Sperm Chromosome Aneuploidy Research Articles

O-107 Sperm chromosome chaos induced by MEIKIN gene mutations leads to blastocyst formation failure

Abstract Study question What are the effect and corresponding mechanisms of chromosome chaos of sperm caused by mutation of the MEIKIN gene on preimplantation embryo development? Summary answer Sperm chromosome chaos induced by MEIKIN gene mutations directly causes blastocyst formation failure by affecting the activation of the embryonic genome and lineage differentiation. What is known already In mice, Meikin is a meiosis-specific kinetochore factor that plays a crucial role in mono-orientation and protection of centromeric cohesion in meiosis I and the regulation of chromosome alignment during meiosis II. Both male and female Meikin gene knockout mice are completely infertile. Infertility in male Meikin-/- mice originates from defects in meiotic chromosome segregation and subsequent spermatogenesis. To our knowledge, no mutation of the MEIKIN gene has been reported in humans. Study design, size, duration In this study, semen from three patients with MEIKIN mutations and arrested embryos from one of them were analyzed to determine the effect of MEIKIN mutations on sperm and early embryonic development. Participants/materials, setting, methods Three male patients with MEIKIN mutations with a specific clinical phenotype were recruited. We assessed mutant sperm morphology using Papanicolaou staining. Sperm FISH and single sperm chromosome aneuploidy analysis（CNV-seq） were applied to identify mutant sperm Chromosomal abnormality. We also investigated the chromosome constitution and gene expression of the arrested embryos from one patient by parallel single-cell genome and transcriptome sequencing. Main results and the role of chance Novel mutations in the MEIKIN gene were identified in three infertility males with a specific clinical phenotype（They had good-quality embryos on day 3, but these embryos repeatedly failed to implant or develop to the blastocyst stage）. Routine semen assessments were conducted based on the WHO’s guidelines, and all these patients were diagnosed with oligoasthenoteratozoospermia. Sperm FISH showed that the frequencies of aneuploidies in spermatozoa were significantly higher than the normal control（89.05%,70.9%,93.24% vs. 5.03%）, and the CNV-seq analysis of single spermatozoa confirmed mutant sperm had severe chromosome chaos. Each cell of the arrested embryos from one patient had complicated chromosomal abnormalities, and the abnormal chromosomes were mainly derived from sperm. At the gene expression level, these embryos were arrested at the 8-cell to morula stage transition, and defects activation of a large ZGA and lineage specification genes led to blastocyst formation failure. Limitations, reasons for caution In this study, we discovered that mutations in MEIKIN caused male infertility manifesting as sperm chromosome chaos and blastocyst formation failure. However, the molecular mechanism of the sperm chromosome chaos involved in blastocyst formation needs to be further illuminated by using Meikin knockout mouse models. Wider implications of the findings We first reported that male with MEIKIN mutations is related to severe sperm chromosome abnormalities and blastocyst formation failure. Therefore, In the process of ICSI, if there are good-quality cleavage embryos that repeatedly fail to implant or develop to the blastocyst stage, it is recommended to examine male factors concurrently Trial registration number not applicable

Biallelic variants in KCTD19 associated with male factor infertility and oligoasthenoteratozoospermia.

