A comparative study of Y chromosome microdeletions in infertile males from two Chinese populations

Gene Scanning for Microdeletions in the Azoospermia Factor Region of Y-Chromosome in Infertile Men of Gujarat, India

INTRODUCTION

Azoospermia Factor (AZF) microdeletions in Yq chromosome is one of the most frequent genetic cause associated with failure of spermatogenesis in males with infertility.

AIM

To figure out the Yq chromosome microdeletions frequency in infertile men from Gujarat region of India.

MATERIALS AND METHODS

In this study, 141 infertile men with azoospermia (n=41) and oligozoospermia (n=100) were examined along with 159 normozoospermic men. Eleven different markers spanning the azoospermia factor region of human Yq chromosome, amplified by sequence-tagged site Polymerase Chain Reaction (PCR) to detect the microdeletions. Sperm morphological analysis was done using papanicolau staining method.

RESULTS

Thirty four infertile men out of 141 presented Yq chromosome microdeletions. The frequency of AZF microdeletions was 31.71% in azoospermia and 21% in oligozoospermia patients. Only two oligozoospermia patients showed morphological defects.

CONCLUSION

Due to the presence of high frequency of Yq chromosome microdeletions in Gujarati infertile men, it is imperative to implement the AZF microdeletion screening in such patients as it results in male spermatogenesis dysfunctioning.

Multicentre study of Y chromosome microdeletions in 1,808 Chinese infertile males using multiplex and real-time polymerase chain reaction

Azoospermia factor (AZF) genes on the long arm of the human Y chromosome are involved in spermatogenesis, and microdeletions in the AZF region have been recognised to be the second major genetic cause of spermatogenetic failure resulting in male infertility. While screening for these microdeletions can avoid unnecessary medical and surgical treatments, current methods are generally time-consuming. Therefore, we established a new method to detect and analyse microdeletions in the AZF region quickly, safely and efficiently. In total, 1,808 patients with spermatogenetic failure were recruited from three hospitals in southern China, of which 600 patients were randomly selected for screening for Y chromosome microdeletions in AZF regions employing real-time polymerase chain reaction with a TaqMan probe. In our study, of 1,808 infertile patients, 150 (8.3%) were found to bear microdeletions in the Y chromosome using multiplex PCR, while no deletions were found in the controls. Among the AZF deletions detected, two were in AZFa, three in AZFb, 35 in AZFc, three in AZFb+c and two in AZFa+b+c. Our method is fast-it permits the scanning of DNA from a patient in one and a half hours-and reliable, minimising the risk of cross-contamination and false-positive and false-negative results.

Chromosomal abnormalities and Y chromosome microdeletions in infertile men from Morocco

Background

Male infertility is responsible for 50 % of infertile couples. Thirty percent of male infertility is due to cytogenetic and genetic abnormalities. In Arab and North African populations, several studies have shown the association of these chromosomal abnormalities with male infertility. Our objective is to evaluate the frequency of chromosomal abnormalities and Y chromosome microdeletions in infertile men from Morocco.

Methods

A total of 573 Moroccan infertile men (444 azoospermic and 129 oligozoospermic men) referred for cytogenetic analysis to the Department of Cytogenetics of the Pasteur Institute of Morocco, were screened for the presence of chromosomal abnormalities and Y chromosome microdeletions.

Results

Chromosomal abnormalities accounted for approximately 10.5 % (60/573). Fifty six cases among them have sex chromosome abnormalities (93.34 %), including Klinefelter’s syndrome in 41 patients (68.34 %). Autosomal chromosome abnormalities (6.66 %) were observed in 4 patients. Chromosomal abnormalities were more prevalent in azoospermic men (13.06 %) than in oligospermic men (1.55 %). Y microdeletions were detected in 16 of 85 patients (AZFc: 14.12 %, AZFbc: 4.70 %), most of them where azoospermic men with no chromosomal abnormality.

