Prevalence of chromosomal abnormalities and Y chromosome microdeletion among men with severe semen abnormalities and its correlation with successful sperm retrieval

Sperm retrieval rate and patient factors in azoospermia factor c microdeletion azoospermia: a systematic review

OBJECTIVE

To reveal the overall sperm retrieval rate (SRR) and range in patients with azoospermia factor c (AZFc) microdeletion azoospermia by microdissection testicular sperm extraction (mTESE) and discuss the differences of preoperative patient factors among studies with various SRRs.

PATIENTS AND METHODS

We searched PubMed, Web of Science and Embase until February 2023. All studies reporting SRRs by mTESE and required parameters of patients with AZFc microdeletions were included. The primary outcome was the SRR and, if available, the pregnancy rate (PR) and live-birth rate (LBR) after intracytoplasmic sperm injection were also investigated as secondary outcomes.

RESULTS

Eventually 11 cohort studies were included in this review. A total number of 441 patients underwent mTESE and in 275 of them sperm was obtained, reaching an overall SRR of 62.4%. The SRRs among studies had a wide range from 25.0% to 85.7%. The studies reporting higher SRRs generally had older mean ages, and higher follicle-stimulating hormone and testosterone levels. Only four studies provided practical data on pregnancies and live-born children of patients with AZFc microdeletions, so the overall PR and LBR were unavailable.

CONCLUSIONS

The overall SRR of patients with AZFc microdeletion azoospermia was 62.4%. The effect of patient factors in SR needs further evidence in future work.

A systemic review and meta-analysis exploring the predictors of sperm retrieval in patients with non-obstructive azoospermia and chromosomal abnormalities

To identify the most prevalent chromosomal abnormalities in patients with non-obstructive azoospermia (NOA), consolidate their surgical sperm retrieval (SSR) rates and determine the significant predictors of positive SSR in this patient population. A systematic review and meta-analysis were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Fifty-three studies including 2965 patients were identified through searching the PubMed database. Klinefelter Syndrome (KS) was the most prevalent chromosomal abnormality reported in 2239 cases (75.5%). Azoospermia factor c (AZFc) microdeletions were the second most common (18.6%), but men with these deletions had higher SSR rates than patients with KS (41.95% with AZFc vs. 38.63% with KS). When examining predictors of SSR in KS patients, younger age was a significant predictor of positive SSR in patients undergoing microsurgical testicular sperm extraction (micro-TESE). Higher testosterone was a favourable predictor in those undergoing micro-TESE and conventional TESE. Lower luteinizing hormone (LH) and follicular stimulating hormone (FSH) values were significantly associated with positive SSR with testicular sperm aspiration (TESA). No parameter predicted SSR rates in patients with AZFc microdeletions. Overall, genetic abnormalities have significant implications on SSR success in patients with NOA.

Karyotypic abnormalities and Y chromosome microdeletions: How do these impact in vitro fertilization outcomes, and how common are they in the modern in vitro fertilization practice?

Objective

To examine the outcomes of in vitro fertilization with intracytoplasmic sperm injection (IVF-ICSI) in couples in whom the male partner has a karyotypic abnormality or Y chromosome microdeletion (YCM).

Design

Retrospective cohort.

Setting

Single infertility center.

Patient(s)

Couples treated with IVF-ICSI from January 2014 to April 2019 with male factor infertility, sperm concentration of <5 × 10⁶ sperm/mL, and results for karyotype and/or YCM panel.

Intervention(s)

In vitro fertilization with intracytoplasmic sperm injection.

Main Outcome Measure(s)

In couples in whom the male partner had a karyotypic abnormality or YCM: live birth rate/ongoing pregnancy rate, lack of partner sperm for fertilization, complete fertilization failure, cycle cancellation, and no embryos for transfer. The prevalence of karyotypic abnormalities and YCMs in the IVF population was calculated.

