversion carriers), monogenic diseases (PGT-M, n = 47), and for Aneuploidies (PGT-A, n = 132) from January 2015 to October 2018. Stepwise multiple linear regression analysis was used to identify the factors relevant for obtaining at least one transferable blastocyst. The factors that predict the number of biopsied blastocysts were further analyzed.

RESULTS

The transferable blastocyst rates were 29.94, 41.99, 49.09, 41.42, and 44.37% in the reciprocal translocation carrier, Robertsonian translocation carrier, inversion carrier, PGT-M, and PGT-A cycles, respectively. The number of transferable blastocysts in these cycles were 0.3004 × the number of biopsied blastocysts (NBB) - 0.0031, 0.4063 × NBB + 0.0460, 0.5762 × NBB - 0.3128, 0.3611 × NBB + 0.1910, and 0.4831 × NBB - 0.0970, respectively. Furthermore, the number of MII oocytes and female age were clinical predictors of NBB in reciprocal translocation and PGT-A couples, while the number of MII oocytes was the only clinical predictor in Robertsonian translocation carriers, inversion carriers, and PGT-M couples.

CONCLUSIONS

The number of biopsied blastocysts was the only clinical predictor of the ability to obtain a transferable blastocyst in PGT cycles; therefore, for clinical practice, theoretically the minimum numbers of biopsied blastocysts is 4 in reciprocal translocation carrier and 3 in couples undergoing PGT for other reasons. The number of MII oocytes and female age were clinical predictors of the number of biopsied blastocysts. With the mathematical models in our study as a reference, in clinical practice, clinicians will be able to conduct a more targeted genetic consultation for different kinds of PGT patients.

Comprehensive preimplantation genetic testing by massively parallel sequencing

STUDY QUESTION

Can whole genome sequencing (WGS) offer a relatively cost-effective approach for embryonic genome-wide haplotyping and preimplantation genetic testing (PGT) for monogenic disorders (PGT-M), aneuploidy (PGT-A) and structural rearrangements (PGT-SR)?

SUMMARY ANSWER

Reliable genome-wide haplotyping, PGT-M, PGT-A and PGT-SR could be performed by WGS with 10× depth of parental and 4× depth of embryonic sequencing data.

WHAT IS KNOWN ALREADY

Reduced representation genome sequencing with a genome-wide next-generation sequencing haplarithmisis-based solution has been verified as a generic approach for automated haplotyping and comprehensive PGT. Several low-depth massively parallel sequencing (MPS)-based methods for haplotyping and comprehensive PGT have been developed. However, an additional family member, such as a sibling, or a proband, is required for PGT-M haplotyping using low-depth MPS methods.

STUDY DESIGN, SIZE, DURATION

In this study, 10 families that had undergone traditional IVF-PGT and 53 embryos, including 13 embryos from two PGT-SR families and 40 embryos from eight PGT-M families, were included to evaluate a WGS-based method. There were 24 blastomeres and 29 blastocysts in total. All embryos were used for PGT-A. Karyomapping validated the WGS results. Clinical outcomes of the 10 families were evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A blastomere or a few trophectoderm cells from the blastocyst were biopsied, and multiple displacement amplification (MDA) was performed. MDA DNA and bulk DNA of family members were used for library construction. Libraries were sequenced, and data analysis, including haplotype inheritance deduction for PGT-M and PGT-SR and read-count analysis for PGT-A, was performed using an in-house pipeline. Haplotyping with a proband and parent-only haplotyping without additional family members were performed to assess the WGS methodology. Concordance analysis between the WGS results and traditional PGT methods was performed.

MAIN RESULTS AND THE ROLE OF CHANCE

For the 40 PGT-M and 53 PGT-A embryos, 100% concordance between the WGS and single-nucleotide polymorphism (SNP)-array results was observed, regardless of whether additional family members or a proband was included for PGT-M haplotyping. For the 13 embryos from the two PGT-SR families, the embryonic balanced translocation was detected and 100% concordance between WGS and MicroSeq with PCR-seq was demonstrated.

LIMITATIONS, REASONS FOR CAUTION

The number of samples in this study was limited. In some cases, the reference embryo for PGT-M or PGT-SR parent-only haplotyping was not available owing to failed direct genotyping.

WIDER IMPLICATIONS OF THE FINDINGS

WGS-based PGT-A, PGT-M and PGT-SR offered a comprehensive PGT approach for haplotyping without the requirement for additional family members. It provided an improved complementary method to PGT methodologies, such as low-depth MPS- and SNP array-based methods.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the research grant from the National Key R&D Program of China (2018YFC0910201 and 2018YFC1004900), the Guangdong province science and technology project of China (2019B020226001), the Shenzhen Birth Defect Screening Project Lab (JZF No. [2016] 750) and the Shenzhen Municipal Government of China (JCYJ20170412152854656). This work was also supported by the National Natural Science Foundation of China (81771638, 81901495 and 81971344), the National Key R&D Program of China (2018YFC1004901 and 2016YFC0905103), the Shanghai Sailing Program (18YF1424800), the Shanghai Municipal Commission of Science and Technology Program (15411964000) and the Shanghai 'Rising Stars of Medical Talent' Youth Development Program Clinical Laboratory Practitioners Program (201972). The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Next-generation sequence-based preimplantation genetic testing for monogenic disease resulting from maternal mosaicism

BACKGROUND

Mosaicism poses challenges for genetic counseling and preimplantation genetic testing for monogenic disorders (PGT-M). NGS-based PGT-M has been extensively used to prevent the transmission of monogenic defects, but it has not been evaluated in the application of PGT-M resulting from mosaicism.

METHODS

Four women suspected of mosaicism were confirmed by ultra-deep sequencing. Blastocyst trophectoderm cells and polar bodies were collected for whole genome amplification, followed by pathogenic variants detection and haplotype analysis based on NGS. The embryos free of the monogenic disorders were transplantable.