Conclusions

These results highlighted the need for efficient molecular genetic testing in male infertility diagnosis. In addition, a genetic screening should be performed in infertile men before starting assisted reproductive treatments.

Association of azoospermia factor region deletions in infertile male subjects among Malaysians

Azoospermia factor region (AZF) deletions (AZFa, AZFb, AZFc and AZFd) in the Y chromosome were analysed in male infertility subjects in various populations with conflicting results. This study comprised of 54 infertile males and 63 fertile controls, and the frequency of AZFa, AZFb, AZFc and AZFd deletions were determined using conventional polymerase chain reaction (PCR) as well as real-time PCR-high resolution melting analysis-based methods. The results of this study showed that, three of 54 cases (5.55%) had AZF (a, b and c) deletions (two had AZFc and one had AZFa deletions). Four cases were found to have AZFd deletions (7.4%) with two of them being associated with AZFc deletions (P = 0.028). The frequency of AZF (a, b and c) deletions in Malaysian infertile male subjects was found to be comparable with other populations. AZFd deletions were found to be significant (P < 0.05) in male infertility and it may be associated with other types of AZF deletions.

Azoospermia factor microdeletions: occurrence in infertile men with azoospermia and severe oligozoospermia from China

Azoospermia factor (AZF) microdeletions are the most frequent genetic cause of male infertility after Klinefelter's syndrome. Although some assisted reproductive techniques such as intracytoplasmic sperm injection (ICSI) have been successfully introduced to clinical treatment for infertile males, the AZF microdeletions might be transmitted from infertile fathers to their male offspring during these procedures. Thus, it is important to carefully evaluate AZF microdeletions in infertile males before assisted reproductive techniques are performed. In this article, we aimed to investigate the frequencies of AZF microdeletions in 137 infertile males with azoospermia and severe oligozoospermia from Jilin province of China and analyse the relationship between the levels of reproductive hormones and AZF microdeletions. Result analysis showed that AZF microdeletions were present in 8 (8.70%) azoospermic males and 3 (6.67%) severely oligozoospermic males. The most frequent microdeletions were detected in the AZFc region, followed by AZFb + c, AZFb and AZFa. And there was no significant correlation between the AZF microdeletion and the levels of reproductive hormones. These findings reinforce the necessity of AZF microdeletion testing among infertile males prior to employment of assisted reproduction techniques in Jilin province of China.

High prevalence of genetic abnormalities in Middle Eastern patients with idiopathic non-obstructive azoospermia

INTRODUCTION

Our objective is to detect the frequency and types of major genetic abnormalities of idiopathic non-obstructive azoospermia (NOA) to give appropriate genetic counseling before assisted reproductive techniques (ART) in Middle East and to compare the frequencies with other regions of the world.

MATERIAL AND METHODS

A total of 880 Middle Eastern patients with NOA were recruited in this multicenter study for genetic evaluation prior to use of ART. Karyotyping was performed on peripheral blood lymphocytes according to standard G-banding methods, polymerase chain reaction (PCR) was performed to screen the microdeletions in the AZF region of the Y chromosome.

RESULTS

The present study shows that the total prevalence of genetic abnormalities is 28.41 %, including 184 patients (20.91 %) with chromosome disorder and 66 patients (7.5 %) with Y chromosome microdeletions. The most prevalent chromosome abnormality is Klinefelter's syndrome, which includes 161 patients (18.3 %), 7 patients had XX reversal male sex (0.8 %), 2 patients had 47XYY (0.23 %) and 2 patients had 45XO/46XY (0.23 %). Structural abnormalities occurred in 12 patients (1.36 %).

CONCLUSIONS

The high prevalence of genetic abnormalities (28.41 %) in our study strongly suggests the need for routine genetic testing and counseling prior to assisted reproduction in such population with idiopathic infertility, as a result may help determine the prognosis, as well as the choice of ART. Moreover it allows specific pre-implantation genetic testing to minimize the risk of transmitting genetic defects to offspring.

