Molecular screening for Yq microdeletion in men with idiopathic oligozoospermia and azoospermia

Infertility affects 15% couples attempting pregnancy and in 40–50% of these cases the male partner has qualitative or quantitative abnormalities of sperm production. Microdeletions in the azoospermia factor (AZF) region on the long arm of the Y chromosome are known to be associated with spermatogenic failure and have been used to define three regions on Yq (AZFa, AZFb and AZFc) which are critical for spermatogenesis and are recurrently deleted in infertile males. Semen analysis was carried out on one hundred and twenty five infertile males with oligozoospermia and azoospermia. Cytogenetic analysis was done for all the cases and in all cytogenetically normal cases (n = 83) microdeletion analysis was carried out on DNA extracted from peripheral blood using PCR. The sequence tagged sites (STS) primers sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc) were used for each case. Eight of the eighty three cases (9.63%) showed deletion of at least one of the STS markers. Correlation of phenotype with microdeletion was done in each case to determine any phenotype association with deletion of particular AZF locus. Based on the present study, the frequency of microdeletion in the Indian population is 9.63%. This study emphasizes the need for PCR analysis for determining genetic aetiology in cases with idiopathic severe testiculopathy.     

Molecular analysis of Y chromosome microdeletions in idiopathic cases of male infertility in Serbia

The aim of this study was to detect frequency of microdeletions of Y chromosome in idiopathic cases of male infertility in Serbian population. Patients were subjected to detailed clinical, endocrinological and cytogenetic examinations. Ninety patients with normal cytogenetic findings with azoospermia and severe oligozoospermia were included in the study. In these patients microdeletion analysis was performed by multiplex polymerase chain reaction (PCR) method on DNA extracted from peripheral blood. In each case 6 markers in azoospermia factor (AZF) regions were tested: sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc). Deletions on Y chromosome were detected in 14 of 90 cases (15.6%), 9 with azoospermia and 5 with severe oligozoospermia. Of total number of 17 deletions, 11 (64.7%) were detected in AZFc region, 3 (17.6%) in AZFa region and 3 (17.6%) in AZFb region. Microdeletions in AZF region of Y chromosome, especially AZFc microdeletions, represent common genetic cause of idiopathic azoospermia and severe oligozoospremia in Serbian infertile men. Therefore, testing for Y chromosome microdeletions should be considered as an important element in diagnosis and genetic counseling of infertile men in Serbia and decisions regarding the assisted reproduction should be made based on the presence and type of AZF microdeletions.     

Molecular analysis of Y chromosome microdeletions in idiopathic cases of male infertility in Serbia

The aim of this study was to detect frequency of microdeletions of Y chromosome in idiopathic cases of male infertility in Serbian population. Patients were subjected to detailed clinical, endocrinological and cytogenetic examinations. Ninety patients with normal cytogenetic findings with azoospermia and severe oligozoospermia were included in the study. In these patients microdeletion analysis was performed by multiplex polymerase chain reaction (PCR) method on DNA extracted from peripheral blood. In each case 6 markers in azoospermia factor (AZF) regions were tested: sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc). Deletions on the Y chromosome were detected in 14 of 90 cases (15.6%), nine with azoospermia and five with severe oligozoospermia. Of total number of 17 deletions, 11 (64.7%) were detected in AZFc region, three (17.6%) in AZFa region and three (17.6%) in AZFb region. Microdeletions in AZF region of the Y chromosome, especially AZFc microdeletions, represent common genetic cause of idiopathic azoospermia and severe oligozoospremia in Serbian infertile men. Therefore, testing for Y chromosome microdeletions should be considered as an important element in diagnosis and genetic counseling of infertile men in Serbia and decisions regarding the assisted reproduction should be made based on the presence and type of AZF microdeletions. The text was submitted by the authors in English.     

