PCR analysis of the Y chromosome long arm in azoospermic patients: evidence for a second locus required for spermatogenesis

Genome medicine in male infertility: From karyotyping to single-cell analysis

Male infertility is a multifactorial pathological condition that affects half of infertile couples. The majority of cases are categorized as idiopathic, especially in cases of nonobstructive azoospermia (NOA). An increasing number of genetic abnormalities have been shown to cause spermatogenic impairment with the development of microarray technologies and next-generation sequencing (NGS), moving beyond classical karyotype and polymerase chain reaction analyses of targeted genes. However, the majority of gene mutations, such as Klinefelter syndrome, azoospermia factor microdeletion, or congenital bilateral absence of the vas deferens, fail to function in a one gene-one phenotype manner. Single-cell transcriptome analysis performed using human testicular samples has begun to be published, which has brought about a more comprehensive understanding of testicular pathology. NGS also enables omics approaches, which provide more powerful tools to interrogate the genome, epigenome, transcriptome, and proteome. Simultaneously, the involvement of environmental factors and comorbidities, which may potentially regulate epigenetic factors, has been shown, resulting in a more complex understanding of the pathophysiology of spermatic disorders, especially NOA. The combination of phenotypic data and large amounts of bioinformatical data obtained by NGS may provide a more comprehensive understanding of the pathophysiology of male infertility, which will contribute not only to a diagnosis but also to the proper selection of infertility treatment and the development of new treatment modalities for male infertility.

Disease gene discovery in male infertility: past, present and future

Identifying the genes causing male infertility is important to increase our biological understanding as well as the diagnostic yield and clinical relevance of genetic testing in this disorder. While significant progress has been made in some areas, mainly in our knowledge of the genes underlying rare qualitative sperm defects, the same cannot be said for the genetics of quantitative sperm defects. Technological advances and approaches in genomics are critical for the process of disease gene identification. In this review we highlight the impact of various technological developments on male infertility gene discovery as well as functional validation, going from the past to the present and the future. In particular, we draw attention to the use of unbiased genomics approaches, the development of increasingly relevant functional assays and the importance of large-scale international collaboration to advance disease gene identification in male infertility.

The Biology and Evolution of Mammalian Y Chromosomes

Mammals have the oldest sex chromosome system known: the mammalian X and Y chromosomes evolved from ordinary autosomes beginning at least 180 million years ago. Despite their shared ancestry, mammalian Y chromosomes display enormous variation among species in size, gene content, and structural complexity. Several unique features of the Y chromosome--its lack of a homologous partner for crossing over, its functional specialization for spermatogenesis, and its high degree of sequence amplification--contribute to this extreme variation. However, amid this evolutionary turmoil many commonalities have been revealed that have contributed to our understanding of the selective pressures driving the evolution and biology of the Y chromosome. Two biological themes have defined Y-chromosome research over the past six decades: testis determination and spermatogenesis. A third biological theme begins to emerge from recent insights into the Y chromosome's roles beyond the reproductive tract--a theme that promises to broaden the reach of Y-chromosome research by shedding light on fundamental sex differences in human health and disease.

High frequency of TTTY2-like gene-related deletions in patients with idiopathic oligozoospermia and azoospermia

Genes located on Y chromosome and expressed in testis are likely to be involved in spermatogenesis. TTTY2 is a Y-linked multicopy gene family of unknown function that includes TTTY2L2A and TTTY2L12A at Yq11 and Yp11 loci respectively. Using PCR amplification, we screened for TTTY2L2A- and TTTY2L12A-associated deletions, in 94 Greek men with fertility problems. Patients were divided into three groups as following: group A (n = 28) included men with idiopathic moderate oligozoospermia, group B (n = 34) with idiopathic severe oligozoospermia and azoospermia, and group C (n = 32) with oligo- and azoospermia of various known etiologies. No deletions were detected in group C patients and 50 fertile controls. However, two patients from group A had deletions in TTTY2L2A (7.1%) and six in TTTY2L12A (21.4%), whereas from group B, four patients had deletions in TTTY2L2A (11.8%) and 10 in TTTY2L12A (29.4%). In addition, five patients from both groups A and B (8%) appeared to have deletions in both studied TTTY2 genes, although these are located very far apart. These results indicate that the TTTY2 gene family may play a significant role in spermatogenesis and suggest a possible mechanism of nonhomologous recombinational events that may cause genomic instability and ultimately lead to male infertility.

Chromosomal Abnormalities and Y Chromosome Microdeletions in Infertile Men With Varicocele and Idiopathic Infertility of South Indian Origin

Various factors cause spermatogenesis arrest in men and, in a large number of cases, the underlying reason still remains unknown. Little attention is paid to determining the genetic defects of varicocele-related infertility. The objective of our present study was to investigate the chromosomal abnormalities and Y chromosome microdeletions in infertile men of South Indian origin with varicocele and idiopathic infertility. Metaphase chromosomes of 251 infertile men with varicocele and unexplained infertility were analyzed using Giemsa-Trypsin-Giemsa (GTG) banding and fluorescence in situ hybridization (FISH). The microdeletions in 6 genes and 18 sequence-tagged-sites (STS) in the Yq region were screened using polymerase chain reaction (PCR) techniques. Out of 251 infertile men, 57 (22.7%) men were with varicocele, of which 8.77% were azoospermic, 26.31% were severely oligozoospermic, 21.05% were mildly oligozoospermic, and 43.85% were oligoasthenoteratozoospermic (OAT), and 194 (77.29%), with idiopathic infertility, of which 51% were azoospermic, 13.40% were severely oligozoospermic, 19.07% were mildly oligozoospermic, and 16.4% were with OAT. Genetic defects were observed in 38 (15.13%) infertile individuals, including 14 (24.56%) men with varicocele and 24 (12.37%) men with idiopathic infertility. The frequencies of chromosomal defects in varicocele and idiopathic infertility were 19.3% and 8.76%, respectively, whereas Y chromosome microdeletions were 5.26% and 3.60%, respectively. Overall rate of incidence of chromosomal anomalies and microdeletions in 251 infertile men were 11.5% and 3.98%, respectively, indicating a very significant higher association of genetic defects with varicocele than idiopathic male infertility. Our data also demonstrate that, among infertile men with varicocele, severely oligozoospermic and OAT men with varicocele have higher incidences of genetic defects than mildly oligozoospermic and azoospermic men.

