Associations of Y-chromosome subdeletion gr/gr with the prevalence of Y-chromosome haplogroups in infertile patients

RNF20 is required for male fertility through regulation of H2B ubiquitination in the Sertoli cells

BACKGROUND

Spermatogenesis depends on the supporting of the Sertoli cells and their communications with germ cells. However, the regulation of crosstalk between the Sertoli cells and germ cells remains unclear.

RESULTS

In this report, we used conditional knockout technology to generate the Sertoli cells-specific knockout of Rnf20 in mice. The Amh-Rnf20^-/- male mice were infertile owing to spermatogenic failure that mimic the Sertoli cell-only syndrome (SCOS) in humans. Knockout of Rnf20 resulted in the H2BK120ub loss in the Sertoli cells and impaired the transcription elongation of the Cldn11, a gene encoding a component of tight junction. Notably, RNF20 deficiency disrupted the cell adhesion, caused disorganization of the seminiferous tubules, and led to the apoptotic cell death of both spermatogonia and spermatocytes in the seminiferous tubules.

CONCLUSIONS

This study describes a Rnf20 knockout mouse model that recapitulates the Sertoli cell-only syndrome in humans and demonstrates that RNF20 is required for male fertility through regulation of H2B ubiquitination in the Sertoli cells.

Analysis of the correlation between gene copy deletion in the AZFc region and male infertility in Japanese men

Deletion of the azoospermia factor c (AZFc), located on the long arm of the Y chromosome, is a cause of male infertility. The structure of the Y chromosome is diversified by the copy number of various genes, such as deleted in azoospermia (DAZ), basic protein Y2, chromodomain Y1, testis-specific transcript Y-linked 4, and Golgi autoantigen golgin subfamily a2 like Y, located in the AZF region. In this study, we investigated the deletion of each gene copy and analyzed its relationship with Japanese male infertility. Deletions of single nucleotide variants of each gene copy in 721 proven fertile men as controls, 139 patients with non-obstructive azoospermia (NOA), and 56 patients with oligozoospermia (OS) were analyzed via polymerase chain reaction-restriction fragment length polymorphism analysis. Their association with infertility was analyzed using logistic regression analysis adjusted for the Y-chromosome haplogroup, D1a2a. Deletions of DAZ/II in the r1 region and DAZ/V in the r1 and r2 regions showed significant associations with NOA (odds ratio [OR] = 4.15, 95 % confidence interval [CI] = 1.18-14.6, P = 0.026; OR = 4.19, 95 % CI = 1.19-14.7, P = 0.025, respectively). They did not show any association with OS. Partial deletion of the AZFc region affects spermatogenesis in Japanese male.

Genetics of Male Infertility - Present and Future: A Narrative Review

Infertility affects 8%–12% of couples worldwide with a male factor contributing to nearly 50% of couples either as a primary or contributing cause. Several genetic factors that include single-gene and multiple-gene defects associated with male infertility were reported in the past two decades. However, the etiology remains ambiguous in a majority of infertile men (~40%). The objective of this narrative review is to provide an update on the genetic factors associated with idiopathic male infertility and male reproductive system abnormalities identified in the last two decades. We performed a thorough literature search in online databases from January 2000 to July 2021. We observed a total of 13 genes associated with nonobstructive azoospermia due to maturation/meiotic arrest. Several studies that reported novel genes associated with multiple morphological abnormalities of the sperm flagella are also discussed in this review. ADGRG2, PANK2, SCNN1B, and CA12 genes are observed in non-CFTR-related vas aplasia. The genomic analysis should be quickly implemented in clinical practice as the detection of gene abnormalities in different male infertility phenotypes will facilitate genetic counseling.

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%.

The effects of Y chromosome microdeletions on in vitro fertilization outcomes, health abnormalities in offspring and recurrent pregnancy loss

Male factor infertility accounts for approximately 50% of all infertility evaluations. A common cause of severe oligozoospermia and azoospermia is Y chromosome microdeletions (YCMs). Men with these genetic microdeletions must typically undergo assisted reproductive technology (ART) procedures to obtain paternity. In this review, we performed a thorough and extensive search of the literature to summarize the effects of YCMs on in vitro fertilization (IVF) outcomes, health abnormalities in offspring and recurrent pregnancy loss (RPL). The PubMed database was searched using specific search terms and papers were identified using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Sperm retrieval amongst men with complete AZFa and/or AZFb deletions is extremely rare and thus data on ARTs is largely unavailable. In AZFc-deleted men undergoing assisted reproduction, the collective fertilization rate (FR) is 59.8%, the clinical pregnancy rate is 28.6% and the live birth rate is 23.4%. When successful, the YCM is always transmitted to the male offspring and the deletion size either remains unchanged or widens. YCMs generally result in decreased fertilization, clinical pregnancy and live birth rates compared to men with intact Y chromosomes during ART interventions. There is a minimal or absent association of YCMs with abnormalities in the offspring or RPL.