Y chromosome microdeletions in Brazilian fertility clinic patients

Microdeletions in Yq are associated with defects in spermatogenesis, while those in the AZF region are considered critical for germ cell development. We examined microdeletions in the Y chromosomes of patients attended at the Laboratory of Human Reproduction of the Clinical Hospital of the Federal University of Goiás as part of a screening of patients who plan to undergo assisted reproduction. Analysis was made of the AZF region of the Y chromosome in men who had altered spermograms to detect possible microdeletions in Yq. Twenty-three patients with azoospermia and 40 with severe oligozoospermia were analyzed by PCR for the detection of six sequence-tagged sites: sY84 and sY86 for AZFa, sY127 and sY134 for AZFb, and sY254 and sY255 for AZFc. Microdeletions were detected in 28 patients, including 10 azoospermics and 18 severe oligozoospermics. The patients with azoospermia had 43.4% of their microdeletions in the AZFa region, 8.6% in the AZFb region and 17.4% in the AZFc region. In the severe oligozoospermics, 40% were in the AZFa region, 5% in the AZFb region and 5% in the AZFc region. We conclude that microdeletions can be the cause of idiopathic male infertility, supporting conclusions from previous studies.     

Idiopathic cases of male infertility from a region in India show low incidence of Y-chromosome microdeletion

Chromosomal and Y-chromosomal microdeletion analysis has been done in cases of idiopathic infertility with the objective of evaluating the frequency of chromosomal and molecular anomaly as the causal factor of infertility. Barring a few cases of Klinefelter syndrome (XXY or XY/XXY mosaics), no chromosomal anomaly was encountered. Y-microdeletion was analysed by PCR-screening of STSs from different regions of the AZF (AZFa, AZFb, AZFc) on the long arm of the Y, as well as by using DNA probes of the genes RBM, DAZ (Yq), DAZLA (an autosomal homologue of DAZ) and SRY (Yp; sex determining gene). Out of 177 cases examined, 9 (azoospermia -8 and oligoasthenospermia -1) showed partial deletion of AZF. The size of deletion varied among patients but AZFc was either totally or partially removed in all of them. In contrast, no deletion was detected in AZFa. Testis biopsy done on a limited number of cases (50) showed diverse stages of spermatogenic arrest with no specific correlation with the genotype. The frequency of Y-chromosome microdeletion in our samples (∼ 5%) is much lower than the frequency (∼ 10%) reported globally and the two previous reports from India. We contend that the frequency may be affected by population structures in different geographical regions.     

对法医学相关的DYS549、DYS527和DYS459基因座在男性不育症人群中的缺失、重复调查

位于Y染色体无精症因子区域(Azoospermia factor, AZF)的基因座位点DYS549、DYS527和DYS459在法医学鉴定和家系分析中被广泛应用。但是,在男性不育患者中,DYS549、DYS527和DYS459位点很可能会表现出特殊的基因型,对应用Y染色体短串联重复序列(Y chromosome short tandem repeat, Y-STR)进行个体识别的结果产生干扰。因此,文章应用14个Y-STR基因座复合扩增体系和Y染色体AZFc区DAZ、CDY1基因的拷贝数检测等方法,探讨男性不育症中法医学相关的3个Y-STR基因座的异常分型,对个体识别和家系分析中的DNA检验异常结果提供合理的解释。在240例男性非梗阻性无精、严重少精、先天性双侧输精管缺如(CBVAD)患者中,采用改良的多重PCR体系进行AZF区域微缺失的序列标签位点(Sequence tagged sites, STSs)检测,发现AZF微缺失40例(AZFa：2例;AZFb：2例;AZFc：30例;AZFb+c：6例),AZF的总缺失率为16.67%。应用14 Y-STR复合扩增体系对上述AZF微缺失的阳性患者样本进行检测,发现所有AZFb缺失患者存在DYS549等位基因缺失,AZFc缺失患者存在DYS527、DYS459等位基因缺失,AZFb+c缺失患者存在DYS549、DYS527和DYS459等位基因缺失。在AZF微缺失阴性的不育症患者中,通过检测DAZ、CDY1基因拷贝数发现10例AZFc部分复制的患者(1例为先天性输精管缺如,2例非梗阻性无精症,7例严重少精子症),占所调查不育人群的4.17%。男性不育人群AZF区域3个Y-STR基因座多态性会造成等位基因缺失或者重复,这些异常分型是由于临床遗传缺陷造成的而不是实验偏差。阐明Y-STR在男性不育人群中的异质性可以更好地完善Y-STR数据库和解释STR实验结果。     

