Clinical-grade whole genome sequencing-based haplarithmisis enables all forms of preimplantation genetic testing.

High-throughput sequencing technologies have increasingly led to discovery of disease-causing genetic variants, primarily in postnatal multi-cell DNA samples. However, applying these technologies to preimplantation genetic testing (PGT) in nuclear or mitochondrial DNA from single or few-cells biopsied from in vitro fertilised (IVF) embryos is challenging. PGT aims to select IVF embryos without genetic abnormalities. Although genotyping-by-sequencing (GBS)-based haplotyping methods enabled PGT for monogenic disorders (PGT-M), structural rearrangements (PGT-SR), and aneuploidies (PGT-A), they are labour intensive, only partially cover the genome and are troublesome for difficult loci and consanguineous couples. Here, we devise a simple, scalable and universal whole genome sequencing haplarithmisis-based approach enabling all forms of PGT in a single assay. In a comparison to state-of-the-art GBS-based PGT for nuclear DNA, shallow sequencing-based PGT, and PCR-based PGT for mitochondrial DNA, our approach alleviates technical limitations by decreasing whole genome amplification artifacts by 68.4%, increasing breadth of coverage by at least 4-fold, and reducing wet-lab turn-around-time by ~2.5-fold. Importantly, this method enables trio-based PGT-A for aneuploidy origin, an approach we coin PGT-AO, detects translocation breakpoints, and nuclear and mitochondrial single nucleotide variants and indels in base-resolution.

Identification of a pathogenic variant and pre-implantation genetic testing for a Chinese family affected with split-hand/foot malformation.

Split-hand/foot malformation is a serious congenital limb malformation characterized by syndactyly and underdevelopment of the phalanges and metatarsals. In this study, we reported a case of a fetus with hand-foot cleft deformity. Whole exome and Sanger sequencing were used to filter out candidate gene mutation sites and provide pre-implantation genetic testing(PGT) for family members. Genetic testing results showed that there was a homozygous mutation c.786G>A (p.Trp262*) in the fetal WNT10B, and both parents were carriers of heterozygous mutations. PGT results showed that out of the two blastocysts, one was a heterozygous mutant and the other was a homozygous mutant. All the embryos had diploid chromosomes. The heterozygous embryo was transferred, and a singleton pregnancy was successfully achieved. This study suggests that homozygous mutations in WNT10B are the likely cause of hand-foot clefts in this family. For families with monogenic diseases, preimplantation genetic testing can effectively prevent the birth of an affected child only after identifying the pathogenic mutation.

Efficacy of non-invasive chromosome screening, preimplantation genetic testing for aneuploidy, and morphological grading in selecting embryos of patients with advanced maternal age: a three-armed prospective cohort study.

BACKGROUND: Non-invasive chromosome screening (NICS) and trophectoderm biopsy preimplantation genetic testing for aneuploidy (TE-PGT) were both applied for embryo ploidy detection, However, the cumulative live birth rates (CLBR) of NICS and TE-PGT in older age groups have yet to be reported. This study aimed to ascertain whether NICS and TE-PGT could enhance the cumulative live birth rates among patients of advanced maternal age. METHODS: A total of 384 couples aged 35-40 years were recruited. The patients were assigned to three groups: NICS, TE-PGT, and intracytoplasmic sperm injection (ICSI). All patients received frozen single blastocyst transfer. Patients in the NICS and TE-PGT groups underwent aneuploidy screening. RESULTS: When compared to the ICSI group, the CLBR was significantly higher in the NICS and TE-PGT groups (27.9% vs. 44.9% vs. 51.0%, p = 0.003 for NICS vs. ICSI, p < 0.001 for TE-PGT vs. ICSI). There were no significant differences in the clinical outcomes between the NICS and TE-PGT groups. Adjusting for confounding factors, the NICS and TE-PGT groups still showed a higher CLBR than the ICSI group (adjusted odds ratio (OR) 3.847, 95% confidence interval (CI) 1.939 to 7.634; adjusted OR 3.795, 95% CI 1.981 to 7.270). Additionally, the cumulative pregnancy loss rates of the NICS and TE-PGT groups were significantly lower than that of the ICSI group (adjusted OR 0.277, 95% CI 0.087 to 0.885; adjusted OR 0.182, 95% CI 0.048 to 0.693). There was no significant difference in the birth weights of the three groups (p = 0.108). CONCLUSIONS: In women 35-40 years old, the CLBR can be increased by selecting euploid embryos using NICS and TE-PGT. For elderly women at high risk of embryonic aneuploidy, NICS, characterized by its safety and non-invasive nature, may emerge as an alternative option for preimplantation genetic testing.

