The frequencies of Y chromosome microdeletions in infertile males

Evaluation of chromosomal abnormalities in the postnatal cohort: A single-center study on 14,242 patients

BACKGROUND AND AIM

Chromosomal analysis is a laboratory technique used to examine the chromosomes of an individual, offering insights into chromosome numbers, structures, and arrangements to diagnose and comprehend genetic diseases. This retrospective study provides a comprehensive understanding of the distribution by indications in a large cohort of 14,242 patients and the frequency of chromosomal abnormalities in different clinical populations.

METHOD

The study examined various indications for karyotype evaluation, with recurrent pregnancy loss being the most common indication, followed by intellectual disability, dysmorphic features, congenital anomalies, and developmental delay.

RESULTS

The overall chromosomal abnormality rate was found to be 5.4%, with numerical abnormalities accounting for the majority of cases (61.7%). Trisomies, particularly trisomy 21, were the most frequent numerical abnormalities. In terms of structural abnormalities, inversions and translocations were the most commonly identified. The rates of chromosomal anomalies varied in specific indications such as amenorrhea, disorders of sex development, and Turner syndrome. The study also highlighted significant differences between males and females in the presence of chromosomal abnormalities across certain indications. Males exhibited a higher incidence of chromosomal abnormalities in cases of Down syndrome and infertility, whereas females showed higher abnormalities in terms of recurrent pregnancy loss.

CONCLUSION

While this study provides valuable insights into the frequency and distribution of chromosomal abnormalities, it has limitations, including its retrospective design and reliance on data from a single medical genetics department. Nevertheless, the findings emphasize the importance of karyotype analysis in diagnosing chromosomal disorders and providing appropriate management, while also pointing to potential gender-related variations in chromosomal abnormalities that warrant further investigation.

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.

First report of frequencies of Y chromosome microdeletions at a reproductive medicine center in Peru

Objective

Y chromosome Microdeletions are the second genetic cause of infertility in men. Despite its importance for infertility treatment, there is no previous research in Peru. The aim of this study was to determine the frequencies and characteristics of Y chromosome microdeletions in a group of men who sought infertility consultation at a specialized reproductive medicine center in Peru.

Methods

In this study, 201 semen samples were analyzed. The samples were obtained from Niu Vida's fertility program. Each seminal sample was analyzed according to the recommendations of the Laboratory Manual of the World Health Organization (WHO) 2010. A buccal swab and a 500 μL aliquot of seminal sample were used for the molecular study of Y chromosome microdeletions in each patient. The frequencies and the type of Y chromosome microdeletion in the AZFa, AZFb and AZFc regions were evaluated.

Results

The prevalence of Y chromosome microdeletions in the AZF region was 6.45% in oligozoospermic and azoospermic patients, and a prevalence of 20% was observed specifically in azoospermic patients. No microdeletions of AZFb type were detected. A partial region microdeletion of AZFa was detected in a teratozoospermic patient with a normal sperm count.

Conclusions

The study represents the first report on the incidence of Y chromosome microdeletions in Peru. Our results indicate a high prevalence of microdeletions in azoospermic patients compared to similar studies. It is suggested to assess the presence of AZFa microdeletions and to evaluate additional genetic markers in this region to identify specific mutations that may cause impaired sperm production and male infertility in the Peruvian male population.

Copy number variations (CNVs) and karyotyping analysis in males with azoospermia and oligospermia

BACKGROUND

Considering the essential roles that genetic factors play in azoospermia and oligospermia, this study aims to identify abnormal chromosomes using karyotyping and CNVs and elucidate the associated genes in patients.

METHODS

A total of 1157 azoospermia and oligospermia patients were recruited, of whom, 769 and 674 underwent next-generation sequencing (NGS) to identify CNVs and routine G-band karyotyping, respectively.

RESULTS

First, 286 patients were co-analyzed using CNV sequencing (CNV-seq) and karyotyping. Of the 725 and 432 patients with azoospermia and oligospermia, 33.8% and 48.9% had abnormal karyotypes and CNVs, respectively. In particular, 47,XXY accounted for 44.18% and 26.33% of abnormal karyotypes and CNVs, respectively, representing the most frequent genetic aberration in azoospermia and oligospermia patients. Nevertheless, big Y and small Y accounted for 7.46% and 16.67% of abnormal karyotypes, respectively. We also identified high-frequency CNVs-loci, such as Xp22.31 and 2p24.3, in azoospermia and oligospermia patients.

