Screening for Y chromosome microdeletions in 226 Slovenian subfertile men.

BACKGROUND: The objective of this study was to estimate the frequency of Y chromosome microdeletions in the Slovenian population of infertile men and to analyse the consequences of mutation in respect to clinical severity and prognosis. METHODS: In a controlled clinical study at the university-based medical genetics service and infertility clinic, 226 infertile men undergoing ICSI were tested. The main outcome measures included polymerase chain reaction amplification of 16 genes and gene families and 42 sequence-tagged sites in the non-recombining region of the Y chromosome, semen, testicular volume and testicular histological analysis, serum FSH concentrations, fertilization and respective pregnancy rates. RESULTS: The incidence of deletions was 4.4%: 8.6% in men with azoospermia and 1.5% in men with oligoasthenoteratozoospermia. Isolated gene deletions were not identified. No statistically significant differences in clinical outcome measures were found in patients with mutations versus patients without mutations. High fertilization (49%) and pregnancy (43%) rates with sperm of patients with Y chromosome deletions were obtained. CONCLUSIONS: Testing for gene-specific microdeletions does not contribute significantly to the sensitivity of microdeletion test. Fertilization and pregnancy rates obtained using sperm of patients with Y chromosome deletions were comparable with those achieved in conventional IVF.     

Y chromosome microdeletions: are they implicated in teratozoospermia?

BACKGROUND: Y chromosome microdeletions are known to impair spermatogenesis. Screenings for these microdeletions are performed mostly in patients with sperm count abnormalities. METHODS: We have screened the Y chromosome of 80 infertile patients with sperm morphological abnormalities. DNA from sperm, peripheral blood or single sperm following multiple displacement amplification (MDA) was utilized to amplify 20 specific sequence-tagged sites (STS) by PCR. RESULTS: Y chromosome microdeletions were detected in sperm DNA from four of the teratozoospermic patients; while none of the 53 men with normal sperm morphology had any deletions. Two of the four patients with deletions also provided peripheral blood and a fresh semen sample. Both patients had none of the STS deleted in the peripheral blood DNA. Y chromosome microdeletion analysis in the MDA amplified SRY-positive single sperm DNA confirmed the presence of the same deletion in all 10 sperm for one patient and eight out of 10 sperm in the second patient. CONCLUSIONS: Our observations suggest that some of the teratozoospermia might be related to gonadal mosaic Y chromosome microdeletions. Gonadal mosaicism can be a source of de novo transmissions of Y chromosome microdeletions. The application of MDA can yield enough DNA from a single sperm for genetic analyses.     

Analysis for microdeletions of Y chromosome in a single spermatozoon from a man with severe oligozoospermia

Since the association between Y chromosome deletions and spermatogenic failure was demonstrated in 1976, there have been many reports of Y chromosome microdeletions. Peripheral blood lymphocytes (PBLs) have been used for the analysis because the method is convenient, materials are easy to obtain, and PBL genomic DNA is similar to that of germ cells such as spermatozoa. However, PBLs originate from somatic tissue, not from germ cells. In this study, we analyzed 30 spermatozoa in semen ejaculated by an infertile male with Y chromosome microdeletions, while 50 spermatozoa from a normal fertile male were used as a control. The same Y chromosome microdeletion as that found in PBL was identified in each of the 12 spermatozoa which contained the Y chromosome in the infertile patient. These results indicated that spermatozoa (germ cells) had the same Y chromosome microdeletion as PBL (somatic cells). This supports the conjecture that microdeletions are transmitted to the next generation via the treatment of infertility by intracytoplasmic sperm injection. Received: October 17, 2000 / Accepted: November 15, 2000     

Y chromosome microdeletions in Tunisian infertile males

AIM: To determine frequency of Y microdeletions in azoospermic and oligospermic Tunisian infertile males. METHODS: A Sample of 146 Tunisian infertile males with a low sperm count (<5 x 10(6) sperms per mililiter) and normal karyotype was screened for Y chromosome microdeletions. 76 men were azoospermic and 70 men were oligospermic. Genomic DNA was isolated from blood and multiplex PCR was carried out with a set of 20 AZFa, AZFb and AZFc STS markers to detect the microdeletions as recommended by the European Academy of Andrology. RESULTS: In 10/146 (6.85%) subjects AZF deletions were observed. Of these ten males with microdeletions, 9/10 subjects were azoospermic (90%), 1/10 was oligospermic (10%). Frequency of microdeletions in azoospermic men was 9/76 (11.84%). None of the patients showed isolated microdeletion in the AZFa region, but one azoospermic man had deletion in the AZFb region. Eight azoospermic patients and one oligospremic man have AZFc microdeletions. AZFc and AZFb were deleted in three azoospermic patients. AZFc, AZFb and AZFa were deleted in three azoospermic patients We estimate the sensitivity of the test comprising six STS in our sample to be 90%. CONCLUSION: The incidence of Yq microdeletions in the study population of infertile Tunisian men falls within the range published in other countries. We suggest to analyze 9STS in the first step to detect efficiently Y microdeletions in our population.     

