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

ChromInst: a multicentre evaluation of robustness in aneuploidy and structural rearrangement testing

BACKGROUND

Preimplantation genetic testing for aneuploidy and for chromosomal structural rearrangement (PGT-A/-SR) can improve clinical pregnancy rates and live birth rates, and shorten the time to pregnancy. The large-scale statistics on their efficacy and accuracy across different centres, as well as the frequency of abnormalities for each chromosome, will provide a valuable supplement to previous research.

METHODS

Patients who had PGT-A or -SR procedures at five reproductive centres from 2018 to 2022 were recruited based on PGT-A/-SR indications. ChromInst and next-generation sequencing (NGS)-based PGT technology were utilised to detect copy number variations in embryos. Sequencing data metrics such as median absolute pairwise difference (MAPD) and detection success rate were analysed to evaluate the robustness of ChromInst. To assess ChromInst's accuracy, the chromosomal results from amniocentesis, abortions, and neonatal blood was as the gold standard for negative PGT results; the fluorescence in situ hybridisation (FISH), which was performed on embryos that identified as aneuploid through PGT was as the gold standard for positive PGT results. The frequency of abnormalities in each chromosome was also explored in aneuploid embryos.

RESULTS

A total of 5,730 embryos were tested from 1,015 patients in the study, 391 of whom had PGT-A and 624 of whom had PGT-SR. 99.5% (5,699/5,730) of the embryos had an NGS sequencing MAPD value < 0.25, and 99.3% (5,689/5,730) of the embryos achieved successful PGT-A/-SR detection. Compared with the gold standard, the concordance of negative PGT-A/-SR results was 99.8% (506/507), and that of positive results was 99.8% (1,123/1,125). The euploidy rate in the PGT-A population was 45.9% (981/2,135). The proportion of euploid + balanced embryos was highest among couples with non-polymorphic inversions (44.6%, 152/341), followed by those with Robertsonian translocations (39.0%, 293/752), and lowest among those with reciprocal translocations (22.5%, 483/2,143). Chromosomes 16, 22, and 15 had the highest frequency of autosomal trisomies among the embryos from PGT-A patients, while chromosomes 16, 22, and 21 had the highest frequency of monosomies. High-frequency chromosomes with de novo chromosomal abnormalities for trisomies and monosomies were similar in the PGT-SR patients to those in the PGT-A patients.

CONCLUSIONS

ChromInst-based PGT-A/-SR could accommodate operational variations among different clinical centres, ensuring accurate results through robust and stable detection performance. Prior to PGT-A/-SR, more trustworthy data could be provided to support the genetic counselling.

Genetics in Reproductive Medicine

Thanks to advances in technology, genetic testing is now available to explore the causes of infertility and to assess the risk of a given couple passing on a genetic disorder to their offspring. This allows at-risk couples to make an informed decision when opting for assisted reproduction and allows professionals to offer pre-implantation diagnosis when appropriate. Genetic screening of an infertile couple has thus become standard practice for an appropriate diagnosis, treatment, and prognostic assessment. This review aims to highlight the conditions under which genetic screening plays a role in improving reproductive outcomes for infertile couples.

Paternal Contributions to Recurrent Pregnancy Loss: Mechanisms, Biomarkers, and Therapeutic Approaches