The current clinical applications of preimplantation genetic testing (PGT): acknowledging the limitations of biology and technology.

INTRODUCTION: Preimplantation Genetic Testing (PGT) is a cutting-edge test used to detect genetic abnormalities in embryos fertilized through Medically Assisted Reproduction (MAR). PGT aims to ensure that embryos selected for transfer are free of specific genetic conditions or chromosome abnormalities, thereby reducing chances for unsuccessful MAR cycles, complicated pregnancies, and genetic diseases in future children. AREAS COVERED: In PGT, genetics, embryology, and technology progress and evolve together. Biological and technological limitations are described and addressed to highlight complexity and knowledge constraints and draw attention to concerns regarding safety of procedures, clinical validity, and utility, extent of applications and overall ethical implications for future families and society. EXPERT OPINION: Understanding the genetic basis of diseases along with advanced technologies applied in embryology and genetics contribute to faster, cost-effective, and more efficient PGT. Next Generation Sequencing-based techniques, enhanced by improved bioinformatics, are expected to upgrade diagnostic accuracy. Complicating findings such as mosaicism, mt-DNA variants, variants of unknown significance, or variants related to late-onset or polygenic diseases will however need further appraisal. Emphasis on monitoring such emerging data is crucial for evidence-based counseling while standardized protocols and guidelines are essential to ensure clinical value and respect of Ethical, Legal and Societal Issues.

Blastocoel fluid as an alternative source of DNA for minimally invasive PGT and biomarker of embryo competence.

The discovery of DNA in blastocoel fluid (BF-DNA) generated new perspectives in the potential development of simpler and safer alternative non-invasive tests in reproductive genetics. Short DNA fragments of apoptotic origin, together with specific expression patterns of pro- and anti-apoptotic genes in the blastocoel fluid of euploid and aneuploid embryos, suggest a self-correction mechanism to preferentially eliminate aneuploid cells, and purge defective and non-viable cells. The correlation of blastocoel fluid content with the genetic status of the whole embryo, and therefore its potential use in minimally invasive preimplantation genetic testing (miPGT), or as an indicator of embryo potential, remains uncertain and needs to be determined. The limited amount and compromised integrity of BF-DNA, with likely apoptotic origination, constrains its amplification, leading to low concordance and reproducibility rates for both aneuploidy screening and monogenic testing. While embryo genotyping constitutes a more ambitious goal, the presence of analysable DNA after amplification in blastocoel fluid may be used as a clinical biomarker of embryo competency to select the most viable embryo(s) for transfer, and potentially improve the implantation rate. Although blastocentesis remains a promising area for future research, several technical and methodological limitations are currently constraining its consideration for clinical practice.

Comparative Analysis of Two NGS-Based Platforms for Product-of-Conception Karyotyping.

Cytogenetic information about the product of conception (POC) is important to determine the presence of recurrent chromosomal abnormalities that are an indication for preimplantation genetic testing for aneuploidy or structural rearrangements. Although microscopic examination by G-staining has long been used for such an evaluation, detection failures are relatively common with this method, due to cell-culture-related issues. The utility of low-coverage whole-genome sequencing (lcWGS) using short-read next-generation sequencing (NGS) has been highlighted recently as an alternative cytogenomic approach for POC analysis. We, here, performed comparative analysis of two NGS-based protocols for this purpose based on different short-read sequencers (the Illumina VeriSeq system using a MiSeq sequencer and the Thermo Fisher ReproSeq system using an Ion S5 sequencer). The cytogenomic diagnosis obtained with each NGS method was equivalent in each of 20 POC samples analyzed. Notably, X chromosome sequence reads were reduced in some female samples with both systems. The possibility of low-level mosaicism for monosomy X as an explanation for this was excluded by FISH analysis. Additional data from samples with various degrees of X chromosome aneuploidy suggested that it was a technical artifact related to X chromosome inactivation. Indeed, subsequent nanopore sequencing indicated that the DNA in the samples showing the artifact was predominantly unmethylated. Our current findings indicate that although X chromosome data must be interpreted with caution, both the systems we tested for NGS-based lcWGS are useful alternatives for the karyotyping of POC samples.