Human Y chromosome microdeletion analysis by PCR multiplex protocols identifying only clinically relevant AZF microdeletions

PCR multiplex assays are the method of choice for quickly revealing genomic microdeletions in the large repetitive genomic sequence blocks on the long arm of the human Y chromosome. They harbor the Azoospermia Factor (AZF) genes, which cause male infertility when functionally disrupted. These protein encoding Y genes are expressed exclusively or predominantly during male germ cell development, i.e., at different phases of human spermatogenesis. They are located in three distinct genomic sequence regions designated AZFa, AZFb, and AZFc, respectively. Complete deletion of an AZF region, also called "classical" AZF microdeletion, is always associated with male infertility and a distinct testicular pathology. Partial AZF deletions including single AZF Y genes can cause the same testicular pathology as the corresponding complete deletion (e.g., DDX3Y gene deletions in AZFa), or might not be associated with male infertility at all (e.g., some BPY2, CDY1, DAZ gene deletions in AZFc). We therefore propose that a PCR multiplex assay aimed to reduce only those AZF microdeletions causing a specific testicular pathology-thus relevant for clinical applications. It only includes Sequence Tagged Site (STS) deletion markers inside the exon structures of the Y genes known to be expressed in male germ cells and located in the three AZF regions. They were integrated in a robust standard protocol for four PCR multiplex mixtures which also include the basic principles of quality control according to the strict guidelines of the European Molecular Genetics Quality Network (EMQN: http://www.emqn.org). In case all Y genes of one AZF region are deleted the molecular extension of this AZF microdeletion is diagnosed to be yes or no comparable to that of the "classical" AZF microdeletion by an additional PCR multiplex assay analyzing the putative AZF breakpoint borderlines.

Molecular and cytogenetic studies of 101 infertile men with microdeletions of Y chromosome in 1,306 infertile Korean men

OBJECTIVES

To determine the prevalence of Y chromosome microdeletions in infertile Korean men with abnormal sperm counts and to assess the clinical features and frequency of chromosomal abnormalities in Korean patients with microdeletions.

METHODS

A total of 1,306 infertile men were screened for Y chromosome microdeletions, and 101 of them had microdeletions. These 101 men were then retrospectively studied for cytogenetic evaluation, testicular biopsy and outcomes of IVF and ICSI.

RESULTS

The overall prevalence of Y chromosome microdeletions in infertile men was 7.7% (101/1,306). Most microdeletions were in the AZFc region (87.1%), including deletions of AZFbc (24.7%) and AZFabc (8.9%). All patients with AZFa, AZFbc and AZFabc deletions had azoospermia, whereas patients with an AZFc deletion usually had low levels of sperm in the ejaculate or in the testis tissues. Chromosomal studies were performed in 99 men with microdeletions, 36 (36.4%) of whom had chromosomal abnormalities. Among the infertile men with Y chromosome microdeletions in this study, the incidence of chromosomal abnormality was 48.6% in the azoospermic group and 3.7% in the oligozoospermic group. Among the 69 patients with microdeletions and available histological results, 100.0% of the azoospermic group and 85.7% of the oligozoospermic group had histological abnormalities. The frequency of both chromosomal abnormalities and histological abnormalities was higher in the azoospermic group compared to the oligozoospermic group. Thirty-four ICSI cycles with either testicular (n = 14) or ejaculated spermatozoa (n = 20) were performed in 23 couples with men with AZFc microdeletion. Thirteen clinical pregnancies (39.4%) were obtained, leading to the birth of 13 babies.

CONCLUSIONS

The study results revealed a close relationship between microdeletions and spermatogenesis, although IVF outcome was not significantly affected by the presence of the AZFc microdeletion. Nevertheless, Y chromosome microdeletions have the potential risk of being transmitted from infertile fathers to their offspring by ICSI. Therefore, before using ICSI in infertile patients with severe spermatogenic defects, careful evaluations of chromosomal abnormalities and Y chromosome microdeletions screening should be performed and genetic counseling should be provided before IVF-ET.

The Y chromosome in the era of intracytoplasmic sperm injection: a personal review

The Y chromosome contains 60 multicopy genes composed of nine different gene families concentrated in regions of multiple repeat sequences called amplicons arranged in mirror images called palindromes. This pattern is susceptible to deletions caused by homologous recombination with itself, and can explain the presence of small numbers of sperm in otherwise azoospermic men.

Y Chromosome microdeletion and altered sperm quality in human males with high concentration of seminal hexachlorocyclohexane (HCH)

Recent studies have shown Y chromosome microdeletions associated with male infertility. The factors responsible for Y chromosome microdeletions in spermatozoa remain unresolved. However, the environmental pollutants are known to damage DNA in differentiating and maturing germ cells in the male reproductive tract. Therefore, the aim of this study was to investigate the effects of seminal hexachlorocyclohexane (HCH) and its isomers, an environmental pollutant, in 50 fertile and 50 infertile males in relation to semen quality and the incidence of Y chromosome microdeletion in azoospermic factor (AZF) region. As compared to control, an increased HCH level and significantly decreased semen quality were observed in the infertile males. A positive significant association was found between sperm count with alpha-HCH and beta-HCH in the infertile males. A negative significant association was observed between sperm counts with gamma-HCH in asthenospermia patients and with beta-HCH and total HCH in oligo-asthenospermic patients. Out of 100 males studied, we found 10 patients with Yq deletion in AZFa and AZFc regions. Subdivision of infertile group revealed a deletion incidence of 61.5% in azoospermic patients, 11.1% in oligospermic patients and 16.6% in oligo-asthenospermic patients. The presence of Yq deletion in azoospermic patients with a significant mean difference of beta-HCH and total HCH in relation to reduced semen quality seem to corroborate with the mutagenic activity of HCH. The results of this study indicated the susceptibility of male germ line to mutagenic potential of HCH which is an acknowledged risk factor leading to spermatogenic failure.

Genetic dissection of the AZF regions of the human Y chromosome: thriller or filler for male (in)fertility?

The azoospermia factor (AZF) regions consist of three genetic domains in the long arm of the human Y chromosome referred to as AZFa, AZFb and AZFc. These are of importance for male fertility since they are home to genes required for spermatogenesis. In this paper a comprehensive analysis of AZF structure and gene content will be undertaken. Particular care will be given to the molecular mechanisms underlying the spermatogenic impairment phenotypes associated to AZF deletions. Analysis of the 14 different AZF genes or gene families argues for the existence of functional asymmetries between the determinants; while some are prominent players in spermatogenesis, others seem to modulate more subtly the program. In this regard, evidence supporting the notion that DDX3Y, KDM5D, RBMY1A1, DAZ, and CDY represent key AZF spermatogenic determinants will be discussed.