Y chromosome structural variation in infertile men detected by targeted next-generation sequencing

PURPOSE

To provide a validated method to identify copy number variation (CNV) in regions of the Y chromosome of infertile men by next-generation sequencing (NGS).

METHODS

Semen analysis was used to determine the quality of semen and diagnose infertility. Deletion of the azoospermia factor (AZF) region in the Y chromosome was detected by a routine sequence-tagged-site PCR (STS-PCR) method. We then used the NGS method to detect CNV in the AZF region, including deletions and duplications.

RESULTS

A total of 326 samples from male infertility patients, family members, and sperm donors were studied between January 2011 and May 2017. AZF microdeletions were detected in 120 patients by STS-PCR, and these results were consistent with the results from NGS. In addition, of the 160 patients and male family members who had no microdeletions detected by STS-PCR, 51 cases were found to exhibit Y chromosome structural variations by the NGS method (31.88%, 51/160). No microdeletions were found in 46 donors by STS-PCR, but the NGS method revealed 11 of these donors (23.91%, 11/46) carried structural variations, which were mainly in the AZFc region, including partial deletions and duplications.

CONCLUSION

The established NGS method can replace the conventional STS-PCR method to detect Y chromosome microdeletions. The NGS method can detect CNV, such as partial deletion or duplication, and provide details of the abnormal range and size of variations.

Genetic disorders and male infertility

BACKGROUND

At present, one out of six couples is infertile, and in 50% of cases, infertility is attributed to male infertility factors. Genetic abnormalities are found in 10%-20% of patients showing severe spermatogenesis disorders, including non-obstructive azoospermia.

METHODS

Literatures covering the relationship between male infertility and genetic disorders or chromosomal abnormalities were studied and summarized.

MAIN FINDINGS RESULTS

Genetic disorders, including Klinefelter syndrome, balanced reciprocal translocation, Robertsonian translocation, structural abnormalities in Y chromosome, XX male, azoospermic factor (AZF) deletions, and congenital bilateral absence of vas deferens were summarized and discussed from a practical point of view. Among them, understanding on AZF deletions significantly changed owing to advanced elucidation of their pathogenesis. Due to its technical progress, AZF deletion test can reveal their delicate variations and predict the condition of spermatogenesis. Thirty-nine candidate genes possibly responsible for azoospermia have been identified in the last 10 years owing to the advances in genome sequencing technologies.

CONCLUSION

Genetic testing for chromosomes and AZF deletions should be examined in cases of severe oligozoospermia and azoospermia. Genetic counseling should be offered before and after genetic testing.

Deletion of b1/b3 shows risk for expanse of Yq microdeletion in male offspring: Case report of novel Y chromosome variations

RATIONALE

This study aimed to report 1 family case with novel Y chromosome structural variations by an established next-generation sequencing (NGS) method using unique STSs.

PATIENT CONCERNS

The case studied was from a family with a father and son (the proband). G-band staining was used for karyotype analysis. Y chromosome microdeletions were detected by sequence-tagged site (STS)-PCR analysis and a new NGS screening strategy.

DIAGNOSES

Semen analysis showed that the proband was azoospermic. The patient had an abnormal karyotype (45,X[48%]/46,XY[52%]). His father exhibited a normal karyotype. STS-PCR analysis showed that the proband had a deletion of the AZFb+c region, and his father had no deletion of STS markers examined. The sequencing method revealed that the patient had DNA sequence deletions from nt 20099846 to nt 28365090 (8.3 Mb), including the region from yel4 to the Yq terminal, and his father exhibited a deletion of b1/b3 and duplication of gr/gr.

INTERVENTIONS

The proband was advised to undergo genetic counseling, and consider the use of sperm from a sperm bank or adoption to become a father.

OUTCOMES

The proband was azoospermic. AZFc partial deletions may produce a potential risk for large AZFb+c deletions or abnormal karyotypes causing spermatogenic failure in men.

LESSONS

The NGS method can be considered a clinical diagnostic tool to detect Y chromosome microdeletions. The partial AZFc deletions and/or duplications can be a risk of extensive deletions in offspring.

Cytogenetic and molecular study of 370 infertile men in South India highlighting the importance of copy number variations by multiplex ligation-dependent probe amplification

Male infertility is a common and severe problem affecting 7% of population. The main objective of this study is to identify the chromosomal abnormalities, Y microdeletions in infertile men and also to access the frequency of abnormal sperm count. Based on the sperm count and viability, the infertile men were grouped as Azoospermia, Asthenospermia, Oligospermia and the remaining as Idiopathic infertility. A total of 370 infertile men and 60 normal control men were recruited. Chromosomal abnormalities were identified in 3 men (3/370). The prevalence of Y microdeletions in the infertile group is 8/370 in the Azoospermia factor (AZF) region with four AZFc deletion/duplication, two AZFa deletion, one AZF b & AZFc deletion and one case of total AZF a, AZFb & AZFc deletion. However, only five cases of Y microdeletions were identified by Multiplex PCR but an additional three cases by MLPA (Multiplex ligation-dependent probe amplification). Fluorescence in situ hybridisation also confirmed the deletions. Here, we performed MLPA post-multiplex PCR, and our study revealed good yield of the Y microdeletion identification. The partial duplications which are difficult to be identified can now be easily identified by MLPA, and hence, we recommend MLPA as the choice of investigation compared to multiplex PCR for infertile men.