Result(s)

The live birth rate/ongoing pregnancy rate for those using partner sperm was 51.4% per transfer. However, 8.5% of cycles that intended to use partner sperm and 22.2% of cycles that intended to use surgically extracted partner sperm had no sperm available. Of cycles that created embryos with partner sperm, 12.5% had no embryo to transfer. The prevalence of karyotypic abnormalities was similar to previous reports (6.0%), while that of YCMs was lower (4.4%). Azoospermia factor a and b mutations were not represented in this population.

Conclusion(s)

It is reasonable to attempt IVF-ICSI with partner sperm in patients with genetic causes of male infertility. Patients should be counseled regarding the possibility of no sperm being available from the male partner, poor/failed fertilization, and genetic implications for potential offspring. Contingency plans, including IVF with donor sperm backup or oocyte cryopreservation, need to be made for these scenarios.

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.

RNA-binding protein Maca is crucial for gigantic male fertility factor gene expression, spermatogenesis, and male fertility, in Drosophila

During spermatogenesis, the process in which sperm for fertilization are produced from germline cells, gene expression is spatiotemporally highly regulated. In Drosophila, successful expression of extremely large male fertility factor genes on Y-chromosome spanning some megabases due to their gigantic intron sizes is crucial for spermatogenesis. Expression of such extremely large genes must be challenging, but the molecular mechanism that allows it remains unknown. Here we report that a novel RNA-binding protein Maca, which contains two RNA-recognition motifs, is crucial for this process. maca null mutant male flies exhibited a failure in the spermatid individualization process during spermatogenesis, lacked mature sperm, and were completely sterile, while maca mutant female flies were fully fertile. Proteomics and transcriptome analyses revealed that both protein and mRNA abundance of the gigantic male fertility factor genes kl-2, kl-3, and kl-5 (kl genes) are significantly decreased, where the decreases of kl-2 are particularly dramatic, in maca mutant testes. Splicing of the kl-3 transcripts was also dysregulated in maca mutant testes. All these physiological and molecular phenotypes were rescued by a maca transgene in the maca mutant background. Furthermore, we found that in the control genetic background, Maca is exclusively expressed in spermatocytes in testes and enriched at Y-loop A/C in the nucleus, where the kl-5 primary transcripts are localized. Our data suggest that Maca increases transcription processivity, promotes successful splicing of gigantic introns, and/or protects transcripts from premature degradation, of the kl genes. Our study identified a novel RNA-binding protein Maca that is crucial for successful expression of the gigantic male fertility factor genes, spermatogenesis, and male fertility.

The Spectrum of Chromosomal Abnormalities and Endocrine Profile of Male Infertility with Nonobstructive Semen Abnormality: A Case-Control Study

Background:

Primary infertility is a common occurrence which affects approximately 15% of couples who desire to begin their family. Chromosomal abnormalities are well-established causes of pregnancy loss but may also have a role in explaining the cause of male infertility, especially with nonobstructive semen abnormalities. Hence, awareness regarding safety of artificial reproductive technology in these individuals due to underlying sperm aneuploidy is required.

Aims:

The aims of the study are to determine the prevalence of chromosomal abnormalities in primary infertile males with nonobstructive semen abnormalities and correlate with their endocrine profile.

Study Design:

A case–control study, in which 100 males with primary infertility and non-obstructive semen abnormalities were evaluated for chromosomal abnormality and hormonal profile; and were compared with 50 healthy males with normal semen analysis and at least one biological child.

Materials and Methods:

Blood T-lymphocytes were cultured using RPMI-1640 medium for obtaining metaphases and chromosomal analysis.

Statistical Analysis:

SPSS software and Student's t-test were used. A p < 0.05 was considered statistically significant.

Results:

Azoospermia (81%) was the most common nonobstructive semen abnormality. Overall prevalence of major chromosomal abnormalities and polymorphic variants was 16% and 7%, respectively. Klinefelter syndrome was the most common sex chromosomal numerical abnormality seen in 6.17% of cases with azoospermia. All healthy control males had 46, XY karyotype. Higher levels of follicle-stimulating hormone and luteinizing hormone and lower levels of testosterone along with testicular volumes were observed in infertile males with abnormal karyotype (p < 0.05).

