Analysis of Yq microdeletions in infertile males by PCR and DNA hybridization techniques

Defects in spermatogenesis have been found associated with deletions of different portions of Y chromosome long arm (Yq), suggesting the presence of the azoospermia factor in the control of spermatogenesis. We studied 67 men with idiopathic azoospermia and severe oligozoospermia, cytogenetically normal, for the presence of microdeletions on Yq chromosome. By using polymerase chain reaction (PCR) and Southern blotting techniques we analysed the AZFa, AZFb and AZFc loci on Yq, where deletions have been associated with defects in spermatogenesis. Deletions of a portion of the Y chromosome were detected in five patients. Four of these patients shared deletions in distal Yq11 interval 6, including the DAZ gene, while one patient lacked loci in the proximal Yq11. Testicular histology of two patients bearing distal Yq11 deletions showed two different spermatogenic defects including Sertoli cell-only (SCO) syndrome and maturation arrest, while the patient with microdeletions in the proximal Yq11 showed a SCO phenotype.      

High frequency of well-defined Y-chromosome deletions in idiopathic Sertoli cell-only syndrome

Idiopathic Sertoli cell-only syndrome (SCOS) is characterized by azoospermia, small testes, absence of germ cells in the testes, elevated follicle stimulating hormone and normal testosterone concentrations. The Y-chromosome is involved in the regulation of spermatogenesis and in the pathogenesis of a fraction of idiopathic male infertility. An azoospermia factor (AZF) is present on the Y- chromosome long arm euchromatic region (Yq11) and two gene families (DAZ and RBM) have been identified within this region. The aim of this study was to investigate whether a specific pattern of Yq11 microdeletions may be associated with idiopathic SCOS. Eighteen idiopathic subjects showing a testicular cytological picture of bilateral SCOS were selected and tested by polymerase chain reaction for a set of 29 Y-specific sequence-tagged sites (STS). We found Yq microdeletions in 10 out of 18 patients (55.5%) while the fathers or brothers of six out of 10 patients deleted for Yq were shown to carry an intact Y-chromosome. These deletions may therefore be considered as de-novo deletions and the cause of SCOS. The analysis of the microdeletions allowed us to identify two homogeneous regions that have a high incidence of deletion. The smallest deletion, common to all patients, is located in Yq interval 5. We therefore speculate that there is a relationship between specific, well-characterized Yq11 microdeletions and a testicular picture of SCOS, identifying an Y- related region frequently deleted in this syndrome. In conclusion, the findings of this study demonstrate that a large percentage of idiopathic SCOS may be genetically determined and identify an Y-related region that seems to possess one or more still unknown genes essential for spermatogenesis.      

Manifestation of Y-chromosomal deletions in the human testis: a morphometrical and immunohistochemical evaluation

BACKGROUND: Deletions of the AZF (azoospermia factor) subregions on the Y chromosome are accompanied by a diverse spectrum of spermatogenic disturbances ranging from hypospermatogenesis to total depletion of germ cells causing infertility. The AZF region encodes gene products which are candidates for the genetic control of spermatogenesis. Although it is known which genes are involved, a general principle of cause and effect cannot yet be deciphered and the deletion type has non-uniform histological phenotypes. METHODS AND RESULTS: We analysed morphological parameters of testicular biopsies from 17 patients diagnosed for Y chromosome microdeletions. As control groups we analysed testes from patients with idiopathic Sertoli cell-only (SCO) syndrome (n = 11), mixed atrophy (n = 10) and complete spermatogenesis (n = 11). A detailed genetic analysis on the extension of the observed microdeletions revealed similar breakpoints in the distal and proximal region of the AZFc region, indicating a common mechanism of homologous recombination for such deletions, as has been suggested before. Morphometric parameters such as the diameter of the tubules, lumen, thickness of the lamina propria and height of the tubule epithelia were investigated. The diameter of the tubules from patients with microdeletions was found to be significantly smaller compared with patients with mixed atrophy. Considering also the size of the tubules, lumen and epithelia, a Y-chromosomal microdeletion represents an intermediate state between an idiopathic SCO and normal spermatogenesis. The immunohistochemical analysis of six different Sertoli cell markers, cytokeratin 18, vimentin, inhibin alpha subunit, 14-3-3 theta, FSH receptor and androgen receptor, revealed no impact of AZF deletion on the specific expression pattern of these genes. CONCLUSIONS: Our results suggest that, notwithstanding the deletion of a common region in the AZFc region, microdeletions of the Y chromosome lead to an intermediate status between idiopathic SCO and complete spermatogenesis, resulting in a heterogeneous histological profile regardless of the seminiferous activity. The Sertoli cell function seems not to be altered.     