RESULTS

Ultra-deep sequencing confirmed that the four women harbored somatic mosaic variants, with the proportion of variant cells at 1.12%, 9.0%, 27.60%, and 91.03%, respectively. A total of 25 blastocysts were biopsied and detected during four PGT cycles and 5 polar bodies were involved in one cycle additionally. For each couple, a wild-type embryo was successfully transplanted and confirmed by prenatal diagnosis, resulting in the birth of four healthy infants.

CONCLUSIONS

Mosaic variants could be effectively evaluated via ultra-deep sequencing, and could be prevented the transmission by PGT. Our work suggested that an NGS-based PGT approach, involving pathogenic variants detection combined with haplotype analysis, is crucial for accurate PGT-M with mosaicism.

Trophectoderm Mitochondrial DNA Content Associated with Embryo Quality and Day-5 Euploid Blastocyst Transfer Outcomes

Mitochondria play a critical role in cell function and embryo development. Recently, increasing studies have investigated whether mitochondrial DNA (mtDNA) can be used as a predictive biomarker of embryo implantation. However, the results of its effect on implantation are still controversial. To further understand the clinical application value of mtDNA content for reproductive potential, we analyzed the influence of relative mtDNA quantity on embryo quality and transfer outcomes based on the results of second-generation sequencing of preimplantation genetic testing patients in our center. Biopsied trophectoderm (TE) from aneuploid blastocysts contained much larger amounts of mtDNA than those from euploid blastocysts (p < 0.000). In an analysis of only euploid blastocysts (n = 769), female age had no effect on mtDNA content (p = 0.216). TE cells biopsied on day 5 (n = 355) contained significantly higher amounts of mtDNA compared to those biopsied on day 6 (n = 388) or day 7 (n = 26) (p < 0.000). Higher quality trophoblast was associated with lower mtDNA content (p = 0.026), but quality of inner cell mass was not correlated with quantity of mtDNA (p = 0.112). For transferred embryos, the biopsied date and mtDNA content were significantly associated with embryo implantation and live birth outcomes. Day-5 euploid blastocysts with lower quantities of mtDNA exhibited higher implantation rate and live birth rate. However, our data indicated that mtDNA content may not be considered an independent predictive marker, it may be a useful reference for the selection of day-5 transferred euploid blastocysts.

Novel variants of the PCCB gene in Chinese patients with propionic acidemia

BACKGROUND AND AIMS

Propionic acidemia (PA) is an autosomal recessive metabolic disorder caused by a deficiency of propionyl-CoA carboxylase and mutations in the PCCA and PCCB genes. In this study, we investigated the clinical characteristics of individuals with PA and conducted genetic analyses to provide new genetic evidence for the diagnosis of PA.

MATERIALS AND METHODS

We conducted whole-exome sequencing and Sanger sequencing in four individuals with PA from three unrelated Chinese families. We also performed a structural analysis of the PCCB protein variants. Couples from the three families included in our study underwent in vitro fertilization with preimplantation genetic testing.

RESULTS

We found five variants of PCCB. These biallelic variants were inherited from heterozygous parental carriers and were located in the functional domain, absent in human population genome datasets, and predicted to be deleterious. These findings indicate that the variants might be responsible for the clinical features observed in these particular patients with PA. Through successful embryo transfer and implantation, one of the couples fortunately gave birth to a healthy child.

CONCLUSION

Overall, our study can expand the mutation spectrum of PCCB and provide useful information for the prenatal diagnosis of PA and genetic counseling for affected individuals.

Reproductive risks and preimplantation genetic testing intervention for X-autosome translocation carriers

RESEARCH QUESTION

What is the genetic cause of multiple congenital disabilities in a girl with a maternal balanced X-autosome translocation [t(X-A)]? Is preimplantation genetic testing (PGT), to distinguish non-carrier from euploid/balanced embryos and prioritize transfer, an effective and applicable strategy for couples with t(X-A)?

DESIGN

Karyotype analysis, whole-exome sequencing and X inactivation analysis were performed for a girl with congenital cardiac anomalies, language impairment and mild neurodevelopmental delay. PGT based on next-generation sequencing after microdissecting junction region (MicroSeq) to distinguish non-carrier and carrier embryos was used in three couples with a female t(X-A) carrier (cases 1-3).

RESULTS

The girl carried a maternal balanced translocation 46,X,t(X;1)(q28;p31.1). Whole-exome sequencing revealed no monogenic mutation related to her phenotype, but she carried a rare skewed inactivation of the translocated X chromosome that spread to the adjacent interstitial 1p segment, contrary to her mother. All translocation breakpoints in cases 1-3 were successfully identified and each couple underwent one PGT cycle. Thirty oocytes were retrieved, and 13 blastocysts were eligible for biopsy, of which six embryos had a balanced translocation and only four were non-carriers. Three cryopreserved embryo transfers with non-carrier status embryos resulted in the birth of two healthy children (one girl and one boy), who were subsequently confirmed to have normal karyotypes.

CONCLUSIONS

This study reported a girl with multiple congenital disabilities associated with a maternal balanced t(X-A) and verified that the distinction between non-carrier and carrier embryos is an effective and applicable strategy to avoid transferring genetic and reproductive risks to the offspring of t(X-A) carriers.

Reproductive outcomes after preimplantation genetic testing in mosaic Turner syndrome: a retrospective cohort study of 100 cycles

PURPOSE

The purpose of this study is to explore the reproductive outcomes of women with Turner syndrome (TS) in preimplantation genetic testing (PGT) cycles.

METHODS

A retrospective study of 100 controlled ovarian stimulating cycles, 68 TS (sixty-four mosaic Turner syndrome (MTS) and four pure Turner syndrome (PTS)) women underwent PGT was conducted from 2013 to 2018.