CONCLUSION

Sex chromosome and autosomal CNV loci, such as Xp22.31 and 2p24.3, as well as the associated genes, such as VCX and NACAP9, could be candidate spermatogenesis genes. The high-frequency abnormal karyotypes, CNV loci, and hot genes represent new targets for future research.

[AZF gene microdeletions in azoospermic-oligozoospermic males]

BACKGROUND AND OBJECTIVE

The presence of microdeletions in the Y-chromosome azoospermia factor (AZF) region (YCMs) is considered the most frequent genetic cause of male infertility along with Klinefelter syndrome. The objective of this study was to investigate the frequencies and type of YCMs in infertile men in Aragon and to analyze the relationship between sex hormones, sperm count and microdeletions in them.

PATIENTS AND METHODS

Retrospective descriptive study of 644 men who during 2006-2019 were screened for YCMs using YChromStrip (Operón, Spain) by PCR+reverse hybridization, spermiogram, karyotype and quantification of sex hormones.

RESULTS

The frequency of YCMs was 3.88% (25/644), not being detected in any patient with mild or normospermic oligozoospermia, that is, in sperm counts higher than 5×10⁶/mL. The group of azoospermic patients was the one that presented a higher frequency of YCMs (14.58%, 14/96). Deletions in the AZFc region were the most frequent (68%). 20% (5/25) of patients with YCMs also presented some type of karyotype abnormality that included aneuploidies, deletions, duplications and/or translocations. Sperm count was significantly lower and FSH and LH concentrations significantly higher in the group of patients with YCMs.

CONCLUSIONS

YCMs screening is a key test in the diagnostic approach to male infertility. Obtaining an adequate result allows choosing suitable assisted reproduction techniques, preventing unnecessary treatments and the transmission of genetic defects to offspring.

Sertoli cell-only syndrome: advances, challenges, and perspectives in genetics and mechanisms

Male infertility can be caused by quantitative and/or qualitative abnormalities in spermatogenesis, which affects men's physical and mental health. Sertoli cell-only syndrome (SCOS) is the most severe histological phenotype of male infertility characterized by the depletion of germ cells with only Sertoli cells remaining in the seminiferous tubules. Most SCOS cases cannot be explained by the already known genetic causes including karyotype abnormalities and microdeletions of the Y chromosome. With the development of sequencing technology, studies on screening new genetic causes for SCOS are growing in recent years. Directly sequencing of target genes in sporadic cases and whole-exome sequencing applied in familial cases have identified several genes associated with SCOS. Analyses of the testicular transcriptome, proteome, and epigenetics in SCOS patients provide explanations regarding the molecular mechanisms of SCOS. In this review, we discuss the possible relationship between defective germline development and SCOS based on mouse models with SCO phenotype. We also summarize the advances and challenges in the exploration of genetic causes and mechanisms of SCOS. Knowing the genetic factors of SCOS offers a better understanding of SCO and human spermatogenesis, and it also has practical significance for improving diagnosis, making appropriate medical decisions, and genetic counseling. For therapeutic implications, SCOS research, along with the achievements in stem cell technologies and gene therapy, build the foundation to develop novel therapies for SCOS patients to produce functional spermatozoa, giving them hope to father children.

Bridging the Gap between AZF Microdeletions and Karyotype: Twelve Years' Experience of an Infertility Center

PURPOSE

Despite all past efforts, the current guidelines are not explicit enough regarding the indications for performing azoospermia factor (AZF) screening and karyotype, burdening clinicians with the decision to assess whether such tests are meaningful for the infertile male patient. These assessments can be costly and it is up to the healthcare practitioner to decide which are necessary and to weigh the benefits against economic/psychological harm. The aim of this study is to address such gaps and provide update on current management options for this group of patients.

MATERIALS AND METHODS

To address such gaps in male infertility management and to elucidate whether AZF screening is indicated in individuals who concomitantly harbor chromosomal abnormalities we conducted a retrospective cohort analysis of 10,388 consecutive patients with non-obstructive azoospermia (NOA) and severe oligozoospermia.