Y chromosome microdeletions in infertile men: prevalence, phenotypes and screening markers for the Indian population

PURPOSE

Yq microdeletions are the leading genetic cause of male infertility and its detection is clinically relevant for appropriate genetic counseling. We aimed to determine the prevalence and type of Yq microdeletions, the associated seminal phenotypes and the STS markers that are relevant for its testing in Indian population.

METHODS

Yq microdeletion analysis was carried out in 1,636 infertile cases in our centers. Additional data was collected from published studies in Indian population leading to a total of 3,647 cases.

RESULTS

In our cohort, 3.4 % (56/1,636) of infertile men had Yq microdeletions. Combining the data from other published studies identified 215/3,647 (5.8 %) infertile individuals to harbor Yq microdeletions; with 6.4 % in azoopsermia, 5.8 % in oligozoospermia and 3.2 % in oligoasthenozoospermia and teratozoospermia cases. No significant differences in the deletion frequencies were observed between idiopathic vs non idiopathic cases (5.8 vs 8.6 % respectively). Deletions of AZFc were at highest frequency (46.6 %) with double deletions most commonly observed in azoospermic subjects. With respect to the STS markers, screening with the six European Academy of Andrology (EAA) markers would miss 3.1 % of cases; additional non EAA markers that would contribute significantly to screening are sY746, sY82, sY121, sY128, sY130, sY143, sY145 & sY160.

INTERPRETATIONS AND CONCLUSIONS

The frequency of Yq microdeletions is lower in Indian population as compared to Western counterparts. There is no major association of Yq microdeletions with seminal parameters or cause of infertility. Clinically it will be necessary to offer Yq microdeletion testing to all the classes of infertile men. The EAA markers may not be adequate to detect microdeletions in Indian infertile men.

The low frequency of Y chromosome microdeletions in subfertile males in a Sinhalese population of Sri Lanka

AIMS

This study was designed to determine the prevalence of azoospermia factor (AZF) microdeletions on the Y chromosome in Sri Lankan Sinhalese infertile men with azoospermia and severe oligozoospermia.

SETTINGS AND DESIGN

The patient group was 207 karyotypically normal infertile Sinhalese males.

MATERIALS AND METHODS

The presence of 13 sequence-tagged site (STS) markers in the AZF region was tested using multiplex polymerase chain reaction (M-PCR). One hundred and twenty unselected men were also studied as a control group.

RESULTS

Three (1.5%) had classic Y chromosome microdeletions in the AZFc sub-region.

CONCLUSIONS

These results suggest a much lower Y chromosome microdeletion frequency than previously thought, even among a strictly selected group of sub-fertile males in Sri Lanka.

Loss of the AZFc region due to a human Y-chromosome microdeletion in infertile male patients

Infertility is a major reproductive health threat; the frequency of male infertility due to Y-chromosome microdeletions is 13-18% in the human population; these microdeletions involve recurrent loss of three non-overlapping regions designated as AZFa, AZFb and AZFc, associated with spermatogenic failure. Several contradictory reports have been published regarding deletion frequency based on sequence-tagged site markers and genotype-phenotype correlation. We examined the prevalence of Yq- deletion in 64 clinically diagnosed infertile male patients. We found a 3% frequency of microdeletion of the AZFc region; hormone profiles (FSH, LH and testosterone) showed significantly (P < 0.001) elevated levels compared to controls. No mutations were observed in the AZFa and AZFb regions, perhaps due to the selective use of sequence-tagged site markers.

Male infertility in China: laboratory finding for AZF microdeletions and chromosomal abnormalities in infertile men from Northeastern China

PURPOSES

To investigate the frequencies of AZF microdeletions and chromosomal abnormalities in infertile men from Northeastern China. Moreover, to compare the prevalence of these abnormalities with other countries and regions in the world.