Can whole-exome sequencing (WES) reveal new genetic factors responsible for male infertility characterized by oligozoospermia? We identified biallelic missense variants in the Potassium Channel Tetramerization Domain Containing 19 gene (KCTD19) and confirmed it to be a novel pathogenic gene for male infertility. KCTD19 is a key transcriptional regulator that plays an indispensable role in male fertility by regulating meiotic progression. Kctd19 gene-disrupted male mice exhibit infertility due to meiotic arrest. We recruited a cohort of 536 individuals with idiopathic oligozoospermia from 2014 to 2022 and focused on five infertile males from three unrelated families. Semen analysis data and ICSI outcomes were collected. WES and homozygosity mapping were performed to identify potential pathogenic variants. The pathogenicity of the identified variants was investigated in silico and in vitro. Male patients diagnosed with primary infertility were recruited from the Reproductive and Genetic Hospital of CITIC-Xiangya. Genomic DNA extracted from affected individuals was used for WES and Sanger sequencing. Sperm phenotype, sperm nuclear maturity, chromosome aneuploidy, and sperm ultrastructure were assessed using hematoxylin and eosin staining and toluidine blue staining, FISH and transmission electron microscopy. The functional effects of the identified variants in HEK293T cells were investigated via western blotting and immunofluorescence. We identified three homozygous missense variants (NM_001100915, c.G628A:p.E210K, c.C893T:p.P298L, and c.G2309A:p.G770D) in KCTD19 in five infertile males from three unrelated families. Abnormal morphology of the sperm heads with immature nuclei and/or nuclear aneuploidy were frequently observed in individuals with biallelic KCTD19 variants, and ICSI was unable to rescue these deficiencies. These variants reduced the abundance of KCTD19 due to increased ubiquitination and impaired its nuclear colocalization with its functional partner, zinc finger protein 541 (ZFP541), in HEK293T cells. The exact pathogenic mechanism remains unclear, and warrants further studies using knock-in mice that mimic the missense mutations found in individuals with biallelic KCTD19 variants. Our study is the first to report a likely causal relationship between KCTD19 deficiency and male infertility, confirming the critical role of KCTD19 in human reproduction. Additionally, this study provided evidence for the poor ICSI clinical outcomes in individuals with biallelic KCTD19 variants, which may guide clinical treatment strategies. This work was supported by the National Key Research and Developmental Program of China (2022YFC2702604 to Y.-Q.T.), the National Natural Science Foundation of China (81971447 and 82171608 to Y.-Q.T., 82101961 to C.T.), a key grant from the Prevention and Treatment of Birth Defects from Hunan Province (2019SK1012 to Y.-Q.T.), a Hunan Provincial Grant for Innovative Province Construction (2019SK4012), and the China Postdoctoral Science Foundation (2022M721124 to W.W.). The authors declare no conflicts of interest. N/A.

P–057 Preliminary evaluation of laser confocal Raman spectroscopy as a noninvasive method for detecting sperm chromosome aneuploidy

Abstract Study question To evaluate the efficiency and accuracy of Raman microspectra in detecting sperm chromosome balance state by DNA content difference. Summary answer Raman spectroscopy can identify the difference of X and Y sperm DNA content, but the accuracy still needed to be improved for clinical application. What is known already Aneuploid sperm fertilization affects embryo quality and leads to the waste of oocytes in Assisted Reproductive Technology (ART). Raman spectroscopy can identify substances and observe molecular changes through specific spectral patterns with high specificity and has become a new hot spot in ART. Previous research has used this technology to detect embryo culture medium to evaluate the aneuploidy of embryos. The DNA content of X and Y in sperm was different, which may serve as a marker for sperm aneuploidy detection by Raman spectroscopy. Study design, size, duration The significant difference in the morphology of the sex chromosomes of X and Y spermatozoa leads to a substantial difference in the DNA content. We perform Raman spectroscopy to identify the spectral differences of the sperms, especially the differences in sperm DNA content. We further verified the accuracy with fluorescence in situ hybridization (FISH). Participants/materials, setting, methods Spermatozoa were provided by healthy donors with normal aneuploidy, and analysis parameters met the current World Health Organization (WHO, 2010) standards. Sperm heads were detected by laser confocal Raman spectroscopy and obtained the corresponding spectra. The sperm chromosome information was classified by Standard principal component analysis (PCA) and identified by fluorescence in situ hybridization (FISH). Student’s t-test and Receiver operating characteristic (ROC) curve analysis was performed for further analysis. Main results and the role of chance Standard principal component analysis (PCA) after unqualified quality control divided spermatozoa into two groups according to the calculation and calibration results, 22 cases in group A and 31 cases in group B. Then, we conducted frequency distribution histogram statistics on the above data, and the results showed that there were differences in frequency distribution at I785 = 23,750 and Area714 –1162 = 3,250,000. The FISH analysis identified sex chromosomes of 59 spermatozoa, which was not exactly one-to-one correspondence with the results of PCA analysis. Then we further analyzed the sperm of 59 cases by statistical analysis. The results showed that there were significant differences between X sperm (n = 39) and Y sperm (n = 20) at 714–1162 cm–1 and 785 (P < 0.05). ROC curve analysis was used to evaluate the sensitivity of correlation between sperm DNA content and Raman spectra. The results showed that the corresponding thresholds of I785 = 24,986.5 and Area714–1162 cm–1 = 3,748,990 were the best for distinguishing the two kinds of sperm. When the sperm’s peak value of 785 or 714–1162cm–1 exceeds the above thresholds, X-sperm’s possibility greatly increased. The AUC of the ROC curve in both cases was 0.662 and 0.696, respectively. Limitations, reasons for caution Current Raman spectroscopy requires spermatozoa elution and fixation, which damage the sperms. Furthermore, current Raman spectral data are not obtained from the whole sperm head, limiting the accuracy of this technique. Wider implications of the findings: Our results indicated that Raman spectroscopy had potential application value for sperm aneuploidy detection and could be used as a noninvasive selector for normal haploid sperms in the ART. Trial registration number LL-SC–2018–038

