Male infertility: establishing sperm aneuploidy thresholds in the laboratory.

PURPOSE: Fluorescence in situ hybridization (FISH) in spermatozoa provides an estimate of the frequency of chromosomal abnormalities, but there is not a clinical consensus on how to statistically analyze sperm FISH results. We therefore propose a statistical approach to establish sperm aneuploidy thresholds in a fertile population. METHODS: We have determined the distribution and variation of the frequency of nullisomy, disomy, and diploidy for a set of 13 chromosomes (1, 2, 9, 13, 15, 16, 17, 18, 19, 21, 22, X, and Y) in sperm nuclei from 14 fertile men by means of automatized FISH. The dispersion of data has been analyzed by the non-parametric Wilcoxon Rank Sum test. We have established the threshold values for each chromosome and aneuploidy type on the basis of the confidence interval values (99.9%). RESULTS: Nullisomy thresholds ranged from 0.49% for chromosome 19 to 3.09% for chromosome 22; disomy thresholds ranged from 0.30% for chromosome 21 to 1.47% for chromosome 15; diploidy thresholds ranged from 0.24% for the 9/19 chromosome set to 1.21% for the 13/21 chromosome set. CONCLUSIONS: Applying this approach with clinical purposes will enable us to categorize the patient as altered or normal regarding his sperm aneuploidy. Any result surpassing the cited threshold values indicates a 99.9% probability of being significantly different from fertile controls.

The use of fluorescence in situ hybridization analysis on sperm: indications to perform and assisted reproduction technology outcomes.

PURPOSE: To determine the consequences of an altered sperm fluorescence in situ hybridization (FISH) result for ART outcomes and the indications for a sperm FISH analysis. METHODS: Data from 439 infertile men were collected. Bivariate analyses were performed to determine the association of men's age, seminal alterations, and sperm FISH indication, with the incidence of X, Y, 13, 18, and 21 sperm chromosomal abnormalities. A multivariate logistic regression analysis was performed to establish the most predictive variables for altered sperm FISH. Results from the IVF/ICSI cycles were collected for 248 out of 439 patients. Two distinct groups were established: 151 couples that used their own oocytes and 97 couples involved in egg donation programs. In both groups, ART outcomes were compared between normal and altered sperm FISH. RESULTS: Teratozoospermia and oligozoospermia were associated with sperm chromosome anomalies (p < 0.05). Indications for sperm FISH analysis with the highest predictability were teratozoospermia, male age, oligozoospermia, and implantation failure (AUC = 0.702). Embryo quality (p = 0.096), pregnancy rate (p = 0.054), and implantation rate (p = 0.089) were higher in own-oocytes couples with normal sperm FISH than in altered sperm FISH couples, although differences were not statistically significant. In donor-oocytes couples, in which high-quality embryos were transferred later than in own-oocytes couples (3.8 vs. 3.0 days), we did not identify differences in the ART outcome between normal and altered sperm FISH couples. In both groups, the possible interference of woman age was negligible. CONCLUSIONS: Sperm FISH is indicated in middle-aged oligoteratozoospermic patients with implantation failures in previous IVF/ICSI cycles. Sperm chromosome anomalies have a moderate detrimental impact on embryo quality, implantation, and pregnancy rates.

Correlation between aneuploidy, apoptotic markers and DNA fragmentation in spermatozoa from normozoospermic patients.

Genetic and biochemical sperm integrity is essential to ensure the reproductive competence. However, spermatogenesis involves physiological changes that could endanger sperm integrity. DNA protamination and apoptosis have been studied extensively. Furthermore, elevated rates of aneuploidy and DNA injury correlate with reproductive failures. Consequently, this study applied the conventional spermiogram method in combination with molecular tests to assess genetic integrity in ejaculate from normozoospermic patients with implantation failure by retrospectively analysing aneuploidy (chromosomes 18, X, Y), DNA fragmentation, externalization of phosphatidylserine and mitochondrial membrane potential status before and after magnetic activated cell sorting (MACS). Aneuploid, apoptotic and DNA-injured spermatozoa decreased significantly after MACS. A positive correlation was detected between reduction of aneuploidy and decreased DNA damage, but no correlation was determined with apoptotic markers. The interactions between apoptotic markers, DNA integrity and aneuploidy, and the effect of MACS on these parameters, remain unknown. In conclusion, use of MACS reduced aneuploidy, DNA fragmentation and apoptosis. A postulated mechanism relating aneuploidy and DNA injury is discussed; on the contrary, cell death markers could not be related. An 'apoptotic-like' route could explain this situation.