Preimplantation Genetic Testing of Spinocerebellar Ataxia Type 3/Machado-Joseph Disease-Robust Tools for Direct and Indirect Detection of the ATXN3 (CAG)n Repeat Expansion.

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a neurodegenerative disorder caused by the ATXN3 CAG repeat expansion. Preimplantation genetic testing for monogenic disorders (PGT-M) of SCA3/MJD should include reliable repeat expansion detection coupled with high-risk allele determination using informative linked markers. One couple underwent SCA3/MJD PGT-M combining ATXN3 (CAG)n triplet-primed PCR (TP-PCR) with customized linkage-based risk allele genotyping on whole-genome-amplified trophectoderm cells. Microsatellites closely linked to ATXN3 were identified and 16 markers were genotyped on 187 anonymous DNAs to verify their polymorphic information content. In the SCA3/MJD PGT-M case, the ATXN3 (CAG)n TP-PCR and linked marker analysis results concurred completely. Among the three unaffected embryos, a single embryo was transferred and successfully resulted in an unaffected live birth. A total of 139 microsatellites within 1 Mb upstream and downstream of the ATXN3 CAG repeat were identified and 8 polymorphic markers from each side were successfully co-amplified in a single-tube reaction. A PGT-M assay involving ATXN3 (CAG)n TP-PCR and linkage-based risk allele identification has been developed for SCA3/MJD. A hexadecaplex panel of highly polymorphic microsatellites tightly linked to ATXN3 has been developed for the rapid identification of informative markers in at-risk couples for use in the PGT-M of SCA3/MJD.

A Method to Study the Meiotic Recombination Map in Human Preimplantation Blastocysts.

Homologous recombination plays pivotal roles in physical attachments and genetic diversity. In the past, it was studied among individuals from different populations. However, only few gametes from individual could generate offspring, which limits its exploration in nature selection. In the last few years, preimplantation blastocysts based on trio SNP-chip data were available in individuals for preimplantation genetic testing (PGT). In this protocol, we demonstrate how to detect meiotic recombination events and construct the genetic map based on trio SNP-chip data, obtained from biopsied blastocysts and their related individuals in PGT cycles, which may allow better understanding of recombination events in nature selection.

Factors affecting biochemical pregnancy loss (BPL) in preimplantation genetic testing for aneuploidy (PGT-A) cycles: machine learning-assisted identification.

PURPOSE: To determine the factors influencing the likelihood of biochemical pregnancy loss (BPL) after transfer of a euploid embryo from preimplantation genetic testing for aneuploidy (PGT-A) cycles. METHODS: The study employed an observational, retrospective cohort design, encompassing 6020 embryos from 2879 PGT-A cycles conducted between February 2013 and September 2021. Trophectoderm biopsies in day 5 (D5) or day 6 (D6) blastocysts were analyzed by next generation sequencing (NGS). Only single embryo transfers (SET) were considered, totaling 1161 transfers. Of these, 49.9% resulted in positive pregnancy tests, with 18.3% experiencing BPL. To establish a predictive model for BPL, both classical statistical methods and five different supervised classification machine learning algorithms were used. A total of forty-seven factors were incorporated as predictor variables in the machine learning models. RESULTS: Throughout the optimization process for each model, various performance metrics were computed. Random Forest model emerged as the best model, boasting the highest area under the ROC curve (AUC) value of 0.913, alongside an accuracy of 0.830, positive predictive value of 0.857, and negative predictive value of 0.807. For the selected model, SHAP (SHapley Additive exPlanations) values were determined for each of the variables to establish which had the best predictive ability. Notably, variables pertaining to embryo biopsy demonstrated the greatest predictive capacity, followed by factors associated with ovarian stimulation (COS), maternal age, and paternal age. CONCLUSIONS: The Random Forest model had a higher predictive power for identifying BPL occurrences in PGT-A cycles. Specifically, variables associated with the embryo biopsy procedure (biopsy day, number of biopsied embryos, and number of biopsied cells) and ovarian stimulation (number of oocytes retrieved and duration of stimulation), exhibited the strongest predictive power.