Background and Objectives: Recurrent pregnancy loss (RPL) affects numerous couples worldwide and has traditionally been attributed mainly to maternal factors. However, recent evidence highlights significant paternal influences on pregnancy viability and outcomes. This review aims to comprehensively examine male contributions to pregnancy loss, focusing on underlying mechanisms, novel biomarkers, and integrated strategies for improved reproductive success. Materials and Methods: A comprehensive narrative review was conducted by searching databases including PubMed and Embase for the literature published from January 2004 to October 2024. Studies focusing on paternal influences in RPL-encompassing oxidative stress, genetic and epigenetic mechanisms, health conditions, lifestyle factors, environmental exposures, and advancements in sperm proteomics-were included. Inclusion criteria were peer-reviewed articles in English that directly addressed paternal factors in RPL; studies not meeting these criteria were excluded. Results: The review identified that paternal factors such as advanced age, metabolic and cardiovascular health issues, chronic diseases, lifestyle habits (e.g., smoking, alcohol consumption, poor diet), and environmental exposures significantly affect sperm integrity through mechanisms like oxidative stress, DNA fragmentation, and epigenetic alterations. Advanced paternal age and poor health conditions are associated with increased risks of miscarriage and adverse pregnancy outcomes. Novel sperm proteomic biomarkers have been identified, offering potential for enhanced diagnostics and personalized interventions. Integrated approaches involving multidisciplinary assessments, preventive strategies, and genetic counseling are essential for effectively addressing RPL. Conclusions: Integrating paternal factors into clinical evaluations is crucial for effectively addressing recurrent pregnancy loss. Recognizing and modifying paternal risk factors through lifestyle changes, medical interventions, and environmental management can improve pregnancy outcomes. The findings underscore the need for incorporating paternal assessments into standard care and highlight the importance of future research focusing on standardizing diagnostic protocols, expanding studies on paternal contributions, and integrating proteomic biomarkers into clinical practice to facilitate personalized treatment strategies.

Role of intra-individual variation in the detection of thresholds for DFI and for misclassification rates: A retrospective analysis of 14,775 SCSA® tests

BACKGROUND

Sperm DNA damage is associated with reduced male fertility after natural conception and intrauterine insemination. However, the impact on in vitro fertilization (IVF) and especially intracytoplasmic sperm injection (ICSI) treatments is still unclear. Few studies have focused on the intra-individual variation in DFI even though it may have an important role to play in terms of detection of thresholds and for misclassification rates.

METHODS

Results for Sperm Chromatin Structure Assay (SCSA®) tests performed for 70 European fertility clinics between January 1st, 2008 and December 31st, 2022 were examined. A small retrospective study included 406 couples receiving their first treatment with IVF or ICSI. These results were then used for a mathematical simulation to investigate the role of intra-individual variation. The large retrospective study included a total of 14,138 diagnostic tests and 637 tests from an IUI study. The distribution of DFI was assessed for the IUI cohort and cohorts of patients attending Sims IVF and Fertility Center Hamburg (FCH). Descriptive analysis of the data was performed regarding time of year, male age, and year.

RESULTS

When DFI was above the thresholds of 15 and 25, a significant reduction in ongoing pregnancies after 12 weeks of gestation was observed for IVF and ICSI treatments, respectively. For IVF treatments, the pregnancy rate was reduced from 45.1% to 24.6%, odds ratio = 2.58 (p = 0.004). For ICSI treatments, the pregnancy rate was reduced from 48.6% to 29.6%, odds ratio = 2.00 (p = 0.032). Intra-individual variation was significantly related to the misclassification rate and the sample size required to identify a threshold. The percentage of patients with a DFI below 15 was 64.8% for the IUI cohort and 51.7% and 41.6% for cohorts of patients attending Sims IVF and FCH, respectively. The median DFI for these cohorts differed significantly and was 11.6, 15.0 and 17.2, respectively. DFI shows a seasonal variation, and increases with male age. During the past 15 years, the median DFI has increased by 0.05% per year (p = 0.02).

DISCUSSION AND CONCLUSIONS

Ongoing pregnancy rates are reduced significantly for both IVF and ICSI treatments when DFI is above the thresholds of 15 and 25, respectively. The misclassification rate and the required sample size increase with increasing intra-individual variation. Couples with a DFI above 15 are more likely to experience failed assisted reproductive technology (ART) cycles. DFI appears to have increased during the past 15 years.