Genetic evaluation of infertile men.

Recently, microdeletions in the azoospermic factor region of the Y chromosome, in addition to chromosomal anomalies, have been detected in men with azoospermia or severe oligozoospermia. In this study we evaluated the molecular and cytogenetic defects of infertile men. The frequency of Y microdeletions among 105 azoospermic, 28 oligozoospermic and 32 fertile men was tested on lymphocyte DNA using a series of 20 sequence-tagged sites. In addition, microdeletions were evaluated on testicular-derived DNA among 26 azoospermic patients who underwent testicular biopsy and in whom no sperm cells could be identified. Karyotype analysis was performed on 72 of the infertile patients. Deletions were detected in 6.7% azoospermic and 3.6% oligozoospermic men. No deletions were identified among the fertile men. Identical results were obtained with DNA derived either from lymphocytes or testicular tissue. The frequency of chromosomal aberrations in the 72 infertile patients tested (62 azoospermic, 10 oligozoospermic) was 16.6%, with a high percentage of gonosome anomalies. Additional andrological parameters (hormone values, cryptorchidism) failed to identify men at risk for having microdeletions before the test. Our findings support the recommendation to perform genetic defect screening among infertile men before their enrollment in an intracytoplasmic injection/in-vitro fertilization programme.     

Detection of Y chromosome microdeletions in AZF region by liquid chip technology]

OBJECTIVE: To establish a liquid chip technology to detect Y chromosome microdeletions in Chinese infertile males with azoospermia or oligozoospermia. METHODS: Multiplex PCR and liquid chip technology were used to detect the Y chromosome microdeletions in AZF region in 178 infertile patients with azoospermia and 134 infertile patients with oligozoospermia as well as 40 fertile control men. RESULTS: Forty out of 312 patients (12.8%) were found to have deletions in AZF region. The microdeletion frequency was 14%(25/178) in the azoospermic group, 9.6%(11/114) in the oligospermic and 20%(4/20) in the severe oligospermic group. CONCLUSION: The authors developed a high-throughput, fast and simple assay to screen the AZF region microdeletions of Y chromosome.     

Prognostic value of Y deletion analysis. The role of current methods

Y chromosome microdeletions represent the most frequent genetic alteration in azoospermic and severely oligozoospermic men, and screening for microdeletions in AZFa, b and c are routinely performed in the major andrology and infertility centres. Since patients with Y microdeletions often require intracytoplasmic sperm injection (ICSI), the question of whether the type of the microdeletion present could have prognostic value for the presence of spermatozoa in the ejaculate or in the testes [by testicular sperm extraction (TESE)] is an interesting one. The review of the literature on this topic showed that there is still no clear genotype--phenotype relationship, i.e. similar testicular alterations may be caused by different types of microdeletions, and apparently identical microdeletions may be associated with diverse tubular damage. Even in azoospermic men, the localization of the microdeletion cannot be used as a valid prognostic parameter before TESE--ICSI to identify patients with spermatozoa in their testes. The only finding with absolute negative prognostic value is the presence of complete AZFa--c deletions, which are invariably associated with an absence of spermatozoa. Microdeletions in AZFa or AZFb seem to have promising prognostic value, but more data and gene-specific deletions have to be provided to draw clear conclusions. The absence of a clear genotype--phenotype relationship, and therefore of a prognostic value of Y deletion analysis, is probably due to the current methods used for the screening of the microdeletions. In fact, to date most centres do not use gene-specific markers but instead use anonymous primers that contribute little information to the pathogenic role of the microdeletions.     

180例无精子症或严重少精子症不育男性的Y染色体微缺失检测

目的探讨不育男性无精子症或严重少精子症与Y染色体微缺失之间的关系.方法利用9个Y染色体特异序列标签位点,以多重PCR法检测无精子症或严重少精子症患者的Y染色体微缺失情况.结果 180例无精子症或严重少精子症患者中共检出Y染色体微缺失15例,缺失率为8.3%.精液正常者(对照组)20例未发现Y染色体微缺失.9例Y染色体微缺失的无精子症患者睾丸细胞学检查均未发现精子.结论 Y染色体微缺失是造成男性精子发生障碍的常见病因之一.     