Conclusion:

Primary infertile males with nonobstructive semen abnormality have high frequency of chromosomal aberrations, which justify the requirement of cytogenetic testing in these patients.

Histology and sperm retrieval among men with Y chromosome microdeletions

In this review of Y chromosome microdeletions, azoospermia factor (AZF) deletion subtypes, histological features and microTESE sperm retrieval rates are summarized after a systematic literature review. PubMed was searched and papers were identified using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Approximately half of infertile couples have a male factor contributing to their infertility. One of the most common genetic etiologies are Y chromosome microdeletions. Men with Y chromosome microdeletions may have rare sperm available in the ejaculate or undergo surgical sperm retrieval and subsequent intracytoplasmic sperm injection to produce offspring. Azoospermia or severe oligozoospermia are the most common semen analysis findings found in men with Y chromosome microdeletions, associated with impaired spermatogenesis. Men with complete deletions of azoospermia factor a, b, or a combination of any loci have severely impaired spermatogenesis and are nearly always azoospermic with no sperm retrievable from the testis. Deletions of the azoospermia factor c or d often have sperm production and the highest likelihood of a successful sperm retrieval. In men with AZFc deletions, histologically, 46% of men demonstrate Sertoli cell only syndrome on biopsy, whereas 38.2% have maturation arrest and 15.7% have hypospermatogenesis. The microTESE sperm retrieval rates in AZFc-deleted men range from 13-100% based on the 32 studies analyzed, with a mean sperm retrieval rate of 47%.

Nonmosaic Isodicentric Y Chromosome: A Rare Cause of Azoospermia- From Genetics to Clinical Practice

Azoospermia is diagnosed when no spermatozoa can be detected after centrifugation of seminal fluid on at least two separate occasions. A number of genetic disorders can be related to nonobstructive azoospermia, and in up to 15% of azoospermic males, a genetic disorder is diagnosed. A 36-year-old male with nonobstructive azoospermia was referred to our department of diabetes and endocrinology due to an aberrant testicular biopsy. The biopsy showed a disrupted spermatogenesis with a maturation arrest at the spermatocyte level in most tubuli seminiferi while others showed a Sertoli cell-only syndrome. Screening for Y chromosome microdeletions on peripheral blood using molecular analysis detected a terminal deletion of AZFbc. The result of karyotyping and fluorescence in situ hybridization (FISH) described an isodicentric Y chromosome with karyotype 46,X,idic(Y)(q11.22). Based on this case and the current available literature, we conclude that performing a testicular biopsy in patients with a nonmosaic idic(Y)(q) is not meaningful and that the prognosis on infertility is poor. Biological fatherhood is extremely unlikely in these patients, and proper counselling should be provided.

DAZL mediates a broad translational program regulating expansion and differentiation of spermatogonial progenitors

Fertility across metazoa requires the germline-specific DAZ family of RNA-binding proteins. Here we examine whether DAZL directly regulates progenitor spermatogonia using a conditional genetic mouse model and in vivo biochemical approaches combined with chemical synchronization of spermatogenesis. We find that the absence of Dazl impairs both expansion and differentiation of the spermatogonial progenitor population. In undifferentiated spermatogonia, DAZL binds the 3' UTRs of ~2,500 protein-coding genes. Some targets are known regulators of spermatogonial proliferation and differentiation while others are broadly expressed, dosage-sensitive factors that control transcription and RNA metabolism. DAZL binds 3' UTR sites conserved across vertebrates at a UGUU(U/A) motif. By assessing ribosome occupancy in undifferentiated spermatogonia, we find that DAZL increases translation of its targets. In total, DAZL orchestrates a broad translational program that amplifies protein levels of key spermatogonial and gene regulatory factors to promote the expansion and differentiation of progenitor spermatogonia.

