Defining regions of the Y-chromosome responsible for male infertility and identification of a fourth AZF region (AZFd) by Y-chromosome microdeletion detection.

Promega Corporation, Department of Obstetrics and Gynecology, University of Wisconsin, Madison 53711, USA.

Cytogenetic and molecular deletion analyses of azoospermic and oligozoospermic males have suggested the existence of AZoospermia Factor(s) (AZF) residing in deletion intervals 5 and 6 of the human Y-chromosome and coinciding with three functional regions associated with spermatogenic failure. Nonpolymorphic microdeletions in AZF are associated with a broad spectrum of testicular phenotypes. Unfortunately, Sequence Tagged Sites (STSs) employed in screening protocols range broadly in number and mapsite and may be polymorphic. To thoroughly analyze the AZF region(s) and any correlations that may be drawn between genotype and phenotype, we describe the design of nine multiplex PCR reactions derived from analysis of 136 loci. Each multiplex contains 4-8 STS primer pairs, amplifying a total of 48 Y-linked STSs. Each multiplex consists of one positive control: either SMCX or MIC2. We screened four populations of males with these STSs. Population I consisted of 278 patients diagnosed as having significant male factor infertility: either azoospermia, severe oligozoospermia associated with hypogonadism and spermatogenic arrest or normal sperm counts associated with abnormal sperm morphology. Population II consisted of 200 unselected infertile patients. Population III consisted of 36 patients who had previously been shown to have aneuploidy, cytological deletions or translocations involving the Y-chromosome or normal karyotypes associated with severe phenotype abnormalities. Population IV consisted of 920 fertile (control) males. The deletion rates in populations I, II and III were 20.5%, 7% and 58.3%, respectively. A total of 92 patients with deletions were detected. The deletion rate in population IV was 0.87% involving 8 fertile individuals and 4 STSs which were avoided in multiplex panel construction. The ability of the nine multiplexes to detect pathology associated microdeletions is equal to or greater than screening protocols used in other studies. Furthermore, the data suggest a fourth AZF region between AZFb and AZFc, which we have termed AZFd. Patients with microdeletions restricted to AZFd may present with mild oligozoospermia or even normal sperm counts associated with abnormal sperm morphology. Though a definitive genotype/phenotype correlation does not exist, large deletions spanning multiple AZF regions or microdeletions restricted to AZFa usually result in patients with Sertoli Cell Only (SCO) or severe oligozoospermia, whereas microdeletions restricted to AZFb or AZFc can result in patients with phenotypes which range from SCO to moderate oligozoospermia. The panel of nine multiplexed reactions, the Y-deletion Detection System (YDDS), provides a fast, efficient and accurate method of assessing the integrity of the Y-chromosome. To date, this study provides the most extensive screening of a proven fertile male population in tandem with 514 infertile males, derived from three different patient selection protocols.

PMID: 10230814 [PubMed - indexed for MEDLINE]

AZF microdeletions and partial deletions of AZFc region on the Y chromosome in Moroccan men.

Human Genetic and Cytogenetic Unit, Research Department, Pasteur Institute of Morocco, Ezzahraoui 20100 Casablanca, Morocco. laila.imken@pasteur.ma

AIM: To evaluate for the first time the frequency of Y chromosome microdeletions and the occurrence of the partial deletions of AZFc region in Moroccan men, and to discuss the clinical significance of AZF deletions. METHODS: We screened Y chromosome microdeletions and partial deletions of the AZFc region of a consecutive group of infertile men (n = 149) and controls (100 fertile men, 76 normospermic men). AZFa, AZFb, AZFc and partial deletions of the AZFc region were analyzed by polymerase chain reaction (PCR) according to established protocols. RESULTS: Among the 127 infertile men screened for microdeletion, four subjects were found to have microdeletions: two AZFc deletions and two AZFb+AZFc deletions. All the deletions were found only in azoospermic subjects (4/48, 8.33%). The overall AZFc deletion frequency was low (4/127, 3.15%). AZF microdeletions were not observed in either oligoasthenoteratozoospermia (OATS) or the control. Partial deletions of AZFc (gr/gr) were observed in a total of 7 of the 149 infertile men (4.70%) and 7 partial AZFc deletions (gr/gr) were found in the control group (7/176, 3.98%). In addition, two b2/b3 deletions were identified in two azoospermic subjects (2/149, 1.34%) but not in the control group. CONCLUSION: Our results suggest that the frequency of Y chromosome AZF microdeletions is elevated in individuals with severe spermatogenic failure and that gr/gr deletions are not associated with spermatogenic failure.