High frequencies of Non Allelic Homologous Recombination (NAHR) events at the AZF loci and male infertility risk in Indian men

Deletions in the AZoospermia Factor (AZF) regions (spermatogenesis loci) on the human Y chromosome are reported as one of the most common causes of severe testiculopathy and spermatogenic defects leading to male infertility, yet not much data is available for Indian infertile men. Therefore, we screened for AZF region deletions in 973 infertile men consisting of 771 azoospermia, 105 oligozoospermia and 97 oligoteratozoospermia cases, along with 587 fertile normozoospermic men. The deletion screening was carried out using AZF-specific markers: STSs (Sequence Tagged Sites), SNVs (Single Nucleotide Variations), PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment Length Polymorphism) analysis of STS amplicons, DNA sequencing and Southern hybridization techniques. Our study revealed deletion events in a total of 29.4% of infertile Indian men. Of these, non-allelic homologous recombination (NAHR) events accounted for 25.8%, which included 3.5% AZFb deletions, 2.3% AZFbc deletions, 6.9% complete AZFc deletions, and 13.1% partial AZFc deletions. We observed 3.2% AZFa deletions and a rare long AZFabc region deletion in 0.5% azoospermic men. This study illustrates how the ethnicity, endogamy and long-time geographical isolation of Indian populations might have played a major role in the high frequencies of deletion events.

An infertile patient with Y chromosome b1/b3 deletion presenting with congenital bilateral absence of the vas deferens with normal spermatogenesis

We report the case of a 46-year-old Chinese male patient who visited our clinic complaining of infertility. Semen analysis revealed azoospermia, and azoospermia factor c region partial deletion (b1/b3) was detected using Y chromosome microdeletion analysis. Testicular sperm extraction was performed after genetic counseling. The bilateral ductus deferens and a portion of the epididymis were absent, whereas the remaining epididymis was expanded. Motile intratesticular spermatozoa were successfully extracted from the seminiferous tubule. On histopathology, nearly complete spermatogenesis was confirmed in almost every seminiferous tubule. To our knowledge, this is the first case report of b1/b3 deletion with a congenital bilateral absence of the vas deferens and almost normal spermatogenesis.

Genetics of the human Y chromosome and its association with male infertility

The human Y chromosome harbors genes that are responsible for testis development and also for initiation and maintenance of spermatogenesis in adulthood. The long arm of the Y chromosome (Yq) contains many ampliconic and palindromic sequences making it predisposed to self-recombination during spermatogenesis and hence susceptible to intra-chromosomal deletions. Such deletions lead to copy number variation in genes of the Y chromosome resulting in male infertility. Three common Yq deletions that recur in infertile males are termed as AZF (Azoospermia Factor) microdeletions viz. AZFa, AZFb and AZFc. As estimated from data of nearly 40,000 Y chromosomes, the global prevalence of Yq microdeletions is 7.5% in infertile males; however the European infertile men are less susceptible to Yq microdeletions, the highest prevalence is in Americans and East Asian infertile men. In addition, partial deletions of the AZFc locus have been associated with infertility but the effect seems to be ethnicity dependent. Analysis of > 17,000 Y chromosomes from fertile and infertile men has revealed an association of gr/gr deletion with male infertility in Caucasians and Mongolian men, while the b2/b3 deletion is associated with male infertility in African and Dravidian men. Clinically, the screening for Yq microdeletions would aid the clinician in determining the cause of male infertility and decide a rational management strategy for the patient. As these deletions are transmitted to 100% of male offspring born through assisted reproduction, testing of Yq deletions will allow the couples to make an informed choice regarding the perpetuation of male infertility in future generations. With the emerging data on association of Yq deletions with testicular cancers and neuropsychiatric conditions long term follow-up data is urgently needed for infertile men harboring Yq deletions. If found so, the information will change the current the perspective of androgenetics from infertility and might have broad implication in men health.

Y chromosome microdeletions frequency in idiopathic azoospermia, oligoasthenozoospermia, and oligospermia

BACKGROUND

Genetic factors are candidates for about 30% of male infertility with sperm production-related abnormalities. Y chromosome microdeletions are responsible for around 10% of male infertility. These microdeletions generally occur in azoospermia factor on the Yq. That is often associated with the quantitative reduction of sperm.

OBJECTIVE

The aim of this cross-sectional study was to determine the frequency of Yq microdeletions among idiopathic azoospermic, oligoasthenozoospermic, and oligospermic men in Shohada infertility center, Chaharmahal va Bakhtiari province.