Semen Quality is Associated with Sperm Aneuploidy and DNA Fragmentation in the United Arab Emirates Population.

Background: Sperm chromosome aneuploidy and the extent of sperm DNA fragmentation (SDF) are contributing factors to male infertility. Their extent can be measured using platforms such as sperm chromatin dispersion (SCD) and sperm fluorescence in situ hybridization (sFISH). Additional studies, however, are needed to understand the clinical applicability of these in vitro tests based on statistically validated thresholds. Aim: The primary objective of this study was to report the incidence of SDF and chromosomal aneuploidy with respect to sperm quality in the United Arab Emirates (UAE) population. In addition, we wished to establish clinically useful SDF and aneuploidy cutoff values. Materials and Methods: A total of 302 subjects were enrolled in this study. The control group consisted of n = 100 (33.11%) reproductively-proven fertile men, and the case group consisted of n = 202 (66.89%) infertile men. The sperm quality of the cases was further subclassified as normospermia ("Normo," n = 88; 43.56%); teratozoospermia ("T," n = 40; 19.80%); oligoasthenoteratozoospermia ("OAT," n = 37; 18.32%); asthenoteratozoospermia ("AT," n = 19; 9.41%); or oligoteratozoospermia ("OT," n = 18; 8.91%). The assessments of SDF were done using SCD tests. Chromosomal aneuploidy (Chr 13, 18, 21, X, and Y) was investigated using sFISH. Furthermore, based on the fragmentation index, cases were divided into subfertile groups defined as low, medium, high, and severe. The Mann-Whitney test was used to set the upper threshold value for sFISH, and the odds ratio was used for SDF assessment. Results: Cases having sperm quality "AT," "OAT," and "OT" together with the moderate, high, and severe subfertile groups had the highest DNA fragmentation indices: 31.58%, 27.03%, and 22.22%, respectively. In the sFISH analyses, groups with sperm quality "OAT," "T," and "OT" exhibited high degrees of abnormalities: 86.49%, 52.50%, and 50%, respectively. The most common chromosomal abnormalities found were "sex chromosome hyperploidy (XY18)" and "diploid (Chr 13, 21)." The incidences of sperm quality with respect to SDF and sFISH are also reported in detail. Conclusions: This is the first study in the UAE which shows SDF and sFISH incidences together with sperm quality. This study also establishes SDF and sFISH cutoff values for the UAE population.

Polychlorinated biphenyls and dibenzofurans increased abnormal sperm morphology without alterations in aneuploidy: The Yucheng study

In 1979, more than 2000 persons ingested rice oil contaminated with polychlorinated biphenyls and polychlorinated dibenzofurans; this event was called the “Yucheng accident.” An increased percentage of oligospermia, reduced ability of sperm to penetrate oocytes, and reduced percentage of male offspring were reported in Yucheng men. This study examined whether the sperm sex ratio and chromosome aneuploidy are responsible for our observed findings in Yucheng men. In 1999–2000, Yucheng men and their neighborhood referents aged 37–50 years were recruited for physical examination, followed by semen analysis. The semen samples were analyzed for chromosomal aneuploidy through fluorescent in situ hybridization according to an established procedure in our laboratory. A total of 50 Yucheng men and 34 neighborhood referents volunteered to participate in the study. Although abnormal morphology was mildly increased, no differences were observed in sperm percentages, with normal numbers of chromosomes X, Y, and 8 in the two groups. The percentage of sperm with aneuploidy of the sex chromosomes or chromosome 8 and of that with diploidy did not vary between both groups. The normal X/Y sperm ratio was not different between the groups. However, among Yucheng men, 8% had a normal X/Y sperm ratio of >1.4, and no neighborhood referent showed such an elevated X/Y ratio. Chromosomal aneuploidy was not elevated in Yucheng men. The mechanisms underlying the reduced sperm capability of oocyte penetration and changed offspring sex ratio in Yucheng men remain undetermined.