PMID: 17712485 [PubMed - indexed for MEDLINE]

Y chromosome microdeletions in Brazilian fertility clinic patients.

Núcleo de Pesquisas Replicon, Universidade Católica de Goiás, Goiânia, GO, Brasil. jalsitacon@yahoo.com.br

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.

PMID: 17952870 [PubMed - indexed for MEDLINE]

[Detecting microdeletions of the Y chromosome in patients with high follicle-stimulating hormone azoospermia]

The Affiliated Obstetrics and Gynecology Hospital, College of Medical Sciences, Zhejiang University, Hangzhou, Zhejiang, 310006 P.R.China.

OBJECTIVE: To explore the relationship between the patients' high follicle-stimulating hormone (FSH) azoospermia and microdeletions in Y chromosome. METHODS: Eleven sequence tagged sites (STSs) in Yq were detected by PCR in 16 male patients' high FSH azoospermia. RESULTS: Microdeletions were observed in 6 of 16 male patients and the deletion rate was 37.5%(6/16). Five types of microdeletions were detected: AZFc(SY152), AZFc (SY152+SY254)+AZFd (SY153), AZFc (SY152+SY254+SY255)+AZFd (SY153), AZFc (SY152+SY158+SY255)+AZFd (SY153),and AZFb (SY130)+AZFc (SY158+SY254+SY255)+AZFd (SY153) respectively. CONCLUSION: Microdeletion of Y chromosome was one of the important reasons of the patients' high FSH azoospermia. Before the application of assisted-reproductive technology (ART) to the patients, it is necessary to detect the microdeletions, especially AZFc and AZFd.

PMID: 15476177 [PubMed - indexed for MEDLINE]

[The prognostic value of the site and extent of Y chromosome microdeletions on spermatogenesis]

Institute for the Study of Fertility Lis Maternity Hospital, Clinical Biochemistry Laboratory, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

Genes on Y-chromosome are involved in the regulation of spermatogenesis. Y-chromosome microdeletions were identified among infertile patients in a frequency of 7.5-15% on the long arm of the chromosome. These microdeletions were clustered in 3 main regions named AZFa, AZFb, and AZFc. Reanalyzing the histological findings in men with well-defined varying extent of Y-chromosome microdeletions improved our understanding of the prospect of finding testicular spermatozoa. The chances of finding spermatozoa were almost nil in men with microdeletions that include the complete AZFa region or AZFb region or at least two AZF regions. Large microdeletions that include the Yq tip were suggested to cause chromosomal instability and were shown to be prone to Y chromosome loss. In addition, a decrease of sperm count over time in men with AZFc deletions has been reported and the option of spermatozoa cryo-preservation need to be taken in consideration. Analysis of the Y-chromosome microdeletion was found to be of prognostic value in cases of infertility both in terms of clinical management as well as for understanding the etiology of the spermatogenesis impairment.

PMID: 11905091 [PubMed - indexed for MEDLINE]

Detection of sperm in men with Y chromosome microdeletions of the AZFa, AZFb and AZFc regions.

Center for Male Reproductive Medicine and Microsurgery, Cornell Institute for Reproductive Medicine and Department of Urology, New York Weill-Cornell Medical Center, 525 East 68th Street, Starr 900, New York, NY 10021, USA.

BACKGROUND: Y chromosome microdeletions are associated with severe male factor infertility. In this study, the success rate of testicular sperm retrieval was determined for men with deletions of AZF regions a, b or c. METHODS: AZF deletions were detected by PCR of 30 sequence-tagged sites within Yq emphasizing the AZFa, b and c regions. Semen analysis and diagnostic testis biopsy or testicular sperm extraction (TESE) findings were correlated with the specific AZF region deleted. RESULTS: A total of 78 men with AZF deletions included three with AZFa deletion, 11 with AZFb, 42 with AZFc, 16 with AZFb+c and six with Yq (AZFa+b+c). All men with AZFa, AZFb, AZFb+c and Yq deletions were azoospermic and no sperm were found with TESE or biopsy. Of men with isolated AZFc deletion, sperm were found in 75% (9/12) by TESE and 45% (9/20) on biopsy (56% overall); 62% (26/42) were azoospermic and 38% (16/42) severely oligozoospermic. A total of 7 patients with deletion patterns that included the complete AZFa region and 23 that included the complete AZFb region who underwent TESE or biopsy did not have sperm detected by these surgical measures. CONCLUSIONS: Microdeletion of the entire AZFa or AZFb regions of the Y chromosome portends an exceptionally poor prognosis for sperm retrieval, whereas the majority of men with AZFc deletion have sperm within the semen or testes available for use in IVF/ICSI.