Tracking microdeletions of the AZF region in a patrilineal line of infertile men

Male infertility is considered to be a difficult-to-treat condition because it is not a single entity, but rather reflects a variety of different pathologic conditions, thus making it difficult to use a single treatment strategy. Structural alterations in the Y chromosome have been the principal factor responsible for male infertility. We examined 26 family members of 13 patients with male infertility who showed deletions in the AZF region. In family 1, the father and a brother did not show microdeletions. However, a son showed a microdeletion in AZFa (sY84) and an azoospermic sperm analysis, but another son had a microdeletion in AZFa (sY84) and AZFb (sY127) and a normal sperm analysis. The father of family 2, with severe oligozoospermia, had a microdeletion in the AZFa region (sY84) and his son, conceived by intracytoplasmic sperm injection, also showed the same microdeletion. In the other families, only the men with an altered sperm analysis had a microdeletion. It is possible that in family 1, the father and brother who did not show microdeletions in this study, could have microdeletions in regions upstream or downstream of the one analyzed. The treatment with intracytoplasmic sperm injection can result in vertical transmission of microdeletions of the AZF region and can also cause the expansion of a de novo mutation. This finding reinforces the necessity of an investigation of microdeletions of the Y chromosome in individuals who are candidates for assisted reproduction, as well as genetic counciling and follow-up.     

Cytogenetic and molecular analysis of male infertility

Reduced male fertility and subfertility can be caused by genetic factors that affect both germ cell development, differentiation, and function; in particular, chromosome abnormalities and Yq microdeletions are a possible cause of spermatogenetic impairment in males as shown by their higher frequency in infertile men than in the general male population. Microdeletion of the long arm of the Y chromosome (Yq) are associated with spermatogenic failure and have been used to define three regions on Yq (AZFa, AZFb, and AZFc) that are critical for germ cell development. With the advent of assisted reproductive technology and intracytoplasmic sperm injection, knowledge about the various factors leading to spermatogenic impairment is one of the most important aspects of scientific research. Therefore, this study was designed to identify the frequency of cytogenetic and submicroscopic interstitial deletions in azoospermia factor loci in infertile Indian males. One hundred and eighty males with nonobstructive oligozoospermia and azoospermia were included in this study. Semen analysis was done in each case to determine the spermatogenic status. Individuals were subjected to detailed clinical examination, family history, and endocrinological and cytogenetic study after consent from the patient. Peripheral blood cultures were set up according to standard protocols and 30 G-banded metaphases were analyzed in each case. Numerical and structural chromosomal abnormalities were detected in 40 infertile cases. Fluorescence in situ hybridization analysis was done in some cases to identify the percentage of mosaic cell lines and any cryptic or low-level mosaicism. Polymerase chain reaction microdeletion analysis was done in 140 cytogenetically normal cases. Of the 140 cases, 8 showed deletion of at least one of the sequence-tagged site markers. Review of literature has shown that the overall frequency of microdeletions varies from 1 to 55%. In the present study, the frequency of microdeletion was 5.8%, and deletions were identified in cases with undescended testis and varicocele and cases with bilateral severe testiculopathy.     