RESULTS

Previously, it has been suggested that all NOA cases with chromosomal defects, except males with 46,XY/45,X karyotype, have no indication for AZF screening. Our findings revealed that cases carrying the following chromosomal abnormalities inv(Y)(p11.2q12); idic(Y)(q11.2); 46,XY,r(Y); idic(Y)(p11.2) and der(Y;Autosome) (76/169; 44.9%; 95% CI, 37.7-52.5) should also be referred for AZF deletion screening. Here, we also report the correlation between sperm count and AZF deletions as a secondary outcome. In accordance with previously reported data from North America and Europe, our data revealed that only 1% of cases with >1×10⁶ sperm/mL had Y chromosome microdeletions (YCMs).

CONCLUSIONS

In the era of assisted reproduction, finding cost-minimization strategies in infertility clinics without affecting the quality of diagnosis is becoming one of the top prioritized topics for future research. From a diagnostic viewpoint, the results reflect a need to reconsider the different karyotype presentations and the sperm count thresholds in male infertility guidelines as indicators for YCM screening during an infertility evaluation.

Abnormal Y chromosome detection in infertile males using multiplex ligation-dependent probe amplification

Y chromosome abnormalities are the leading cause of male infertility. The clinical detection of abnormalities is necessary for appropriate genetic counselling. This study describes the prevalence, distribution and characteristics of Y chromosome abnormalities, which should be considered in the clinical management of infertile males. A total of 121 patients with oligozoospermia, 120 with azoospermia and 88 normal individuals were recruited between June 2019 and July 2021. Y chromosome microdeletions were assessed using multiplex ligation-dependent probe amplification (MLPA). The abnormal Y chromosome prevalence was 30.70%, and it was most common in patients aged 26-40 years. The frequencies of azoospermia factor (AZF) deletion, duplication and deletions/duplications were 19.76%, 9.42% and 1.52% respectively. The most common abnormalities were AZFc deletion (19.80%), AZFc partial deletion (40.59%) and AZFc partial duplication (17.82%). Oligozoospermia was associated with an increased incidence of AZF deletion. In the subgroup analysis, patients <30 years old with azoospermia exhibited elevated follicle-stimulating hormone levels and oestradiol. Moreover, the incidence of AZF deletion was higher in those with azoospermia (OR: 2.12; 95% CI: 1.05-5.28; p = 0.023) or oligozoospermia (OR: 2.54; 95% CI: 1.13-5.79; p = 0.008) than in normal individuals for ages ≥30 years.

Investigation of genotype-phenotype correlation in patients with AZF microdeletion in a single-reference centre

In this study, we aimed to elucidate the relationship between AZF deletion type and clinical information of azoospermic patients with AZF microdeletion in the Turkish population. Azoospermic patients with normal karyotype and AZF microdeletion were analysed retrospectively by collecting clinical data including hormone profile, demographic characteristics and micro-TESE results. As a result of the AZF microdeletion tests of 42 cases with 46 XY karyotype, AZFa deletion was detected in 3 cases, AZFb deletion in 2 cases, AZFc deletion in 31 cases, AZFb + AZFc deletion in 4 cases and AZFa + AZFb + AZFc deletion in 2 cases respectively. Spermatozoon was obtained in 16 cases with AZFc microdeletion with micro-TESE. Pregnancy was achieved in 2 cases. There was no statistically significant difference between the type of deletion and age, height, weight, body mass index, hormone profile and testicular volume. When AZF is evaluated according to the type of microdeletion, it will be appropriate to plan the medical and surgical options more carefully in a multidisciplinary manner in cases with deletions including AZFa, AZFb or their combinations. Also, genotype-phenotype correlation was found to be consistent with the literature; particularly patients having AZFc deletions were found to have a chance for pregnancy.