A genetic survey of 1935 Turkish men with severe male factor infertility

Male factor infertility is the sole reason in approximately 25% of couples who suffer from infertility. Genetic factors such as numerical and structural chromosomal abnormalities and microdeletions of the Y chromosome might be the cause of poor semen parameters. The results of karyotype analyses and Y-chromosome microdeletions of 1935 patients with severe male factor infertility, which is the largest series from Turkey, were assessed retrospectively. The frequency of cytogenetic abnormalities among 1214 patients with non-obstructive azoospermia (NOA) and 721 patients with severe oligoasthenoteratozoospermia (OAT) were 16.40 and 5.83% respectively. The overall incidence of Y-chromosome microdeletion was 7.70%. The incidence of Y chromosome microdeletion in patients with NOA and OAT was 9.51 and 1.86% respectively. The abnormality rate increased with the severity of infertility. Some patients (n = 22) were carriers of both chromosomal abnormalities and Y-chromosome microdeletions. Results suggest the need for genetic screening and proper genetic counselling before initiation of assisted reproduction treatment.

SRY and AZF gene variation in male infertility: a cytogenetic and molecular approach

AIM

The aim of this study was to identify the genetic effects of Y chromosome and azoospermia factor (AZF) gene variation in men with infertility and to elucidate the molecular mechanism responsible for the identified point mutation.

METHODS

Chromosome analysis was performed according to standard methods on lymphocyte cultured cells and genomic DNA was extracted from the peripheral blood. Three sets of primers were used encompassing the AZFb, AZFc and SRY14 gene regions. Products were genotyped with single-strand comformational polymorphisim (SSCP) analysis.

RESULTS

The profiles of the mutated genes were detected in five of three azoospermic and two oligoasthenozoospermic infertile males. The SSCP variability of the AZFc gene was detected in all of the cases, while sex-determining region Y (SRY) gene variation was detected in two of the current cases. Three cases with oligoasthenozoospermia showed mutated SSCP profiles in both their SRY and AZFc gene regions. No AZFb variation was detected in the presented cases.

CONCLUSION

The AZF locus is assumed to contain the genes responsible for spermatogenesis in human. Deletions in these genes are thought to be involved in male infertility associated with azoospermia, oligozoospermia and/or both. AZF microdeletions and variations that are seen in infertile males suggest the need for molecular screening of such cases. Advance studies are also needed to detect of these variations and their relevance to male infertility before using assisted reproduction techniques in such cases.

Altered expression pattern of heat shock transcription factor, Y chromosome (HSFY) may be related to altered differentiation of spermatogenic cells in testes with deteriorated spermatogenesis

OBJECTIVE

To evaluate the expression patterns of heat shock transcription factor, Y chromosome (HSFY), in the testes showing deteriorated spermatogenesis.

DESIGN

Prospective study.

SETTING

University hospital, its branch hospital, and academic laboratory.

PATIENT(S)

Men undergoing testicular biopsy for the investigation of infertility and men undergoing orchiectomy for testicular cancer.

INTERVENTION(S)

After pathologic evaluation, specimens were subdivided into three groups: normal spermatogenesis (n = 8), maturation arrest (n = 5), and Sertoli cell-only syndrome (n = 4). Immunostaining and Western blotting techniques determined the expression of HSFY.

MAIN OUTCOME MEASURE(S)

Expression of HSFY in testes.

RESULT(S)

Western blotting data revealed HSFY in the testicular tissues with normal spermatogenesis, maturation arrest, and Sertoli cell-only syndrome, but the amount of the protein in the maturation arrest and Sertoli cell-only syndrome samples was altered. The immunohistochemical data demonstrated that HSFY was expressed in spermatogenic cells and Sertoli cells in all specimens. However, the expression of HSFY was low or absent in spermatogenic cells of maturation arrest specimens, and the ratio of HSFY expressed in Sertoli cells was different in the specimens with maturation arrest and with Sertoli cell-only syndrome.

CONCLUSION(S)

Altered expression of the HSFY in the testis showing deteriorated spermatogenesis may be associated with alteration of spermatogenic cell differentiation.

A rapid and simple system of detecting deletions on the Y chromosome related with male infertility using multiplex PCR

Around 10% of males with idiopathic azoospermia or oligozoospermia, which are important causes of male infertility, have partial deletions on the long arm of the Y chromosome. To develop a rapid and accurate detection system for screening major Y deletions found in infertile men, we developed a multiplex PCR system that can simultaneously amplify five loci on the Y chromosome, SRY, AMELY, DBY, RBMY, DAZ and one locus on the X chromosome, AMELX. The size of the PCR products was designed to increase gradually from the distal Yp to the distal Yq. Our system could detect deletions of three major candidate regions for the azoospermic factor, AZFa, AZFb and AZFc on the Y chromosome together with sex. The gradual increase in the size of the PCR products was convenient for imaging the location of deletions on the Y chromosome. Moreover, the multiplex PCR system was combined with microchip-based electrophoresis, and the PCR products derived from each locus were separated within 4 min. Our system is useful for screening Y chromosomes bearing the structural anomalies including three major AZF deletions found among azoospermic or oligozoospermic males.

Survey of the two polymorphisms in DAZL, an autosomal candidate for the azoospermic factor, in Japanese infertile men and implications for male infertility

The DAZL (DAZ-like) gene is suggested to be an ancestral gene of the DAZ (deleted in azoospermia) gene on the Y chromosome, which is a strong candidate for the azoospermic factor. Recently, it has been reported that the T54A (Thr54-->Ala) polymorphism in exon 3 of the DAZL gene is associated with spermatogenic failure in the Taiwanese population. In this study, to investigate whether this polymorphism is associated with spermatogenic failure in Japanese males, we analysed genomic DNA derived from 234 patients with azoospermia or oligozoospermia and 131 fertile controls. The T54A polymorphism was completely absent in both the patients and the controls. The T12A (Thr12-->Ala) polymorphism in exon 2 of the DAZL gene was found at a similar frequency in the patients and controls, 15.4% and 13.7%, respectively (P = 0.67). However, the frequency of T12A was higher for the azoospermic (20.5%) than oligozoospermic (9.6%) individuals in infertile men without DAZ deletions, although statistical difference was not so apparent (chi2 test: P = 0.037, OR = 2.413, 95% CI = 1.035-5.629; Yate's chi2 test: P = 0.058, OR = 2.319, 95% CI = 0.973-6.166). Our results show that the T54A polymorphism in DAZL has no major role in Japanese males with azoospermia or oligozoospermia. The distribution of the T54A polymorphism may be restricted to the narrow area including Taiwan.