MATERIALS AND METHODS

A total of 81 idiopathic azoospermic, oligoasthenozoospermic, and oligospermic infertile men were selected as cases and 81 fertile men assigned to control group. For molecular investigations, 13 sequence-tagged site markers were chosen from azoospermia factor (AZF) region for detection of Y chromosome microdeletions and amplified by two separate multiplex-polymerase chain reaction. The relationship between the AZF microdeletions and incidence of male infertility in the family, consanguineous parents, smoking, and the levels of reproductive hormones among infertile men were investigated.

RESULTS

The total frequency of the microdeletions was 6.17% (2 cases in azoospermic, 3 cases in oligoasthenozoospermic subgroups, and none in the oligospermic participants and the control group). Most deletions (3.7%) were seen in the AZFb followed by the AZFc (2.46%) and none in AZFa. No significant association was seen between the microdeletions and clinical characteristics.

CONCLUSION

Although the frequency of Yq chromosome microdeletions in Chaharmahal va Bakhtiari province is lower than the mean frequency of Iran, the frequency is comparable to those reported by some studies in Iran.

gr/gr-DAZ2-DAZ4-CDY1b deletion is a high-risk factor for male infertility in Tunisian population

The azoospermia factor c (AZFc) region harbors multi-copy genes that are expressed in the testis. Deletions of this region lead to reduced copy numbers of these genes. In this present study we aimed to determine the frequency of AZFc subdeletion in infertile and fertile men from Tunisia and to identify whether deletions of DAZ and CDY1 gene copies are deleterious on spermatogenesis and on semen quality. We studied a group of 241 infertile men and 115 fertile healthy males using a sequence tagged site (STS)±method. To gain insight into the molecular basis of the heterogeneous phenotype observed in men with the deletion we defined the type of DAZ and CDY1 genes deleted. We reported in the present study and for the first time a new type of AZFc deletion (gr/gr-DAZ2-DAZ4-CDY1b) and hypothesis that this new deletion is the result of two successive events. We also demonstrated that this deletion constitutes a relative high-risk factor for male infertility in Tunisian population.

Y chromosome b2/b3 deletions and male infertility: A comprehensive meta-analysis, trial sequential analysis and systematic review

The correlation of Y-chromosome b2/b3 partial deletions with spermatogenic failure remains dubious. We undertook a systematic review of the literature followed by meta-analyses and trial sequential analyses in order to compare the frequency of b2/b3 deletions between oligo/azoospermic infertile and normozoospermicmen. Out of twenty-four studies reviewed for meta-analysis, twenty reported no correlation between this deletion and male infertility and two studies each reported a direct and inverse correlation. In the collective analysis, 241 out of 8892 (2.71%) oligo/azoospermic individuals and 118 out of 5842 (2.02%) normozoospermic controls had a b2/b3 deletion, suggesting a relatively higher frequency of deletions in the cases. Eventually, meta-analysis showed a significant correlation between b2/b3 deletions and the risk of spermatogenic loss/infertility (Fixed model: OR=1.313, 95% CI=1.04-1.65, p=0.02; Random model: OR=1.315, 95% CI=1.02-1.70, p=0.037). Further meta-analysis on studies grouped by ethnicity and geographic regions showed that the b2/b3 deletions are significantly associated with spermatogenic loss/infertility in Mongolians, Nigro-Caucasians, East Asians and Africans, but not in Caucasians, Europeans, South Asians and Dravidians. In summary, the Y-chromosome b2/b3 deletions increase infertility risk; however, it may be significant only in the Mongolian populations and the East Asian region.

Gr/gr deletions on Y-chromosome correlate with male infertility: an original study, meta-analyses, and trial sequential analyses

We analyzed the AZFc region of the Y-chromosome for complete (b2/b4) and distinct partial deletions (gr/gr, b1/b3, b2/b3) in 822 infertile and 225 proven fertile men. We observed complete AZFc deletions in 0.97% and partial deletions in 6.20% of the cases. Among partial deletions, the frequency of gr/gr deletions was the highest (5.84%). The comparison of partial deletion data between cases and controls suggested a significant association of the gr/gr deletions with infertility (P = 0.0004); however, the other partial deletions did not correlate with infertility. In cohort analysis, men with gr/gr deletions had a relatively poor sperm count (54.20 ± 57.45 million/ml) in comparison to those without deletions (72.49 ± 60.06), though the difference was not statistically significant (p = 0.071). Meta-analysis also suggested that gr/gr deletions are significantly associated with male infertility risk (OR = 1.821, 95% CI = 1.39–2.37, p = 0.000). We also performed trial sequential analyses that strengthened the evidence for an overall significant association of gr/gr deletions with the risk of male infertility. Another meta-analysis suggested a significant association of the gr/gr deletions with low sperm count. In conclusion, the gr/gr deletions show a strong correlation with male infertility risk and low sperm count, particularly in the Caucasian populations.

