Y chromosome microdeletions in Chinese men with infertility: prevalence, phenotypes, and intracytoplasmic sperm injection outcomes.

BACKGROUND: The incidence of Y chromosome microdeletions varies among men with infertility across regions and ethnicities worldwide. However, comprehensive epidemiological studies on Y chromosome microdeletions in Chinese men with infertility are lacking. We aimed to investigate Y chromosome microdeletions prevalence among Chinese men with infertility and its correlation with intracytoplasmic sperm injection (ICSI) outcomes. METHODS: This single-center retrospective study included 4,714 men with infertility who were evaluated at the Reproductive Center of the First Affiliated Hospital of Sun Yat-sen University between May 2017 and January 2021. Semen analysis and Y-chromosome microdeletion via multiplex polymerase chain reaction were conducted on the men. The study compared outcomes of 36 ICSI cycles from couples with male azoospermia factor (AZF)cd deletions with those of a control group, which included 72 ICSI cycles from couples without male Y chromosome microdeletions, during the same period. Both groups underwent ICSI treatment using ejaculated sperm. RESULTS: Among 4,714 Chinese men with infertility, 3.31% had Y chromosome microdeletions. The combined deletion of sY254 and sY255 in the AZFc region and sY152 in the AZFd region was the prevalent pattern of Y chromosome microdeletion, with 3.05% detection rate. The detection rates of AZF deletions in patients with normal total sperm count, mild oligozoospermia, severe oligozoospermia, cryptozoospermia, and azoospermia were 0.17%, 1.13%, 5.53%, 71.43%, and 7.54%, respectively. Compared with the control group, the AZFcd deletion group exhibited no significant difference in the laboratory results or pregnancy outcomes of ICSI cycles using ejaculated sperm. CONCLUSIONS: This is the largest epidemiological study on Y chromosome microdeletions in Chinese men with infertility. The study results underline the necessity for detecting Y chromosome microdeletion in men with infertility and severe sperm count abnormalities, especially those with cryptozoospermia. The combined deletion of sY254 and sY255 in the AZFc region and sY152 in the AZFd region was the most prevalent Y chromosome microdeletion pattern. Among patients with AZFcd deletion and ejaculated sperm, ICSI treatment can result in pregnancy outcomes, similar to those without AZFcd deletion.

Effects of different oocyte cytoplasmic granulation patterns on embryo development and euploidy: a sibling oocyte control study.

PURPOSE: This study evaluated the relationship between cytoplasmic granulation patterns and the developmental potential of mature sibling oocytes. METHODS: Data from 54 cycles of preimplantation genetic tests for structural rearrangement from July 2019 to June 2022 were analyzed. In total, 564 embryos were cultured using a time-lapse system. Sibling oocytes were divided into four groups based on cytoplasmic granulation patterns: fine granulation (FG) group (n = 177), central granulation (CG) group (n = 183), dispersed granulation (DG) group (n = 161), and uneven granulation (UG) group (n = 43). The CG group was further divided into three groups (grades I, II, and III) based on the tertile of the ratio of central granular distribution area to oocyte area. Fertilization rate, embryo morphokinetics, chromosomal ploidy, and clinical outcomes of the groups were compared. RESULTS: No significant differences were observed in morphokinetic parameters, fertilization rate, embryo production, blastocyst formation, and aneuploidy rates among the different cytoplasmic-granulation pattern groups. However, embryos derived from CG oocytes showed significantly higher aneuploidy rates in grade III compared to grade I (86.21% vs 61.54%, P = 0.036) or grade II (86.21% vs 56.00%, P = 0.013). Thirty embryos were transferred to the uteri of female patients and the clinical pregnancy and live birth rates did not significantly differ among groups. CONCLUSIONS: Cytoplasmic granulation patterns may not affect embryo fertilization, development speed, and aneuploidy rates. However, a higher grade of CG may be associated with increased aneuploidy rates. Larger sample sizes are required to explore the impact of oocyte cytoplasmic granulation patterns on embryo implantation potential.