Embryo outcome in Y-chromosome microdeleted infertile males after ICSI

A prospective study involving 118 infertile Japanese couples to assess the embryo outcomes in both azoospermic and oligoasthenoteratoazoospermic (OAT) patients with Y-chromosome microdeletion. The men were divided into two groups; azoospermia (n = 27), and OAT, sperm concentration <5 x 10(6)/ml (n = 91). They were investigated for Y-chromosome microdeletions by a polymerase chain reaction (PCR) amplification of the Y-chromosome-specific sequence tag site (STS). The embryo outcomes of patients found to have Y-microdeletion were determined. The frequency of microdeletion was 8.8% (9) and two had microdeletions distal to DAZ. The mean fertilization rate and the cleavage rate in the eight cycles of both azoospermic and oligospermic patients were 59.3 and 87.5%, respectively. The percentages of grade 1 & 2 embryos, > or =6 cells embryos, and blastocyts were 51.7, 65.6, and 45.3%, respectively. Three pregnancies resulted from the eight cycles (37.5%).

CONCLUSION

in Y-chromosome microdeletion cycles in which sperm cells were available for intracytoplasmic sperm injection (ICSI), embryo outcome was comparable to conventional IVF.

Semen characteristics: Advancement in andrological assessment

Progress in diagnosis of infertility, has been dramatically increased during the past decades with changes occurring in virtually all aspects of infertility research, thus providing innovative diagnostic testing and sophisticated instrumentation for improved management and treatment of infertility. There are about 50% of infertile couples who are suffering because of male infertility. Semen examination is a basic investigation for these infertile couples. It not only reveals the quantity and quality of sperm but also the quality of the seminal plasma, which is essential for normal sperm function. In this review, the recent advancement in investigation procedures has been analyzed which are very important in clinical practice to (a) evaluate the sperm fertilizing ability (Acrosin, aniline blue, HOS), (b) characterization of male accessory sex glands secretions (Fructose, alpha-glucosidase, PSA) and (c) the management of azoospermic patients. It is believed that use of such diagnostic procedures will facilitate wide selection of patients for whom an effective therapy might be then possible.

Male infertility and mitochondrial DNA

The mitochondrial machinery plays a key role in the energy production and maintenance of spermatozoa motility. In this paper 200 idiopathic oligo-asthenozoospermic patients were classified on the basis of rapid progressive motility ("a") and sperm concentration. Mitochondrial enzymatic activity was studied and correlated to the viability of sperm cells. Mitochondrial DNA purified from both motile and non-motile sperm of the same individuals was amplificated using PCR. Results suggested that only motile sperm have organelles functional in oxygen consumption, unequivocally demonstrating that motility depends on the mitochondrial activity. Mitochondrial DNA of oligo-asthenozoospermic patients seemed to present some defects that made DNA unavailable for amplification.

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 (approximately 5%) is much lower than the frequency (approximately 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.

Genomics of the human Y-chromosome. 1. Association with male infertility

The human Y chromosome contains over 60 million nucleotides, but least number of genes compared to any other chromosome and acts as a genetic determinant of the male characteristic features. The male specific region, MSY, comprising 95% of the Y chromosome represents a mosaic of heterochromatic and three classes of euchromatic (X-transposed, X-degenerate and ampliconic) sequences. Thus far, 156 transcription units, 78 protein-coding genes and 27 distinct proteins of the Y chromosome have been identified. The MSY euchromatic sequences show frequent gene conversion. Of the eight massive palindromes identified on the human Y chromosome, six harbor vital testis specific genes. The human male infertility has been attributed to mutations in the genes on Y chromosome and autosomes and failures of several physical and physiological attributes including paracrine controls. In addition, deletion of any one or all the three azoospermia (AZFa, AZFb or AZFc) factor(s) and some still unidentified regulatory elements located elsewhere in the genome result in infertility. Characterization of palindromic complexes on the long arm of Y chromosome encompassing AZFb and AZFc regions and identification of HERV15 class of endogenous retroviruses close to AZFa region have facilitated our understanding on the organization of azoospermia factors. Considerable overlap of the AZFb and AZFc regions encompassing a number of genes and transcripts has been shown to exist. However, barring details on AZF, information on the exact number of genes or the types of mutations prevalent in the infertile male is not available. Similarly, roles of sizable body of repetitive DNA present in close association with transcribing sequences on the Y chromosome are yet not clear. In a clinical setting with known cases of infertility, systematic search for loss or gain of these repeat elements would help understand their biological role(s). We present a brief overview on the genetic complexity of the human Y chromosome in the context of human male infertility.

[Molecular detection of Y chromosome microdeletions: a new approach based on the denaturing gradient gel electrophoresis]

Ten percent of couples trying for a child fail to conceive. In approximately 50% of cases, infertility is due to the inability of the male partner to produce spermatozoa in sufficient numbers to effect conception. Over the past 5 years, molecular studies have suggested that interstitial microdeletions in Yq11 represent an etiological factor for male infertility. Y-microdeletions have been detected in 12% of non-obstructive azoospermia and 6% of severe oligozoospermia. In general, microdeletions were detected by separate multiplex-polymerase chain reaction (PCR) reactions using primer pairs for single tagged sites (STSs) of all three azoospermia factor (AZF) regions (AZFa, AZFb and AZFc). This review describes the molecular methods and laboratory guidelines for molecular diagnosis of Y-chromosomal microdeletions. The diagnostics of Y-chromosomal microdeletions should be performed in two steps: in any case, the routine diagnostic should include six STS loci, two STS loci localised in each AZF region, and once a deletion is detected, the analysis can be extended to STS loci known to cross the proximal and the distal borderlines of each AZF region. Other molecular techniques such as DGGE, Southern blot should be performed to detect partial deletions of gene copies or mosaicism. These different molecular approaches should allow explaining 10% of male infertility, to evaluate the risk to pass the defect onto their male offspring (by intracytoplasmic sperm injection) and improve the genetic counselling of couples undergoing micromanipulative assisted reproduction.

Members of the CDY family have different expression patterns: CDY1 transcripts have the best correlation with complete spermatogenesis

The CDY family of genes is of special interest because some of them are included in chromosome-Y microdeletions detected among infertile men and are apparently involved in the spermiogenetic process. In this study, we employed the reverse transcriptase/polymerase chain reaction technique to test the RNA expression of the various transcripts of these genes in testicular biopsies of 84 azoospermic men who had been classified by comprehensive histology and cytology analyses. We also evaluated the feasibility of detecting CDY expression in biopsies taken by testicular sperm extraction versus acquisition by aspiration. There was a significant association between the type of testicular impairment and the expression of CDY1 and CDY2 transcripts. CDY2 was expressed whenever germ cells were present, but CDY1 major and especially CDY1 minor and short transcripts were identified almost exclusively when mature spermatids/spermatozoa were detected. The expression of CDY1 minor and short transcripts detected in aspirated specimens was less efficient than that in testicular tissue acquired by extraction. It is suggested that CDY2 is apparently required in the early stages of spermatogenesis, whereas CDY1 transcripts are required later on in the process. The findings of this study imply different functional roles for CDY isoforms during spermatogenesis. However, in consideration of the high levels of identity between CDY1 and CDY2 (98% at the protein level), the delayed up-regulation of CDY1 transcripts could be attributable to temporal changes in dosage requirements.