Copy number variation and microdeletions of the Y chromosome linked genes and loci across different categories of Indian infertile males

We analyzed 34 azoospermic (AZ), 43 oligospermic (OS), and 40 infertile males with normal spermiogram (INS) together with 55 normal fertile males (NFM) from the Indian population. AZ showed more microdeletions in the AZFa and AZFb regions whereas oligospermic ones showed more microdeletions in the AZFc region. Frequency of the AZF partial deletions was higher in males with spermatogenic impairments than in INS. Significantly, SRY, DAZ and BPY2 genes showed copy number variation across different categories of the patients and much reduced copies of the DYZ1 repeat arrays compared to that in normal fertile males. Likewise, INS showed microdeletions, sequence and copy number variation of several Y linked genes and loci. In the context of infertility, STS deletions and copy number variations both were statistically significant (p = 0.001). Thus, semen samples used during in vitro fertilization (IVF) and assisted reproductive technology (ART) must be assessed for the microdeletions of AZFa, b and c regions in addition to the affected genes reported herein. Present study is envisaged to be useful for DNA based diagnosis of different categories of the infertile males lending support to genetic counseling to the couples aspiring to avail assisted reproductive technologies.

Multiplex PCR based screening for micro/partial deletions in the AZF region of Y-chromosome in severe oligozoospermic and azoospermic infertile men in Iran

BACKGROUND

Infertility is a health problem which affects about 10-20% of married couples. Male factor infertility is involved approximately 50% of infertile couples. Most of male infertility is regarding to deletions in the male-specific region of the Y chromosome.

OBJECTIVE

In this study, the occurrence of deletions in the AZF region and association between infertility and paternal age were investigated in Iranian men population.

MATERIALS AND METHODS

To assess the occurrence of Y chromosomal microdeletions and partial deletions of the AZF region, 100 infertile men and 100 controls with normal spermatogenesis were analyzed. AZFa, AZFb, AZFc and partial deletions within the AZFc region were analyzed using multiplex PCR method. Finally, the association between paternal age and male infertility was evaluated.

RESULTS

No AZFa, AZFb or AZFc deletions were found in the control group. Seven infertile men had deletions as the following: one AZFb, five AZFc, and one AZFab. Partial deletions of AZFc (gr/gr) in 9 of the 100 infertile men (9/100, 9%) and 1 partial AZFc deletions (gr/gr) in the control group (1/100, 1%) were observed. In addition, five b2/b3 deletions in five azoospermic subjects (5/100, 5%) and 2 partial AZFc deletions (b2/b3) in the control group (2/100, 2%) were identified. Moreover, the risk of male infertility was influenced by the paternal age.

CONCLUSION

The results of this study suggested that the frequency of Y chromosome AZF microdeletions increased in subjects with severe spermatogenic failure and gr/gr deletion associated with spermatogenic failure.

Impact of partial DAZ1/2 deletion and partial DAZ3/4 deletion on male infertility

This study aims to investigate the effect of the partial DAZ1/2 deletion and partial DAZ3/4 deletion on male infertility through a comprehensive literature search. All case-control studies related to partial DAZ1/2 and DAZ3/4 deletions and male infertility risk were included in our study. Odd ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the association and its precision, respectively. Eleven partial DAZ1/2 deletion and nine partial DAZ3/4 deletion studies were included. Partial DAZ1/2 deletion was significantly associated with male infertility risk in the overall analysis (ORs=2.58, 95%CI: 1.60-4.18, I(2)=62.1%). Moreover, in the subgroup analysis stratified by ethnicity, partial DAZ1/2 deletion was significantly associated with male infertility risk in the East Asian populations under the random effect model (ORs=2.96, 95%CI: 1.87-4.71, I(2)=51.3%). Meanwhile, the analysis suggested that partial DAZ3/4 deletion was not associated with male infertility risk in East-Asian ethnicity (ORs=1.02, 95%CI: 0.54-1.92, I(2)=71.3%), but not in Non-East Asian under the random effect model (ORs=3.56, 95%CI: 1.13-11.23, I(2)=0.0%,). More interestingly, partial DAZ1/2 deletion was associated with azoospermia (ORs=2.63, 95%CI: 1.19-5.81, I(2)=64.7%) and oligozoospermia (ORs=2.53, 95%CI: 1.40-4.57, I(2)=51.8%), but partial DAZ3/4 deletion was not associated with azoospermia (ORs=0.71, 95%CI: 0.23-2.22, I(2)=71.7%,) and oligozoospermia (ORs=1.21, 95%CI: 0.65-2.24, I(2)=55.5%). In our meta-analysis, partial DAZ1/2 deletion is a risk factor for male infertility and different ethnicities have different influences, whereas partial DAZ3/4 deletion has no effect on fertility but partial DAZ3/4 deletion might have an impact on Non-East Asian male.

Susceptibility of gr/gr rearrangements to azoospermia or oligozoospermia is dependent on DAZ and CDY1 gene copy deletions

PURPOSE

The purpose of this study was to determine the association of AZFc subdeletions (gr/gr, b1/b3 and b2/b3) and deletion of DAZ and CDY1 gene copies with male infertility

METHODS

Three hundred twelve controls, 172 azoospermic and 343 oligozoospermic subjects were subjected to AZFc subdeletion typing by STS PCR. Deletion of DAZ and CDY1 gene copies was done using sequence family variant analysis. Sperm concentration and motility were compared between men with and without AZFc subdeletions. Effect of the AZFc subdeletions on ICSI outcome was evaluated.