[Application of single-sperm sequencing in resolving the carrier status of preimplantation genetic testing for chromosomal structural rearrangements in Robertsonian translocations].

OBJECTIVE: To investigate the application value of single-sperm sequencing in resolving the carrier status of preimplantation genetic testing (PGT) for chromosomal structural rearrangements in Robertsonian translocations. METHODS: Haplotypes were constructed by single-sperm isolation combined with single-sperm sequencing for a patient with 45, XY, der(13; 14)(q10; q10). Twenty single-sperm samples were isolated by mechanical braking and subjected to whole-genome amplification (WGA), and then the Asian Screening Array (ASA) gene chip was used to detect the 183 708 single nucleotide polymorphisms (SNP) of the WGA products. The single sperm associated with the translocation that could be used as haplotype inference was detected by copy number variation (CNV) sequencing, and the chromosomal haplotypes with normal and Robertsonian translocations were inferred. Three biopsy samples of embryonic trophoblast cells were used as the objects. After whole-genome amplification, high-throughput sequencing was employed to determine the status of the translocation chromosome carried by the embryos. The available blastocysts were selected for transfer, and the amniotic fluid samples were taken at 18 weeks of gestation to confirm whether the fetus carried the pathogenic mutation. RESULTS: A total of 6 037 SNP sites were screened by single-sperm sequencing, and 30 sites selected to distinguish normal and translocation haplotypes. Preimplantation haplotype analysis showed that all the three embryos were euploids without Robertsonian translocation chromosome. Genetic testing of amniotic fluid in the second trimester confirmed that the karyotype of the fetus was 46, XN, carrying no Robertsonian translocation chromosome. CONCLUSION: For male carriers of Robertsonian translocation, single sperm sequencing can be used to screen SNP sites to construct haplotypes for distinguishing normal and Robertsonian translocation embryos, and to provide a basis for embryo selection by preimplantation chromosomal structural genetic testing.

[Genetic analysis and PGT-SR outcome of a male carrier of exceptional complex chromosome rearrangement].

OBJECTIVE: To investigate the clinical and genetic characteristics of a male carrier of exceptional complex chromosome rearrangement (CCR) and the outcome of preimplantation genetic testing for chromosomal structural rearrangement (PGT-SR). METHODS: Using the modified high resolution G banding technique and whole-genome low-coverage sequencing (WGLCS), we analyzed the cellular karyotype and molecular karyotype of a male carrier of CCR, performed an analysis of the single-sperm chromosome copy number and conducted PGT-SR for the patient by next-generation sequencing (NGS). In addition, we reviewed the literature on reported male carriers of CCRs and summarized their normal/balanced sperm ratios and PGT-SR outcomes. RESULTS: The karyotype of the patient was 46,XY,der(5)inv(5)(q14.3q23.2)t(5;14;11) (q23.2;q31.1;q21),der(11)t(5;14;11);der(14)t(5;14;11), with the translocation breakpoints located in the intergenic region. Single-sperm sequencing revealed 20.0%（7/35）of normal haploids in the male's spermatozoa， and the results PGT-SR showed a proportion of 25.0%（4/16）of normal/balanced embryos. After thawing and transferring of 2 euploid blastocysts, a healthy male infant was successfully delivered. CONCLUSION: The proportion of normal haploids in the spermatozoa of male CCR carriers may be higher than theoretically predicted, and PGT-SR can effectively improve the pregnancy outcome in male CCR carriers and provide valuable data for genetic counseling.

The density of the inner cell mass is a new indicator of the quality of a human blastocyst: a valid supplement to the Gardner scoring system.