Prognostic value of Y deletion analysis: How reliable is the outcome of Y deletion analysis in providing a sound prognosis?

Y chromosomal microdeletions at the azoospermia factor (AZF) locus have been implicated as one of the major causes of idiopathic male infertility. The availability of intracytoplasmic sperm injection (ICSI) in treating a variety of male infertility has raised the risk of the transmission of Y microdeletions from father to son. In many IVF centres, Y microdeletion analysis has been used as a diagnostic tool for genetic counselling of infertile couples. Presently, the only prognosis that can be derived from Y microdeletion analysis is that the affected male offspring would benefit from proper clinical management of their infertility. Prognoses based on the pattern of Y microdeletions in relation to phenotype are rather subjective and inconclusive because of insufficient data to derive a definitive correlation whose significance can be determined by statistical analysis. Standardization of the number and choice of sequence-tagged sites (STS), whose deletions result in defective spermatogenesis, for the polymerase chain reaction (PCR) analysis of Y microdeletions would enhance its reliability in the interpretation of the results which is crucial for therapeutic decision-making. Furthermore, in-depth understanding of the gene functions in male infertility, especially at the AZF locus, would contribute greatly to the quality of the prognostic value of Y microdeletion analysis.     

Azoospermia factor deletions in varicocele cases with severe oligozoospermia

BACKGROUND: Varicocele is the most common cause of male infertility. The etiology and pathophysiology of varicocele are multifactorial. When low sperm counts are associated with varicocele, varicocelectomy can partially restore spermatogenesis and fertility. Few recent studies have reported that in some varicocele cases, there may be an associated genetic etiology. Presence of a genetic factor like azoospermia factor microdeletions may lead to irreversible spermatogenic arrest in these cases, but very few reports support these findings. However, it is still not understood why some cases improve after varicocelectomy and why some cases show no improvement in semen parameters postoperatively. AIM: It is important to distinguish varicocele cases from Yq microdeletions as these cases have irreversible testicular damage and thus carry a poor prognosis after varicocelectomy. SETTINGS: Research and Referral tertiary care hospital. Design: Prospective study. MATERIALS AND METHODS: Seventy-two infertile men with varicocele were referred for Yq microdeletion analysis from the infertility clinic of AIIMS and Army Research and Referral Hospital. Genomic DNA was isolated from blood and polymerase chain reaction microdeletion screening was done in these cases to determine the presence or deletion of AZF loci. RESULTS: In this study 7 (9.7%) varicocele cases harbored Yq microdeletion. The sperm count in cases which harbored Yq microdeletion was significantly lower than in cases without Yq microdeletion. CONCLUSION: Varicocele cases with Yq microdeletion do not show improvement in semen parameters post-varicocelectomy. Detection of Yq microdeletion determines prognosis and future management in such cases.     

Y chromosome microdeletion in a father and his four infertile sons.

Microdeletions of Yq are associated with azoospermia and severe oligozoospermia. In general, men with deletions are infertile and therefore deletions are not transmitted to sons unless in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are performed. We report an unusual family characterized by multiple members with infertility and Yq microdeletion. Complete reproductive history, semen analyses and blood samples were elicited from relevant family members. DNA preparation and quantification were performed using commercial kits. A total of 27 pairs of sequence tagged sites based primer sets specific for the Y microdeletion region loci were used for screening. Southern blots using deleted in azoospermia (DAZ) and ribosomal binding motif (RBM) cDNAs were then analysed for confirmation. The proband, his three brothers and father were all found to be deleted for DAZ but not RBM. At the time of analysis, the proband's father was azoospermic whereas his four sons were either severely oligozoospermic or azoospermic. Unlike their father, the four sons are infertile and have no offspring, except for one of them who achieved a daughter only after IVF/ICSI treatment for infertility. Microdeletions of Yq involving the DAZ gene are associated with a variable phenotypic expression that can include evidently normal fertility.     