Prevalence of Y chromosome deletions in a Brazilian population of nonobstructive azoospermic and severely oligozoospermic men

We determined the prevalence of Y chromosome deletions in a population of 60 Brazilian nonobstructive azoospermic and severely oligozoospermic men. PCR-based screening of microdeletions was performed on lymphocyte DNA for the presence of 14 sequence-tagged sites (STS) located in the azoospermic factor (AZF) on the Yq chromosome. All STS were amplified efficiently in samples from 12 fertile men tested, but failed to be amplified in samples from fertile women, indicating the specificity of PCR conditions for Yq screening. Overall, 4 of the 60 infertile patients tested (6.7%) exhibited deletion of the Y chromosome, 2 of them being severely oligozoospermic patients (P10 and P32) and 2 azoospermic men (patients P47 and P57). Patients P47 and P57 presented larger deletions in the AZFa, AZFb and AZFc subregions, with apparent loss of Yq material evidenced by karyotype analysis. Patients P10 and P32 presented deletions confined to the AZFc region, involving the DAZ locus. Male relatives of patients P10 and P32 had no Y chromosome deletions and presented a normal karyotype, suggesting a de novo status of the deletions found. Our data add to the growing literature showing that microdeletions of the Y chromosome can be the cause of male idiopathic infertility.

A simplified method for the detection of Y chromosome microdeletions in infertile men using a multiplex sequence-tagged site-based amplification

Sixteen sequence-tagged sites (STSs) were combined in five amplification reactions, to screen for deletions of DNA fragments located within the AZFa, AZFb, and AZFc regions of the Y chromosome. This multiplex strategy is fast and reliable, and most of the azoospermia-associated deletions reported so far are detected with this simplified method. Internal control STSs are included that allow discrimination between deletion and failure of amplification.

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 (</=5 x 10(6) sptz/ml). Based on an extensive analysis of the literature, we have established a cost-effective preliminary PCR-based diagnostic screening test, with a set of six pairs of primers ("set-of-6") that have the capability of detecting up to 95% of the Y microdeletion cases already published. These primers are: sY84 in AZFa, sY114, sY129, sY143 in AZFb, and sY149, sY254 in AZFc. Initially, the set-of-6 was tested with 13 other pairs of primers covering the three AZF subregions. A sample of 114 infertile men was tested and 10 (8.8%) microdeletions were found, 3 of which were among the 26 (11.5%) idiopathic azoospermic men. These results showed that all detected microdeletions would be identified using the set-of-6 only. Another sample of 34 patients was subsequently tested using the set-of-6 and 3 (8.8%) microdeletions were found in this group. A comparison of our results with those reported in the literature showed similar microdeletion detection frequencies, demonstrating that the set-of-6 primers provides a reliable, simple and cost-effective way of detecting AZF deletions.

Comprehensive office evaluation in the new millennium

The success of a comprehensive office-based evaluation of male-factor infertility depends on the physician's thorough understanding of risk assessment in the history, identification of pertinent physical examination findings, and correct assessment of laboratory data. Office-based ultrasonographic techniques have already increased the urologist's ability to visualize suspected anatomic abnormalities, and the use of functional tests of sperm has given greater depth to the limited, but essential, prognostic capabilities of the routine semen analysis.

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

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.

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

PURPOSE

To compare the prevalence and type of Y-microdeletions in Hong Kong and Shanghai men with severe male-factor infertility.

METHODS

Seven Y-linked sequence tagged site (STS) primers and seven gene-specific primers were screened in 293 infertile males (139 from Hong Kong and 154 from Shanghai) and 161 fertile men (61 from Hong Kong and 100 from Shanghai). Serum FSH, LH, and testosterone levels were also measured in these men.

RESULTS

The incidence of Yq microdeletions in nonobstructive azoospermic men from Hong Kong (8.5%) and Shanghai (6%) was similar. Yq microdeletions were observed in severe oligospermic patients (8.5%) from Hong Kong but not from Shanghai. Among the 9 Hong Kong men with Y-microdeletions, 8 had AZFc deletion and one had AZFb deletion. In contrast, 6 of 9 men from Shanghai with Y-microdeletions had AZFb deletion. The incidence of AZFb deletion among Y-microdeleted men was statistically different between the two populations. Two of the men with AZFb deletion also had AZFa and AZFc deletions.

CONCLUSIONS

Regional variations in the type of Y-microdeletion existed between Hong Kong and Shanghai infertile males.

Spontaneous transmission from a father to his son of a Y chromosome microdeletion involving the deleted in azoospermia (DAZ) gene

Microdeletions of the so-called azoospermia factor (AZF) locus of the Y chromosome long arm (Yq) have been recognized as an etiological factor of severe oligozoospermia or azoospermia. Because of this, patients affected are generally infertile unless assisted reproductive techniques are used. We report the case of an oligozoospermic patient (proband) who inherited an extensive Yq microdeletion from his father through a spontaneous pregnancy. Leukocyte DNA was extracted using a commercially available kit. A total of 22 pairs of sequence-tagged site (STSs) based primers, spanning the entire AZF region, were used for the screening. Both the proband and his father carried a Yq microdeletion of the most distal AZF subregion (AZFc) where the deleted in azoospermia (DAZ) gene is located. The proband's father was a sixty-nine-yr-old man who had 3 other children, 2 females and 1 male. This case adds further evidence that the deletion of the DAZ gene is associated with different phenotypic expressions, including normal fertility.