STUDY QUESTION: Can the density of the inner cell mass (ICM) be a new indicator of the quality of the human blastocyst? SUMMARY ANSWER: The densification index (DI) developed in this study can quantify ICM density and provide positive guidance for ploidy, pregnancy, and live birth. WHAT IS KNOWN ALREADY: In evaluating the quality of ICM, reproductive care clinics still use size indicators without further evaluation. The main disadvantage of this current method is that the evaluation of blastocyst ICM is relatively rough and cannot meet the needs of clinical embryologists, especially when multiple blastocysts have the same ICM score, which makes them difficult to evaluate further. STUDY DESIGN, SIZE, DURATION: This observational study included data from 2272 blastocysts in 1991 frozen-thawed embryo transfer (FET) cycles between January 2018 to November 2021 and 1105 blastocysts in 430 preimplantation genetic testing cycles between January 2019 and February 2023. PARTICIPANTS/MATERIALS, SETTING, METHODS: FET, ICSI, blastocyst culture, trophectoderm biopsy, time-lapse (TL) monitoring, and next-generation sequencing were performed. After preliminary sample size selection, the 11 focal plane images captured by the TL system were normalized and the spatial frequency was used to construct the DI of the ICM. MAIN RESULTS AND THE ROLE OF CHANCE: This study successfully constructed a quantitative indicator DI that can reflect the degree of ICM density in terms of fusion and texture features. The higher the DI value, the better the density of the blastocyst ICM, and the higher the chances that the blastocyst was euploid (P < 0.001) and that pregnancy (P < 0.001) and live birth (P = 0.005) were reached. In blastocysts with ICM graded B and blastocysts graded 4BB, DI was also positively associated with ploidy, pregnancy, and live birth (P < 0.05). ROC analysis showed that combining the Gardner scoring system with DI can more effectively predict pregnancy and live births, when compared to using the Gardner scoring system alone. LIMITATIONS, REASONS FOR CAUTION: Accurate calculation of the DI value places high demands on image quality, requiring manual selection of the clearest focal plane and exposure control. Images with the ICM not completely within the field of view cannot be used. The association between the density of ICM and chromosomal mosaicism was not evaluated. The associations between the density of ICM and different assisted reproductive technologies and different culture conditions in embryo laboratories were also not evaluated. Prospective studies are needed to further investigate the impact of ICM density on clinical outcomes. WIDER IMPLICATIONS OF THE FINDINGS: ICM density assessment is a new direction in blastocyst assessment. This study explores new ways of assessing blastocyst ICM density and develops quantitative indicators and a corresponding qualitative evaluation scheme for ICM density. The DI of the blastocyst ICM developed in this study is easy to calculate and requires only TL equipment and image processing, providing positive guidance for clinical outcomes. The qualitative evaluation scheme of ICM density can assist embryologists without TL equipment to manually evaluate ICM density. ICM density is a simple indicator that can be used in practice and is a good complement to the blastocyst scoring systems currently used in most centers. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Key Research & Development Program of China (2021YFC2700603). The authors report no financial or commercial conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Total gonadotropin dose did not affect euploid blastocyst rates: an analysis of more than 19,000 oocytes.

BACKGROUND: To evaluate whether increasing total gonadotropin (Gn) dose is associated with changes in euploid blastocyst rate in preimplantation genetic testing (PGT) oocytes. METHODS: This retrospective cohort study was conducted between 2017 and 2022, and 19,246 oocytes were grouped and analyzed based on tri-sectional quantiles of total Gn doses. SETTING: Single reproductive medical center. SUBJECTS: All the patients who underwent PGT cycles, including PGT for aneuploidy, monogenic disorders, and structural rearrangements, were included. EXPOSURE: Next-generation sequencing platforms for chromosomal analysis. MAIN OUTCOME MEASURES: Blastocyst formation and euploid blastocyst rates. RESULTS: In total, 19,246 oocytes and 5375 PGT blastocysts were analyzed. There were significant differences in blastocyst formation and euploid blastocyst rates among the groups classified according to tri-sectional quantiles of total Gn doses. Significant differences in age, body mass index (BMI), proportion of primary infertility, anti-Müllerian hormone (AMH) levels, number of oocytes retrieved, controlled ovarian stimulation (COS) regimen, type of Gn, and PGT category were observed among the three groups. After stratifying the analysis by age, BMI, infertility diagnosis, AMH levels, number of oocytes retrieved, PGT category, type of Gn, and COS regimen, significant differences were only seen in a small number of specific subgroups. Furthermore, the results of the multiple logistic regression analysis showed that the blastocyst formation and euploid blastocyst rates did not significantly increase or decrease with the total Gn dose, whether treated as a continuous variable or divided into three Gn groups as categorical variables. Notably, advancing age was a risk factor for blastocyst formation and euploid blastocyst rates. PGT for structural rearrangements was a risk factor for blastocyst formation and euploid blastocyst rates as compared with PGT for aneuploidy. CONCLUSION: In the total PGT cycles, advancing age, and preimplantation genetic testing for structural rearrangements negatively affected blastocyst formation and euploid blastocyst rates; however, the total Gn dose did not affect blastocyst formation and euploid blastocyst rates.