RESULTS

Amongst the three AZFc subdeletions, the frequency of gr/gr was higher in oligozoospermic (10.5 %) and azoospermic (11.6 %) men as compared to controls (5.1 %). In men with AZFc subdeltions, loss of two DAZ and one CDY1 gene copy made them highly susceptible to azoospermia and severe oligozoospermia with OR of 29.7 and 26, respectively. These subdeletions had no effect on ICSI outcome, albeit there were an increased number of poor quality embryos in AZFc subdeleted group.

CONCLUSION

AZFc subdeletions are a major risk factor for male infertility in the Indian population. In the subjects with AZFc subdeletions, the deletion of DAZ and CDY1 gene copies increases its susceptibility to azoospermia or severe oligozoospermia. Since these deletions can be vertically transmitted to the future male offspring by ICSI, it will be essential to counsel the couples for the transmission of the genetic defect in the male offspring born after assisted reproduction and the risk of perpetuating infertility in future generation.

Impact of Y chromosome AZFc subdeletion shows lower risk of fertility impairment in Siddi tribal men, Western Ghats, India

Background

India is characterized by the presence of a large number of endogamous castes, tribes and religions, having second largest concentration of tribal population in the World with differed genetic ethnicity, lifestyle and environmental habitat from those of mainstream population. Lack of data is constraint when it comes to tracking the tribal population health status, specifically reproductive health aspects by experimental approaches. The male fertility impairment depends on Y chromosome azoospermia factor c (AZFc) subdeletions, which varies highly in different geographical populations and in an Indian admixed population the frequency and effect of deletion on fertility is relatively poorly documented. Therefore, the current study has been initiated to enumerate and characterize the strength of association between Yq11 AZFc subdeletions and fertility impairment among Siddi tribal men of Western Ghats, India.

Methods

Here, using predesigned performa we collected personal as well as familial information of 200 volunteered male subjects and grouped them into: (i) 104 married individuals with proven fertility, and (ii) 96 unmarried men with unknown fertility status. Quantification of reproductive hormones such as follicle stimulating hormone (FSH), leutinizing hormone (LH) and testosterone were studied. Oxidative stress markers like total antioxidant capacity (TAC) and super oxide dismutase (SOD) along with analysis of five sequence tagged site (STS) hotspot markers were employed for mapping of Y chromosome AZFc subdeletions. Statistical analyses were performed using SPSS software.

Results

Hormonal analysis and estimation of oxidative stress markers showed normal values with no significant differences between two subgroups. However, the Y chromosome AZFc subdeletion mapping revealed evident results as an individual displayed absence of STS sY1191 marker indicating b2/b3 deletion, whereas rest of the subjects exhibited no deletion for all the five STS markers. While, the individual has fathered two children, at this point it is difficult to draw a causal link between the observed deletion and its effect on fertility.

Conclusion

Thus, our current study suggests that the association between AZFc subdeletions with its effect on infertility varies highly in this study cohort compared to other Indian ethnic groups, exhibiting lower risk factor and non-association reaching insignificance among Siddi tribal men.

Electronic supplementary material

The online version of this article (doi:10.1186/s12610-014-0017-5) contains supplementary material, which is available to authorized users.

Screening for AZFc partial deletions in Dravidian men with nonobstructive azoospermia and oligozoospermia

CONTEXT

Dravidians are the predominant population residing in South India with a diverse genetic structure. Considering various genetic discoveries taking place today, it is evident that deletions in the AZFc region are the most common cause of severe spermatogenic failure (SSF) in various populations studied. However, it is significant to note that there is a paucity of scientific literature on AZFc subdeletion screening among the Dravidian population.

OBJECTIVE

To investigate the prevalence and association of AZFc subdeletion patterns among Dravidian men with nonobstructive azoospermia (NOA) and oligozoospermia.

METHODS

A population of 354 subjects, including 120 patients with NOA, 109 with oligozoospermia, and 125 normal male controls, were screened using locus-specific sequence tag site markers.

RESULTS

We found 21 (9.17%) patients with classical AZF deletion, while no deletions were observed in controls. After excluding the samples with AZF deletions, the remaining 208 infertile and 125 control samples were screened for partial AZFc deletions using a standardized multiplex polymerase chain reaction and on analysis revealed that 13 (6.25%) of the infertile samples possessed gr/gr subdeletions and 15 (7.21%) of the infertile samples possessed b2/b3 subdeletions. Six (4.8%) of the normal samples were found to carry gr/gr subdeletions and two (1.6%) had b2/b3 deletions. The b1/b3 deletion was not observed in any of the patient and control samples screened.