A nation-based population screening for azoospermia factor deletions in Greek-Cypriot patients with severe spermatogenic failure and normal fertile controls, using a specific study and experimental design

Y chromosome microdeletions in the azoospermia factor (AZF) locus have been associated with spermatogenic failure. The frequency of AZF deletions is estimated to be about 10-18% in subgroups of idiopathic azoospermia and severe oligospermia, whereas the deletion frequency is estimated to be about 1.5-10.6% in the general population. Patient selection criteria as well as experimental and study design are the major factors that influence the deletion frequency. We designed a nation-based population screening with a well-defined study and experimental criteria to answer, first, what is the deletion frequency in a study population of high risk for Y deletion in the Greek-Cypriot origin and second, if there are any differences in the deletion frequency in the investigated specific subgroup of patients from different geographic/ethnic origin. Eighty Greek-Cypriot patients who met the selection criteria were included in this study as well as 50 fertile control males. The sample size is quite large when compared with the size of the population. All samples were collected from all districts of the island of Cyprus as the population is of the same religious, geographic and ethnic origin. All patients and controls had detailed clinical information and at least two semen-analysis reports based on World Health Organization standards. Samples with abnormal karyotypes, obstructive azoospermia or oligospermia with >2 x 106/mL were excluded from this study. The experimental design required a referral team and laboratory to undertake the responsibility to collect all the samples, all clinical and laboratory information, isolate DNA and carry out all tests, data analysis and interpretation. In our study, Y chromosome microdeletions have been found in patients with spermatogenic failure. Under the specific patient selection criteria and experimental design, the overall frequency is 5%, while among azoospermic patients it is 12.5%. In the subgroups of patients with idiopathic cause it is 5.9% and in idiopathic azoospermia it is 14.3%. No variation in the overall deletion frequency or the specific subgroups deletion frequency were found, as compared with frequencies found in patients from different geographic/ethnic origin.

Deletion of RBM and DAZ in azoospermia: evaluation by PRINS

Molecular and cytogenetic studies from infertile men have shown that one or more genes controlling spermatogenesis are located in proximal Yq11.2 in interval 6 of the Y chromosome. Microdeletions within the azoospermia factor region (AZF) are often associated with azoospermia and severe oligospermia in men with idiopathic infertility. We evaluated cells from a normal-appearing 27-year-old man with infertility and initial karyotype of 45,der(X)t(X;Y)(p22.3;p11.2)[8]/46,t(X;Y)(p22.3;p11.2)[12]. By fluorescence in situ hybridization with dual-color whole chromosome paint probes for X and Y chromosomes, we confirmed the Xp-Yp interchange. By primed in situ labeling, we identified translocation of the SRY gene from its original location on Yp to the patient's X chromosome at band Xp22. We also obtained evidence that the apparent marker was a der(Y) (possibly a ring) containing X and Y domains, and observed that the patient's genome was deleted for RBM and DAZ, two candidate genes for AZF.

Molecular analysis of the Y chromosome AZFc region in Japanese infertile males with spermatogenic defects

Cytogenetic and molecular studies of azoospermic and oligozoospermic males have suggested the presence of azoospermia factors (AZF) in the human Y chromosome. Deletion in three Y chromosomal regions--AZFa, AZFb and AZFc--has been reported to disrupt spermatogenesis and cause infertility. Several candidate genes responsible for spermatogenesis have been identified in these regions and some of them are thought to be functional in human spermatogenesis. Here we report on clinical and molecular studies of Y chromosome micro-deletions in Japanese. In these studies the data from 157 infertile Japanese men with azoospermia and oligozoospermia was analyzed and divided into 5 categories based on spermatozoa count. Sixteen sets of primers were used for polymerase chain reaction (PCR) to amplify sequence tagged site markers. One common deletion in the AZFc region was identified in infertile men. On the other hand, no deletions around the AZFc region were identified in fertile men. Japanese infertile men in our study had a common deletion in the AZFc region of the Y chromosome. A genomic clone was obtained by PCR screening of the P1 phage artificial chromosome (PAC) library. This clone was analyzed by Southern blotting using a PCR amplified probe of sY240. Our analysis of the genomic sequence of the clone suggests that this locus may contain specific genes for spermatogenesis.

Male infertility, genetic analysis of the DAZ genes on the human Y chromosome and genetic analysis of DNA repair

Many genes that are required for fertility have been identified in model organisms (). Mutations in these genes cause infertility due to defects in development of the germ cell lineage, but the organism is otherwise healthy. Although human reproduction is undoubtedly as complex as that of other organisms, very few fertility loci have been mapped (). This is in spite of the prevalence of human infertility, the lack of effective treatments to remedy germ cell defects, and the cost to couples and society of assisted reproductive techniques. Fifteen percent of couples are infertile and half of all cases can be traced to the male partner. Aside from defects in sperm production, most infertile men are otherwise healthy. This review is divided into two distinct parts to discuss work that: (i) led to the identification of several genes on the Y chromosome that likely function in sperm production; and (ii) implicates DNA repair in male infertility via increased frequency of mutations in DNA from men with meiotic arrest.

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

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.

Invited review: sex-based differences in gene expression

Certain diseases are more prevalent among women than men. The reasons for this increased prevalence are unknown, but there could be a genetic basis. Increased expression of X-linked genes in females, protective effects of Y-linked genes in males, or sex-limited gene expression that is developmentally or hormonally regulated could all account for these differences. Analysis of individuals with and without genetic sex reversal provides a means for distinguishing between genetic and hormonal causes. This can be complemented by genetic linkage and gene expression profiling to aid in the identification of candidate genes.

The AZFc region of the Y chromosome features massive palindromes and uniform recurrent deletions in infertile men

Deletions of the AZFc (azoospermia factor c) region of the Y chromosome are the most common known cause of spermatogenic failure. We determined the complete nucleotide sequence of AZFc by identifying and distinguishing between near-identical amplicons (massive repeat units) using an iterative mapping-sequencing process. A complex of three palindromes, the largest spanning 3 Mb with 99.97% identity between its arms, encompasses the AZFc region. The palindromes are constructed from six distinct families of amplicons, with unit lengths of 115-678 kb, and may have resulted from tandem duplication and inversion during primate evolution. The palindromic complex contains 11 families of transcription units, all expressed in testis. Deletions of AZFc that cause infertility are remarkably uniform, spanning a 3.5-Mb segment and bounded by 229-kb direct repeats that probably served as substrates for homologous recombination.

Multiplex PCR for screening of microdeletions on the Y chromosome

PURPOSE

The aim of this study was to develop a multiplex PCR protocol, which could be suitable for screening of microdeletions in the three azoospermia factor (AZF) regions on the Y chromosome.

METHODS

In the screening protocol, 36 known sequence tagged site (STS) primer pairs were first tested in single PCR reactions and thereafter combined in multiplex PCR to test for specificity and sensitivity in order to develop a stable and reliable multiplex PCR assay to detect Y microdeletions.