Artificial intelligence system for outcome evaluations of human in vitro fertilization-derived embryos.

BACKGROUND: In vitro fertilization (IVF) has emerged as a transformative solution for infertility. However, achieving favorable live-birth outcomes remains challenging. Current clinical IVF practices in IVF involve the collection of heterogeneous embryo data through diverse methods, including static images and temporal videos. However, traditional embryo selection methods, primarily reliant on visual inspection of morphology, exhibit variability and are contingent on the experience of practitioners. Therefore, an automated system that can evaluate heterogeneous embryo data to predict the final outcomes of live births is highly desirable. METHODS: We employed artificial intelligence (AI) for embryo morphological grading, blastocyst embryo selection, aneuploidy prediction, and final live-birth outcome prediction. We developed and validated the AI models using multitask learning for embryo morphological assessment, including pronucleus type on day 1 and the number of blastomeres, asymmetry, and fragmentation of blastomeres on day 3, using 19,201 embryo photographs from 8271 patients. A neural network was trained on embryo and clinical metadata to identify good-quality embryos for implantation on day 3 or day 5, and predict live-birth outcomes. Additionally, a 3D convolutional neural network was trained on 418 time-lapse videos of preimplantation genetic testing (PGT)-based ploidy outcomes for the prediction of aneuploidy and consequent live-birth outcomes. RESULTS: These two approaches enabled us to automatically assess the implantation potential. By combining embryo and maternal metrics in an ensemble AI model, we evaluated live-birth outcomes in a prospective cohort that achieved higher accuracy than experienced embryologists (46.1% vs. 30.7% on day 3, 55.0% vs. 40.7% on day 5). Our results demonstrate the potential for AI-based selection of embryos based on characteristics beyond the observational abilities of human clinicians (area under the curve: 0.769, 95% confidence interval: 0.709-0.820). These findings could potentially provide a noninvasive, high-throughput, and low-cost screening tool to facilitate embryo selection and achieve better outcomes. CONCLUSIONS: Our study underscores the AI model's ability to provide interpretable evidence for clinicians in assisted reproduction, highlighting its potential as a noninvasive, efficient, and cost-effective tool for improved embryo selection and enhanced IVF outcomes. The convergence of cutting-edge technology and reproductive medicine has opened new avenues for addressing infertility challenges and optimizing IVF success rates.

The impact of implementing a non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) embryo culture protocol on embryo viability and clinical outcomes.