AZF and DAZ gene copy-specific deletion analysis in maturation arrest and Sertoli cell-only syndrome

Deletions of the AZFc region in Yq11.2, which include the DAZ gene family, are responsible for most cases of male infertility and were associated with severe oligozoospermia and also with a variable testicular pathology. To uncover the functional contribution of DAZ to human spermatogenesis, a DAZ gene copy-specific deletion analysis was previously established and showed that DAZ1/DAZ2 deletions associate with oligozoospermia. In this study we applied the same screening method to 50 control fertile males and 91 non-obstructive azoospermic males, 39 with Sertoli cell-only syndrome (SCOS) and 52 with meiotic arrest (MA). Samples were also screened with 24 sequence-tagged sites to the different AZF regions, including 114 control fertile males. After biopsy (testicular sperm extraction, TESE), residual spermiogenesis was found in 57.7% MA and 30.8% SCOS cases (incomplete syndromes). DAZ1/DAZ2 deletions were associated with the testicular phenotype of residual spermiogenesis as they were only found in two patients (8%) with incomplete MA. Differences between incomplete (23.3%) and complete (4.5%) MA cases regarding AZFc and DAZ1/DAZ2 deletion frequencies, and between incomplete (58.3%) and complete (11.1%) SCOS cases for AZFc deletions, suggest that incomplete syndromes might represent an aggravation of the oligozoospermic phenotype. As successful TESE was achieved in 87.5% of MA cases with AZFc and DAZ1/DAZ2 deletions and in 58.3% of SCOS cases with AZFc deletions, the present results also suggest that these molecular markers might be used for the establishment of a prognosis before TESE.     

AZFa deletions in Sertoli cell-only syndrome: a retrospective study

Lack of data on the genotype-phenotype relationship in cases of AZF microdeletions is due to the limited number of histological investigations in human male infertility cases. We investigated the possibility of retrospective detection of Yq11 microdeletions by using DNA extracted from diagnostic testicular biopsies. We used histological criteria to select two series of material: 22 biopsies with Sertoli cell-only syndrome and 14 biopsies with maturation arrest at the spermatocyte I stage. Two markers, DFFRY and DAZ, were tested by nested polymerase chain reaction (PCR) in the two series. In the Sertoli cell-only syndrome series, we found four deletions affecting the DFFRY gene (18.2%). In the second series, no deletions were detected. Two conclusions may be considered, although the number of specimens analysed is limited: (i) the frequency of deletions observed in Sertoli cell-only syndrome allows us to suggest that deletion in the AZFa region may be involved in this pathology; and (ii) retrospective studies may yield some additional elements in our search for eventual genotype-phenotype relationships.     

Correlation of testicular pathology and sperm extraction in azoospermic men with ejaculated spermatids detected by immunofluorescent localization

Limiting testicular biopsy for intracytoplasmic sperm injection (ICSI) to those with a high chance of having testicular spermatozoa has not been possible because of the poor predictive value of current clinical and laboratory methods. In order to predict testicular pathology and sperm extraction, we characterised the semen of 28 men with azoospermia due to gonadal failure in terms of the presence of spermatids using an immunological method. The results were compared with the assessment of testicular biopsies by histology and the extraction of spermatozoa into culture medium. Washed cellular elements in the ejaculate were smeared on microscope slides and fixed in 100% methanol, before incubation with acrosome-specific monoclonal antibody (18.6), fluorescein isothiocyanate-labelled anti-mouse goat IgG, and examination by epifluorescent microscopy. Semen from men with oligozoospermia and obstructive azoospermia served as positive and negative controls, respectively. Twelve patients who had positive immunofluorescence (one or more spermatids present) had spermatozoa retrieved from their testes (five hypospermatogenesis, seven focal spermatogenesis), and 16 patients with negative immunofluorescence (spermatids absent) had apparent Sertoli cell-only syndrome (12) or maturation arrest histological pattern (four). However, four patients with apparent Sertoli cell-only syndrome had testicular spermatozoa present after extraction from the biopsy. Plasma follicle stimulating hormone concentration and testicular volume did not predict retrieval of seminal spermatids or testicular spermatozoa. We conclude that the immunofluorescent localization of one or more spermatids in the ejaculate can be used to predict the likelihood of obtaining testicular spermatozoa for ICSI. However, in some patients with Sertoli cell-only syndrome, spermatozoa could still be recovered in the absence of apparent seminal spermatids.      