PMID: 12871878 [PubMed - indexed for MEDLINE]

Screening for Y chromosome microdeletions in idiopathic and nonidiopathic infertile men with varicocele and cryptorchidism.

Department of Urology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China.

BACKGROUND: Cytogenetic and molecular studies of azoospermic and oligozoospermic males have suggested the presence of azoospermia factors (AZF) in the Y chromosome. Deletion in AZF regions has been reported to disrupt spermatogenesis and cause infertility. Several candidate genes responsible for spermatogenesis have been identified in this region and some of them are thought to be functional in human spermatogenesis. And we reported clinical and molecular studies of Y chromosome microdeletions in Chinese. This study aimed at assessing the frequency of microdeletions in Chinese men with idiopathic and nonidiopathic infertility problems and dicussing the clinical significance of the AZF region. METHODS: In this study, we screened 143 infertile men (62 with idiopathic infertilitas and 81 with nonidiopathic infertilitas), in whom karyotype, sperm count, hormonal parameters and fine needle aspiration cytology were evaluated. Genomic DNA was extracted from the peripheral leukocytes. Molecular analysis was performed by two multiplex polymerase chain reactions (PCR) using a set of a sequence tagged sites (STS) from 3 different regions of the Y chromosome: AZFa (sY84, sY86), AZFb (sY127, sY134), AZFc (sY254, sY255). RESULTS: Nineteen point four percent of idiopathic males (12/62, 19.4%) had microdeletions of either the AZFa, AZFb, AZFc or AZFb + c region. Significantly, a high frequency of microdeletions (9/81, 11.1%) was found in nonidiopathic patients with varicocele and cryptorchidism. No deletions were found in healthy fertile men. There were no significant differences in the localization and extent of deletions between idiopathic and nonidiopathic patients. CONCLUSIONS: The knowledge of the presence of these deletions in idiopathic and nonidiopathic cases is important to understand the prognosis, better management and counsel these patients accordingly. Furthermore, a more extended screening for Y chromosome microdeletions in idiopathic and nonidiopathic men, particularly candidates for intracytoplasmic sperm injection, is recommended.

PMID: 16157049 [PubMed - indexed for MEDLINE]

[Molecular analysis of microdeletions of the Y chromosome in Venezuelan males with idiopathic infertility]

Instituto de Investigaciones Clínicas Dr. Am6rico Negrette, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela. erfernandez@luz.edu.ve

Today infertility is a major health problem affecting about 10-20% of couples. A male factor is assumed to be responsible in about 50% of the infertile couples. The origin of reduced testicular sperm function is unknown in about 60-70% of cases. There are several causes of male infertility such as varicocele, spermatic duct obstruction, and endocrine disorders. Micro-deletions in the Yq are known to represent the pathogenic mechanisms for infertile males. Three different non-overlapping regions designated as AZFa, AZFb, and AZFc are located in interval 5-6 of Yq, and are associated with impaired spermatogenesis in humans. To determine the prevalence of Y chromosomal microdeletions in Venezuelan males with idiopathic infertility, chromosomal, seminal, histological and molecular analyses were carried out in 29 Venezuelan males with idiopathic azoospermia or oligoospermia. Y-microdeletions analyses were performed using a multiplex polymerase chain reaction (PCR)-based technique with 22 sequences-tagged-sites (STSs). One of 29 patients (3.4%) had Yq microdeletions on AZFc. The frequency of AZF microdeletions in Venezuelan patients was similar to other populations with different ethnical or geographical origin.

PMID: 17176907 [PubMed - indexed for MEDLINE]

Study of microdeletions in the Y chromosome of infertile men with idiopathic oligo- or azoospermia.