RESULTS

Of the 36 primers tested, 11 turned out not to be specific or produced PCR products that were too weak, and they were therefore not used in the multiplex PCR. The remaining 25 STSs were selected on the basis of their ability to be reproducibly amplified with each other using identical amplification conditions. Five multiplex sets, each consisting of five primer pairs, were established in the multiplex PCR setup.

CONCLUSION

The multiplex PCR protocol presented in this study is an easy and reliable method for detection of Y chromosome microdeletions and could be used for screening of infertile men to allow genetic counseling about the risk of transmitting infertility from father to son.

Y chromosome microdeletions and alterations of spermatogenesis

Three different spermatogenesis loci have been mapped on the Y chromosome and named "azoospermia factors" (AZFa, b, and c). Deletions in these regions remove one or more of the candidate genes (DAZ, RBMY, USP9Y, and DBY) and cause severe testiculopathy leading to male infertility. We have reviewed the literature and the most recent advances in Y chromosome mapping, focusing our attention on the correlation between Y chromosome microdeletions and alterations of spermatogenesis. More than 4,800 infertile patients were screened for Y microdeletions and published. Such deletions determine azoospermia more frequently than severe oligozoospermia and involve especially the AZFc region including the DAZ gene family. Overall, the prevalence of Y chromosome microdeletions is 4% in oligozoospermic patients, 14% in idiopathic severely oligozoospermic men, 11% in azoospermic men, and 18% in idiopathic azoospermic subjects. Patient selection criteria appear to substantially influence the prevalence of microdeletions. No clear correlation exists between the size and localization of the deletions and the testicular phenotype. However, it is clear that larger deletions are associated with the most severe testicular damage. Patients with Y chromosome deletions frequently have sperm either in the ejaculate or within the testis and are therefore suitable candidates for assisted reproduction techniques. This possibility raises a number of medical and ethical concerns, since the use of spermatozoa carrying Y chromosome deletions may produce pregnancies, but in such cases the genetic anomaly will invariably be passed on to male offspring.

Expression of CDY1 may identify complete spermatogenesis

OBJECTIVE

To investigate the expression of deleted in azoospermia (DAZ), RNA-binding motif (RBM), and chromodomain y1 (CDY1) genes in the testes of men with azoospermia with variable histopathologies.

DESIGN

Prospective study.

SETTING

Andrology laboratory of a university-affiliated maternity hospital.

PATIENT(S)

Sixty-six men with azoospermia.

INTERVENTION(S)

Testicular sperm extraction.

MAIN OUTCOME MEASURE(S)

The results of gene expression in testicular tissue tested by RT-PCR were correlated with those of histopathologically and microscopically examined minced testicular tissue. Y chromosome microdeletion testing and karyotyping were performed, as was direct sequencing of CDY1-PCR products.

RESULT(S)

CDY1-minor expression was detected in all biopsies in which mature spermatids/spermatozoa were observed by histological analysis and/or in the minced tissue. CDY1-minor expression was also detected in two biopsies with arrest at the spermatocyte stage during which no mature spermatids/spermatozoa were observed. A previously unreported CDY1-minor alternative splicing transcript was identified. DAZ and RBM gene expressions were detected in all biopsies in which at least a few germinal cells in early stages were found and in one biopsy histologically determined as Sertoli cell only.

CONCLUSION(S)

Our preliminary results suggest that CDY1-minor expression might increase the prospect for complete spermatogenesis, while RBM and DAZ expression can only be indicative of the presence of germinal cells.

Y-chromosome microdeletion and its effect on reproductive decisions in taiwanese patients presenting with nonobstructive azoospermia

OBJECTIVES

To investigate the position, extent, and frequency of Y chromosome microdeletions in Taiwanese patients presenting with nonobstructive azoospermia, and to investigate the effect of microdeletions on reproductive decisions.

METHODS

We studied 176 consecutive men with azoospermia in our urology clinic. Polymerase chain reaction tests were performed in 94 patients with nonobstructive azoospermia, and a series of 27 sequence-tagged sites (STSs) mapped within intervals 5 and 6 of Yq11 was selected for analysis. Clinical genetics counseling was provided to couples with microdeletions, and these couples made their own choices about further treatment modalities.

RESULTS

Among 94 patients screened for microdeletion, 11 (11.7%) showed microdeletions of one or more STSs. One had a deletion confined to the azoospermia factor b (AZFb) region (encompassing the RBM gene). Two were found to have deletions of both the AZFb and AZFc regions. Eight patients had deletions in the AZFc region (encompassing the DAZ gene). Five had deletions distal to the DAZ gene family. One had multiple, noncontiguous deletions. In 8 patients with testicular histology available, a lack of genotype/phenotype correlation was noted. Of the 11 couples with deletions, 3 thought microdeletion was a serious defect and opted for an artificial insemination of donor or adoption, 5 chose intracytoplasmic sperm injection, and the other 3 decided to undergo treatment with Chinese medicinal herbs.

CONCLUSIONS

The most commonly deleted region in the Taiwanese population is AZFc. The genes implicated in Taiwanese spermatogenesis defects are the DAZ and RBM gene families. Twenty-seven percent of couples with microdeletions deferred assisted reproductive technologies because of concern about their underlying genetic defects.

Pericentric inversion of the Y chromosome of infertile male

The authors report a case with pericentric inversion of the Y chromosome associated with asthenonecrozoospermia. The conventional karyotype was 46, X, inv (Y) (p11q11). Polymerase chain reaction (PCR) analysis revealed the deletion of DYZ3, DYS139, and RBM1. Three-color fluorescent in situ hybridization (FISH) analysis of the sperm chromosomes showed normal ratio between X- and Y-bearing sperm. In this case, the frequencies of aneuploidy of the sperm are not significantly higher compared with those from the normal volunteers. Cytogenetic analysis is recommended when the patients with pericentric inversion of the Y chromosome are attending an infertility clinic.

Genetically determined male infertility and assisted reproduction techniques

This is a review of the common chromosome and genetic disorders associated with male infertility that need to be considered by the clinician and the couple in the context of treatment. Until recently the most relevant disorders have been those inherited from parents, however, with the advent of technologies enabling recovery of sperm from the testicle in men with severely damaged spermatogenesis there is increased interest in those genetic abnormalities that may occur in mitosis and meioses. It is likely that over the next ten years there will be increasing focus on this aspect of male fertility genetic disorders. This article needs to be read in conjunction with the specific in depth reviews in this journal edition.