Clinical application of next generation sequencing-based haplotype linkage analysis in the preimplantation genetic testing for germline mosaicisms.

BACKGROUND: Preimplantation genetic testing (PGT) for monogenic disorders (PGT-M) for germline mosaicism was previously highly dependent on polymerase chain reaction (PCR)-based directed mutation detection combined with linkage analysis of short tandem repeats (STRs). However, the number of STRs is usually limited. In addition, designing suitable probes and optimizing the reaction conditions for multiplex PCR are time-consuming and laborious. Here, we evaluated the effectiveness of next generation sequencing (NGS)-based haplotype linkage analysis in PGT of germline mosaicism. METHODS: PGT-M with NGS-based haplotype linkage analysis was performed for two families with maternal germline mosaicism for an X-linked Duchenne muscular dystrophy (DMD) mutation (del exon 45-50) or an autosomal TSC1 mutation (c.2074C > T). Trophectoderm biopsy and multiple displacement amplification (MDA) were performed for a total of nine blastocysts. NGS and Sanger sequencing were performed in genomic DNA of family members and embryonic MDA products to detect DMD deletion and TSC1 mutation, respectively. Single nucleotide polymorphism (SNP) sites closely linked to pathogenic mutations were detected with NGS and served in haplotype linkage analysis. NGS-based aneuploidy screening was performed for all embryos to reduce the risk of pregnancy loss. RESULTS: All nine blastocytes showed conclusive PGT results. Each family underwent one or two frozen-thawed embryo transfer cycles to obtain a clinical pregnancy, and the prenatal diagnosis showed that the fetus was genotypically normal and euploid for both families. CONCLUSIONS: NGS-SNP could effectively realize PGT for germline mosaicism. Compared with PCR-based methods, the NGS-SNP method with increased polymorphic informative markers can achieve a greater diagnostic accuracy. Further studies are warranted to verify the effectiveness of NGS-based PGT of germline mosaicism cases in the absence of surviving offsprings.

Evaluating the application value of NGS-based PGT-A by screening cryopreserved MDA products of embryos from PGT-M cycles with known transfer outcomes.

PURPOSE: To determine the application value of next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidies (PGT-A). METHODS: We conducted a retrospective case-control study on a cohort of frozen-thawed embryo transfer (FET) cycles following preimplantation genetic testing for monogenic disorders (PGT-M) between 2014 and 2017. Cycles that produced live births or early miscarriages were divided into live birth group (n = 76) or miscarriage group (n = 19), respectively. The NGS-based aneuploidy screening was performed on the multiple displacement amplification (MDA) products of the embryonic trophectoderm biopsy samples that were cryopreserved following PGT-M. RESULTS: In the live birth group, 75% (57/76) embryos were euploid and 14.5% (11/76) were aneuploid. The remaining 10.5% (8/76) embryos were NGS-classified mosaic with the high- (≥ 50%) and low-level (< 50%) mosaicism rates at 7.9% (6/76) and 2.6% (2/76), respectively. In the miscarriage group, only 23.5% (4/17) embryos were aneuploid, while 58.8% (10/17) were euploid and 17.6% (3/17) were NGS-classified mosaic with the high- and low-level mosaicism rates at 11.8% (2/17) and 5.9% (1/17), respectively. For live birth and miscarriage groups, the transferable rate was 82.9% (63/76) and 70.6% (12/17), respectively, whereas the untransferable rate was 17.1% (13/76) and 29.4% (5/17), respectively. CONCLUSION: The application of NGS-based PGT-A remains questionable, as it may cause at least one in six embryos with reproductive potential to be discarded and prevent miscarriage in less than one in three embryos in single-gene disease carriers.

Long-read sequencing on the SMRT platform enables efficient haplotype linkage analysis in preimplantation genetic testing for ß-thalassemia.