Male infertility: Y-chromosome deletion and testicular aetiology in cases of azoo-/oligospermia

The spermatogenesis locus azoospermia factor (AZF) in Yq11 has been delineated into three microdeletion intervals designated as AZFa, AZFb andAZFc. AZFc is the most frequently deleted region. We have studied 270 male infertile patients for various genetic disorders associated with infertile phenotype. In this study, we have presented results of our studies on Y-chromosome deletions, chromosomal abnormalities (Klinefelter syndrome) and histology of testis with the objective of seeing whether there were cases of gonosomic mosaicism and a causal correlation between the genetic disorder; and testicular aetiology could be drawn. In all the 13 cases of Y-chromosome microdeletion, AZFc region and DAZ gene were deleted, while no case of AZFa deletion was detected. This result was at variance with other reports from India, where a considerable fraction of cases showed deletion in AZFa region of the Y-chromosome. Both Y-deleted and non-Y-deleted cases revealed heterogeneous testicular phenotype with comparable severity. This disparity among testicular phenotype in cases with known genetic aetiology and even in cases of unknown aetiology can be attributed to different genetic backgrounds and effect of modifiers. Since male infertility is a multifactorial disorder, the contributions of environmental and occupational insults may not be underestimated.     

Prevalence of Y chromosome microdeletions in infertile men with severe oligozoospermia in Serbia

AIM: The aim of this study was to determine the prevalence and type of microdeletions of the Y chromosome of men with severe oligozoospermia-ICSI candidates in the Serbian population and to compare our findings with those from other parts of the world. METHODS: In all patients spermiogram has been performed in order to determine the sperm concentration. Patients were subjected to detailed clinical, endocrinological and cytogenetic examinations. Microdeletion analysis was performed by polymerase chain reaction (PCR) on 203 patients with normal cytogenetic findings. The STS markers tested in each case were sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc). RESULTS: at least one of the STS markers was deleted in 11 of the 203 cases (5.4%). CONCLUSION: AZFc microdeletions were identified with a rather high prevalence in men with severe oligozoospermia ICSI candidates in Serbian population.     

中国无精症、严重寡精症患者的染色体异常和Y染色体微缺失

染色体异常和Y染色体微缺失被认为是两个白种人群中常见的生精障碍相关遗传因素。为了解中国无精症、严重寡精症患者中的染色体异常和Y染色体微缺失,运用染色体G显带技术,在358个原发无精症（256人）和严重寡精症（102人）不育患者中进行染色体核型分析;同时运用多重PCR技术,在核型正常的患者和100个正常生育男性中,对Y染色体AZF区微缺失进行筛查。在358个患者中,39人（10．9％）发现有染色体异常,Klinefelter（47,XYY）最为常见。无精症患者性染色体异常频率明显高于严重寡精症患者（12．1％VS1％）。在319个核型正常的患者中,46（14．4％）发现有AZF区微缺失,无精症和寡精症患者中Y染色体微缺失频率分别为15％和13．1％,AZFc区的微缺失最为常见,AZFa区的微缺失只见于无精症患者,正常生育男性中未发现AZF区的微缺失。结果显示,在中国无精症、严重寡精症患者中,大约25％的患者有染色体异常或Y染色体AZF区微缺失,提示这两种遗传异常是中国人群生精障碍的重要相关遗传病因,有必要在男性不育的诊断以及利用细胞浆内精子注射技术进行辅助生育时,对患者的这些遗传异常进行筛查。     

Screening of Y chromosome microdeletion which contains AZF regions in 71 Turkish azoospermic men

Screening of Y chromosome microdeletion which contains AZF regions in 71 turkish azoospermic men: In 71 Turkish men Y chromosome microdeletions have been studied before intracytoplasmic sperm injection (ICSI). DNA samples were amplified with 18 STS primers of the azoospermia factor (AZF) region on the Y chromosome by using multiplex polymerase chain reaction (PCR). Microdeletions were detected in 4 azoospermic men (5.6 %); one with a deletion in the AZFb region, while the 3 others had a large deletion extending over multiple chromosomal regions (AZFb+c+d and AZFa+b+c+d). In the patients with microdeletion, no spermatogenetic activity could be detected in testis biopsies. This result confirms the idea that Y chromosome microdeletion analysis is important in investigating the possibility of finding sperm in testicular sperm extraction (TESE). Therefore, we point out the importance of genetic testing and counselling regarding Y chromosome microdeletion for couples requesting ICSI.     