Genetic screening for patients with azoospermia and severe oligo-asthenospermia

In order to explore the genetic defects of patients with azoospermia or severe oligo-asthenospermia, screening examinations were carried out for the chromosome disorder and gene deletion of the Y chromosome for 220 male infertility patients. The present results show that the total prevalence of genetic defects is 23.6%, including 38 patients (28.4%) with chromosome disorder and 14 patients (16.8%) with gene deletion in the Yq arm. The most prevalent chromosome anomaly is 47XXY (Klinefelter's syndrome), which includes 18 cases of pure type and three cases of mosaic type. Variable autosomal translocations occurred in both the azoospermia group (5.2%) and the oligo-astheno-spermia group (5.8%) with similar prevalence. A total of 22 patients had deletions of the variable, interstitial portion of the Yq arm. These gene deletions are distributed not only inside the AZF region, but also outside of this region. The severity of deletions is not well correlated to the clinical testicular function of the patients. We conclude that chromosome disorder and gene deletions are the causative factors of patients with azoospermia and oligo-asthenospermia. Genetic screening should be a routine examination for them before the use of assisted-reproductive technologies.

Outcome of testicular sperm retrieval procedures in non-obstructive azoospermia: percutaneous aspiration versus open biopsy

The aim of this study was to evaluate whether the extraction of testicular spermatozoa with percutaneous versus open biopsy has an effect on the treatment outcome with intracytoplasmic sperm injection (ICSI) in men with non-obstructive azoospermia. Regardless of testicular size, follicle stimulating hormone concentration, and previous biopsy result, percutaneous testicular sperm aspiration (PTSA) using a 21-gauge butterfly needle was attempted first and if this failed testicular sperm extraction (TESE) was performed. In 63 men spermatozoa were found with PTSA whereas in 228 men TESE had to be undertaken. More men in the PTSA group had previously been diagnosed with hypospermatogenesis (82 versus 50%). Compared with the PTSA group, more men in the TESE group had germ cell aplasia (27 versus 10%) or maturation arrest (22 versus 8%). There was no difference between the groups regarding mean age of men and their partners, duration of stimulation, oestradiol concentration on the day of human chorionic gonadotrophin, number of oocytes retrieved, fertilization rate, and embryo quality between the two groups. The number of embryos transferred (4.38 versus 3.90) was significantly higher in the PTSA group (P < 0.05), reflecting the increased number of embryos available for transfer. Implantation rate per embryo was 20.7% in the PTSA and 13.3% in the TESE group (P < 0.05). Clinical pregnancy rates were 46 and 29% in the PTSA and TESE groups respectively (P < 0.05). Clinical abortion rates were similar (21.2 versus 24%). It is concluded that in men with non-obstructive azoospermia, easier sperm retrieval, which is most likely indicative of a more favourable histopathology, is associated with higher implantation rates per embryo.

Genetics and male infertility

This article reviews chromosomal and genetic disorders in the context of male fertility. Particular emphasis is on those disorders, which are encountered, in clinical practice including Klinefelter's syndrome, Kallman's syndrome, Androgen insensitivity, Y microdeletions, Y fertility gene deletions, and cystic fibrosis gene mutations. These disorders are discussed in relation to the aetiology of male fertility and also risks to children who are born of fathers with these disorders. A list of fathers' categories is proposed for outcome studies for children born after IVF-ICSI. Finally a question is proposed to catalyse debate about germ line therapy.

Y chromosome microdeletions in infertile men with varicocele

The pathogenic mechanisms by which varicocele disrupt spermatogenesis are not clearly understood and it is possible that when varicocele is associated with a severe bilateral testiculopathy, other causes may represent the actual aetiological factor. Since microdeletions in the Y chromosome long arm (Yq) have become in last years a major cause of male infertility, we perform a Yq microdeletion screening in infertile men with varicocele. We selected 40 patients with severe oligozoospermia (sperm count<5x10(6)/ml, group 1) and 80 with varicocele and mild oligozoospermia (sperm count 10-20x10(6)/ml, group 2). Deletions of Yq was observed in seven out of 40 patients (17.5%) of group 1, while no deletions were found in patients of group 2, suggesting that the bilateral testicular damage observed in patients of group 1 is due to the underlying genetic anomaly, and not to varicocele itself. The finding of a genetic aetiology in infertile men with varicocele suggests that in such patients a Yq microdeletion screening should be performed, both for a proper diagnosis and to avoid unnecessary treatments that will probably not improve the sperm count.

Assisted reproductive technology (ART) in humans: facts and uncertainties

Since the first in vitro fertilization (IVF) in human, the number of patients using Assisted Reproductive Technologies (ART) has increased tremendously. ART technologies have increased in number and their spectrum has also widened. The first IVF babies are now more than 20 years old. All the retrospective analyses have demonstrated that the obstetrical and pediatrical impact has not really affected single births. The main problems observed occur with multiple pregnancies, including high costs for the couples and for society. The decrease in the number of embryos transferred has improved the situation and moreover does not impair the final results. IntraCytoplasmic Sperm Injection (ICSI) is a more debatable and questionable technique with a real negative genetic impact. The main problem is chromosome abnormalities more specifically related to the sex chromosomes. The question of a systematic genetic work-up on the patients entering ICSI programs is discussed. No negative impact of cryopreservation has been demonstrated even though some controversy arises from time to time. Pre-implantation Genetic Diagnosis (PGD) is now a interesting tool for patients carrying genetic defects. Blastocyst biopsy now has a future role in reproductive medicine. Gender selection through sperm sorting is also now a reality. As with the other developing bio-technologies related to reproduction, there are ethical questions. The decisions concerning these technologies do not belong solely to scientists but are rather a matter for society to decide.

Evaluation of the role of mitotic instability in karyotypically normal men with oligozoospermia

OBJECTIVE

To estimate the incidence of sex chromosome aneuploidies in the somatic cells of karyotypically normal infertile men and fertile donors.

DESIGN

A prospective, two-phase, controlled study.

SETTING

Reproductive medicine and medical genetics units of a teaching hospital.

PATIENT(S)

Ten patients with oligozoospermia and 10 sperm donors with proved fertility, all with a normal karyotype 46 XY.

INTERVENTION(S)

Multicolor fluorescence in situ hybridization (FISH) of peripheral blood lymphocytes using a probe cocktail containing the alpha satellites DXZ1 for the X centromere and DYZ1 for the heterochromatic region of the long arm of the Y and the radiolabeled alpha satellite D18Z1 for chromosome 18.

MAIN OUTCOME MEASURE(S)

The incidence of sex chromosome aneuploidies in both groups.

RESULT(S)

A 13-fold increase in sex chromosome aneuploidies was observed in the somatic cells of infertile men with "unexplained" oligozoospermia compared to donors (P=.008).

CONCLUSION(S)

These findings provide suggestive evidence for the existence of an inherent mitotic instability in men with unexplained oligozoospermia.