Cryopreservation of bovine sperm causes single-strand DNA breaks that are localized in the toroidal regions of chromatin

BACKGROUND

Sperm cryopreservation is widely used in the cattle industry, as it allows for disassociating the localization of sires and the collection of semen from the timing of artificial insemination. While freeze-thawing is known to impair sperm DNA integrity, whether the damage induced consists of single- (SSB) or double-strand breaks (DSB) has not been determined. In addition, no previous study has addressed if DNA breaks preferentially reside in specific genome regions such as those forming the toroid linker regions, or are rather spread throughout the regions linked to protamines. The main aim of the present work, therefore, was to elucidate the type and localization of the DNA damage generated by cryopreservation and to evaluate its impact on artificial insemination outcomes in cattle.

RESULTS

The incidence of SSB and DSB was evaluated in 12 ejaculates before and after cryopreservation with the Comet assay, and the localization of the DNA breaks was assessed using pulsed-field gel electrophoresis (PFGE). Before cryopreservation, the incidence of SSB was 10.99% ± 4.62% and involved 20.56% ± 3.04% of sperm cells, whereas these figures significantly (P < 0.0001) increased up to 34.11% ± 3.48% and 53.36% ± 11.00% in frozen-thawed sperm. In contrast, no significant differences in the incidence of DSB were observed (P > 0.990) before and after cryopreservation (before: incidence of 13.91% ± 1.75% of sperm DNA affecting 56.04% ± 12.49% of sperm cells; after: incidence of 13.55% ± 1.55% of sperm DNA involving 53.36% ± 11.00% of sperm cells). Moreover, PFGE revealed that the percentage of sperm DNA fragments whose length was shorter than a toroid (< 31.5 kb) was greater (P < 0.0001) after (27.00% ± 4.26%) than before freeze-thawing (15.57% ± 4.53%). These differences indicated that the DNA breaks induced by cryopreservation affect the regions condensed in protamines, which are structured in toroids. On the other hand, in vivo fertility rates were associated to the incidence of SSB and DSB in frozen-thawed sperm (P = 0.032 and P = 0.005), but not with the size of the DNA fragments resulting from these breaks (P > 0.05).

CONCLUSION

Cryopreservation of bovine sperm generates single-strand DNA breaks, which are mainly located in protamine-condensed toroidal regions. The incidence of DNA breaks in cryopreserved sperm has an impact on cattle fertility, regardless of the size of generated fragments.

Leukocytospermia does not negatively impact outcomes in in vitro fertilization cycles with intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidy: findings from 5435 cycles

PURPOSE

To investigate whether leukocytospermia (defined as the presence of ≥ 1 × 106 white blood cells/mL) affects clinical and embryologic outcomes in in vitro fertilization (IVF) cycles with intracytoplasmic sperm injection (ICSI) and preimplantation genetic testing for aneuploidy (PGT-A).

METHODS

This was a retrospective cohort study including 5425 cycles between January 2012 to December 2021 at a single large university-affiliated fertility clinic. The primary outcome was live birth rate (LBR).

RESULTS

The prevalence of leukocytospermia was 33.9% (n = 1843). Baseline characteristics including female age, BMI, AMH, Day 3 FSH, and male partner's age were similar in cycles with and without leukocytospermia. The LBR after the first euploid embryo transfer was similar in those with and without leukocytospermia (62.3% vs. 63% p = 0.625). Secondary outcomes including clinical pregnancy rate (CPR), sustained implantation rate (SIR), fertilization (2PN) rate, blastulation rate, and aneuploidy rate were also evaluated. The CPR (73.3% vs 74.9%, p = 0.213) and SIR (64.6% vs. 66%, p = 0.305) were similar in both groups. The 2PN rate was also similar in both groups (85.7% vs. 85.8%, p = 0.791), as was the blastulation rate per 2PN (56.7% vs. 57.5%, p = 0.116). The aneuploidy rate was not significantly different between groups (25.7% vs 24.4%, p = 0.053). A generalized estimation equation with logistic regression demonstrated that the presence leukocytospermia did not influence the LBR (adjusted OR 0.878; 95% CI, 0.680-1.138).

CONCLUSION

Leukocytospermia diagnosed just prior to an IVF cycle with PGT-A does not negatively impact clinical or embryologic outcomes.