Dynamic and regulated TAF gene expression during mouse embryonic germ cell development.

Germ cells undergo many developmental transitions before ultimately becoming either eggs or sperm, and during embryonic development these transitions include epigenetic reprogramming, quiescence, and meiosis. To begin understanding the transcriptional regulation underlying these complex processes, we examined the spatial and temporal expression of TAF4b, a variant TFIID subunit required for fertility, during embryonic germ cell development. By analyzing published datasets and using our own experimental system to validate these expression studies, we determined that both Taf4b mRNA and protein are highly germ cell-enriched and that Taf4b mRNA levels dramatically increase from embryonic day 12.5-18.5. Surprisingly, additional mRNAs encoding other TFIID subunits are coordinately upregulated through this time course, including Taf7l and Taf9b. The expression of several of these germ cell-enriched TFIID genes is dependent upon Dazl and/or Stra8, known regulators of germ cell development and meiosis. Together, these data suggest that germ cells employ a highly specialized and dynamic form of TFIID to drive the transcriptional programs that underlie mammalian germ cell development.

Partial-AZFc deletions in Chilean men with primary spermatogenic impairment: gene dosage and Y-chromosome haplogroups.

PURPOSE: To investigate the association of partial-AZFc deletions in Chilean men with primary spermatogenic failure and their testicular histopathological phenotypes, analyzing the contribution of DAZ dosage, CDY1 copies, and Y-chromosome haplogroups. SUBJECTS AND METHODS: We studied 479 Chilean men: 334 infertile patients with histological examination (233 cases with spermatogenic defects and 101 normal spermatogenesis, obstructive controls, OC), and 145 normozoospermic controls (NC). AZFc subdeletions were detected by single-tagged sequences and single nucleotide variants analysis. DAZ-copy number was quantified by real-time qPCR. Y-chromosome haplogroups (Y-hg) were hierarchically genotyped through 16 biallelic-markers. RESULTS: The prevalence of AZFc-partial deletions was increased in cases (6%) compared with NC (1.4%) (P = 0.035). There was no difference between 143 Sertoli-cell only syndrome, 35 maturation arrest, or 35 mix atrophy patients and controls. However, gr/gr deletions were more frequent in 16 subjects with hypospermatogenesis compared with NC (P = 0.003) and OC (P = 0.013). Y-hg R was the most prevalent (~ 50%), but decreased among gr/gr deletions (21%, P = 0.03). The prevalence of Y-hg M increased in cases versus controls, both in total and non-deleted men (3.9 and 3.7% versus 0.4%, P = 0.009 and P = 0.016, respectively). Among gr/gr deletions, Y-hg H increased compared with non-deleted men (14.3% versus 0.4%, P = 0.0047). CONCLUSION: Partial-AZFc deletions in a Chilean admixed population are associated with secretory azo/oligozoospermia and might have a role in the development of hypospermatogenesis. Low represented haplogroups, Y-hg M and Y-hg H, show an association with the occurrence of spermatogenic failure and gr/gr deletions respectively; however, additional studies are required.

Effects of ten-eleven translocation 1 (Tet1) on DNA methylation and gene expression in chicken primordial germ cells.

Ten-eleven translocation 1 (Tet1) is involved in DNA demethylation in primordial germ cells (PGCs); however, the precise regulatory mechanism remains unclear. In the present study the dynamics of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in developing PGCs and the role of Tet1 in PGC demethylation were analysed. Results show that 5mC levels dropped significantly after embryonic Day 4 (E4) and 5hmC levels increased reaching a peak at E5-E5.5. Interestingly, TET1 protein was highly expressed during E5 to E5.5, which showed a consistent trend with 5hmC. The expression of pluripotency-associated genes (Nanog, PouV and SRY-box 2 (Sox2)) and germ cell-specific genes (caveolin 1 (Cav1), piwi-like RNA-mediated gene silencing 1 (Piwi1) and deleted in azoospermia-like (Dazl)) was upregulated after E5, whereas the expression of genes from the DNA methyltransferase family was decreased. Moreover, the Dazl gene was highly methylated in early PGCs and then gradually hypomethylated. Knockdown of Tet1 showed impaired survival and proliferation of PGCs, as well as increased 5mC levels and reduced 5hmC levels. Further analysis showed that knockdown of Tet1 led to elevated DNA methylation levels of Dazl and downregulated gene expression including Dazl. Thus, this study reveals the dynamic epigenetic reprogramming of chicken PGCs invivo and the molecular mechanism of Tet1 in regulating genomic DNA demethylation and hypomethylation of Dazl during PGC development.