A cost-effective screening test for detecting AZF microdeletions on the human Y chromosome

PCR-based screening of microdeletions in the azoospermic factor (AZF) on the Yq chromosome is an accepted means of identifying a common genetic cause of male infertility, responsible for 5-15% of cases associated with a low sperm count (相似文献   

Chromosomal Abnormality and Y Chromosome Microdeletion in Chinese Patients with Azoospermia or Severe Oligozoo-spermia

Chromosomal abnormality and Y chromosome microdeletion are regarded as two frequent genetic causes associated with spermatogenic failure in Caucasian population. To investigate the distribution of the two genetic defects in Chinese patients with azoospermia or severe oligozoospermia, karyotype analysis by G-banding was carried out in 358 idiopathic infertile men, including 256 patients with azoospermia and 102 patients with severe oligozoospermia, and screening of AZF region microdeletion of Y chromosome by multiplex PCR was performed in those patients without detectable chromosomal abnormality and 100 fertile controls. Of 358 patients, 39(10.9%) were found to have chromosomal abnormalities in which Klinefelters syndrome (47, XXY) was the most common chromosomal aberration. The incidence of sex chromosomal abnormality in patients with azoospermia was significantly higher than that in patients with severe oligozoospermia (12.1% vs 1%). Among the rest of the 319 patients with normal karyotype, 46 (14.4%) were found to have microdeletions in AZF region. The prevalence rates of AZF microdeletion was 15% and 13.1% in patients with azoospermia and severe oligozoospermia respectively. The microdeletion in AZFc was the most frequent deletion and all the microdeletions in AZFa were found in azoospermic patients. No microdeletion in AZF region was detected in fertile controls. In conclusion, chromosomal abnormality and AZF region microdeletion of Y chromosome might account for about 25% of Chinese infertile patients with azoospermia or severe oligozoospermia, suggesting the two abnormalities are important genetic etiology of spematogenic failure in Chinese population and it is essential to screen them during diagnosis of male infertility before in vitro assisted fertilization by introcytoplasmic sperm injection.     

Y-chromosome microdeletions as a prognostic marker of male infertility

The results of molecular-genetic study of Y-chromosome microdeletions in men with spermatogenesis failure and in patients with cryptorchism are presented. The molecular-genetic studies of regions AZFa, AZFb, AZFc in STS loci - sY84, sY86, sY127, sY134, sY254, sY255 and SRY gene have been performed. Y-chromosome microdeletions were detected in 13,3% infertile men with spermogram failure. The frequency of genetic (cyto- and molecular) abnormalities among boys with isolated cryptorchism was 4%. The results show the necessity of additional study ofgenetic factors ofcryptorchism development.     

QF-PCR筛查男性不育患者Y染色体无精子症因子微缺失

为评估定量荧光PCR(Quantitative fluorescent polymerase chain reaction, QF-PCR)技术在快速筛查无精子症因子(Azoospermia factor, AZF)微缺失中的应用, 文章对1218例非梗阻性无精子症、少精子症的男性不育患者, 采用多重QF-PCR结合毛细管电泳技术, 检测Y染色体长臂AZF区9个序列标签位点(Sequence tagged site, STS)以及性染色体短臂的AMEL(Amelogenin)和SRY(Sex-determining region of Y chromosome)位点, 辅以常规染色体G显带方法进行核型分析。结果显示, 1218例患者中105例可见AZF区微缺失(8.62%), 其中AZFc区缺失(67.62%)最常见, 其次为AZFb,c区缺失(20.95%); AZFb区缺失(7.62%)和AZFa区缺失(3.81%)则较少见; 另有5例患者为AZFa,b,c区缺失合并AMEL-Y缺失, 提示可能缺少Y染色体, 经核型分析验证为46,XX(性反转)。105例AZF区微缺失患者的染色体核型分析显示染色体异常16例, 其中“Yqh-”12例。根据AMEL-X/AMEL-Y比值, 可见1218例患者中86例可能存在性染色体异常, 经核型分析验证, 68例为性染色体非整倍体。多重QF-PCR技术, 一个反应即能检测样本的多个位点, 并可提示性染色体是否存在异常, 有助于男性不育患者尽早明确病因, 也为后续的检查和治疗提供依据。     

Existe-il, dans la population générale masculine un risque plus fort de développer des délétions du chromosome Y qui entraîneraient une infertilité?