STUDY QUESTION: Are modifications in the embryo culture protocol needed to perform non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) affecting clinical reproductive outcomes, including blastocyst development and pregnancy outcomes? SUMMARY ANSWER: The implementation of an embryo culture protocol to accommodate niPGT-A has no impact on blastocyst viability or pregnancy outcomes. WHAT IS KNOWN ALREADY: The recent identification of embryo cell-free (cf) DNA in spent blastocyst media has created the possibility of simplifying PGT-A. Concerns, however, have arisen at two levels. First, the representativeness of that cfDNA to the real ploidy status of the embryo. Second, the logistical changes that need to be implemented by the IVF laboratory when performing niPGT-A and their effect on reproductive outcomes. Concordance rates of niPGT-A to invasive PGT-A have gradually improved; however, the impact of culture protocol changes is not as well understood. STUDY DESIGN, SIZE, DURATION: As part of a trial examining concordance rates of niPGT-A versus invasive PGT-A, the IVF clinics implemented a specific niPGT-A embryo culture protocol. Briefly, this involved initial culture of fertilized oocytes following each laboratory standard routine up to Day 4. On Day 4, embryos were washed and cultured individually in 10 µl of fresh media. On Day 6 or 7, blastocysts were then biopsied, vitrified, and media collected for the niPGT-A analysis. Six IVF clinics from the previously mentioned trial were enrolled in this analysis. In the concordance trial, Clinic A cultured all embryos (97 cycles and 355 embryos) up to Day 6 or 7, whereas in the remaining clinics (B-F) (379 cycles), nearly a quarter of all the blastocysts (231/985: 23.5%) were biopsied on Day 5, with the remaining blastocysts following the niPGT-A protocol (754/985: 76.5%). During the same period (April 2018-December 2020), the IVF clinics also performed standard invasive PGT-A, which involved culture of embryos up to Days 5, 6, or 7 when blastocysts were biopsied and vitrified. PARTICIPANTS/MATERIALS, SETTING, METHODS: In total, 428 (476 cycles) patients were in the niPGT-A study group. Embryos from 1392 patients underwent the standard PGT-A culture protocol and formed the control group. Clinical information was obtained and analyzed from all the patients. Statistical comparisons were performed between the study and the control groups according to the day of biopsy. MAIN RESULTS AND THE ROLE OF CHANCE: The mean age, number of oocytes, fertilization rates, and number of blastocysts biopsied were not significantly different for the study and the control group. Regarding the overall pregnancy outcomes, no significant effect was observed on clinical pregnancy rate, miscarriage rate, or ongoing pregnancy rate (≥12 weeks) in the study group compared to the control group when stratified by day of biopsy. LIMITATIONS, REASONS FOR CAUTION: The limitations are intrinsic to the retrospective nature of the study, and to the fact that the study was conducted in invasive PGT-A patients and not specifically using niPGT-A cases. WIDER IMPLICATIONS OF THE FINDINGS: This study shows that modifying current IVF laboratory protocols to adopt niPGT-A has no impact on the number of blastocysts available for transfer and overall clinical outcomes of transferred embryos. Whether removal of the invasive biopsy step leads to further improvements in pregnancy rates awaits further studies. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by Igenomix. C.R., L.N.-S., and D.V. are employees of Igenomix. D.S. was on the Scientific Advisory Board of Igenomix during the study. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT03520933).

An expert opinion on rescuing atypically pronucleated human zygotes by molecular genetic fertilization checks in IVF.

IVF laboratories routinely adopt morphological pronuclear assessment at the zygote stage to identify abnormally fertilized embryos deemed unsuitable for clinical use. In essence, this is a pseudo-genetic test for ploidy motivated by the notion that biparental diploidy is required for normal human life and abnormal ploidy will lead to either failed implantation, miscarriage, or significant pregnancy complications, including molar pregnancy and chorionic carcinoma. Here, we review the literature associated with ploidy assessment of human embryos derived from zygotes displaying a pronuclear configuration other than the canonical two, and the related pregnancy outcome following transfer. We highlight that pronuclear assessment, although associated with aberrant ploidy outcomes, has a low specificity in the prediction of abnormal ploidy status in the developing embryo, while embryos deemed abnormally fertilized can yield healthy pregnancies. Therefore, this universal strategy of pronuclear assessment invariably leads to incorrect classification of over 50% of blastocysts derived from atypically pronucleated zygotes, and the systematic disposal of potentially viable embryos in IVF. To overcome this limitation of current practice, we discuss the new preimplantation genetic testing technologies that enable accurate identification of the ploidy status of preimplantation embryos and suggest a progress from morphology-based checks to molecular fertilization check as the new gold standard. This alternative molecular fertilization checking represents a possible non-incremental and controversy-free improvement to live birth rates in IVF as it adds to the pool of viable embryos available for transfer. This is especially important for the purposes of 'family building' or for poor-prognosis IVF patients where embryo numbers are often limited.

Multiple collapses of blastocysts after full blastocyst formation is an independent risk factor for aneuploidy - a study based on AI and manual validation.