PURPOSE: This study aimed to evaluate the value of long-read sequencing for preimplantation haplotype linkage analysis. METHODS: The genetic material of the three ß-thalassemia mutation carrier couples was sequenced using single-molecule real-time sequencing in the 7.7-kb region of the HBB gene and a 7.4-kb region that partially overlapped with it to detect the presence of 17 common HBB gene mutations in the Chinese population and the haplotypes formed by the continuous array of single-nucleotide polymorphisms linked to these mutations. By using the same method to analyze multiple displacement amplification products of embryos from three families and comparing the results with those of the parents, it could be revealed whether the embryos carry disease-causing mutations without the need for a proband. RESULTS: The HBB gene mutations of the three couples were accurately detected, and the haplotype linked to the pathogenic site was successfully obtained without the need for a proband. A total of 68.75% (22/32) of embryos from the three families successfully underwent haplotype linkage analysis, and the results were consistent with the results of NGS-based mutation site detection. CONCLUSION: This study supports long-read sequencing as a potential tool for preimplantation haplotype linkage analysis.

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.

Comparison of two mainstream endometrial preparation regimens in vitrified-warmed embryo transfers after PGT.

RESEARCH QUESTION: Which of the two mainstream endometrial preparation regimens, assisted natural cycle (NC) or hormone replacement treatment cycle (HRT), help frozen-thawed embryo transfer (FET) cycles after preimplantation genetic testing (PGT) achieve better clinical outcomes? DESIGN: This retrospective analysis included 3400 vitrified-warmed single blastocyst transfer cycles after PGT from January 2011 to November 2020, and involved 2332 patients with regular menstrual cycles. The decision to proceed with an assisted NC (n = 827) or HRT (n = 2573) before FET was reached based on a combination of patient preference and physician guidance. Clinical pregnancy rate, live birth rate, early miscarriage rate and obstetric outcomes were compared. RESULTS: No significant difference was observed between the assisted NC and HRT groups in terms of clinical pregnancy rate (51.6% versus 50.7%, P = 0.634), live birth rate (44.0% versus 43.4%, P = 0.746) or early miscarriage rate (12.6% versus 12.0%, P = 0.707). Multivariate analysis indicated that the endometrial preparation protocol was not an independent factor for a clinical pregnancy or live birth. In the HRT group, the Caesarean section rate (64.7% versus 51.9%, P < 0.001) and pregnancy complication rate (20.2% versus 13.8%, P = 0.003) were significantly higher. The two groups were not statistically different with respect to gestational age, early preterm birth rate, fetal weight or fetal birth defect rate. CONCLUSIONS: For patients undergoing a PGT-FET cycle involving a single blastocyst transfer, using assisted NC and HRT for the endometrial preparation could lead to comparable rates of clinical pregnancy and live birth. Additionally, NC is safer than HRT in terms of avoiding pregnancy complications and adverse obstetric outcomes.

Successful four-factor preimplantation genetic testing: α- and ß-thalassemia, human leukocyte antigen typing, and aneuploidy screening.

Our study established an effective next-generation sequencing (NGS) protocol for four-factor preimplantation genetic testing (PGT) using  α- and ß-thalassemia, human leukocyte antigen (HLA) typing, and aneuploidy screening. Three couples, in whom both partners were α- and ß-double thalassemia carriers, underwent PGT between 2016 and 2018. These individuals sought an opportunity for hematopoietic stem cell transplantation to save their children from ß-thalassemia major. A total of 35 biopsied trophectoderm samples underwent multiple displacement amplification (MDA). PGT for α- and ß-thalassemia and HLA typing were performed on MDA products using NGS-based single-nucleotide polymorphism (SNP) haplotyping. Although two samples failed MDA, 94.3% (33/35) of samples were successfully amplified, achieving conclusive PGT results. Furthermore, 51.5% (17/33) of the embryos were diagnosed as unaffected non-carriers or carriers. Of the 17 unaffected embryos, nine (52.9%) were tested further  and identified as euploid via NGS-based aneuploid screening, in which five had HLA types matching affected children. One family did not achieve any unaffected euploid embryos. The two other families transferred HLA-matched and unaffected euploid embryos, resulting in two healthy 'savior babies.' NGS-PGT results were confirmed in prenatal diagnosis. Therefore, NGS-SNP was effective in performing PGT for multipurpose detection within a single PGT cycle.