Genetic counseling for men with recurrent pregnancy loss or recurrent implantation failure due to abnormal sperm chromosomal aneuploidy.

The purpose of this study is to review recurrent pregnancy loss (RPL) due to sperm chromosomal abnormalities and discuss the genetic counseling that is required for men with sperm chromosomal abnormalities. The literature was reviewed, and a genetic counselor lends her expertise as to how couples with RPL and sperm chromosomal abnormalities ought to be counseled. The review of the literature was performed using MEDLINE. Sperm fluorescence in situ hybridization (FISH) can be used to determine if disomy or unbalanced chromosomal translocations are present. In men with aneuploidy in sperm or who carry a chromosomal translocation, pre-implantation genetic screening (PGS) combined with in vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI) can increase chances of live birth. In men with abnormal sperm FISH results, the degree of increased risk of abnormal pregnancy remains unclear. Genetic counselors can provide information to couples about the risk for potential trisomies and sex chromosome aneuploidies and discuss their reproductive and testing options such as PGS, use of donor sperm, and adoption. The provision of genetic counseling also allows a couple to be educated about recommended prenatal testing since pregnancies conceived with a partner who has had abnormal sperm FISH are considered to be at increased risk for aneuploidy. We review the literature and discuss genetic counseling for couples with RPL or recurrent implantation failure due to increased sperm aneuploidy.

Analysis of Sperm DNA Fragmentation and Aneuploidy in 109 Infertile Patients: Are the Two Parameters Correlated?

Purpose: To evaluate the association between sperm DNA integrity and chromosomes aneuploidies in a considerable population of infertile patients undergoing assisted reproductive treatment (109 male) characterized by both normal and abnormal semen parameters. Methods: In 109 infertile patients with normal and abnormal semen parameters, the assessments of sperm DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) and chromosome aneuploidy by fluorescence in situ hybridization (FISH) have been performed on the same semen sample. Sperm samples were collected by masturbation into sterile cups after 3-5 days of sexual abstinence, allowed to liquefy for 30 min at room temperature and then divided in two aliquots, one processed by double gradient centrifugation (DGC) and used for TUNEL assay, whereas the remained aliquot was left unprocessed and used for FISH test. Results: The main results indicate a significant positive correlation between sperm chromosome aneuploidies and DNA integrity in patients with abnormal semen parameters (R=0.516 p=0,000) and negative not significant correlation in patients with normal seminal parameters (R=-0.105, p=0.476). Conclusions: Assuming the positive correlation between the two biomarkers in patients with defective spermatogenesis, high DNA fragmentation index (DFI) could perhaps be indicator of high chromosome aneuploidies level, thus increasing the risk of generating aneuploid embryos. Therefore, a clinical strategy could probably be to integrate also the preimplantation genetic screening (PGS) in ART treatment plan, in addition to the evaluation of sperm DNA fragmentation and/or sperm chromosome aneuploidy, to avoid transfer of chromosomally abnormal embryos.

Evaluación del factor masculino en reproducción asistida: nuevas tecnologías

Los parámetros seminales analizados en un espermatograma (concentración, motilidad, morfología) no discriminan claramente a pacientes con problemas de fertilidad. Por esto se hace necesaria la búsqueda de nuevos marcadores que nos permitan correlacionar la causa de la infertilidad de factor masculino con la probabilidad de lograr un embarazo a término. En los últimos años muchas investigaciones se han enfocado en el área molecular, evaluando la fragmentación del ADN y las aneuploidías cromosómicas del espermatozoide, lo cual ha llevado a denominarlas infertilidad de factor masculino genómico. Es así como actualmente se está aplicando metodologías que permiten seleccionar espermatozoides con un menor grado de estas patologías, para ser utilizados en procedimientos de reproducción asistida (RA). Entre ellas tenemos la selección morfológica de espermatozoides por alta magnificación (IMSI), las columnas de anexina-V y la selección espermática por unión al ácido hialurónico. En esta revisión detallaremos la utilidad de las pruebas de fragmentación de ADN y FISH en espermatozoides, como las técnicas de selección espermática en técnicas de RA.