特发性无精子症和严重少精子症患者DAZ基因缺失的分析

目的　评估特发性无精子症和严重少精子症患者Y染色体上DAZ基因缺失的发生情况。方法　采用聚合酶链反应技术 (PCR)扩增 33例特发性无精子症和严重少精子症患者DAZ基因中的 4个序列标记位点SY15 4、SY2 5 4、SY2 5 5和SY15 5。 5 0例生育男性为阳性对照组 ,5例女性为阴性对照组。结果　 33例特发性无精子症和严重少精子症患者DAZ基因缺失率为 15 2 % ,其中 2 6例特发性无精子症患者有 4例缺失 (15 4 % ) ,1例染色体核型为 4 7,XXY ;7例特发性严重少精子症患者中有 1例缺失 (14 3% )。 4个序列标记位点在阳性对照组中均有条带扩增 ,在阴性对照组中未见条带扩增。结论　特发性无精子症和严重少精子症患者均存在DAZ基因缺失 ,特发性无精子症患者缺失率高于特发性严重少精子症患者 ,与国外报道相一致。聚合酶链反应扩增DAZ基因位点是筛选Y染色体缺失的有效方法。     

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.     

Absence of anti-Müllerian hormone (AMH) and M2A immunoreactivities in Sertoli cell-only syndrome and maturation arrest with and without AZF microdeletions

BACKGROUND: Some genes identified in the AZF locus are expressed only in germinal cells; others are ubiquitous. AZF microdeletions seem to occur at the earliest stages of ontogenetic development, and one might therefore assume that Sertoli cells preserve some immature characteristics and that their immunophenotype may be modified by the existence of a molecular defect. MATERIALS AND METHODS: Two immunohistological markers of Sertoli cell immaturity [anti-Müllerian hormone (AMH) and M2A] were tested in two histopathological groups (maturation arrest at spermatocyte I stage and Sertoli cell-only syndrome). We analysed 68 testicular samples obtained from 39 patients with non-obstructive azoospermia associated or not with AZF microdeletions. RESULTS: The absence of M2A and AMH immunoreactivity in adult gonads was observed without any correlation to spermatogenetic impairment or molecular deficit in the AZF region. In the samples of these two series, Sertoli cells showed a mature phenotype for AMH and M2A markers. CONCLUSIONS: In patients with AZF microdeletions, the genotype-phenotype correlations seem to be more complex than has been suggested previously; more detailed characterization of the immunohistochemical phenotype associated with the molecular defect may be useful in understanding the spermatogenic failure mechanism.     

A comparison of mitochondrial and nuclear DNA status in testicular sperm from fertile men and those with obstructive azoospermia

BACKGROUND: Mitochondria are vital to sperm as their motility powerhouses. They are also the only animal organelles with their own unique genome; encoding subunits for the complexes required for the electron transfer chain. METHODS: A modified long PCR technique was used to study mitochondrial DNA (mtDNA) in ejaculated and testicular sperm samples from fertile men undergoing vasectomy (n = 11) and testicular sperm from men with obstructive azoospermia (n = 25). Nuclear DNA (nDNA) fragmentation was measured by an alkaline gel electrophoresis (comet) assay. RESULTS: Wild-type mtDNA was detected in only 60% of fertile men's testicular sperm, 50% of their ejaculated sperm and 46% of testicular sperm from men with obstructive azoospermia. The incidence of mitochondrial deletions in testicular sperm of fertile and infertile men was not significantly different, but the mean size of the deletions was significantly less in testicular sperm from fertile men compared with men with obstructive azoospermia (P < 0.02). NDNA fragmentation in testicular sperm from fertile men and men with obstructive azoospermia was not significantly different. CONCLUSION: Multiple mtDNA deletions are common in testicular and ejaculated sperm from both fertile and infertile men. However, in males with obstructive azoospermia, the mtDNA deletions in testicular sperm are of a larger scale.     