METHODS

305 infertile men were enrolled. A complete semen analysis and reproductive hormones were measured according to standard methods. Multiplex polymerase chain reaction (PCR) amplification using nine specific sequence-tagged sites (STS) were used to detect AZF microdeletions. Karyotype analyses were performed on peripheral blood lymphocytes with standard G-banding.

RESULTS

Of the 305 infertile men, 28 (9.2%) had AZF microdeletions and 26 (8.5%) had chromosomal abnormalities. The most frequent microdeletions were in the AZFc+d, followed by AZFc, AZFb+c+d and AZFa. A total of 19 patients (82.6%) had Klinefelter's syndrome (47, XXY) in the azoospermic group.

CONCLUSIONS

The freqencies of AZF microdeletions and chromosomal abnormalities in infertile men from Northeastern China were comparable with infertile men from other countries and regions. However, there was a slightly higher prevalence rate of AZF microdeletions in oligozoospermic patients than reported in previous studies.

Clinical consequences of microdeletions of the Y chromosome: the extended Münster experience

A total of 3179 patients were screened for Y-chromosome microdeletions and 821 patients for partial AZFc deletions. Thirty-nine Y-chromosomal microdeletions were found (2.4% of men with <1 x 10(6)/ml spermatozoa): two AZFa, two AZFb, one AZFbc, one partial AZFb, one partial AZFb+c and 32 AZFc (b2/b4). Partial AZFc deletions were found in 45 patients (5.5%), mostly gr/gr deletions (n = 28). In patients with AZFc deletion, azoospermia was found in 53.1% and sperm concentrations of mostly <0.1 x 10(6)/ml were found in 46.9%. Semen analyses and FSH measurements showed no trend over time. Elongated spermatids were seen in 6/15 AZFc patients and bilateral Sertoli cell-only was found in 4/15. Testicular sperm extraction (TESE) was attempted in 10 patients and spermatozoa were found in six. Compared with infertile men matched by sperm concentration, no differences in hormonal and seminal parameters could be found in patients with AZFc or gr/gr deletions. It is concluded that: (i) frequency of AZF deletions in Germany is much lower than in other countries; (ii) AZFc deletions are associated with severe disturbances of spermatogenesis and TESE is not possible in half of these patients; (iii) AZFc and gr/ gr deletions are not associated with any clinical diagnostic parameter; (iv) and no trend is apparent over time.

Frequency of Y chromosome microdeletions and chromosomal abnormalities in infertile Thai men with oligozoospermia and azoospermia

AIM

To investigate the possible causes of oligozoospermia and azoospermia in infertile Thai men, and to find the frequencies of Y chromosome microdeletions and cytogenetic abnormalities in this group.

METHODS

From June 2003 to November 2005, 50 azoospermic and 80 oligozoospermic men were enrolled in the study. A detailed history was taken for each man, followed by general and genital examinations. Y chromosome microdeletions were detected by multiplex polymerase chain reaction (PCR) using 11 gene-specific primers that covered all three regions of the azoospermic factor (AZFa, AZFb and AZFc). Fifty men with normal semen analysis were also studied. Karyotyping was done with the standard G- and Q-banding. Serum concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone were measured by electrochemiluminescence immunoassays (ECLIA).

RESULTS

Azoospermia and oligozoospermia could be explained by previous orchitis in 22.3%, former bilateral cryptorchidism in 19.2%, abnormal karyotypes in 4.6% and Y chromosome microdeletions in 3.8% of the subjects. The most frequent deletions were in the AZFc region (50%), followed by AZFb (33%) and AZFbc (17%). No significant difference was detected in hormonal profiles of infertile men, with or without microdeletions.

CONCLUSION

The frequencies of Y chromosome microdeletions and cytogenetic abnormalities in oligozoospermic and azoospermic Thai men are comparable with similarly infertile men from other Asian and Western countries.