Department of Obstetrics and Gynecology, The Third Hospital, Peking University, Beijing, China. guimei2613@yahoo.com.cn

PURPOSE: To determine the relationships between idiopathic oligo- or azoospermia and microdeletions of the Y chromosome. METHODS: Eighteen Y-linked sequence-tagged sites (STSs) in AZF (Azoospermia Factor) region were screened by means of multiplex PCR (Polymerase Chain Reaction) in 50 idiopathic infertile men, including 16 patients with azoospermia, 13 severe oligospermia, and 21 oligospermia. RESULTS: Microdeletions in the genomic DNA were observed in 8 of 50 cases, 3 with azoospermia, I severe oligospermia, and 4 oligospermia. Total deletion rate was 16.0% (8/50). The deletion regions were concentrated on AZFd and AZFc. CONCLUSIONS: Microdeletions of the Y chromosome are an important cause for idiopathic oligo- or azoospermia. Multiplex PCR is a useful technique for detecting the microdeletions. To avoid transmission to their offspring, patients with idiopathic oligo- or azoospermia should be screened for microdeletions of the Y chromosome before ICSI treatment for infertility.

PMID: 11804431 [PubMed - indexed for MEDLINE]

Polymorphic DAZ gene family in polymorphic structure of AZFc locus: Artwork or functional for human spermatogenesis?

Section Molecular Genetics & Infertility, Department Gynecol. Endocrinol. & Reproductive Medicine, University of Heidelberg, D-69115 Heidelberg, Germany. peter_vogt@med.uni-heidelberg.de

Human spermatogenesis is regulated by a network of genes located on autosomes and on sex chromosomes, but especially on the Y chromosome. Most results concerning the germ cell function of the Y genes were obtained by genomic breakpoint mapping studies of the Y chromosome of infertile patients. Although this approach has the benefit of focussing on those Y regions that contain most likely the Y genes of functional importance, its major drawback is the fact that fertile control samples were often missing. In fertile men, molecular and cytogenetic analyses of the Y chromosome has revealed highly polymorphic chromatin domains especially in the distal euchromatic part (Yq11.23) and in the heterochromatic part (Yq12) of the long arm. In sterile patients cytogenetic analyses mapped microscopically visible Y deletions and rearrangements in the same polymorphic Y regions. The presence of a Y chromosomal spermatogenesis locus was postulated to be located in Yq11.23 and designated as AZoospermia Factor (ZF). More recently, molecular deletion mapping in Yq11 has revealed a series of microdeletions that could be mapped to one of three different AZF loci: AZFa in proximal Yq11 (Yq11.21), AZFb and AZFc in two non-overlapping Y-regions in distal Yq11 (Yq11.23). This view was supported by the observation that AZFa and AZFb microdeletions were associated with a specific pathology in the patients' testis tissue. Only AZFc deletions were associated with a variable testicular pathology and in rare cases AZFc deletions were even found inherited from father to son. However, AZFc deletions were found with a frequency of 10-20% only in infertile men and most of them were proved to be "de novo", i.e. the AZFc deletion was restricted to the patient's Y chromosome. Based mainly on positional cloning experiments of testis cDNA clones and on the Y chromosomal sequence now published in GenBank, a first blueprint for the putative gene content of the AZFc locus can now be given and the gene location compared to the polymorphic DNA domains. This artwork of repetitive sequence blocks called AZFc amplicons raised the question whether the AZFc chromatin is still part of the heterochromatic domain of the Y long arm well known for its polymorphic extensions or is decondensed and part of the Yq11.23 euchromatin? We discuss also the polymorphic DAZ gene family and disclose putative origins of its molecular heterogeneity in fertile and infertile men recently identified by the analyses of Single Nucleotide Variants (SNVs) in this AZFc gene locus.

PMID: 12752250 [PubMed - indexed for MEDLINE]

Genomic heterogeneity and instability of the AZF locus on the human Y chromosome.

Section of Molecular Genetics and Infertility, Department of Gynecological Endocrinology and Reproductive Medicine, University of Heidelberg, Vossstrasse 9, D-69115 Heidelberg, FRG, Heidelberg, Germany. peter_vogt@med.uni-heidelberg.de

The spermatogenesis locus azoospermia factor (AZF) in Yq11 has been mapped to three microdeletion intervals designated as AZFa, AZFb, and AZFc. They are caused by intrachromosomal recombination events between large homologous repetitive sequence blocks, and AZFc microdeletions are now recognised as the most frequent known genetic lesion causing male infertility. However, in the same Y-region, large genomic heterogeneities are also observed in fertile men, and only complete AZFa and AZFb deletions are associated with a specific testicular pathology. Partial AZF deletions are associated with variable pathologies and partial AZFc deletions may even have no impact on male fertility. This suggests a genetic redundancy of the multi-copy genes in AZFb and AZFc and a causative relationship between the occurrence of first microdeletions then macrodeletions in the repetitive structure of Yq11 where large palindromes are probably promoting multiple gene conversions and AZF rearrangements.