424例非梗阻性无精子症和严重少精子症患者的细胞与分子遗传学研究

目的探讨非梗阻性无精子症和严重少精子症患者的细胞与分子遗传学特点。方法应用染色体核型分析、Y染色体微缺失检测和荧光原位杂交（FISH）、PCR等技术对非梗阻性无精子症（n=291）和严重少精子症患者（n=133）男性不育患者（共424例）进行细胞和分子遗传学检测。结果424例患者中有98例明确为遗传异常引起的,其中66例检测到染色体畸变,44例Y染色体微缺失检测见缺失,12例患者染色体核型和微缺失检测均见异常。部分AZF缺失患者精液或睾丸中有精子,但其生精功能呈进行性下降的特点。结论男性不育最常见的遗传学病因为K linefelter综合征和Y染色体AZFc缺失。Y染色体微缺失检测对Y染色体长臂异染色质区缺失是否为多态性具有明确诊断的作用。细胞与分子遗传学检测为男性不育的诊断、治疗和预后以及ICSI治疗前遗传咨询提供重要依据。     

Fertilization, pregnancy and embryo implantation rates after ICSI in cases of obstructive and non-obstructive azoospermia

The aetiology of azoospermia can be grossly divided into obstructive and non-obstructive causes. Although in both cases testicular spermatozoa can be used to treat male fertility, it is not well established whether success rates following intracytoplasmic sperm injection (ICSI) are comparable. Therefore, a retrospective analysis of fertilization, pregnancy and embryo implantation rates was performed following ICSI with testicular spermatozoa in obstructive or non-obstructive azoospermia. In total, 193 ICSI cycles were carried out with freshly retrieved testicular spermatozoa; in 139 cases of obstructive and 54 cases of non-obstructive azoospermia. The fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia was significantly lower than in obstructive azoospermia (67.8% versus 74.5%; P = 0.0167). Within the non-obstructive group, the fertilization rate in the group of maturation arrest (47.0%) was significantly lower than in case of Sertoli cell-only (SCO) syndrome (71.2%) or germ cell hypoplasia (79. 5%). Embryo quality on day 2 after ICSI was similar for all groups. Pregnancy rates per transfer between obstructive (36.8%) and non-obstructive groups (36.7%) were similar. In cases of maturation arrest the pregnancy rate per transfer was lowest (20.0%) although not significantly different from SCO syndrome or hypoplasia groups. Embryo implantation rates were not different between the obstructive (19.6%) and non-obstructive groups (25.8%), and were lowest in cases of germ cell hypoplasia (15.8%). This retrospective analysis shows that although fertilization rate after ICSI with testicular spermatozoa in non-obstructive azoospermia is significantly lower than in obstructive azoospermia, pregnancy and embryo implantation rates are similar.     

无精和严重少精子症患者Y染色体的微缺失

目的 检测我国无精和严重少精子症患者Y染色体微缺失的发生情况和位点,及其与睾丸病理学类型的关系.方法 取584例无精子症和80例严重少精子症患者精液中细胞或外周血白细胞,裂解提取DNA,用4组多重聚合酶链反应检测分布于AZFa、AZFb、AZFc区,包括欧洲男科学会和欧洲分子遗传学质量控制体系推荐的6个位点在内的共15个序列标签位点(sequence tagged site,SIS)的缺失.对部分有Y染色体微缺失患者进行睾丸细针抽吸活检,检查睾丸病理学类型.结果 584例无精子症患者中,共有66例(11.3%)发生Y染色体微缺失,各区发生率构成比由高到低依次为:AZFc区48例(72.7%),AZFb+c区9例(13.6%),AZFa+b+c区4例(6.1%),AZFb区3例(4.5%),A2Fa区2例(3.0%).80例严重少精子症患者共有10例发生Y染色体微缺失(12.5%),均为AZFc区缺失.AZFc区缺失患者(19例)睾丸病理学类型多样化;AZFb+c区或AZFa+b+c区缺失患者(7例)睾丸病理学类型为唯支持细胞综合征或生精阻滞于精原细胞.结论 Y染色体微缺失在我国的发生情况与其他国家大多数报道基本一致,跨区大缺失对精子发生造成严重影响.     