293 The clinical value of assessing sperm chromosomal aneuploidy in couples undergoing failed intracytoplasmic sperm injection (ICSI) and its correlation with semen parameters

293 The clinical value of assessing sperm chromosomal aneuploidy in couples undergoing failed intracytoplasmic sperm injection (ICSI) and its correlation with semen parameters

No difference in high-magnification morphology and hyaluronic acid binding in the selection of euploid spermatozoa with intact DNA

In this study, we compared conventional sperm selection with high-magnification morphology based on the motile sperm organellar morphology examination (MSOME) criteria, and hyaluronic acid (HA) binding for sperm chromosome aneuploidy and DNA fragmentation rates. Semen from 50 severe male factor cases was processed through density gradient centrifugation, and subjected to sperm selection by using the conventional method (control), high magnification at ×6650 or HA binding. Aneuploidy was detected by fluorescence in situ hybridization with probes for chromosomes 13, 18, 21, X and Y, and DNA fragmentation by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) method. Spermatozoa selected under high-magnification had a lower DNA fragmentation rate (2.6% vs. 1.7%; P=0.032), with no significant difference in aneuploidy rate (0.8% vs 0.7%; P=0.583), than those selected by the HA binding method. Spermatozoa selected by both methods had much lower aneuploidy and DNA fragmentation rate than the controls (7% aneuploidy and 26.8% DNA fragmentation rates, respectively). In the high-magnification group, the aneuploidy rate was lower when the best spermatozoa were selected than when only the second-best spermatozoa were available for selection, but the DNA fragmentation rate was not different. In conclusion, sperm selection under high magnification was more effective than under HA binding in selecting spermatozoa with low DNA fragmentation rate, but the small difference (0.9%) might not be clinically meaningful. Both methods were better than the conventional method of sperm selection.

Quality of Sperm Obtained by Penile Vibratory Stimulation and Percutaneous Vasal Sperm Aspiration in Men With Spinal Cord Injury

The aim of this study was to explore sperm chromosomal aneuploidy and DNA integrity in infertile patients with spinal cord injury (SCI). Semen samples were collected from 12 infertile men with SCI by percutaneous vasal sperm aspiration (PVSA) and from 14 male SCI patients by penile vibratory stimulation (PVS). These semen samples as well as samples from 16 donors were analyzed using the hypo-osmotic swelling (HOS) test, the sperm chromatin dispersion test, terminal deoxynucleotidyl transferase-mediated terminal uridine nick-end labeling assay, and multicolor fluorescence in situ hybridization with probes specific for the chromosomes 13, 18, 21, X, and Y. There were significant differences in the percentages of motile sperm, normal morphologic sperm, normal HOS/eosin staining, and sperm DNA fragmentation between the infertile men with SCI and the control group (P < .05 and P < .01). The sperm forward motility was significantly greater in the PVSA group than in the PVS group (P < .01). The number of round cells per milliliter of semen obtained from the 14 SCI patients by PVS was between 1 million and 12 million. The rate of sperm DNA fragmentation, as identified by the sperm chromatin dispersion test, was higher in the PVS group than in the PVSA group (P < .05). The aneuploidy rates for the SCI patients were 1.5- to 1.6-fold higher for chromosomes 13, 18, and 21, and were 2.3- to 2.4-fold higher for chromosomes X and Y than for patients in the control group (P < .001). These results suggest that for men with SCI, the semen quality is poorer, the prevalence of abnormal HOS/eosin staining is greater, and sperm DNA fragmentation and sperm chromosomal aneuploidies are seen at a higher rate compared with healthy, fertile, and normospermic men.