Pregnancy Outcomes Following Letrozole Use in Frozen-thawed Embryo Transfer Cycles: A Systematic Review and Meta-analysis.

While widely used for ovulation induction in assisted reproductive technology, the clinical efficacy of letrozole for endometrial preparation prior to frozen-thawed embryo transfer (FET) cycles remains yet to be elucidated. We performed a meta-analysis to compare pregnancy outcomes after letrozole use with those of other endometrial preparation protocols in patients undergoing FET. PubMed, Scopus, Embase and the Cochrane Library were searched for eligible studies. Clinical pregnancy rate (CPR), live birth rate (LBR) and birth defect rate (BDR) were analysed using odds ratio (OR) and 95% confidence interval (CI). A total of 10 studies representing 75 968 FET cycles were included. Comparable CPR and LBR were observed when comparing letrozole administration with natural cycle (OR 1.24, 95% CI: 0.69 - 2.24; OR 1.18, 95% CI: 0.60 - 2.32), artificial cycle (OR 1.46, 95% CI: 0.87 - 2.44; OR 1.39, 95% CI: 0.77 - 2.52), and artificial cycle with gonadotropin-releasing hormone agonist suppression (OR 1.11, 95% CI: 0.78 - 1.59; OR 1.18, 95% CI: 0.82 - 1.68). Pooled results of the limited studies comparing letrozole with human menopausal gonadotropin demonstrated a similar CPR between groups (OR 1.46, 95% CI: 0.29 - 7.21, two studies), but the letrozole group had a statistically lower LBR (OR 0.67, 95% CI: 0.52 - 0.86, one study). No increased BDR was observed in the letrozole group compared to natural cycles or artificial cycles (OR 0.98, 95% CI: 0.60 - 1.61; OR 1.39, 95% CI; 0.84 - 2.28). This pooled analysis supports the use of letrozole as an efficacious and safe alternative to mainstream regimens for endometrial preparation in FET cycles.

Eleven healthy live births: a result of simultaneous preimplantation genetic testing of α- and ß-double thalassemia and aneuploidy screening.

PURPOSE: To evaluate the efficacy of preimplantation genetic testing (PGT) for α- and ß-double thalassemia combined with aneuploidy screening using next-generation sequencing (NGS). METHODS: An NGS-based PGT protocol was performed between 2017 and 2018 for twelve couples, each of which carried both α- and ß-thalassemia mutations. Trophectoderm biopsy samples underwent whole-genome amplification using multiple displacement amplification (MDA), followed by NGS for thalassemia detection and aneuploidy screening. A selection of several informative single nucleotide polymorphisms (SNPs) established haplotypes. Aneuploidy screening was performed only on unaffected noncarriers and carriers. Unaffected and euploid embryos were transferred into the uterus through frozen-thawed embryo transfer (FET). RESULTS: A total of 280 oocytes were retrieved following 18 ovum pick-up (OPU) cycles, with 182 normally fertilized and 112 cultured to become blastocysts. One hundred and seven (95.5%, 107/112) blastocysts received conclusive PGT results, showing 56 (52.3%, 56/107) were unaffected. Thirty-seven (66.1%, 37/56) of the unaffected were also identified as euploid. One family had no transferable embryos. Unaffected and euploid embryos were then transferred into the uterus of the other 11 couples resulting in 11 healthy live births. The clinical pregnancy rate was 61.1% (11/18) per OPU and 68.8% (11/16) per FET, with no miscarriage reported. Seven families accepted the prenatal diagnosis and received consistent results with the NGS-based PGT. CONCLUSION: This study indicated that NGS could realize the simultaneous PGT of double thalassemia and aneuploidy screening in a reliable and accurate manner. Moreover, it eliminated the need for multiple biopsies, alleviating the potential damages to the pre-implanted blastocysts.