CONCLUSION

Our finding shows that there is a strong association between b2/b3 subdeletion and SSF in the Dravidian population (odds ratio, 4.78; 95% confidence interval 1.07-21.26) (p=0.018). Further studies, including gene copy typing for DAZ and CDY genes and a comprehensive haplogrouping analysis, are recommended in a large and well-selected patient group to elude the genetic mechanism behind this association.

Combined deletion of DAZ2 and DAZ4 copies of Y chromosome DAZ gene is associated with male infertility in Tunisian men

The relationship between male infertility and AZFc micro-deletions that remove multiple genes of the Y chromosome varies among countries and populations. The purpose of this study was to analyze the prevalence and the characteristics of different Deleted in azoospermia (DAZ) gene copy deletions and their association with spermatogenic failure and male infertility in Tunisian men. 241 infertile men (30.7% azoospermic (n=74), 31.5% oligozoospermic (n=76) and 37.7% normozoospermic (n=91)) and 115 fertile healthy males who fathered at least one child were included in the study. Three DAZ-specific single nucleotide variant loci and six bi-allelic DAZ-SNVs (I-VI) were analyzed using polymerase chain reaction (PCR)-restriction fragment length polymorphism and PCR. Our findings showed high frequencies of infertile men (73.85%) and controls (78.26%) having only three DAZ gene copies (DAZ1/DAZ2/DAZ3 or DAZ1/DAZ3/DAZ4 variants); so deletion of DAZ2 or DAZ4 were frequent both in infertile (36.5% and 37.3%, respectively) and fertile groups (33.9% and 44.3%, respectively) and removing DAZ4 copy was significantly more frequent in oligospermic than in normospermic men (p=0.04) in infertile group. We also report for the first time that simultaneous deletion of both DAZ2 and DAZ4 copies was significantly more common in infertile men (12.4%) than in fertile men (4.3%) (p=0.01). However, deletions of DAZ1/DAZ2 and DAZ3/DAZ4 clusters were very rare. Analysis of DAZ gene copies in Tunisian population, suggested that the simultaneous deletion of DAZ2 and DAZ4 gene copies is associated with male infertility, and that oligospermia seems to be promoted by removing DAZ4 copy.

Y chromosome gr/gr subdeletion is associated with lower semen quality in young men from the general Japanese population but not in fertile Japanese Men

Several case-control studies have investigated whether Y chromosome haplogroups or deletions are associated with spermatogenic failure. However, the relationships between Y chromosome haplogroups or deletions and semen quality in general population have not been elucidated. In this study, we assessed relationships between Y chromosome haplogroups or deletions and semen parameters in 791 fertile Japanese men and 1221 young men from the general Japanese population. We found that the haplogroup D2 (M55 lineage) was significantly associated with lower semen parameters, especially total motile sperm count (P = 0.00051, beta = -0.097), in men from the general population but not in fertile men. In addition, we found that the gr/gr subdeletion was associated with semen quality and in particular, strongly associated with decreased sperm motility (P = 0.00041, beta = -3.14) and total motile sperm count (P = 0.00031, beta = -0.099) in men from the general population but not in fertile men. The combined analysis of fertile Japanese men and men from the general Japanese population showed that the haplogroup D2 (M55 lineage) and the gr/gr subdeletion were strongly associated with reduced sperm motility (P = 0.00056, beta = -2.71, and P = 7.7 × 10(-5), beta = -3.05, respectively) and that haplogroup O2b1 was strongly associated with elevated sperm motility (P = 0.00089, beta = 2.94). These observations add further support for the view that the gr/gr subdeletion diminishes sperm motility that consequently may result in male infertility.

Analysis of partial AZFc deletions in Malaysian infertile male subjects

Complete deletions in the AZF (a, b, and c) sub-regions of the Y-chromosome have been shown to contribute to unexplained male infertility. However, the role of partial AZFc deletions in male infertility remains to be verified. Three types of partial AZFc deletions have been identified. They are gr/gr, b1/b3, and b2/b3 deletions. A recent meta-analysis showed that ethnic and geographical factors might contribute to the association of partial AZFc deletions with male infertility. This study analyzed the association of partial AZFc deletions in Malaysian infertile males. Fifty two oligozoospermic infertile males and 63 fertile controls were recruited to this study. Screening for partial AZFc deletions was done using the two sequence-tagged sites approach (SY1291 and SY1191) which were analyzed using both the conventional PCR gel-electrophoresis and the high resolution melt, HRM method. Gr/gr deletions were found in 11.53% of the cases and 9.52% of the controls (p = 0.725). A B2/b3 deletion was found in one of the cases (p = 0.269). No B1/b3 deletions were identified in this study. The results of HRM analysis were consistent with those obtained using the conventional PCR gel-electrophoresis method. The HRM analysis was highly repeatable (95% limit of agreement was -0.0879 to 0.0871 for SY1191 melting temperature readings). In conclusion, our study showed that partial AZFc deletions were not associated with male infertility in Malaysian subjects. HRM analysis was a reliable, repeatable, fast, cost-effective, and semi-automated method which can be used for screening of partial AZFc deletions.