RESULTS

Embryo X chromosome abnormal rates of TS women were significantly higher than women with normal karyotype (7.04 vs 1.61%, P<0.01). Cumulative live birth rates (CLBR) after PGT-NGS treatment were lower in TS than control (31.15 vs 45.59%, P<0.05). Clinical pregnancy rates per transfer (CPR), miscarriage rates (MR) and live birth rates per transfer (LBR) remained comparable between TS and control group. Reproductive outcomes (X chromosome abnormal rates, CPR, MR, LBR and CLBR) among low (<10%), medium (10-50%) and high (>50%) level 45,X mosaicism groups were not statistically different.

CONCLUSIONS

To avoid high risk of embryo X chromosome abnormalities, prenatal or preimplantation genetic testing should be recommended to mosaic or pure TS patients.

Mitochondrial DNA Copy Number in Human Blastocyst: A Novel Biomarker for the Prediction of Implantation Potential

The relationship between mitochondrial DNA (mtDNA) copy number and the outcome of embryo transfer is under debate. Our aim was to explore the relationship between mtDNA copy number in human blastocysts and embryonic development to determine whether mtDNA represents a novel biomarker for the prediction of implantation potential. A total of 246 blastocysts were analyzed by next-generation sequencing. There was no correlation between mtDNA copy number and maternal age in all blastocyst groups and euploid blastocyst groups. Additionally, the mtDNA copy number was not significantly higher in aneuploid blastocysts. Subsequently, no relationship was observed between mtDNA copy number and blastocyst quality. The assessment of clinical pregnancy outcome after the transfer of euploid blastocysts to the uterus indicated that the mtDNA copy number was significantly lower in the clinical pregnancy group than in those who failed implantation. The cut-off value of mtDNA copy number was 320.5, which was a highly predictive value. Blastocysts with an increased mtDNA copy number had lower implantation potential, and mtDNA copy number was largely equal in terms of maternal age, chromosome ploidy, and quality of blastocysts.

Y chromosome structural variation in infertile men detected by targeted next-generation sequencing

PURPOSE

To provide a validated method to identify copy number variation (CNV) in regions of the Y chromosome of infertile men by next-generation sequencing (NGS).

METHODS

Semen analysis was used to determine the quality of semen and diagnose infertility. Deletion of the azoospermia factor (AZF) region in the Y chromosome was detected by a routine sequence-tagged-site PCR (STS-PCR) method. We then used the NGS method to detect CNV in the AZF region, including deletions and duplications.

RESULTS

A total of 326 samples from male infertility patients, family members, and sperm donors were studied between January 2011 and May 2017. AZF microdeletions were detected in 120 patients by STS-PCR, and these results were consistent with the results from NGS. In addition, of the 160 patients and male family members who had no microdeletions detected by STS-PCR, 51 cases were found to exhibit Y chromosome structural variations by the NGS method (31.88%, 51/160). No microdeletions were found in 46 donors by STS-PCR, but the NGS method revealed 11 of these donors (23.91%, 11/46) carried structural variations, which were mainly in the AZFc region, including partial deletions and duplications.

CONCLUSION

The established NGS method can replace the conventional STS-PCR method to detect Y chromosome microdeletions. The NGS method can detect CNV, such as partial deletion or duplication, and provide details of the abnormal range and size of variations.

Normalized Mitochondrial DNA Copy Number Can Optimize Pregnancy Outcome Prediction in IVF

The aim of this study is to explore the relationship between mitochondrial DNA (mtDNA) copy number and embryo implantation potential in in vitro fertilization (IVF). A retrospective study of 319 blastocysts from patients undergoing preimplantation genetic testing (PGT) at Reproductive Medicine Center in Tongji Hospital from January 2016 to February 2018 was conducted. We used multiple annealing- and looping-based amplification cycles (MALBAC) technology to amplify the genetic materials from the trophectoderm cells of blastocysts, and next-generation sequencing (NGS) technology to test mitochondrial DNA copy number. Box-Cox transformation was introduced to eliminate the skewness distribution of mtDNA copy number, and the transformed data were defined as adjusted mtDNA. Subsequently, associations between adjusted mtDNA and the clinical characteristics of patients were assessed by univariate analysis and multiple linear regression. In addition, Gaussian Naive Bayes classifier was also used to predict pregnancy outcomes. We observed that only antral follicle count (AFC) was significantly associated with adjusted mtDNA without the influence of multicollinearity. What's more, the distribution of the adjusted mtDNA of blastocysts resulting in live birth was more concentrated than that of others. The area under the curve (AUC) of the prediction model that combined adjusted mtDNA with other clinical characteristics of patients was up to 0.81, higher than that excluded adjusted mtDNA. Among patient clinical characteristics, AFC was significantly associated with adjusted mtDNA. Mitochondrial DNA copy number may help to optimize the pregnancy outcome prediction in IVF.

The genetic cause of intellectual deficiency and/or congenital malformations in two parental reciprocal translocation carriers and implications for assisted reproduction

PURPOSE

To elucidate the genetic cause of intellectual deficiency and/or congenital malformations in two parental reciprocal translocation carriers and provide appropriate strategies of assisted reproductive therapy (ART).

MATERIALS AND METHODS

Two similar couples having a child with global developmental delay/intellectual disability symptoms attended the Reproductive and Genetic Hospital of CITIC-Xiangya (Changsha, China) in 2017 and 2019, respectively, in order to determine the cause(s) of the conditions affecting their child and to seek ART to have a healthy baby. Both of the healthy couples were not of consanguineous marriage, denied exposure to toxicants, and had no adverse life history. This study was approved by the Institutional Ethics Committee of the Reproductive & Genetic Hospital of CITIC-Xiangya, and written informed consent was obtained from the parents. Genetic diagnoses were performed by karyotype analysis, breakpoint mapping analysis of chromosomal translocation(s), single-nucleotide polymorphism (SNP) microarray analysis, and whole-exome sequencing (WES) for the two children and different appropriate reproductive strategies were performed in the two families.