Chromosomal abnormalities and Y chromosome microdeletions in infertile men with azoospermia and oligozoospermia in Eastern China

Objective

The objective was to investigate the frequency and type of chromosomal abnormalities and Y chromosome microdeletions in infertile men with azoospermia and oligozoospermia to ensure appropriate genetic counseling before assisted reproduction in Eastern China.

Methods

A total of 201 infertile men (148 with azoospermia and 53 with oligozoospermia) were enrolled. Real-time PCR using six Y-specific sequence-tagged sites of the azoospermia factor (AZF) region was performed to screen for microdeletions. Karyotype analyses were performed on peripheral blood lymphocytes with standard G-banding.

Results

Out of 201 infertile patients, 22 (10.95%) had Y microdeletions [17/148 (11.49%) men with azoospermia and 5/53 (9.43%) men with oligozoospermia]. The most frequent microdeletions were in the AZFc region, followed by the AZFa+b + c, AZFb+c, AZFa, and AZFb regions. Chromosomal abnormalities were detected in 18.91% (38/201) of patients, 34 of which were sex chromosome abnormalities (16.92%) and 4 of which were autosomal abnormalities (1.99%). Chromosomal abnormalities were more prevalent in men with azoospermia (22.97%) than in those with oligozoospermia (7.55%).

Conclusions

We detected a high incidence of chromosomal abnormalities and Y chromosomal microdeletions in infertile Chinese men with azoospermia and oligozoospermia. These findings suggest the need for genetic testing before the use of assisted reproduction techniques.

Clinical and molecular characterization of Y microdeletions and X-linked CNV67 implications in male fertility: a 20-year experience

BACKGROUND

Approximately 15% of couples worldwide are affected with infertility, attributed to a male co-factor in about half of the cases. Y chromosome microdeletions are the second most common genetic cause for male infertility, with a global prevalence of 2-10% in infertile men. Recently, CNV67, localized in X chromosome, has emerged as potential contributor to male infertility, with a described frequency of 1.1% in the oligo/azoospermic men.

OBJECTIVES

To investigate the prevalence of Y-linked CNVs in a cohort of Portuguese infertile men and correlate the patients' phenotypes with a genetic alteration; to investigate the CNV67 deletion in a subset of patients and corroborate the role of this CNV in male infertility.

MATERIALS AND METHODS

We retrospectively analysed a database of 4000 Portuguese infertile men for karyotype anomalies and Y microdeletions and selected a cohort of 400 for CNV67 screening analysis by quantitative PCR or single PCR plus/minus.

RESULTS

Karyotype anomalies were present in 263 patients (6.6%), with Klinefelter syndrome representing the most frequent karyotype anomaly (2.8%). Among the 4000 patients, the prevalence of Yq microdeletions was 4.6%. Ninety microdeletions (10.0%) were found in the azoospermic group, 44 deletions (4.5%) in the severe oligozoospermic group, 1 AZFc partial deletion (0.3%) in the mild-moderate oligozoospermic group and 2 partial AZFc deletions (0.4%) in the normozoospermic group. Complete AZFc deletions represented 56.8% of the Yq microdeletions. The CNV67 deletion frequency was 1.2% in the studied sample.

CONCLUSIONS

This study presents one of the largest samples of infertile men worldwide with the main purpose of correlating the Yq microdeletions with sperm count. Our findings are supported by previous reviews with large data and provide a reliable estimation of the prevalence of these anomalies in a Portuguese population. CNV67 was exclusively deleted in patients with spermatogenic impairment, showing a consistent genotype-phenotype correlation and a significant prevalence.

Reproductive success of assisted reproductive technology in couples with chromosomal abnormalities

PURPOSE

Infertility is estimated to affect 15% of couples, having chromosome abnormalities an important role in its etiology. The main objective of this work was to access the reproductive success of ART in infertile couples with chromosomal abnormalities comparing to a control group with normal karyotype.