Preimplantation Genetic Testing for Monogenic Disease of Spinal Muscular Atrophy by Multiple Displacement Amplification: 11 unaffected livebirths.

Background: Preimplantation genetic testing for monogenic disease (PGT-M) has become an effective method for providing couples with the opportunity of a pregnancy with a baby free of spinal muscular atrophy (SMA). Multiple displacement amplification (MDA) overcomes the innate dilemma of very limited genetic material available for PGT-M. Objective: To evaluate the use of MDA, combined with haplotype analysis and mutation amplification, in PGT-M for families with SMA. Methods: MDA was used to amplify the whole genome from single blastomeres or trophectoderm (TE) cells. Exon 7 of the survival motor neuron gene 1 (SMN1) and eleven STRs markers flanking the SMN1 gene were incorporated into singleplex polymerase chain reaction (PCR) assays on MDA products. Results: Sixteen cycles (19 ovum pick-up cycles) of PGT-M were initiated in 12 couples. A total of 141 embryos were tested: 90 embryos were biopsied at the cleavage stage and 51 embryos were biopsied at the blastocyst stage. MDA was successful on 94.44% (85/90) of the single blastomeres and on 92.16% (47/51) of the TE cells. And the PCR efficiency were 98.4% (561/570) and 100% (182/182), respectively. In addition, the average allele drop-out (ADO) rates were 13.3% (60/392) and 9.8% (11/112), respectively. The results for SMN1 exon 7 were all matched with haplotype analysis, which allowed an accurate diagnosis of 93.62% (132/141) embryos. Twelve families had unaffected embryos available for transfer and a total of 38 embryos were transferred in 20 embryo transfer cycles. Eight transfers were successful, resulting in a clinical pregnancy rate of 40% (8/20) and an implantation rate of 28.95% (11/38). Finally, 11 healthy babies were born. Among them, 5 SMA carriers were singleton live births and 3 SMA carriers had twin births. Conclusion: Careful handling during the MDA procedure can improve subsequent PCR efficiency and reduce the ADO rate. We suggest that this protocol is reliable for increasing the accuracy of the PGT-M for SMA.

Multiple displacement amplification as the first step can increase the diagnostic efficiency of preimplantation genetic testing for monogenic disease for ß-thalassemia.

AIM: To evaluate whether using multiple displacement amplification (MDA) as the first step can increase the diagnostic efficiency of preimplantation genetic testing for monogenic disease (PGT-M) for ß-thalassemia. METHODS: This is a retrospective cohort study. All included patients underwent PGT-M cycles (n = 307) for ß-thalassemia in our center from January 2014 to February 2018. We divided the patients into two groups based on two different detection methods. For the polymerase chain reaction (PCR) group (n = 115), multiplex nested PCR+ reverse dot blot analysis was performed directly after cell lysis. For the MDA group (n = 192), the whole genomes of single cells were directly amplified using MDA and then examined by singleplex PCR + reverse dot blot for ß-thalassemia. RESULTS: A total of 2315 embryos were tested. The overall diagnostic efficiency of the MDA group was significantly higher than that of the PCR group (96.99% vs 88.15%, P < 0.001). The percentage of embryos available for transfer was significantly higher in the MDA group than in the PCR group (74.28% vs 64.98%, P < 0.001). Furthermore, the carrier embryo rate of the MDA group was significantly higher than that of the PCR group (50.11% vs 35.95%, P < 0.001). CONCLUSION: This study indicates that MDA, as the first step in PGT-M for ß-thalassemia, can increase diagnostic efficiency.