RESULTS

Karyotype analysis revealed that both patients carried parental reciprocal translocations [46,XY,t(7;16)(p13;q24)pat and 46,XY,t(13;17)(q12.3;p11.2)pat, respectively]. Follow-up breakpoint mapping analysis showed no interruption of associated genes, and SNP microarray analysis identified no significant copy number variations (CNVs) in the two patients. Moreover, WES results revealed that patients 1 and 2 harbored candidate compound heterozygous mutations of MCOLN1 [c.195G>C (p.K65N) and c.1061G>A (p.W354*)] and MCPH1 [c.877A>G (p.S293G) and c.1869_1870delAT (p.C624*)], respectively, that were inherited from their parents and not previously reported. Furthermore, the parents of patient 1 obtained 10 embryos during ART cycle, and an embryo of normal karyotype and non-carrier of observed MCOLN1 mutations according to preimplantation genetic testing for structural rearrangement and monogenic defect was successfully transferred, resulting in the birth of a healthy boy. The parents of patient 2 chose to undergo ART with donor sperm to reduce the risk of recurrence.

CONCLUSIONS

Systematic genetic diagnosis of two carriers of inherited chromosomal translocations accompanied by clinical phenotypes revealed their cause of disease, which was critical for genetic counseling and further ART for these families.

The effect of blastomere loss during frozen embryo transfer on the transcriptome of offspring's umbilical cord blood

Blastomere loss is a common issue during frozen-thawed embryo transfer (FET). Our previous study showed that blastomere loss was associated with an increased risk of small-for-gestational-age (SGA) neonates. The present study assessed the impact of blastomere loss during cryopreservation by comparing the mRNA profiles of umbilical cord blood of FET offspring from the prospective cohort study. Umbilical cord blood samples were collected from 48 neonates, including 12 from the loss group, 11 from the intact group, and 25 from the matched spontaneous pregnancy group. RNA-seq technology was used to compare the global gene expression profiles of the lymphocytes. Then, we used TopHat software to map the reads and quantitative real-time PCR to validate some important differentially expressed genes (DEGs). We identified 92 DEGs between the loss group and the spontaneous pregnancy group, including IGF2 and H19. Ingenuity Pathway Analysis (IPA) showed that the DEGs were most affected in the blastomere loss group. Downstream analysis also predicted the activation of organismal death pathways. In conclusions, our pilot study sheds light on the mechanism underlying how human blastomere loss may affect offspring at the gene expression level. These conclusions are, however, only suggestive, as the current study is based on a very limited sample size and type or nature of biological samples. Additional studies with larger sample sizes and independent experiments with placental samples should be conducted to verify these findings.

Sperm chromosome abnormalities in patients with normal karyotype and in translocation carriers: clinical relevance for assisted reproductive technology

RESEARCH QUESTION

What is the proportion of chromosomally abnormal spermatozoa in men with a history of reproductive failure, including patients with normal karyotype and carriers of translocations? Should this analysis be included in a clinical setting to define the best treatment options for infertile couples?

DESIGN

Aneuploidy for chromosomes XY, 13, 15, 16, 17, 18, 21, 22 was tested by fluorescent in-situ hybridization (FISH) in 1665 samples from couples with normal karyotype having had at least three previous IVF failures, miscarriages, or both (group-A). A FISH test was also carried out in 76 samples from carriers of translocations (group B) to detect the proportion of spermatozoa with unbalanced rearrangement.

RESULTS

In group A, the lowest incidence of aneuploid sperm cells was found in men with normozoospermia (1.3%, range 0.09-6.31%) compared with men with moderate oligoasthenoteratozoospermia (2.1%, range 0.41-16.6%, P < 0.001), severe oligoasthenoteratozoospermia (4.7%, range 0.53-30.77, P < 0.001), microepididymal sperm aspiration (3.1%, range 1.19-24.24, P < 0.001) and testicular sperm extraction samples (5.8%, range 1.54-33.3, P < 0.001). In group B, the proportion of spermatozoa with unbalanced rearrangement was significantly higher in reciprocal (63%, range 10.0-87.6%) than in Robertsonian translocations (16%, range 4.3-51.0%, P < 0.001).

CONCLUSIONS

Patients with poor prognosis of term pregnancy tend to generate high proportions of chromosomally abnormal spermatozoa, especially in severe male factor cases. Corresponding frequencies occur at wide ranges; therefore, the FISH test is needed to assess the proportion of spermatozoa with altered chromosome condition. A flowchart, which included the FISH test, was designed to assist clinicians guide couples with poor prognosis of pregnancy, on the most indicated treatment options.

Mitochondrial DNA content decreases during in vitro human embryo development: insights into mitochondrial DNA variation in preimplantation embryos donated for research

OBJECTIVE

To assess the mitochondrial DNA (mtDNA) load and variation in human oocytes and during preimplantation embryo development using specimens donated for research.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENTS

A total of 50 in vitro fertilization patients and 11 oocyte donors whose specimens were obtained between July 2017 and July 2018.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

All specimens were separately collected. Quantitative polymerase chain reaction was performed with SurePlex DNA Amplification System (Illumina). Primers for the adenosine triphosphate 8 mitochondrial gene and the β-actin were used. Data were statistically analyzed by analysis of variance with the Scheffé multiple pairwise comparison for categorical variables and by linear regression for numerical variables.

RESULTS

Human metaphase II (MII) oocytes had significantly more total mtDNA copy number than day 3 embryos, and day 3 embryos had more total and per-cell mtDNA copy number than aneuploid blastocysts. There was a significant decrease in mtDNA content associated with failed-fertilized oocytes compared to noninseminated metaphase II oocytes.