PMID: 15353175 [PubMed - indexed for MEDLINE]

Male infertility: polymerase chain reaction-based deletion mapping of genes on the human chromosome.

School of Biotechnology, Dr. G.R. Damodaran College of Science, Civil Aerodrome Post, Coimbatore 641014, Tamil Nadu, India.

INTRODUCTION: Y chromosome microdeletions are common in about 10-15 percent of men with azoospermia or severe oligospermia. These microdeletions are too small to be detected by karyotyping. They can be easily identified using polymerase chain reaction (PCR). Most of the microdeletions that cause azoospermia or oligospermia occur in the non-overlapping regions of the long arm of the Y chromosome. These regions, also called azoospermia factor regions (AZF), are responsible for spermatogenesis. The loci are termed AZFa, AZFb and AZFc from proximal to distal Yq. Several genes located in AZF regions for spermatogenesis is viewed as "AZF candidate genes". This study aims at PCR-based rapid analysis of Y chromosome microdeletion, which is a cause for male infertility. METHODS: PCR amplification using Y-specific STS (sequence tagged sites) of AZF regions for AZFa: DBY and sY84, AZFb: RBM1 and sY127, and AZFc: BPY2 and sY254, were conducted. RESULTS: Of the 30 infertile men, 17 were azoospermic and 13 were severely oligospermic. Severe oligospermia was diagnosed in those patients who produced only one-third the concentrations of the sperm of that found in fertile men. Four patients showed a deletion of one or more STS. Two patients had complete deletion of AZFc loci, three patients had complete deletion of AZFa loci and two patients had complete deletion of AZFb loci. CONCLUSION: The frequency involving the microdeletion in the AZF region was found in four out of 30 azoospermic and severely oligospermic infertile men, i.e. 13.3 percent of the total deletions.

PMID: 18043844 [PubMed - indexed for MEDLINE]

Multiplex sequence-tagged site PCR for efficient screening of microdeletions in Y chromosome in infertile males with azoospermia or severe oligozoospermia.

Department of Urology, School of Medicine, Kanazawa University, Kanazawa, Ishikawa, Japan.

The multiplex STS-PCR method was used to detect microdeletions in the long arm of the Y chromosome (Yq) of cytogenetically normal men. One hundred infertile men with azoospermia or oligozoospermia were screened with the multiplex PCR method using 58 STSs, which are specific to Yq for detecting microdeletions on this chromosome. Correlations between the microdeletions on Yq and phenotypes of spermatogenetic disturbance were also examined. Ten patients (10%) had microdeletions on Yq. Seven of the 60 azoospermic patients (11.7%), and 3 of the 40 oligozoospermic patients (7.5%) had microdeletions on Yq. None of the patients showed microdeletions in the AZFa region, but 2 had deletions in the AZFb region, another 2 in the AZFc region, including DAZ, and 1 had deletions in both the AZFb and in the AZFc, including RBM and DAZ. Single microdeletions were found in 4 patients, all of them in the AZFc around DAZ, and 1 patient had 2 microdeletions in the AZFb. The improved multiplex STS-PCR method efficiently detected microdeletions in 10% of azoospermic or severe oligozoospermic men who were cytogenetically normal. All of these microdeletions were presented in the AZFb and/or AZFc regions. This suggests that these regions contain candidate genes for spermatogenesis.

PMID: 12230821 [PubMed - indexed for MEDLINE]

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

Institute of Human Genetics, Medical Faculty, University of Belgrade, 11000 Belgrade, Serbia and Montenegro. ristanmomo@beotel.yu

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.

PMID: 17853812 [PubMed - indexed for MEDLINE]

Y chromosome microdeletions in infertile men with idiopathic oligo- or azoospermia.

Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. serdar@kfshrc.edu.sa.