The role of the Y-chromosome in spermatogenesis remains one of the hottest topics in andrology. Three non overlapping recurrently deleted regions on Yq (AZFa, AZFb, AZFc) have been defined, each of them containing several genes that are candidates for male infertility. The causes and mechanisms leading to microdeletion formation on the Y are largely unknown. Theoretically, it could be possible that some groups of Y-chromosomes (haplogroups) currently distributed in the population could confer a selective advantage/disadvantage towards deletion formation. A precedent in the field is the recent identification of a Y-chromosome haplotype that confers a selective advantage against a translocation of Yp leading to another form of male infertility, the Y+XX-male phenotype. In order to test if selection is acting on Y-chromosome haplotype distribution, we have defined and compared Y-chromosome haplotypes in a group of around 60 individuals with Y microdeletions from North-Western Europe using 10 biallelic Y-markers (SRY-2627, SRY-1532, SRY-8299, 92R7, Tat, YAP, sY81, LLY22g, M9, DYS257). The defined heplotypes were compared to a control normospermic population of the same ethnic/geographic origin (in the framework of the European Biodiversity Project). We evaluatte the relationship between different Y-chromosome backgrounds and microdeletions, and to which extent selection on this chromosome could have influenced fifness of certain individuals/populations. We also discuss the selective forces that are acting on this chromosome and speculate on the mechanisms underlying deletion formation.     

Microdeletions in the Y chromosome as a predictive marker of infertility in males

Results of a molecular-genetics study of microdeletions in the Y chromosome among males with disturbances in spermatogenesis and among patients with cryptorchism are presented. A study of subregions AZFa, AZFb and AZFc with the use of DNA analysis in the STS loci sY84, sY86, sY127, sY134, sY254, sY255, and the gene SRY is performed. Microdeletions in the Y chromosome were found in 13.3% of infertile males studied who exhibited failed spermogram indicators, attesting to the significant information value of the study. The frequency of genetic (cyto- and molecular-genetic) damage among young boys with isolated cryptorchism amounted to 4%, which points to a need for further study of the genetic basis of cryptorchism. Management and optimization of the molecular-genetics study of microdeletions in the Y chromosome are of great importance for medical practice.     

High-Throughput Screening for Spermatogenesis Candidate Genes in the AZFc Region of the Y Chromosome by Multiplex Real Time PCR Followed by High Resolution Melting Analysis

Microdeletions in the AZF region of the Y chromosome are among the most frequent genetic causes of male infertility, although the specific role of the genes located in this region is not fully understood. AZFa and AZFb deletions impair spermatogenesis since no spermatozoa are found in the testis. Deletions of the AZFc region, despite being the most frequent in azoospermic patients, do not correlate with spermatogenic failure. Therefore, the aim of this work was to develop a screening method to ascertain the presence of the main spermatogenesis candidate genes located in the AZFc region in the light of the identification of those responsible for spermatogenic failure. DAZ, CDY, BPY2, PRY, GOLGA2LY and CSGP4LY genes were selected on the basis of their location in the AZFc region, testis-only expression, and confirmed or predicted protein codification. AMEL and SRY were used as amplification controls. The identification of Real Time PCR products was performed by High Resolution Melting analysis with SYTO 9 as intercalating dye. The herein described method allows a rapid, simple, low-cost, high-throughput screening for deletions of the main AZFc genes in patients with spermatogenic failure. This provides a strategy that would accelerate the identification of spermatogenesis candidate genes in larger populations of patients with non-obstructive idiopathic azoospermia.