CONCLUSIONS

During preimplantation development, before implantation, human embryos undergo a significant decrease in total mtDNA content and no increase in mtDNA content at the blastocyst stage. Oocytes need to carry a correct threshold of mitochondrial load in the oocyte in order to successfully fertilize. An active degradation of mtDNA before implantation occurs after fertilization takes place. These findings could be used to improve knowledge about the best embryo culture conditions and would serve as a basis for further studies addressing again the use of mtDNA content as an embryo viability marker.

Mitochondrial oxygen consumption rate of human embryos declines with maternal age

PURPOSE

The fertility of women decreases with age because of factors such as an increased incidence of aneuploidies and-possibly-decreased mitochondrial activity in oocytes. However, the relationship between maternal aging and mitochondrial function of their embryos remains unknown. Here, we assessed the relationship between maternal age and mitochondrial functions in their oocytes and embryos METHODS: The relationships between maternal age and oxygen consumption rates (OCRs), mitochondrial DNA (mtDNA) copy numbers, or blastocyst development was investigated using 81 embryos donated from 63 infertility couples. The developmental rates from morulae to blastocysts were retrospectively analyzed using data of 105 patients.

RESULTS

The OCRs of morulae decreased with maternal age (r² = 0.48, P < 0.05) although there were no relationships between maternal age and mtDNA copy number in any stages. The more oxygen consumed at the morula stage, the shorter time was required for embryo development to the mid-stage blastocyst (r² = 0.236, P < 0.05). According to the clinical data analysis, the developmental rate from morulae to blastocysts decreased with maternal age (P < 0.05, < 37 years, 81.1%, vs. ≥ 37 years, 64.1%).

CONCLUSIONS

The data of the present study revealed that mitochondrial function at the morula stage of human embryos decreased with their maternal age and a decrease of mitochondrial function led to slow-paced development and impaired developmental rate from morulae to blastocysts.

Improved clinical outcomes of preimplantation genetic testing for aneuploidy using MALBAC-NGS compared with MDA-SNP array

BACKGROUND

To assess whether preimplantation genetic testing for aneuploidy with next generation sequencing (NGS) outweighs single nucleotide polymorphism (SNP) array in improving clinical outcomes.

METHODS

A retrospective analysis of the clinical outcomes of patients who underwent PGT-A treatment in a single center from January 2013 to December 2017.A total of 1418 couples who underwent PGT-A treatment were enrolled, of which 805 couples used NGS for PGT-A, while the remaining 613 couples used SNP array for PGT-A. Clinical pregnancy rate, miscarriage rate and healthy baby rate were compared between the MALBAC-NGS-PGT-A and MDA-SNP-PGT-A groups.

RESULTS

After testing karyotypes of 5771 biopsied blastocysts, 32.2% (1861/5771) were identified as chromosomally normal, while 67.8% were chromosomally abnormal. In terms of clinical outcomes, women in the MALBAC-NGS-PGT-A group had a significantly higher clinical pregnancy rate (50.5% vs 41.7%, p = 0.002) and healthy baby rate (39.6% vs 31.4%, p = 0.003), and a lower miscarriage rate (15.5% vs 22.8%, p = 0.036).

CONCLUSION

This is the largest study reporting the extensive application of NGS-based PGT-A, whilst comparing the clinical outcomes of MALBAC-NGS-PGT-A and MDA-SNP-PGT-A. The results provide greater evidence supporting the wider use of NGS in PGT-A, not only for its lower cost but also for its improved clinical outcomes compared to SNP-based PGT-A.

The role of total chromosomal disomy in human spermatozoa as a predictor of the outcome of pre-implantation genetic screening

OBJECTIVE

To assess the efficacy of sperm disomy rate as a predictor of preimplantation genetic screening (PGT-A) outcomes.

DESIGN

Retrospective cohort study.

SETTING

Andrology laboratory and in vitro fertilization center.

PATIENT(S)

All patients (n = 123) who underwent sperm fluorescence in situ hybridization and PGT-A at the China International Trust and Investment Corporation Xiangya Reproductive and Genetic Hospital between January 2015 and November 2018 were included.

INTERVENTION(S)

Sperm samples of all patients evaluated for elevated disomy levels of 24 chromosomes using multicolor sperm fluorescence in situ hybridization and all embryos were cultured and biopsied at the blastocyst stage for PGT-A.

MAIN OUTCOME MEASURE(S)

The relationship between the whole genome of sperm disomy rate and PGT-A outcome and the predictive effect of the whole genome of sperm disomy rate on PGT-A outcome.

RESULT(S)

A statistically significant correlation was observed between the sperm disomy rate and PGT-A outcome. Many confounders were considered, such as patients' factors, semen or laboratory characteristics, which may affect PGT-A outcome. Regression analysis excluding these confounding factors indicated a 2.071-fold decrease in odds of probability of not obtaining any euploid embryo to transfer for every 1% decrease in total disomy rate. Based on a total disomy rate threshold of 4.84%, the prediction ability of total disomy rate on PGT-A outcome reached 75.6%.

CONCLUSION(S)

There is a negative correlation between the whole genome of sperm disomy rate and PGT-A outcome. It is a potential role for whole genome of sperm disomy rate in the PGT-A patients as a predictor, as well as in future genetic counselling. Based on these results, genetic counselors can advise couples on the risk of not obtaining any euploid embryo and help them choose the best reproductive and diagnostic method.

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.

Successful clinical application of pre-implantation genetic diagnosis for infantile neuroaxonal dystrophy

Infantile neuroaxonal dystrophy (INAD) is a rare, lethal, autosomal recessive neurodegenerative disease and leads to progressive impairment of movement and cognition. A couple with a proband child with calcium-independent group VI phospholipase A2 (PLA2G6)-associated INAD and a previous affected pregnancy sought pre-implantation genetic diagnosis (PGD) to bear a healthy child. Intracytoplasmic sperm injection treatment was performed and 15 blastocystic embryos were obtained at days 5 and 6, and these biopsies were amplified. PGD was performed by next-generation sequencing-based linkage analysis in conjunction with aneuploidy screening. Only two embryos were considered for transfer. In the second frozen-thawed embryo transfer cycle, transfer of a mosaic PLA2G6 c.692G>T heterozygous embryo resulted in a singleton ongoing pregnancy. Prenatal diagnosis was performed using amniotic fluid cells, providing results consistent with those of PGD. The aneuploidy screen and karyotype analysis indicated that the chromosomes of the fetus were normal without any mosaicism. The present study reported the first successful PGD for INAD. For parents at risk, this strategy may successfully lead to pregnancies with embryos unlikely to develop INAD, thus providing valuable experience in reproductive management regarding INAD and potentially other single-gene disorders.