Y chromosome microdeletion screening using a new molecular diagnostic method in 1030 Japanese males with infertility

The azoospermia factor (AZF) region is important for spermatogenesis, and deletions within these regions are a common cause of oligozoospermia and azoospermia. Although several studies have reported this cause, the present research, to the best of our knowledge, is the first large-scale study assessing this factor in Japan. In this study, 1030 male patients with infertility who were examined for Y chromosome microdeletion using the polymerase chain reaction-reverse sequence-specific oligonucleotide (PCR-rSSO) method, a newly developed method for Y chromosome microdeletion screening, were included. The study enrolled 250 patients with severe oligospermia and 717 patients with azoospermia. Among the 1030 patients, 4, 4, 10, and 52 had AZFa, AZFb, AZFb+c, and AZFc deletions, respectively. The sperm recovery rate (SRR) of microdissection testicular sperm extraction in patients with AZFc deletions was significantly higher than that in those without AZF deletions (60.0% vs 28.7%, P = 0.04). In patients with gr/gr deletion, SRR was 18.7%, which was lower than that in those without gr/gr deletion, but was not statistically significant. In conclusion, our study showed that the frequency of Y chromosome microdeletion in male patients in Japan was similar to that reported in patients from other countries, and SRR was higher in patients with AZFc deletion.

Evaluation of Y chromosome microdeletions and chromosomal anomalies in infertile men

OBJECTIVES

Chromosome anomalies and Y chromosome microdeletions are one of the reasons that can be seen in infertile patients and affect fertility. In this study, it was aimed to determine the frequencies of chromosomal anomalies and Y chromosome microdeletions in primary infertile male patients.

METHODS

We included 374 patients with primary infertility in this study. Cytogenetic analysis was performed with the GTG banding technique by using trypsin and Giemsa stain. Y microdeletion analysis was studied by multiplex polymerase chain reaction using 28 Y chromosome-specific sequence-tagged sites.

RESULTS

Chromosomal irregularities were detected in 27 (7.22%) of infertile cases. It was observed that 7 (25.92%) of chromosomal irregularities detected in cases were in autosomal and 20 (%74.08) were in gonosomal chromosomes. The incidence of Y chromosome microdeletion was 1.07% (4/374) and the microdeletions were observed in AZFb, AZFc and AZFd regions. AZFc + AZFd deletion was detected in three patients (0.81%) and AZFb + AZFc + AZFd deletion in one patient (0.26%).

CONCLUSIONS

In conclusion, gonosomal chromosome irregularity was higher than autosomal chromosome irregularity in infertile men. The frequency of Y microdeletion has different rates according to some factors such as ethnic differences of patients, patient selection criteria, differences in the number of cases, and methodological aspects.

Non-obstructive azoospermia: current and future perspectives

Infertility affects 1 in 6 couples, and male factor infertility has been implicated as a cause in 50% of cases. Azoospermia is defined as the absence of spermatozoa in the ejaculate and is considered the most extreme form of male factor infertility. Historically, these men were considered sterile but, with the advent of testicular sperm extraction and assisted reproductive technologies, men with azoospermia are able to biologically father their own children. Non-obstructive azoospermia (NOA) occurs when there is an impairment to spermatogenesis. This review describes the contemporary management of NOA and discusses the role of hormone stimulation therapy, surgical and embryological factors, and novel technologies such as proteomics, genomics, and artificial intelligence systems in the diagnosis and treatment of men with NOA. Moreover, we highlight that men with NOA represent a vulnerable population with an increased risk of developing cancer and cardiovascular comorbodities.

Y-microdeletions: a review of the genetic basis for this common cause of male infertility

The human Y-chromosome contains genetic material responsible for normal testis development and spermatogenesis. The long arm (Yq) of the Y-chromosome has been found to be susceptible to self-recombination during spermatogenesis predisposing this area to deletions. The incidence of these deletions is estimated to be 1/4,000 in the general population but has been found to be much higher in infertile men. Currently, Y-microdeletions are the second most commonly identified genetic cause of male infertility after Klinefelter syndrome. This has led to testing for these deletions becoming standard practice in men with azoospermia and severe oligospermia. There are three commonly identified Y-microdeletions in infertile males, termed azoospermia factor (AZF) microdeletions AZFa, AZFb and AZFc. With increased understanding and investigation of this genetic basis for infertility a more comprehensive understanding of these deletions has evolved, with several other deletion subtypes being identified. Understanding the genetic basis and pathology behind these Y-microdeletions is essential for any clinician involved in reproductive medicine. In this review we discuss the genetic basis of Y-microdeletions, the various subtypes of deletions, and current technologies available for testing. Our understanding of this issue is evolving in many areas, and in this review we highlight future testing opportunities that may allow us to stratify men with Y-microdeletion associated infertility more accurately

Potential Pathogenic Bacteria in Seminal Microbiota of Patients with Different Types of Dysspermatism