No AZF deletion in 160 patients with testicular germ cell neoplasia

Testicular germ cell cancer is aetiologically linked to genital malformations and male infertility and is most probably caused by a disruption of embryonic programming and gonadal development during fetal life. In some cases, germ cell neoplasia is associated with a relative reduction of Y chromosomal material (e.g. 45,X/46,XY) or other abnormalities of the Y chromosome. The euchromatic long arm of the human Y chromosome (Yq11) contains three azoospermia factors (AZFa, AZFb, AZFc) functionally important in human spermatogenesis. Microdeletions encompassing one of these three AZF loci result in the deletion of multiple genes normally expressed in testis tissue and are associated with spermatogenic failure. The aim of our study was to investigate whether AZF microdeletions, in addition to causing infertility, predispose also to germ cell neoplasia, since subjects with poor spermatogenesis have an increased risk of testicular cancer. We screened for putative deletions of AZF loci on the Y chromosome in DNA isolated from white blood cells of 160 Danish patients with testicular germ cell neoplasia. Interestingly, although AZF microdeletions are found frequently in patients with idiopathic infertility, in all cases studied of testicular germ cell cancer the Yq region was found to be intact. We conclude that the molecular aetiology of testicular germ cell neoplasia of the young adult type most likely does not involve the same pathways as male infertility caused by AZF deletions. Malignant transformation of germ cells is thus caused by the dysfunction of some other genes that still need to be identified.     

Testicular sperm extraction in azoospermic men submitted to bilateral orchidopexy

BACKGROUND: This study was carried out to evaluate whether bilateral orchidopexy represents a poor or good prognostic factor in azoospermic men undergoing testicular sperm extraction (TESE). METHODS: One hundred and seven presumed non-obstructive azoospermia (NOA) patients, according to conventional clinical parameters (volume of testis, FSH, clinical history) were submitted to testicular biopsy with TESE. Thirty men (28%) had a history of bilateral orchidopexy for cryptorchidism. RESULTS: Normal spermatogenesis or mild hypospermatogenesis was diagnosed in 12/30 ex-cryptorchid patients and in 7/77 presumed NOA patients (P = 0.0004). Conversely, pure Sertoli cell-only syndrome or complete maturation arrest was found in 10/30 ex-cryptorchid patients and in 48/77 presumed NOA patients (P = 0.0094). In 53/107 patients (49.5%), TESE allowed a positive sperm retrieval. At least one spermatozoon was observed in 22/30 ( approximately 73%) ex-cryptorchid patients and in 31/77 ( approximately 40%) presumed NOA patients (P = 0.0026). A large number of spermatozoa (equivalent to an obstructive pathology) were retrieved in 13/30 ex-cryptorchid and in 10/77 presumed NOA patients (P = 0.001). A history of bilateral orchidopexy in presumed NOA patients correlates positively for the chance of retrieving testicular spermatozoa (odds ratio 3.8; 95% confidence interval 1.41-10.21; P = 0.008). CONCLUSIONS: Although bilateral cryptorchidism is usually considered a testicular secretive dysfunction, TESE permits retrieval of a large number of spermatozoa in almost 40% of cases. Our data suggest the existence of congenital or acquired obstructive anomalies of the seminal ducts in azoospermic orchidopexed men.     

Human chromosome deletions in Yq11, AZF candidate genes and male infertility: history and update

Human chromosome deletions in Yq11 seem to occur frequently as de novo mutation events in men with idiopathic azoospermia or severe oligozoospermia. However, the molecular extensions of these deletions are variable. They can be large and therefore visible under the microscope or small, not visible under the microscope, and containing the deletion of one or more DNA loci recently mapped in an apparently consecutive order along the Yq11 chromosome region. The results of 20 extensive microdeletion screening programmes have now corroborated the prevalence of the deletion of three non-overlapping DNA regions in proximal, middle and distal Yq11, which were designated earlier as AZFa, AZFb and AZFc. Deletions of single DNA loci were also reported, but as de novo and as polymorphic mutation events. Their clinical significance with regard to the men's infertility should therefore initially be handled with caution. Multiple Y genes expressed in human testis have now been mapped to each AZF region. At least one of them should be functional in human spermatogenesis and, if mutated, cause azoospermia. However, gene-specific mutations leading to the azoospermia phenotype have not yet been found for any of these AZF candidate genes. This might raise the question as to whether an AZF gene really exists in Yq11 or if the azoospermia phenotypes are only observed after deletion of a complete AZF region, after deletion of its complete gene content.      