Analysis of molecular cytogenetic features and PGT-SR for two infertile patients with small supernumerary marker chromosomes

RESEARCH QUESTION

Can preimplantation genetic testing for structural rearrangement (PGT-SR) with next-generation sequencing (NGS) be used to infertile patients carrying small supernumerary marker chromosomes (sSMCs)?

DESIGN

In this study, two infertile patients carrying ring sSMCs were recruited. Different molecular cytogenetic techniques were performed to identify the features of the two sSMCs, followed by clinical PGT-SR cycles.

RESULTS

The results of G-banding and FISH showed that patient 1's sSMC originated from the 8p23-p10 region, with a resulting karyotype of [ 47,XY, del(8)(p23p10), +r(8)(p23p10).ish del(8)(CEP8+,subtle 8p+,subtle 8q+),r(8)(CEP8+,subtle 8p-,subtle 8q-)[55/60].arr(1-22) ×2,(X,Y)×1]. The sSMC of patient 2 was derived from chromosome 3 and further microdissection with next-generation sequencing (MicroSeq) revealed it contained the region of chromosome 3 between 93,504,855 and 103,839,892 bp (GRCh37), which involved 52 known genes. So the karyotype of patient 2 was 47,XX, +mar.ish der(3)(CEP3+,subtle 3p-,subtle 3q-)[49/60].arr[GRCh37] 3q11.2q13.1(93,500,001_103,839,892) ×3(0.5). PGT-SR with NGS was performed to provide reproductive guidance for the two patients. For patient 1, four balanced euploid embryos and four embryos with partial trisomy/monosomy of (8p23.1-8p11.21) were obtained, and a balanced euploid embryo was successfully implanted and had resulted in a healthy baby. For patient 2, an embryo with monosomy of sex chromosomes and another embryo with a duplication at (3q11-q13.1), neither of which was available for implantation.

CONCLUSIONS

The identification of the origins and structural characteristics of rare sSMCs should rely on different molecular cytogenetic techniques. PGT-SR is an alternative fertility treatment for these patients carrying sSMCs. This study may provide directions for the assisted reproductive therapy for infertile patients with sSMC.

Next-generation sequencing analysis of embryos from mosaic patients undergoing in vitro fertilization and preimplantation genetic testing

OBJECTIVE

To investigate the effects of parental mosaicism on their preimplantation embryos.

DESIGN

Case series.

SETTING

An institute for reproductive and stem cell engineering.

PATIENT(S)

Sixty-eight mosaic couples.

INTERVENTION(S)

Assisted reproduction with preimplantation genetic testing (PGT).

MAIN OUTCOME MEASURE(S)

Karyotypes, embryo-related chromosomal abnormalities, and PGT results.

RESULT(S)

A total of 209 embryos were obtained from 68 mosaic couples, and 153 (73.21%) of 209 of the total embryos were obtained from 55 mosaic couples with abnormal sex chromosome numbers. Of these 153 embryos, 2 (1.31%) had an abnormal copy number of X chromosome, 1 had mosaicism with 46,XN,+X(mosaic, 40%), 1 (0.65%) had an extra Y chromosome, 3 (1.96%) exhibited both X chromosomal and autosomal abnormalities, and 4 (2.61%) exhibited de novo X chromosome structural abnormalities. A total of 56 (26.79%) of 209 embryos were obtained from mosaic couples (n = 13) with abnormal autosomal structures. Notably, of these 56 embryos, 5 (8.93%) had a 16q21-q24.3 copy number abnormality related to the parental karyotype, with a fragile site at 16q22; 5 (7.14%) exhibited 46,XX,dup(8p23.1-8p11.21) and 46,XY,del(8p22-8p11.21), which were related to the parental karyotype; and 10 (17.86%) were de novo chromosome abnormalities.

CONCLUSION(S)

Our data demonstrate that the risk of embryo-related chromosome abnormalities in mosaic patients with abnormal sex chromosomes is very low. Therefore, PGT may not need to be recommended for mosaic patients with abnormal copy numbers of sex chromosomes, especially for patients with financial difficulties. By contrast, the mosaic patients with structural abnormalities of autosomes may have a relatively high risk of abnormal embryos with an unbalanced segment of the involved chromosomes. Thus, PGT is highly recommended for mosaic patients with autosomal structure abnormalities, especially those with a fragile site at 16q22.

Retrospective analysis of meiotic segregation pattern and interchromosomal effects in blastocysts from inversion preimplantation genetic testing cycles

OBJECTIVE

To determine factors affecting unbalanced chromosomal rearrangement originating from parental inversion and interchromosomal effect occurrence in blastocysts from inversion carriers.

DESIGN

Retrospective study.

SETTING

University-affiliated center.

PATIENT(S)

Couples with one partner carrying inversion underwent preimplantation genetic testing for chromosomal structural rearrangement cycles.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Unbalanced rearrangement embryo rate, normal embryo rate, interchromosomal effect.