METHODS

A 7-year retrospective karyotype analysis of infertile couples was done. Data regarding type of infertility, couples' ages, ART performed, and their reproductive success were obtained. Adjusted odds ratio (OR) were used to estimate magnitude of association between the reproductive success and the different groups.

RESULTS

We found a prevalence of 7.83% of chromosome abnormalities in our population (233 couples out of 2989). Chromosomal anomalies were found in 82 men (34.75%) and 154 women (65.25%), with low-grade mosaicism being the most prevalent (50.85%), followed by autosomal translocations (17.37%) and sex chromosomes abnormalities (13.56%). Only 2359 couples were treated with ART. There was a non-significant lower reproductive success rate in the cases (OR = 0.899, p = 0.530) with IVF providing the higher success rate. In general, female carriers of chromosome anomalies had a higher success rate, although not significant.

CONCLUSION

Although the differences regarding success rate between groups were not found statistically significant, we still advocate that cytogenetic analysis should be performed routinely in all infertile couples namely before ART. This might help deciding the best treatment options including Preimplantation Genetic Testing for aneuploidies or structural rearrangements and minimize the risk of transmission of anomalies to the offspring.

Molecular and cytogenetic analysis of infertile Hakka men with azoospermia and severe oligozoospermia in southern China

OBJECTIVE

To determine the prevalence of chromosome abnormalities and azoospermia factor (AZF) microdeletions in Hakka men with infertility in southern China.

METHODS

Hakka male patients, who received clinical counselling for infertility between August 2016 and October 2017, and fertile male controls, were enrolled into this retrospective study. Patients diagnosed with infertility and controls underwent cytogenetic analysis by standard G-banding; AZF microdeletions were examined by multiplex polymerase chain reaction and capillary electrophoresis.

RESULTS

Out of 918 male patients who received fertility counselling, 57 were diagnosed with infertility due to azoospermia or severe oligozoospermia. Of these infertile patients, 22.81% (13/57) carried chromosome abnormalities, with 47, XXY being the most common abnormal karyotype. In addition, 36.84% (21/57) presented with Y chromosome microdeletions, most frequently in the complete AZFc and partial AZFc region. Duplication of the AZFc region was found in three patients. No AZF microdeletions were found in 60 fertile male controls.

CONCLUSION

The high AZF microdeletion frequency in the current Hakka population suggests that AZF microdeletion analysis is essential in fertility screening, and combined with cytogenetic analysis, may influence the choice of assisted reproductive techniques and reduce the risk of inherited genetic disease.

Molecular microdeletion analysis of infertile men with karyotypic Y chromosome abnormalities

Objectives

To investigate azoospermic factor (AZF) microdeletions in infertile men from northeastern China with karyotypic Y chromosome abnormalities.

Methods

G-banding of metaphase chromosomes and karyotype analysis were performed in all infertile male patients. Genomic DNA was isolated and used to analyze classical AZF microdeletions by PCR. The regions and sequence-tagged sites of AZFa (SY86, SY84), AZFb (SY127, SY134, SY143), and AZFc (SY152, SY254, SY255, SY157) were sequenced by multiplex PCR.

Results

A total of 190 Y chromosome abnormality carriers were found, of whom 35 had AZF microdeletions. These were most common in 46,X,Yqh− patients, followed by 45,X/46,XY patients. Most microdeletions were detected in the AZFb + c region, including 48.57% of all AZF microdeletion cases. AZF partial deletions were also seen in these patients. Overall, AZF microdeletions were detected in 38.5% Y chromosome abnormality carriers, and most were observed in 46,X,Yqh− individuals. Loss of SY152 was seen in all 35 patients, with SY254/SY255 detected in 34 of 35 patients.

Conclusions

AZF microdeletions were detected in 38.5% of Y chromosome abnormality carriers. This indicates that AZF microdeletion screening is advisable for individuals with karyotypic Y chromosome abnormalities.