Exploring the relationship between the severity of oligozoospermia and the frequencies of sperm chromosome aneuploidies

The study was aimed to investigate the association between the degree of oligozoospermia and sperm chromosome aneuploidy frequencies in male infertility and to determine whether chromosomal profiles of sperm nuclei would be used for a supportive test before additive reproduction technics. The meiotic segregation profiles of chromosomes X, Y, 13, 18 and 21 were compared by fluorescent in-situ hybridisation (FISH) on the spermatozoa of 30 normally karyotyped oligozoospermic (10 mild, 11 moderate, nine severe) cases without Y-microdeletions, and 10 normozoospermic cases. The results showed significantly higher frequencies of chromosomes 13, 18, 21 disomies (P<0.001) in the group of patients with moderate and severe oligozoospermia compared with the disomy frequencies of normozoospermic group. The statistically significant differences were also determined in disomy frequencies of sex chromosomes (XY, XX and YY) in between oligozoospermic and normozoospermic groups (P<0.001, P<0.001, P<0.040, respectively). Because oligozoospermic patients are the ones consulted the most for assisted reproductive techniques, identification of sperm aneuploidy rates in men could be considered as an appropriate supportive test before the reproductive implementations. Furthermore, the patients should be counselled with respect to genetic screening results for the potential risk of aneuploid embryo and pre-implantation genetic diagnosis or prenatal diagnosis.

Sperm chromosomal aneuploidy and DNA integrity of infertile men with anejaculation

To explore sperm chromosomal aneuploidy, sperm membrane and DNA integrity in infertile patients with anejaculation. Semen samples were collected from 18 infertile men with spinal cord injury (SCI) by penile vibratory stimulation (PVS) and from 14 psychogenic anejaculation (PA) patients by percutaneous vasal sperm aspiration (PVSA). These semen samples as well as samples from 16 donors were analyzed using the hypo-osmotic swelling (HOS) test, the sperm chromatin dispersion (SCD) test and multi-color fluorescence in situ hybridization (FISH) with probes specific for chromosomes 13, 18, 21, X and Y. There were significant differences in the percentages of motile sperm, normal morphologic sperm and sperm DNA fragmentation between the infertile men with SCI and the control group (P < 0.05 and P < 0.01). The sperm motility was significantly greater in the PA-PVSA group than in the SCI-PVS group (P < 0.01). The number of round cells per mL of semen obtained from the 18 SCI patients by PVS was between 1 and 8 million. The rate of sperm DNA fragmentation in the SCI-PVS group was higher than that of the PA-PVSA group (P < 0.05). The aneuploidy rates for the SCI patients were 2.4-fold higher for chromosomes 13, 18 and 21 and 2.2-fold higher for chromosomes X and Y than for patients in the control group (P < 0.0001). The semen quality is poorer, sperm DNA fragmentation and sperm chromosomal aneuploidies are seen at a higher rate for SCI patients compared to healthy, fertile and normospermic men. Whether the difference in yield is due to increased scrotal temperature, genitourinary infection, or other reasons requires further study.

Impact of DNA damage on the frequency of sperm chromosomal aneuploidy in normal and subfertile men.

Various frequencies of sperm aneuploidy are reported in sperms of subfertile patients compared to normal individuals. Moreover, sperm DNA damage is shown to be associated with male infertility. In this study, the rate of DNA damage and frequencies of aneuploidy in sperms of subfertile patients was investigated. Semen samples were obtained from healthy normal and subfertile (oligozoospermia, asthenozoospermia, and oligoasthenozoospermia) men. The frequency of aneuploidy was assessed using primed in situ labeling (PRINS) analysis with specific primers for chromosomes 18, 21, X, and Y. Sperm DNA damage was assessed using alkaline comet assay. The mean frequencies of disomy for the patients were significantly higher than normal for all chromosomes (P < 0.01). The extent of DNA damage in sperms of subfertiles was significantly higher than in normal individuals (P < 0.001). The obtained results indicated that higher rate of DNA damages led to higher frequency of chromosomal disomy except for asthenozoospermia samples which exhibited higher rate of DNA damage and lower frequency of chromosomal disomy. These results demonstrate that men with oligozoospermia and oligoasthenozoospermia have an elevated risk for chromosome abnormalities in their sperm, particularly sex chromosomes. DNA damage might be involved in the process of malsegregation of chromosomes.