RESULT(S)

Preimplantation genetic testing was performed for 576 blastocysts from 57 paracentric (PAI) and 94 pericentric (PEI) inversion carriers. The percentage of normal/balanced blastocysts was significantly higher in PAI than PEI carriers (70.4% vs. 57.5%). Logistic regression indicated the inverted segment size ratio was a statistically significant risk factor for abnormality from parental inversion in both PEI and PAI. The optimal cutoff values to predict unbalanced rearrangement risk were 35.7% and 57%. In PAI, rates of abnormality from parental inversion were 0% and 12.1% in the <35.7% and ≥35.7% groups, respectively, with no gender difference. For PEI, the rates of abnormality from parental inversion were 7.9% and 33.1% in the <57% and ≥57% groups, respectively. In the ≥57% group, the rate of unbalanced rearrangement was significantly higher from paternal than maternal inversion (43.3% vs. 23.6%). In inversion carriers, 21,208 chromosomes were examined, and 187 (0.88%) malsegregations were identified from structurally normal chromosomes. In controls, 56,488 chromosomes were assessed, and 497 (0.88%) aneuploidies were identified, indicating no significant difference.

CONCLUSION(S)

The risk of unbalanced rearrangement is affected by the ratio of inverted segment size in both PAI and PEI carriers and is associated with gender.

Analysis of meiotic segregation modes in biopsied blastocysts from preimplantation genetic testing cycles of reciprocal translocations

Purpose

To analyse the meiotic segregation modes of chromosomal structural rearrangements (PGT-SR) of reciprocal translocation in biopsied blastocysts from preimplantation genetic testing and to investigate whether any features of reciprocal translocation, such as carrier gender or the presence of acrocentric chromosomes or terminal breakpoints, affect meiotic segregation modes.

Methods

Comprehensive chromosomal screening was performed by next generation sequencing (NGS) on 378 biopsied blastocysts from 102 PGD cycles of 89 reciprocal translocation carriers. The segregation modes of a quadrivalent in 378 blastocysts were analysed according to the carrier’s gender, chromosome type and the location of chromosome breakpoints.

Results

The results showed that 122 out of 378 blastocysts (32.3%) were normal or balanced, 209 (55.3%) were translocated chromosomal abnormalities, and 47 (12.4%) were abnormalities of non-translocated chromosomes. The proportion of translocated chromosomal abnormalities in translocations without acrocentric chromosomes was significantly higher than that in blastocysts from carriers with acrocentric chromosomes (14.8% versus 5.9%, P = 0.032). Translocation with acrocentric chromosomes exhibited a significantly higher proportion of 3:1 segregation (24.8% versus 5.1%, P < 0.0001) and a lower rate of 2:2 segregation (70.3% versus 87.0%, P = 0.00028) compared with the proportions in blastocysts from carriers without acrocentric chromosomes. The frequency of adjacent-2 segregation was significantly different in translocations with terminal breakpoints compared to the frequency in blastocysts from carriers without terminal breakpoints (6.7% versus 15.5%, P = 0.013).

Conclusions

This study indicates that the segregation modes in blastocysts were affected by the presence of acrocentric chromosomes and terminal breakpoints, but not by the carrier’s sex. Our data may be useful for predicting the segregation pattern of a reciprocal translocation and could support genetic counselling for balanced translocation carriers for PGT cycles using blastocyst biopsy.

Evaluation of preimplantation genetic testing based on next-generation sequencing for balanced reciprocal translocation carriers

RESEARCH QUESTION

Can next-generation sequencing (NGS) based on copy number variation sequencing (CNV-Seq) identify normal/balanced embryos in balanced reciprocal translocation carriers and what are their reproductive outcomes?

DESIGN

One hundred couples with balanced reciprocal translocation who underwent a total of 134 preimplantation genetic testing (PGT) cycles between January 2015 and October 2017 were evaluated. Trophectoderm cells of blastocysts were biopsied for CNV-Seq-based NGS. All the balanced/normal blastocysts were vitrified and cryopreserved. Single balanced/normal blastocysts were warmed and transferred in the subsequent frozen embryo transfer (FET) cycle.

RESULTS

During the study period, 400 blastocysts were analysed by NGS-PGT, of which 109 (27.25%) were balanced and euploid. A total of 52 blastocysts were transferred in the FET cycle. Clinical pregnancy was confirmed in 34 women (65.38%), with a miscarriage rate of 2.94%; 26 healthy term babies were born, including 24 singletons and one set of twins, while eight couples had ongoing pregnancies. Amniocentesis revealed a fetal chromosome status that was consistent with the NGS-PGT results. Female carriers had a significantly higher blastocyst rate than did the male carriers (37.01% versus 31.27%, P = 0.04). The transferable blastocyst rate was higher in couples treated with gonadotrophin-releasing hormone (GnRH) antagonist than in those treated with GnRH agonist (38.20% versus 24.37%, P = 0.01). However, neither carrier sex nor ovarian stimulation protocol influenced the clinical pregnancy rate.

CONCLUSIONS

CNV-Seq-based NGS is an efficient and reliable PGT method for balanced reciprocal translocation.

Early blastulation of day 4 embryo correlates with the increased euploid rate of preimplantation genetic screening cycles

OBJECTIVE

It is known that embryos with faster growing potential, especially in blastocyst development, correlate with the increased euploid rate. Our study investigated the preimplantation genetic screening cycle to analyze the correlation between early blastulation (EB) on day 4 embryo and the euploid rate.

MATERIALS AND METHODS

This is a retrospective study examining 273 biopsied blastocysts after preimplantation genetic screening obtained from 54 patients from March 2013 to March 2017. Of the 273 biopsied embryos, 81 had early blastulation on day 4 and were classified as the EB (+) group, while the other 192 had no early blastulation and were classified as the EB (-) group. Euploid rates were compared between the two groups. A total of 34 single euploid embryos were transferred, with 14 from the EB (+) group and 20 from the EB (-) group. Clinical pregnancy was compared between the groups.

RESULTS

There is a statistically significant increase in the euploid rate in the EB (+) group (49.4% vs. 34.4%, p = 0.02). The clinical pregnancy rate was also increased in the single euploid embryo transfer group with early blastulation, but did not reach statistical significance (71.4% vs. 50.0%, p = 0.211).