High frequency of Y chromosome microdeletions in idiopathic azoospermic men with high follicle-stimulating hormone levels

Y chromosome microdeletions were detected in 33.3% (6 out of 18) of idiopathic azoospermic patients with high serum follicle-stimulating hormone (FSH) levels in the present study. The results suggest that it may be necessary to detect microdeletions in patients with azoospermia, especially for those with high serum FSH levels, before assisted reproductive technology (ART) is provided to them.

Cytogenetic and molecular analysis of the Y chromosome: absence of a significant relationship between CAG repeat length in exon 1 of the androgen receptor gene and infertility in Indian men

The genetic basis of male infertility remains unclear in the majority of cases. Recent studies have indicated an association between microdeletions of the azoospermia factor a (AZFa)-AZFc regions of Yq and severe oligospermia or azoospermia. Increased (CAG)n repeat lengths in the androgen receptor (AR) gene have also been reported in infertile men. Therefore, in order to assess the prevalence of these genetic defects to male infertility, 183 men with non-obstructive azoospermia (n = 70), obstructive azoospermia (n = 33), severe oligospermia (n = 80) and 59 fertile men were examined cytogenetically and at molecular level for Yq deletions, microdeletions, and AR-CAG repeat lengths along with hormonal profiles [luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T)]. We used high resolution cytogenetics to detect chromosome deletions and multiplex polymerase chain reaction (PCR) involving 27 sequence-tagged site (STS) markers on Yq to determine the rate and extent of Yq microdeletions. PCR amplification with primers flanking exon 1 of AR gene was used to determine the AR-(CAG)n repeat lengths. Hormonal profiles (LH, FSH and T levels) were also analysed in infertile and fertile men. Testicular biopsies showed Sertoli cell only (SCO) morphology, maturation arrests (MA) and hypospermatogenesis. No chromosome aberrations were found in infertile men but there was a significant increase (p < 0.001) in the association of acrocentric chromosomes including the Y chromosome. Yq microdeletions were found in 16 non-obstructive azoospermic men (16 of 70; 22%) and seven severe oligospermic individuals (seven of 80; 8.7%) and most of them had deletions in the sY240 locus. No Yq microdeletions were detected in patients with obstructive azoospermia. No statistically significant difference in the mean length of CAG repeats in AR gene was observed between infertile and fertile men (22.2 +/- 1.5 and 21.5 +/- 1.4 respectively). No significant increase or decrease in levels of LH, FSH and T was observed in infertile and fertile men. In some infertile men, significantly elevated levels of FSH alone or in combination with LH were found to be indicative of failure of spermatogenesis and/or suggestive of testicular failure. Y-chromosome microdeletions contribute to infertility in some patients but no relationship could be established with the (CAG)n repeat lengths in exon 1 of the AR gene in infertile Indian men.

Absence of microdeletions in the azoospermia-factor region of the Y-chromosome in viennese men seeking assisted reproduction

PURPOSE

The azoospermia-factor region of the Y-chromosome is essential for spermatogenesis in humans. In the literature, a wide range is given for the frequency of microdeletions in this region. The purpose of this study was to evaluate our own population of patients.

METHODS

During a two-year period at Vienna Medical School, all male patients (n = 383) seeking assisted reproduction were screened for microdeletions. Thirty-three men had azoospermia and 154 severe oligozoospermia. Genomic DNA was prepared from peripheral lymphocytes and polymerase chain reaction analysis of the azoospermia-factor region was performed using the Promega kit.

RESULTS

No case tested positive for azoospermia-factor microdeletions. In all cases amplification of 18 non-polymorphic sequence tagged sites was obtained.

CONCLUSIONS

Y-chromosome microdeletions do not seem to be an important factor for male infertility in our patients. This suggests that screening should be restricted to men with azoospermia or severe oligozoospermia only.