Impaired spermatogenesis and gr/gr deletions related to Y chromosome haplogroups in Korean men

Microdeletion of the Azoospermia Factor (AZF) regions in Y chromosome is a well-known genetic cause of male infertility resulting from spermatogenetic impairment. However, the partial deletions of AZFc region related to spermatogenetic impairment are controversial. In this study, we characterized partial deletion of AZFc region in Korean patients with spermatogenetic impairment and assessed whether the DAZ and CDY1 contributes to the phenotype in patients with gr/gr deletions. Total of 377 patients with azoo-/oligozoospermia and 217 controls were analyzed using multiplex polymerase chain reaction (PCR), analysis of DAZ-CDY1 sequence family variants (SFVs), and quantitative fluorescent (QF)-PCR. Of the 377 men with impaired spermatogenesis, 59 cases (15.6%) had partial AZFc deletions, including 32 gr/gr (8.5%), 22 b2/b3 (5.8%), four b1/b3 (1.1%) and one b3/b4 (0.3%) deletion. In comparison, 14 of 217 normozoospermic controls (6.5%) had partial AZFc deletions, including five gr/gr (2.3%) and nine b2/b3 (4.1%) deletions. The frequency of gr/gr deletions was significantly higher in the azoo-/oligozoospermic group than in the normozoospermic control group (p = 0.003; OR = 3.933; 95% CI = 1.509-10.250). Concerning Y haplogroup, we observed no significant differences in the frequency of gr/gr deletions between the case and the control groups in the YAP+ lineages, while gr/gr deletion were significantly higher in azoo-/oligozoospermia than normozoospermia in the YAP- lineage (p = 0.004; OR = 6.341; 95% CI = 1.472-27.312). Our data suggested that gr/gr deletion is associated with impaired spermatogenesis in Koreans with YAP- lineage, regardless of the gr/gr subtypes.

Association of spermatogenic failure with the b2/b3 partial AZFc deletion

Infertility affects around 1 in 10 men and in most cases the cause is unknown. The Y chromosome plays an important role in spermatogenesis and specific deletions of this chromosome, the AZF deletions, are associated with spermatogenic failure. Recently partial AZF deletions have been described but their association with spermatogenic failure is unclear. Here we screened a total of 339 men with idiopathic spermatogenic failure, and 256 normozoospermic ancestry-matched men for chromosome microdeletions including AZFa, AZFb, AZFc, and the AZFc partial deletions (gr/gr, b1/b3 and b2/b3).

AZFa and AZFc deletions were identified in men with severe spermatogenic failure at similar frequencies to those reported elsewhere. Gr/gr deletions were identified in case and control populations at 5.83% and 6.25% respectively suggesting that these deletions are not associated with spermatogenic failure. However, b2/b3 deletions were detected only in men with spermatogenic failure and not in the normospermic individuals. Combined with our previous data this shows an association of the b2/b3 deletion (p = 0.0318) with spermatogenic failure in some populations. We recommend screening for this deletion in men with unexplained spermatogenic failure.

CTNNB1 signaling in sertoli cells downregulates spermatogonial stem cell activity via WNT4

Constitutive activation of the WNT signaling effector CTNNB1 (β-catenin) in the Sertoli cells of the Ctnnb1^tm1Mmt/+;Amhr2^{tm3(cre)Bhr/+} mouse model results in progressive germ cell loss and sterility. In this study, we sought to determine if this phenotype could be due to a loss of spermatogonial stem cell (SSC) activity. Reciprocal SSC transplants between Ctnnb1^tm1Mmt/+;Amhr2^{tm3(cre)Bhr/+} and wild-type mice showed that SSC activity is lost in Ctnnb1^tm1Mmt/+;Amhr2^{tm3(cre)Bhr/+} testes over time, whereas the mutant testes could not support colonization by wild-type SSCs. Microarray analyses performed on cultured Sertoli cells showed that CTNNB1 induces the expression of genes associated with the female sex determination pathway, which was also found to occur in Ctnnb1^tm1Mmt/+;Amhr2^{tm3(cre)Bhr/+} testes. One CTNNB1 target gene encoded the secreted signaling molecule WNT4. We therefore tested the effects of WNT4 on SSC-enriched germ cell cultures, and found that WNT4 induced cell death and reduced SSC activity without affecting cell cycle. Conversely, conditional inactivation of Wnt4 in the Ctnnb1^tm1Mmt/+;Amhr2^{tm3(cre)Bhr/+} model rescued spermatogenesis and male fertility, indicating that WNT4 is the major effector downstream of CTNNB1 responsible for germ cell loss. Furthermore, WNT4 was found to signal via the CTNNB1 pathway in Sertoli cells, suggesting a self-reinforcing positive feedback loop. Collectively, these data indicate for the first time that ectopic activation of a signaling cascade in the stem cell niche depletes SSC activity through a paracrine factor. These findings may provide insight into the pathogenesis of male infertility, as well as embryonic gonadal development.