CONCLUSIONS

Early blastulation of day 4 embryo correlates significantly with the euploid rate. Early blastulation of day 4 embryo may serve as a potential aid for embryo selection for transfer in preimplantation genetic screening cycles.

Preimplantation genetic testing for complex chromosomal rearrangement carriers by next-generation sequencing

RESEARCH QUESTION

Can preimplantation genetic testing (PGT) with next-generation sequencing (NGS) increase the chance of achieving a balanced euploid pregnancy in complex chromosome rearrangement (CCR) carriers?

DESIGN

Six couples underwent PGT at the Clinical Centre of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University. The CCR carriers in the six couples were: Case A: 46,XY,t(1;4;11)(p31;p16;q22); Case B: 46,XY,t(3;13;5)(p14;q21;p14); Case C: 46,XX,t(6;11;21)(q21;q21;q13); Case D: 46,XX,inv(9)(p12; q13),t(13;15)(q14;q24); Case E: 46,XX,inv(9)(p12;q13),t(7;9)(q22;p22); and Case F: 46,XX,t(2;7)(q21;q36),t(2;4)(p10;q10),t(2;4)(q15;q10). After ovarian stimulation followed by oocyte retrieval and embryo culture, PGT was performed on day 5 or 6 blastocyst biopsies using NGS to identify normal/balanced euploid embryos. Vitrified-warmed single embryo transfers were performed using normal/balanced euploid embryos.

RESULTS

After seven cycles, 84 oocytes were retrieved. Whole genome sequencing by NGS was performed on 25 trophectoderm biosies. Six (24%) embryos were identified as normal/balanced euploid, four were transferred resulting in four live births. Case A, C, D and E each gave birth to a healthy baby after their first cycle. There was no transferable embryo after two cycles for Case B and one cycle for Case F. The implantation rate per transfer was 4/4 and the live birth rate was 4/4.

CONCLUSION

These results strongly support the use of NGS for CCR carriers.

The interval transfer of a frozen-thawed embryo is more successful than a fresh embryo transfer for women undergoing IVF with recurrent implantation failure after cleavage stage embryo biopsy

BACKGROUND

Recurrent implantation failure (RIF) is repeated unsuccessful embryo transfers (ETs).

AIMS

To identify predictive embryonic markers of implantation in RIF, following pre-implantation genetic screening (PGS) of cleavage stage embryos, after accounting for male and female factors.

MATERIALS AND METHODS

Retrospective analysis of RIF patients undergoing PGS after correction of modifiable causes.

RESULTS

Eighty-four patients underwent 140 in vitro ferilisation cycles. Forty-one cycles were excluded: 12 (no embryo for transfer), four (double ETs) and 25 (no biopsy). Sixty-three patients underwent 99 single euploid ETs (48 fresh, 51 frozen) resulting in 11 biochemical pregnancies, 36 clinical pregnancies (CP), and six miscarriages and 30 live births (LB). Frozen ET was more successful than fresh; respective live birth rate (LBR) and clinical pregnancy rate (CPR), 39.2% versus 20.8%, (P = 0.02), 45.1% versus 27.1% (P = 0.04). LBR and CPR were lower when 5-6 blastomeres were present at embryo biopsy, compared to embryos with ≥7 blastomeres: 15.4% versus 32.6% (P = 0.185) and 15.4% versus 39.5% (P = 0.074) respectively. Serum β human chorionic gonadotropin (βhCG) concentration was greater when a more developed embryo was biopsied (r = 0.448, P = 0.017 and r = 0.476, P = 0.118, fresh and frozen transfers, respectively). Embryo morphokinetic analysis demonstrated faster development to blastocyst stage when more cells were present at biopsy: mean 103.3, 102.2 and 96.0 h for biopsy at the 5-6, 7-8 or ≥9 cell stage respectively (P = 0.040 for difference between 7-8 cells vs ≥9).

CONCLUSIONS

After cleavage stage biopsy, frozen ET was more successful than fresh ET. Chance of conception and serum βhCG concentration correlated with number of cells present at time of biopsy.

Evaluation of preimplantation genetic testing for chromosomal structural rearrangement by a commonly used next generation sequencing workflow

OBJECTIVES

To evaluate the applicability of a commonly used next generation sequencing workflow in detecting unbalanced meiotic segregation products for reciprocal translocation and inversion carriers.

STUDY DESIGN

All preimplantation genetic testing treatment cycles performed for reciprocal translocation or inversion carriers from 2012 to April 2017 were included. Three hundreds and forty-two archived whole genome amplified DNA, which had previously analyzed by array comparative genomic hybridization (aCGH), were retrospectively analyzed by next generation sequencing (NGS). Concordance on overall diagnosis and segmental aneuploidies related to the translocation/inversion breakpoints between aCGH and NGS were determined.

RESULTS

Retrospective analysis of 287 blastomere biopsies and 55 trophectoderm (TE) biopsies showed that the concordance rate on the overall diagnosis between aCGH and NGS on abnormal samples was 100% (266/266), irrespective to the type of biopsy. The concordance rates of normal biopsies were 98.4% (61/62) on blastomere and 78.6% (11/14) on TE biopsies. NGS detected a de novo segmental aneuploidy on one blastomere biopsy and three possible low level mosaic aneuploidies on 3 TE biopsies, which were previously concluded as euploid by aCGH. Using the karyotype of reciprocal translocation/inversion carriers, size of anticipated segmental aneuploidies could be calculated and be used to predict the applicability of NGS before proceeding to treatment.

CONCLUSION

This is the first report to evaluate the applicability of a commercial NGS-based workflow for preimplantation testing for reciprocal translocations/inversions. Our study demonstrated that NGS can diagnose unbalanced translocation/inversion products with the same efficiency as aCGH. The applicability of NGS, with respect to individual karyotype, can be predicted before proceeding to treatment.