BACKGROUND: The occurrence of blastocyst collapse may become an indicator of preimplantation embryo quality assessment. It has been reported that collapsing blastocysts can lead to higher rates of aneuploidy and poorer clinical outcomes, but more large-scale studies are needed to explore this relationship. This study explored the characteristics of blastocyst collapse identified and quantified by artificial intelligence and explored the associations between blastocyst collapse and embryo ploidy, morphological quality, and clinical outcomes. METHODS: This observational study included data from 3288 biopsied blastocysts in 1071 time-lapse preimplantation genetic testing cycles performed between January 2019 and February 2023 at a single academic fertility center. All transferred blastocysts are euploid blastocysts. The artificial intelligence recognized blastocyst collapse in time-lapse microscopy videos and then registered the collapsing times, and the start time, the recovery duration, the shrinkage percentage of each collapse. The effects of blastocyst collapse and embryo ploidy, pregnancy, live birth, miscarriage, and embryo quality were studied using available data from 1196 euploid embryos and 1300 aneuploid embryos. RESULTS: 5.6% of blastocysts collapsed at least once only before the full blastocyst formation (tB), 19.4% collapsed at least once only after tB, and 3.1% collapsed both before and after tB. Multiple collapses of blastocysts after tB (times ≥ 2) are associated with higher aneuploid rates (54.6%, P > 0.05; 70.5%, P < 0.001; 72.5%, P = 0.004; and 71.4%, P = 0.049 in blastocysts collapsed 1, 2, 3 or ≥ 4 times), which remained significant after adjustment for confounders (OR = 2.597, 95% CI 1.464-4.607, P = 0.001). Analysis of the aneuploid embryos showed a higher ratio of collapses and multiple collapses after tB in monosomies and embryos with subchromosomal deletion of segmental nature (P < 0.001). Blastocyst collapse was associated with delayed embryonic development and declined blastocyst quality. There is no significant difference in pregnancy and live birth rates between collapsing and non-collapsing blastocysts. CONCLUSIONS: Blastocyst collapse is common during blastocyst development. This study underlined that multiple blastocyst collapses after tB may be an independent risk factor for aneuploidy which should be taken into account by clinicians and embryologists when selecting blastocysts for transfer.

A study on methods for preimplantation genetic testing (PGT) on in vivo- and in vitro-produced equine embryos, with emphasis on embryonic sex determination.

Two methods for preimplantation genetic testing (PGT) have been described for equine embryos: trophoblast cell biopsy (TCB) or blastocoele fluid aspiration (BFA). While TCB is widely applied for both in vivo- and in vitro-produced embryos, BFA has been mostly utilized for in vivo-produced embryos. Alternative methods for PGT, including analysis of cell-free DNA (CFD) in the medium where in vitro-produced embryos are cultured, have been reported in humans but not for equine embryos. In Experiment 1, in vivo- (n = 10) and in vitro-produced (n = 13) equine embryos were subjected to BFA, cultured for 24 h, then subjected to TCB, and cultured for additional 24 h. No detrimental effect on embryonic diameter or re-expansion rates was observed for either embryo group (P > 0.05). In Experiment 2, the concordance (i.e., agreement on detecting the same embryonic sex using two techniques) among BFA, TCB, and the whole embryo (Whole) was studied by detecting the sex-determining region Y (SRY) or testis-specific y-encoded protein 1 (TSPY) (Y-chromosome), and androgen receptor (AR; X-chromosome) genes using PCR. Overall, a higher concordance for detecting embryonic sex was observed among techniques for in vivo-produced embryos (67-100 %; n = 14 embryos) than for in vitro-produced embryos (31-92 %; n = 13 embryos). The concordance between sample types increased when utilizing TSPY (77-100 %) instead of SRY (31-100 %) as target gene. In Experiment 3, CFD analysis was performed on in vitro-produced embryos to determine embryonic sex via PCR (SRY [Y-chromosome] and amelogenin - AMEL [X- and Y-chromosomes]). Overall, CFD was detected in all medium samples, and the concordance between CFD sample and the whole embryo was 60 % when utilizing SRY and AMEL genes. In conclusion, equine embryos can be subjected to two biopsy procedures (24 h apart) without apparent detrimental effects on embryonic size. For in vivo-, but not for in vitro-produced equine embryos, BFA can be considered a potential alternative to TCB for PGT. Finally, CFD can be further explored as a non-invasive method for PGT in in vitro produced equine embryos.