Human microbiota play an important role in the health of their human hosts. Recent studies have demonstrated that microbiota exist in seminal plasma. The current study aims to elucidate whether seminal microbiota exist in patients with different types of dysspermatism and whether bacterial biomarkers can be identified for them. A total of 159 study participants were recruited, including 22 patients with oligoasthenospermia, 58 patients with asthenospermia, 8 patients with azoospermia, 13 patients with oligospermia, and 58 matched healthy controls. Seminal microbiota composition was analyzed using 16S rRNA gene-based sequencing. The results showed that the composition of seminal microbiota of patients with dysspermatism differed from those of healthy controls. Comparison of the microbiota composition in semen samples from patients with different types of dysspermatism showed that microbiota in patients with asthenospermia and oligoasthenospermia were distinct from healthy controls in beta diversity (P < 0.05). Characteristic biomarkers, including Ureaplasma, Bacteroides, Anaerococcus, Finegoldia, Lactobacillus and Acinetobacter lwoffii, were identified based on LEfSe analysis. Inferred functional analysis based on seminal microbiome data further indicated the presence of potential pathogenic biomarkers in patients with asthenospermia and oligoasthenospermia. These results provided profiles of seminal microbiota exhibited in different types of dysspermatism, thus providing new insights into their pathogenesis.

Evaluation of chromosomal abnormalities and Y-chromosome microdeletions in 1696 Turkish cases with primary male infertility: A single-center study

OBJECTIVE

The aim of this study was to determine the frequencies of chromosomal abnormalities and Y-chromosome microdeletions in Turkish cases with primary male infertility in a single center.

MATERIAL AND METHODS

Chromosomal abnormalities and Y-chromosome microdeletions were investigated in 1696 cases with primary male infertility between 2012 and 2017. Karyotype analyzes and Y-chromosome microdeletions analyzes [azoospermia factor (AZF) regions] were performed in all cases by using standard cytogenetic methods and the multiplex polymerase chain reaction method, respectively.

RESULTS

Chromosomal abnormalities were found in 142 cases (8.4%; 142/1696). Y-chromosome microdeletions were detected in 46 cases (2.7%; 46/1696). Y-chromosome microdeletions in the AZFc region were found in 20 of 46 cases (43%).

CONCLUSION

This study is one of the few were a large number of cases was studied in Turkey. It indicates that cytogenetic and Y-chromosome microdeletion studies should be conducted in cases with primary male infertility prior to selecting assisted reproductive techniques.

A different look at genetic factors in individuals with non-obstructive azoospermia or oligospermia in our research study: To whom, which threshold, when, in what way?

INTRODUCTION

In our study, we sought answers to many questions about male infertility from a different perspective. The first step in male infertility is anamnesis, physical examination and sperm count. The European Academy of Andrology recommends examination of genetic causes in individuals with fewer than 5million/ml semen counts. The American Urological Association and American Society for Reproductive Medicine have guidelines recommending performing karyotype and AZF subgroup deletion testing in azoospermia and fewer than 5 million sperm total count. Klinefelter syndrome and Y chromosome microdeletions are still very important in male infertility. Based on patients with Klinefelter syndrome or Y microdeletion, we sought answers to many questions in male infertility.

MATERIALS AND METHODS

In the presented study 327 male patients with having fewer than 15millionsperm/ml detected in at least two consecutive sperm analysis were examined. Patients were divided into sub-groups according to the presence of semen count, chromosomal anomaly and Y microdeletion. In addition, FSH, LH and testosterone levels were analyzed.

RESULTS

Numerical chromosomal anomalies were observed in 34 (10.4%) of 327 patients, and all of these anomalies were found as 47, XXY. Individuals with no AZF microdeletion constituted 95.1% (n=311) of the study group. The overall frequency of AZF microdeletions was 4.9% (16/327). No AZF microdeletions were detected for the patients who have sperm counts above 2million/ml. FSH, LH and testosterone levels were found significantly different between the groups.

DISCUSSION

The results of our study provide another layer of evidence to demonstrate the controversial threshold value of the EAA. In light of our data and current literature, we recommend to set the threshold value at 2million/ml for semen analysis. Further studies conducted in different ethnic groups and larger patient groups would contribute to clarify what exact value should be used to apply genetic tests.