Higher Proportion of Haploid Round Spermatids and Spermatogenic Disomy Rate in Relation to Idiopathic Male Infertility

To investigate the possible association between the spermatogenic chromosomal aberrations and idiopathic male infertility with normal semen volume, sperm concentration, sperm number per ejaculum, and sperm motility. Male infertility can be considered as a syndrome that results from many congenital or acquired illness. Currently, there is an increasing awareness of the potential role of chromosomal factors in the idiopathic forms of male infertility. A total of 202 idiopathic infertile men and 41 normal fertile donors were recruited into this study, through eligibility screening procedures. Proportions and chromatin status of sperm were assessed by flow cytometry after staining the DNA with propidium iodide. Sperm chromosome aneuploidy rates for chromosome 13, 18, 21, X, and Y were evaluated by fluorescence in situ hybridization using five-color probes. Infertile males showed a significantly lower percentage of mature haploid sperm cells and higher percentage of haploid round spermatids than the controls. A significantly higher frequency of disomy on spermatozoa was also detected in infertile males compared with the controls. These findings suggest that higher frequencies of haploid round spermatids and spermatogenic disomy rate may contribute to elevated risk of idiopathic male infertility.

The use of fluorescent in situ hybridization in male infertility

Male factors are implicated in up to 50% of couples being evaluated and treated for infertility with advanced assisted reproductive technologies. Genetic abnormalities, including sperm chromosome aneuploidy as well as structural aberrations, are one of the major causes of infertility. The use of chromosome-specific DNA probes labeled with fluorochromes, particularly the combination with multiple probes, has been used to indirectly study the sperm chromosome by fluorescent in situ hybridization (FISH). Clinically, this technique is also used to assess the sperm of men recovering from gonadotoxic treatment. Recent advances in this technology facilitate the evaluation of sperm aneuploidy. Sperm FISH is a widely used screening tool to aid in counseling couples with severe male factor infertility, especially in cases of prior repeated in vitro fertilization/intracytoplasmic sperm injection failure or recurrent pregnancy loss. Automation of FISH imaging and analysis, as well as the development of emerging techniques such as comparative genomic hybridization, will all contribute to the promise of future diagnostic approaches aimed at improving the quality, ease, and efficiency of aneuploidy analysis.

ANDROLOGY LAB CORNER*: The Clinical Implementation of Sperm Chromosome Aneuploidy Testing: Pitfalls and Promises

Severe male infertility has been shown to be associated with improper meiotic recombination and elevated sperm chromosome aneuploidy. Elevated sperm aneuploidy increases the risk of embryo lethality or fetal anomalies. Although difficulties in interpreting aneuploidy data still exist, advances in fluorescent in situ hybridization (FISH) technology have facilitated the study of sperm from patients with severe spermatogenesis defects, which has demonstrated the prudence of evaluating sperm chromosome aneuploidy in men with severe male factor infertility, such as nonobstructive azoospermia or severe ultrastructure defects, especially in cases of previous repeated in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) failure. Testing is also advisable in men with chromosome translocations and unexplained recurrent pregnancy loss, and it may be beneficial in patients with unexplained, repeated IVF failure. Automated FISH imaging and analysis technology is now available and is beneficial in reducing technician time analyzing sperm aneuploidy. Emerging technologies, such comparative genomic hybridization, may be beneficial in further improving the quality of data derived from aneuploidy analysis and reducing the cost of the assay.

Individual variation in the frequency of sperm aneuploidy in humans

To examine interindividual differences in sperm chromosome aneuploidy, repeated semen specimens were obtained from a group of ten healthy men, aged 20–21 at the start of the study, and analyzed by multi-color fluorescence in situ hybridization (FISH) analysis to determine the frequencies of sperm aneuploidy for chromosomes X, Y, 8, 18 and 21 and of diploidy. Semen samples were obtained three times over a five-year period. Statistical analysis examining the stability of sperm aneuploidy over time by type and chromosome identified two men who consistently exhibited elevated frequencies of sperm aneuploidy (stable variants): one with elevated disomy 18 and one with elevated MII diploidy. Differences among frequencies of aneuploidy by chromosome were also seen. Overall, disomy frequencies were lower for chromosome X, 8 and 18 than for chromosomes 21 or Y and for XY aneuploidy. The frequency of chromosome Y disomy did not differ from XY sperm frequency. Also, the frequency of meiosis I (XY) and II (YY + XX) sex chromosome errors did not differ in haploid sperm, but the frequency of MII errors was lower than MI errors in diploid sperm. Frequencies of sperm aneuploidy were similar between the first sampling period and the second, two years later. However, the frequency of some types of aneuploidy (XY, disomy Y, disomy 8, total autosomal disomies, total diploidy, and subcategories of diploidy) increased significantly between the first sampling period and the last, five years later, while others remained unchanged (disomy X, 21 and 18). These findings confirm inter-chromosome differences in the frequencies of disomy and suggest that some apparently healthy men exhibit consistently elevated frequencies of specific sperm aneuplodies. Furthermore, time/age-related changes in sperm aneuploidy may be detected over as short a period as five years in a repeated-measures study.