ABSTRACT : About 30-40% of male infertility is due to unknown reasons. Genetic contributions to the disruption of spermatogenesis are suggested and amongst the genetic factors studied, Y chromosome microdeletions represent the most common one. Screening for microdeletions in AZFa, b and c region of Y chromosome showed a big variation among different studies. The purpose of this study was to investigate the prevalence of such deletions in Saudi men. A total of 257 patients with idiopathic oligo- or azoospermia were screened for Y chromosome microdeletions by 19 markers in AZF region. Ten (3.9%) patients had chromosomal rearrangements, six of them showed sex chromosome abnormalities and four patients had apparently balanced autosomal rearrengements. Eight of the remaining 247 patients (3.2%) with a normal karyotype and no known causes of impaired spermatogenesis had Y chromosome microdeletions. Among these, six patients had deletions in AZFc region, one case had a deletion in AZFb and another had both AZFa and AZFc deletions.In conclusion, our study shows that Y chromosome microdeletions are low in our population. We also report for the first time a case with unique point deletions of AZFa and AZFc regions. The lower frequency of deletions in our study suggest that other genetic, epigenetic, nutritional and local factors may be responsible for idiopathic oligo- or azoospermia in the Saudi population.

PMID: 16445861 [PubMed - in process]

PMCID: PMC1382266

The prognostic role of the extent of Y microdeletion on spermatogenesis and maturity of Sertoli cells.

Institute for the Study of Fertility, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, the Sackler Faculty of Medicine, Tel Aviv University, Israel. ser@tasmc.health.gov.il

Substantial involvement of the Y chromosome in sexual development and spermatogenesis has been demonstrated. Over the last decade, varying extent of Y chromosome microdeletions have been identified among infertile patients with azoospermia or oligozoospermia. These microdeletions were clustered in three main regions named AZFa, AZFb, and AZFc. Analysis of the Y chromosome microdeletion was found to be of prognostic value in cases of infertility, both in terms of clinical management as well as for understanding the aetiology of the spermatogenesis impairment. However, the accumulated data are difficult to analyse, due to the variable extent of these deletions, the different sequence-tagged sites (STS) used to detect the microdeletions, and the non-uniformity of the histological terminology used by different investigators. This debate discusses the chances of finding testicular spermatozoa in men with a varying extent of Y chromosome microdeletions. The genotype and germ cell findings in men with AZFa microdeletions as well as those that include more than a single AZF region are reviewed, as is the effect of Y chromosome AZF microdeletions on the maturity of the Sertoli cells.

PMID: 11228202 [PubMed - indexed for MEDLINE]

Comment in:

Fertil Steril. 2006 Dec;86(6):1801-2; author reply 1802-3.

Role of the AZFd locus in spermatogenesis.

Department of Medical Genetics, Osmangazi University Medical Faculty, Meşelik, Eskişehir, Turkey.

To determine the prevalence of Y-chromosome microdeletions among infertile men and to correlate the clinical presentation of the men with specific deletions, microdeletion analysis in 53 infertile men (30 nonobstructive azoospermic, 23 severely oligozoospermic patients), and 100 age-matched, fathered normospermic men who had fathered children was performed by the multiplex PCR with 18 different Y-chromosome-specific STS primer sets, spanning the AZFa, AZFb, AZFd, and AZFc regions. Detection of the same locus deletion of the AZFd region in three cases indicated the possible importance of the genes located in this region in spermatogenesis.

PMID: 16084901 [PubMed - indexed for MEDLINE]

Y chromosome deletions in azoospermic men in India.

Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, India.

Genetic factors cause about 10% of male infertility. Azoospermia factors (AZFa, AZFb, AZFc) are considered to be the most important for spermatogenesis. We therefore made an attempt to evaluate the genetic cause of azoospermia, Y chromosome deletion in particular, in Indian men. We have analyzed a total of 570 men, including 340 azoospermic men and 230 normal control subjects. DNA samples were initially screened with 30 sequence-tagged site (STS) markers representing AZF regions (AZFa, AZFb, AZFc). Samples, with deletion in the above regions were mapped by STS walking. Further, the deletions were confirmed by Southern hybridization using the probes from both euchromatic and heterochromatic regions. Of the total 340 azoospermic men analyzed, 29 individuals (8.5%) showed Y chromosome deletion, of which deletion in AZFc region was the most common (82.8%) followed by AZFb (55.2%) and AZFa (24.1%). Microdeletions were observed in AZFa, whereas macrodeletions were observed in AZFb and AZFc regions. Deletion of heterochromatic and azoospermic regions was detected in 20.7% of the azoospermic men. In 7 azoospermic men, deletion was found in more than 8.0 Mb spanning AZFb and AZFc regions. Sequence analysis at the break points on the Y chromosome revealed the presence of L1, ERV, and other retroviral repeat elements. We also identified a approximately 240-kb region consisting of 125 bp tandem repeats predominantly comprised of ERV elements in the AZFb region. Histological study of the testicular tissue of the azoospermic men, who showed Y chromosome deletion, revealed complete absence of germ cells and presence of only Sertoli cells.