Combined cytogenetic and Y chromosome microdeletion screening in males undergoing intracytoplasmic sperm injection

We evaluated the frequency of chromosomal aberrations and microdeletions of the Y chromosome in a sample of 204 patients included in an intracytoplasmic sperm injection (ICSI) programme. The prevalence of Y chromosome deletions in males with severely or only moderately reduced sparm counts is mainly unknown, so that patients were chosen with sperm counts ranging from mild oligozoospermia to azoospermia. While six out of 158 (3.8%) patients showed constitutional chromosomal aberrations, only two out of 204 (0.98%) patients were diagnosed with a microdeletion of Yq11. One had a terminal deletion in subinterval 6 of Yq11.23 which included the DAZ gene and a corresponding sperm count < 0.1 x 10(6) spermatozoa/ml. The second patient had an isolated deletion of marker Y6PH54c, a more proximal site in subinterval 5 on Yq11.23, but repeatedly showed sperm counts of 3-8 x 10(8) spermatozoa/ml. Thus, of the 158 patients who underwent a combined cytogenetic and Y- microdeletion screening, eight patients (5.1%) showed chromosomal abnormalities, either at the cytogenatic (n = 6) or the molecular level (n = 2). In conclusion, although rare in number, microdeletions of the Y chromosome can also be observed in patients with moderately reduced sperm counts. A more proximal site of the deletion breakpoint does not necessarily imply a more severe impairment of spermatogenesis than a distal deletion site. In our sample, the overall frequency of constitutional chromosomal aberrations exceeded the incidence of microdeletions of the Y chromosome even in patients with idiopathic azoo- or severe oligozoospermia.      

Sex chromosome mosaicism in males carrying Y chromosome long arm deletions

Microdeletions of the long arm of the Y chromosome (Yq) are a common cause of male infertility. Since large structural rearrangements of the Y chromosome are commonly associated with a 45,XO/46,XY chromosomal mosaicism, we studied whether submicroscopic Yq deletions could also be associated with the development of 45,XO cell lines. We studied blood samples from 14 infertile men carrying a Yq microdeletion as revealed by polymerase chain reaction (PCR). Patients were divided into two groups: group 1 (n = 6), in which karyotype analysis demonstrated a 45,X/46,XY mosaicism, and group 2 (n = 8) with apparently a normal 46,XY karyotype. 45,XO cells were identified by fluorescence in-situ hybridization (FISH) using X and Y centromeric probes. Lymphocytes from 11 fertile men were studied as controls. In addition, sperm cells were studied in three oligozoospermic patients in group 2. Our results showed that large and submicroscopic Yq deletions were associated with significantly increased percentages of 45,XO cells in lymphocytes and of sperm cells nullisomic for gonosomes, especially for the Y chromosome. Moreover, two isodicentric Y chromosomes, classified as normal by cytogenetic methods, were detected. Therefore, Yq microdeletions may be associated with Y chromosomal instability leading to the formation of 45,XO cell lines.     

男性不育患者Y染色体AZF基因微缺失检测

目的探讨原发性无精子症、严重少精子症及少精子症患者与Y染色体无精子因子（azoospermia factor,AZF）区微缺失的关系。方法采用多重PCR方法对对照组192例已正常生育男性和实验组448例男性不育患者进行AZF区域内的15个序列标签位点（STS）的检测。结果对照组未发现AZF基因微缺失,实验组448例患者检测出五种AZF微缺失类型共41例,总缺失率为9.2%（41/448）,其中无精子症、严重少精子症和少精子症患者的缺失率分别为12.0%（19/158）、10.8%（17/157）、3.8%（5/133）,无精子症和严重少精子症患者Y染色体AZF微缺失率明显高于少精子症组,差别有统计学意义（P〈0.05）。使用15个STS位点进行检测其检出率较利用欧洲男科学会（European Academy of Andrology,EAA）推荐的6个STS位点提高约14%（5/36）。结论AZF微缺失是引起原发性无精子症、严重少精子症和少精子症的重要原因之一;增加STS位点检测数有利于提高AZF微缺失的检出率。     

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

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.     

200例男性不育患者的Y染色体微缺失检测

目的探讨男性不育患者与Y染色体微缺失之间的关系。方法利用15个Y染色体特异序列标签位点,以多重PCR法检测男性不育患者的Y染色体微缺失情况。结果 200例男性不育患者中共检出Y染色体微缺失7例,缺失率为3.5%。其中单纯A;ZFc缺失2例,缺失率为1%(2/200);A;ZFb缺失率为3例,缺失率为1.5%(3/200);单纯A;ZFa缺失2例,缺失率为1%(2/200),尚未发现联合缺失或大片段缺失患者。精液正常者(对照组)30例未发现Y染色体微缺失。结论 Y染色体微缺失是造成男性不育的常见病因之一。     

Prognostic value of Y deletion analysis: what is the clinical prognostic value of Y chromosome microdeletion analysis?