PCBs AND PCDFs EXPOSURE DOES NOT INDUCE SPERM ANEUPLOIDY IN HUMANS

ISEE-131 Introduction: Among men heavily exposed to polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs), increased percentage of oligospermia, reduced sperm capability of penetrating oocytes, and reduced percentage of male offspring were reported by our study group. The mechanism of such effects is unknown. Aim: We test the hypothesis that effects on gender ratio and sperm functioning is related to sperm chromosomal aneuploidy. Methods: During 1978-79, over 2,000 Taiwanese ingested rice oil contaminated with PCBs and its pyrolytic products, mainly PCDFs. This episode was referred to as “Yucheng” (“oil-disease” in Chinese) exposure. In 1999-2000, exposed men and their controls, aged 37-50 years, were recruited for physical examination followed by semen analysis. Semen samples were studied for chromosomal aneuploidy by fluorescent in situ hybridization (FISH). After semen sample preparation, hybridization procedures were done using centromere-specific probes directly labeled by fluorescence dyes (Vysis, Downers Grove, IL), including CEP X (SpectrumAqua), CEP Y (SpectrumOrange) and CEP 8 (SpectrumGreen). Each cell was scored for the number of fluorescent spots. Results: A total of 50 men exposed to PCBs/PCDFs and 34 unexposed matched controls volunteered to participate in the study. The age, body height and weight, percent of smokers, and period of abstinence from ejaculation were not different between exposed and control subjects. Percentage of sperm with normal numbers of chromosomes X,Y, and 8 were not different between the two groups. Percentage of sperm with aneuploidy of sex chromosomes or chromosome 8, and those with diploidy were not different between Yucheng and control subjects. Ratios of normal X/normal Y sperm were not different between the exposed and control groups. However, among Yucheng men, 4 (8%) had normal X/normal Y sperm ratio of >1.4, and among controls, none had such elevated X/Y ratio (not statistically significant by Fisher’s exact test). Discussion: Chromosomal aneuploidy was not elevated in PCB/PCDF-exposed men. Offspring gender-ratio (male:female) was reduced for approximately 10 years after Yucheng men were exposed to PCB/PCDF-contaminated rice oil. In this study, disproportional reduction of normal Y sperm was not seen in Yucheng subjects. However, among Yucheng men, 4 (8%) had normal X/normal Y sperm ratio of >1.4, and among controls, none had such elevated X/Y ratio (not statistically significant by Fisher’s exact test). Whether individuals had different susceptibility, among exposed people, remains to be determined. Conclusion: Chromosomal aneuploidy, diploidy, and X/Y sperm ratio were not increased in men highly exposed to PCBs/PCDFs despite reduced sperm capability of oocyte penetration, mildly increased abnormal morphology, and changed gender ratio in exposed men. The mechanisms of the latter remain to be determined.

Alteraciones de la cromatina espermática en la etiopatogenia de la infertilidad masculina

Sperm DNA is known to contribute one half of the genomic material to offspring. Normal sperm genetic material is required for fertilization, embryo and fetal development and adequate postnatal development. Abnormal DNA can lead to derangements in any of these processes. Sperm DNA is normally resistant to many types of insult. Recent reports have raised concern about decreasing male fertility caused by genomic abnormalities. Several reports describe increased congenital anomalies and testicular cancer in children. Defects in the genomic material may take the form of condensation or nuclear maturity defects, DNA breaks or DNA integrity defects and sperm chromosomal aneuploidy. Recently, sperm DNA has been recognized as an independent measure of sperm quality. The quality of sperm DNA has been shown to affect fertility both in vivo and in vitro. The cause of infertility in infertile men with normal semen parameters could be related to abnormal sperm DNA. The evaluation of sperm DNA integrity, in addition to routine sperm parameters, could add further information on the quality of spermatozoa. This could help in the correct identification of male infertility and in advising couples on the management of infertility.