PMID: 12826698 [PubMed - indexed for MEDLINE]

Recombination between palindromes P5 and P1 on the human Y chromosome causes massive deletions and spermatogenic failure.

Howard Hughes Medical Institute, Whitehead Institute, and Department of Biology, Massachusetts Institute of Technology, Cambridge 02142, USA.

It is widely believed that at least three nonoverlapping regions of the human Y chromosome-AZFa, AZFb, and AZFc ("azoospermia factors" a, b, and c)-are essential for normal spermatogenesis. These intervals are defined by interstitial Y-chromosome deletions that impair or extinguish spermatogenesis. Deletion breakpoints, mechanisms, and lengths, as well as inventories of affected genes, have been elucidated for deletions of AZFa and of AZFc but not for deletions of AZFb or of AZFb plus AZFc. We studied three deletions of AZFb and eight deletions of AZFb plus AZFc, as assayed by the STSs defining these intervals. Guided by Y-chromosome sequence, we localized breakpoints precisely and were able to sequence nine of the deletion junctions. Homologous recombination can explain seven of these deletions but not the remaining two. This fact and our discovery of breakpoint hotspots suggest that factors in addition to homology underlie these deletions. The deletions previously thought to define AZFb were found to extend from palindrome P5 to the proximal arm of palindrome P1, 1.5 Mb within AZFc. Thus, they do not define a genomic region separate from AZFc. We also found that the deletions of AZFb plus AZFc, as assayed by standard STSs heretofore available, in fact extend from P5 to the distal arm of P1 and spare distal AZFc. Both classes of deletions are massive: P5/proximal-P1 deletions encompass up to 6.2 Mb and remove 32 genes and transcripts; P5/distal-P1 deletions encompass up to 7.7 Mb and remove 42 genes and transcripts. To our knowledge, these are the largest of all human interstitial deletions for which deletion junctions and complete intervening sequence are available. The restriction of the associated phenotype to spermatogenic failure indicates the remarkable functional specialization of the affected regions of the Y chromosome.

PMID: 12297986 [PubMed - indexed for MEDLINE]

PMCID: PMC419997

Y chromosome microdeletions, in azoospermic or near-azoospermic subjects, are located in the AZFc (DAZ) subregion.

Department of Obstetrics and Gynaecology, National University Hospital, Republic of Singapore.

Submicroscopic deletions of the Y chromosome and polymorphisms of the androgen receptor (AR) gene in the X chromosome have been observed in men with defective spermatogenesis. To further define the subregions/genes in the Y chromosome causing male infertility and its relationship to polymorphisms of the AR polyglutamine tract, we screened the genomic DNA of 202 subfertile males and 101 healthy fertile controls of predominantly Chinese ethnic origin. Y microdeletions were examined with 16 sequence-tagged site (STS) probes, including the RBM and DAZ genes, spanning the AZFb and AZFc subregions of Yq11, and related to the size of trinucleotide repeat encoding the AR polyglutamine tract. Y microdeletions were detected and confirmed in three out of 44 (6.8%) of azoospermic and three out of 86 (3.5%) severely oligozoospermic patients. No deletions were detected in any of the patients with sperm counts of >0.5 x 10(6)/ml, nor in any of the 101 fertile controls. All six affected patients had almost contiguous Y microdeletions spanning the entire AZFc region including the DAZ gene. The AZFb region, containing the RBM1 gene, was intact in five of the six subjects. Y deletions were not found in those with long AR polyglutamine tracts. Our study, the first in a Chinese population, suggest a cause and effect relationship between Y microdeletions in the AZFc region (possibly DAZ), and azoospermia or near-azoospermia. Y microdeletions and long AR polyglutamine tracts appear to be independent contributors to male infertility.

PMID: 9733433 [PubMed - indexed for MEDLINE]