Maturation phenotype of Sertoli cells in testicular biopsies of azoospermic men

The involvement of Sertoli cells in different spermatogenic impairments has been studied by an immunohistomorphometric technique using cytokeratin-18 (CK-18) as a marker for immature Sertoli cells. CK-18 is known to be expressed in Sertoli cells during prenatal and prepubertal differentiation and is normally lost at puberty. Forty-nine azoospermic men were included in the current study. Quantitative measurements on testicular biopsies revealed the highest CK-18 expression in the mixed atrophy biopsies (22 men), a lower expression in the Sertoli cell-only (SCO) biopsies (12 men), and minimal residual staining in the group considered as representing normal spermatogenesis (six obstructive azoospermia patients). The cytokeratin immunopositive-stained tubules were associated either with arrest in spermatogenesis or with SCO. Examination of sections from nine men with microdeletions in the AZF region of the Y chromosome revealed that these men were either negative for CK-18 expression or showed only weak residual staining. This may suggest that the spermatogenic defect in the AZF-deleted men originates in the germ cell and has no impact on Sertoli cell maturation. The cause that determined the spermatogenic defect in the other cases of male infertility with high CK-18 expression may have damaged both the Sertoli and the germ cells.     

Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11

In a large collaborative screening project, 370 men with idiopathic azoospermia or severe oligozoospermia were analysed for deletions of 76 DNA loci in Yq11. In 12 individuals, we observed de novo microdeletions involving several DNA loci, while an additional patient had an inherited deletion. They were mapped to three different subregions in Yq11. One subregion coincides to the AZF region defined recently in distal Yq11. The second and third subregion were mapped proximal to it, in proximal and middle Yq11, respectively. The different deletions observed were not overlapping but the extension of the deleted Y DNA in each subregion was similar in each patient analysed. In testis tissue sections, disruption of spermatogenesis was shown to be at the same phase when the microdeletion occurred in the same Yq11 subregion but at a different phase when the microdeletion occurred in a different Yq11 subregion. Therefore, we propose the presence of not one but three spermatogenesis loci in Yq11 and that each locus is active during a different phase of male germ cell development. As the most severe phenotype after deletion of each locus is azoospermia, we designated them as: AZFa, AZFb and AZFc. Their probable phase of function in human spermatogenesis and candidate genes involved will be discussed.      

Spontaneous regression over time of the germinal epithelium in a Y chromosome-microdeleted patient: Case report

Azoospermia factor (AZF) region microdeletions, which account for about 10-15% of patients with oligoazoospermia, seem to lack a close genotype-testicular phenotype correlation. Although many genetic and non-genetic factors may contribute to this outcome, it was thought that a spontaneous regression of testicular germ cells might also play a relevant role. The opportunity for carrying out two different testicular biopsies one year apart in an AZFc-microdeleted patient enabled corroboration of this possibility. Indeed, the first biopsy showed a spermatocyte maturation arrest with mean Johnsen scores of 4 and 3.9 in the right and left testes respectively. One year later, the right testicular biopsy showed a picture of Sertoli cell-only syndrome in 90% of the tubules examined, and of spermatogonial maturation arrest in the remaining tubules, with a mean Johnsen score of 2.1. The almost complete absence of germinal cells was confirmed by four left testicular sperm aspirations (TESA), conducted at the same time as the biopsy during an intracytoplasmic sperm injection cycle, which showed the almost exclusive presence of Sertoli cells (85% of the whole cell population). No spermatozoa could be retrieved by TESA or testicular biopsy. To our knowledge, this is the first case of a spontaneous regression of the germinal cell epithelium over time in a patient with a Yq microdeletion without the apparent intervention of any cause known to affect the germinal epithelium.