In many centres, Y chromosome deletion analysis is still not performed routinely and if so, the results are used for genetic counselling but are not considered as having a useful prognostic value. The type of deletion (AZFa, b or c) has been proposed as a potential prognostic factor for sperm retrieval in men undergoing TESE. AZFc deletions and partial AZFb deletions are associated with sperm retrieval in approximately 50% of cases while in the case of a patient with complete AZFb deletion the probability of finding mature spermatozoa is virtually nil. Therefore the extent and position of a Y microdeletion is important (complete or partial). The prognostic value of Y chromosome deletion analysis in cases of oligozoospermia is important when one considers the progressive decrease of sperm number over time in men with AZFc deletions. Cryo-conservation of spermatozoa in these cases could avoid invasive techniques, such as TESE/ICSI, in the future. Male offspring that are conceived by ICSI or IVF techniques from father with oligozoospermia or azoospermia would also benefit from knowledge of their Y status, since the identification of the genetic defect will render future medical or surgical therapies unnecessary. Y microdeletion screening is therefore important, not only to define the aetiology of spermatogenic failure, but also because it gives precious information for a more appropriate clinical management of both the infertile male and his future male child.     

不育男性的AZF检测与Y染色体缺失的对照分析

目的探讨精子发生障碍的男性不育患者AZF缺失与Y染色体缺失的临床意义。方法对616例非阻塞性无精子症或少精子症患者进行AZF的检测,同时观察G显带Y染色体的形态。结果从616例患者中检测出48例患者分别为AZFa、AZFb、AZFc或AZFb+AZFc的微缺失,但显微镜下观察不到Y染色体形态改变。另外4例患者经AZF检测,2例为AZFc+sY160缺失,1例为AZFb+AZFc+sY160缺失,1例为AZFa+AZFb+AZFc+sY160缺失,显微镜下发现Yq部分或完全缺失。25例已育男性的G-显带的Y染色体和AZF也进行对照检测,均未发现AZF的缺失,但其中1例核型分析显示Y染色体长臂部分缺失,但PCR检测仅缺失sY160,即Yq12的缺失。结论Yq11.23上7Mb的缺失在细胞水平不能分辨。q11.23+q12的缺失或仅有Yq12的缺失的Y染色体显微镜下不能区分,但后者不是精子发生障碍的病因。对男性不育精子发生障碍患者,要结合细胞遗传学和AZF分子检测综合判断。     

Screening for microdeletions of Y chromosome genes in patients undergoing intracytoplasmic sperm injection.

The potential of assisted reproduction techniques to transmit genetic defects causing male infertility raises questions concerning the need for a systematic genetic screen and counselling. Deletions of the long arm of the Y chromosome are frequently associated with a failure of spermatogenesis. The search for Y specific sequences and for the gene families RNA binding motif (RBM) and deleted in azoospermia (DAZ) have been introduced in many laboratories. The incidence of Y microdeletions varies widely between studies, from 1-55%. These differences are mainly related to study design. The highest incidence of microdeletions has been reported in well selected idiopathic azoospermic patients. Since microdeletions have been reported also in non-idiopathic patients, it is important to define what is the deletion frequency in unselected patients. We report Y chromosome microdeletion screening in 134 unselected patients undergoing intracytoplasmic sperm injection (ICSI). In the first part of the study we tested six Y chromosome markers. We found three patients with microdeletions (2.2%). Subdivision of the study population revealed a deletion incidence of 4.7% in azoospermic/cryptozoospermic patients; an incidence of 7% in idiopathic patients and an incidence of 16% in idiopathic azoospermic/cryptozoospermic patients. The second part of the study consisted of a screen for the presence of the Y chromosome genes, DBY, CDY, XKRY, eIF-1A, DAZ and BPY2. No additional gene-specific deletions were found. Further data on gene specific screening are needed especially for selected idiopathic patients.     

Transmission of Y chromosomal microdeletions from father to son through intracytoplasmic sperm injection

 We conducted chromosomal analysis of three male infants fathered by severe oligozoospermic males with Y chromosomal microdeletions through intracytoplasmic sperm injection (ICSI). Two of the infants had the same Y chromosomal microdeletions as their fathers. The third infant also had a Y chromosomal microdeletion, which was longer than that found in his father. The results confirm that Y chromosomal microdeletions are transmitted from a father to a son via ICSI and also suggest that the microdeletions may be expanded during such transmission. Genetic counseling for infertile couples contemplating ICSI is important if the male carries Y chromosomal microdeletions. Received: January 11, 2002 / Accepted: May 19, 2002