Identification and characterization of human VCY2-interacting protein: VCY2IP-1, a microtubule-associated protein-like protein

VCY2 is a testis-specific protein that locates in a frequently deleted azoospermia factor c region on chromosome Yq. Although its genomic structure has been characterized, the function of VCY2 is still unknown. To gain insight regarding the likely function of VCY2, we investigated the proteins that interact with VCY2 using the yeast two-hybrid system. We identified a novel VCY2 interaction partner, named VCY2IP-1, that encodes an open reading frame of 1059 amino acids. The amino acid sequence of VCY2IP-1 shows 59.3% and 41.9% homology to two human microtubule-associated proteins (MAPs), MAP1B and MAP1A, respectively. VCY2IP-1 has an extensive homology to the N-terminus and C-terminus regions of MAP1B and MAP1A, placing it within a large family of MAPs. We mapped VCY2IP-1 to chromosome 19p13.11. The VCY2IP-1 gene spans 15 kilobases (kb) and consists of seven exons. Northern blot analysis identified a single, intense band of approximately 3.2-kb VCY2IP-1 transcript, predominantly expressed in human testis. In situ hybridization of human testicular sections showed the localization of VCY2IP-1 transcripts in germ cells, and reverse transcription-polymerase chain reaction analysis demonstrated the presence of VCY2 and VCY2IP-1 transcripts in human ejaculated spermatozoa. Our expression data support the involvement of VCY2 and VCY2IP-1 in spermatogenesis. Based on the high homology of VCY2IP-1 with MAPs, we propose the involvement of VCY2 in the cytoskeletal network via interaction with VCY2IP-1.

Specific expression of VCY2 in human male germ cells and its involvement in the pathogenesis of male infertility

Abnormal spermatogenesis in men with Y-chromosome microdeletions suggests that genes important for spermatogenesis have been removed from these individuals. VCY2 is a testis-specific gene that locates in the most frequently deleted azoospermia factor c region in the Y chromosome. We have raised an antiserum to VCY2 and used it to characterize the localization of VCY2 in human testis. Using Western blot analysis, the affinity-purified polyclonal VCY2 antibody gave a single specific band of approximately 14 kDa in size, corresponding to the expected size of VCY2 in all the collected human testicular biopsy specimens with normal spermatogenesis. Immunohistochemical analyses showed that VCY2 localized to the nuclei of spermatogonia, spermatocytes, and round spermatids, except elongated spermatids. At the ultrastructural level, VCY2 expression was found in the nucleus of human ejaculated spermatozoa. To determine the possible relationship of VCY2 with the pathogenesis of male infertility, we examined a group of infertile men with and without Y-chromosome microdeletions and with known testicular pathology using VCY2 antibody. VCY2 was weakly expressed at the spermatogonia and immunonegative in spermatocytes and round spermatids in testicular biopsy specimens with maturation arrest or hypospermatogenesis. The specific localization of the protein in germ cell nuclei indicates that VCY2 is likely to function in male germ cell development. The impaired expression of VCY2 in infertile men suggests its involvement in the pathogenesis of male infertility.

Molecular analysis of the androgen receptor gene in Hong Kong Chinese infertile men

PURPOSE

To investigate the relationship between CAG repeat length in the androgen receptor gene and impaired spermatogenesis in Hong Kong Chinese population.

METHODS

The CAG repeat region was amplified by polymerase chain reaction (PCR) in 85 nonobstructive azoospermic or severe oligozoospermic men, and 45 fertile males. The number of CAG repeat was analyzed by DNA sequencing. Serum FSH, LH, and testosterone levels were also determined in these men.

RESULTS

Among nonobstructive azoospermic males, three men (5.7%) possessed short CAG repeats (< 16), and three (5.7%) other men possessed long CAG repeats (> 30). Short CAG repeats (< 16) were also found in two severe oligozoospermic males (6.3%). The incidence of infertile men with short or long CAG repeats is significantly higher in the azoospermic group (p = 0.03) but not in the severe oligozoospermic group (p = 0.17) when compared with the fertile controls

CONCLUSION

Our data suggest an association between CAG repeat lengths and impaired spermatogenesis in azoospermic males in our population.