New protocol based on massive parallel sequencing for aneuploidy screening of preimplantation human embryos.

Novel next-generation sequencing procedures have rapidly emerged into the preimplantation genetic screening framework. This work presents the design and validation of a new low-coverage whole-genome sequencing assay for aneuploidy detection in single blastomeres and trophectodermal samples from preimplantation embryos. The validation ensures analytical sensitivity, specificity, robustness, precision, limit of detection, resolution, and reproducibility. Specific parameters to measure the performance are defined, and the results are compared with a standardized array-based method to stablish the concordance. From the single cell genomics point of view, the main novelties are the length of reads of the libraries (150 nucleotides) together with a paired-end strategy and the design of an original algorithm and copy number viewer. A total of 129 samples were included in six experimental runs using a MiSeq Illumina platform. Samples included: single amniocytes, single blastomeres (cleavage-stage embryos), trophectoderm samples (blastocyst), and diluted DNA. Sensitivity and specificity were calculated per chromosome yielding 96% and 99%, respectively. The percentage of concordant samples was 98.2% and all of the aneuploid samples were confirmed. In conclusion, the validation yields highly reliable and reproducible results, representing an accurate and cost-effective strategy for the routine detection of aneuploidy in human embryos.

¿A qué velocidad «muere» el ácido desoxirribonucleico del espermatozoide tras descongelar muestras seminales procedentes de donantes? / At what speed does sperm deoxyribonucleic acid “die” after donor semen samples are thawed?

Objetivo. Analizar los niveles de daño que se registran en el ADN de espermatozoides de donantes y estimar la velocidad a la que este se degrada tras la descongelación. Material y métodos. Dosis seminales procedentes de donantes (n = 50) y un grupo control formado por pacientes normozoospérmicos (n = 40). Se estudiaron los valores de fragmentación del ADN espermático (SDF) en su nivel basal, así como los valores de SDF tras incubación de las muestras a 37 °C durante 2, 6 y 24 h. Se calcularon las velocidades de degradación del ADN por tramos de incubación. Resultados. El semen criopreservado de donante presenta unos niveles basales de SDF 2 veces inferiores a los observados en los controles, y su ADN es 2,5 veces más longevo que el del grupo control. Niveles basales de SDF sobre un 8% generan una sensibilidad de un 82% y una especificidad de un 65% para discriminar entre los donantes y los controles. Los valores de incremento del daño de 1,8% por hora, analizados durante las 2 primeras horas de incubación, identifican a los donantes con un 77% de sensibilidad y un 65% de especificidad. Ambos valores no muestran ninguna correlación dentro del grupo de los controles, ni entre los donantes. Conclusiones. El establecimiento de este tipo de valores umbral se podría utilizar para identificar donantes considerados como «superdonantes» en relación con sus bajos niveles de SDF y su alta estabilidad de la cromatina. Los donantes que se seleccionaron en las diferentes clínicas presentan características equiparables para estos parámetros(AU)

Objective. The study was made to analyze the baseline levels of damage recorded in sperm DNA fragmentation (SDF) and to estimate sperm DNA longevity as observed in donors after thawing. Material and methods. Fifty donors and forty individuals attending a clinic and classified as a normo-zoospermic population were compared. The baseline SDF levels and the increasing rate of SDF (r-SDF) obtained after thawing when the sperm was incubated for a period of 24 h with different sub-sampling performed after 2, 6 and 24 h of incubation were considered as the independent variables and compared. Results. Cryopreserved donor sperm exhibited baseline SDF values approximately 2 times lower than those observed in the control group. DNA stability was 2.5 times higher than that observed in the control cohort. Baseline values of SDF of approximately 8% generates 65% sensitivity and 82% specificity to discriminate between the donors and controls. Values of increase of damage of 1.8% per hour, analyzed during the first hours of incubation, identify the donor characteristics with 77% sensibility and 65% specificity. Neither value show any correlation within the control and donor cohorts group. Conclusion. The establishment of these types of threshold values can be used to identify donors considered as “super-donors” in relation to their low levels of SDF and high chromatin stability. The donors selected from the different clinics participating in this study showed similar characteristics for these parameters(AU)