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BackgroundRecurrent pregnancy loss (RPL) is defined as the loss of at least three pregnancies in the first trimester. Although the most common cause is embryo aneuploidy, and despite female checkup and couple karyotyping, in about 50% of cases RPL remain unexplained. Male implication has little been investigated and results are discordant. In this context, we conducted a multi-center prospective case-control study to investigate male gamete implication in unexplained RPL.MethodsA total of 33 cases and 27 controls were included from three university hospitals. We investigated environmental and family factors with a detailed questionnaire and andrological examination, sperm characteristics, sperm DNA/chromatin status using the sperm chromatin structure assay (SCSA) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and sperm aneuploidy using fluorescence in situ hybridization (FISH). The Mann-Whitney test and the Wilcoxon or Fisher exact tests were used. A non-parametric Spearman correlation was performed in order to analyze the relationship between various sperm parameters and FISH and sperm DNA fragmentation results.ResultsWe found significant differences between cases and controls in time to conceive, body mass index (BMI), family history of infertility and living environment. In cases, total sperm motility and the percentage of morphologically normal spermatozoa were significantly decreased. No difference was found between cases and controls in sperm DNA fragmentation or chromatin integrity. In cases, spermatozoa with aneuploidy, hyperhaploidy and chromosome 18 disomy were significantly increased.ConclusionsThis prospective case-control study is one of the largest to examine environmental factors, sperm characteristics, sperm DNA fragmentation and chromatin, and chromosome anomalies in spermatozoa in relation to unexplained recurrent pregnancy loss. The originality of our study lies in the comprehensive andrological examination and search for risk factors and fertility history. Further studies are needed to confirm the links between unexplained RPL and a male family history of infertility or miscarriages. The increased sperm aneuploidy observed in unexplained RPL supports a male etiology. These data pave the way for further studies to demonstrate the value of preimplantation genetic screening in men with increased sperm aneuploidy whose partners experience unexplained RPL.

The study was funded by a grant from Association pour la Recherche sur les Traitements de la Stérilité. There are no competing interests to declare.

BackgroundApproximately 1% of the spermatozoa found in ejaculate of healthy men are aneuploid and this rate increases in the population of subfertile and infertile men. Moreover, fertilization with these aneuploid sperm can lead to impaired embryo development. Fluorescent In Situ Hybridization (FISH) is the common cytogenetic tool used for aneuploidy screening on sperm. However, it is a time-consuming technique and cytogenetic or in vitro fertilization laboratories cannot routinely use it and face the increasing demand of such analyses before Assisted Reproductive Techniques (ART). As automation can be a clue for routine practice, this study compares manual and automated scoring of sperm aneuploidy rates using a Metafer Metasystems® device. The results obtained also contribute to global data about FISH on sperm cells.MethodsWe recruited 100 men addressed for sperm cryopreservation. They all signed an informed consent to participate in the study. 29 men were donors or consulted before vasectomy (control group) and 71 were suffering of Hodgkin’s disease or non Hodgkin lymphoma (patient group). One semen sample was collected for each patient, analyzed according to WHO criteria and prepared for a triple-color FISH using centromeric probes for chromosomes 18, X and Y. Automated scoring was performed using a Metafer Metasystems® device.Results507,019 cells were scored. We found a strong concordance between the automated and the manual reading (d < 0.01 in Bland-Altman test). We also did not find a statistically significant difference between the automated and the manual reading using Wilcoxon test for total aneuploidy rate (p = 0.06), sex chromosomes disomy (p = 0.33), chromosome 18 disomy (p = 0.39) and diploidy (p = 0.21). Cumulative rate of total aneuploidy was 0.78% ± 0.212% for patient group and 0.54% ± 0.15 for control group and among this, sex chromosome XY disomy rate was of 0.54% for patient group and 0.27% for control group.ConclusionThis study validates the automated reading for FISH on sperm with a Metafer Metasystems® device and allows its use in a laboratory routine.

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