Evaluation of chromosomal abnormalities and Y chromosome microdeletion in infertile males of 10 families.

This study was designed to investigate the hormonal, seminal changes and chromosomal aberrations in cases of male infertility. A total of ten infertile families from Khyber Pakhtunkhwa of Pakistan were included in the study. The families were clinically evaluated by standard criteria; diagnosis of azoospermic and oligospermic males was confirmed. Seminal, hormonal, ultra sonographic and histopathological examinations were carried out for all the affected participants of the study. Karyotyping was performed on peripheral blood lymphocytes according to standard methods. Hormones were altered in six families. Ultrasonographic abnormal finding was observed in six families. Karyotyping analysis revealed numerical aberration in family G (0X) and family I (XXY). The remainingfamilies had no structural or numerical aberration. Y chromosome microdeletion analysis revealed AZFc deletion in both the affected participants of the family C. The remaining families were found normal for microdeletion. The occurrence of chromosomal anomalies and Y chromosome microdeletions among infertile males strongly suggests the need to include these two tests in routine investigations of male in fertility cases.

Immunolocalization of proteins in the spermatogenesis process of canine.

Spermatogenesis is a process in which differentiated cells are produced and the adult stem cell population-known as spermatogonial stem cells (SSCs)-is continuously replenished. However, the molecular mechanisms underlying these processes are not fully understood in the canine species. We addressed this in this study by analysing the expression of specific markers in spermatogonia of seminiferous tubules of canine testes. SSCs at different stages of reproductive development (prepubertal and adult) were examined by immunohistochemistry and flow cytometry. Glial cell-derived neurotrophic factor family receptor alpha-1 (GFRA1), deleted in azoospermia-like (DAZL) and promyelocytic leukaemia zinc finger (PLZF) were expressed in SSCs, while stimulated by retinoic acid gene 8 (STRA8) was detected only in undifferentiated spermatogonia in prepubertal testis and differentiated spermatogonia and spermatocytes in adult canine. Octamer-binding transcription factor 4 (OCT4) showed an expression pattern, and the levels did not differ between the groups examined. However, C-kit expression varied as a function of reproductive developmental stage. Our results demonstrate that these proteins play critical roles in the self-renewal and differentiation of SSCs and can serve as markers to identify canine spermatogonia at specific stages of development.

Analysis of partial azoospermia factor c deletion and DAZ copy number in azoospermia and severe oligozoospermia.

Microdeletions of the azoospermia factor (AZF) regions in the Y chromosome are a well-known genetic cause of male infertility, resulting in impairment of spermatogenesis. However, the partial deletions of AZFc region related to spermatogenetic impairment are controversial. We investigated partial deletion of AZFc region and DAZ copy number in a population of Iranian infertile men and normozoospermic controls. In total, 154 infertile men (113 patients with azoospermia, 41 with oligozoospermia) and 111 normozoospermic controls were analysed using PCR. Gene dosage analysis of the DAZ genes was performed by fragment analysis. Our results showed that the frequencies of gr/gr deletion in the azoospermic, severe oligozoospermic and normozoospermic men were 4.4% (5/113), 7.3% (3/41) and 1.8% (2/111) respectively. In the azoospermic patients, the frequency of b2/b3 was 1.8% (2/113). Partial AZFc deletions were not significantly different between the infertile and normozoospermic men. The frequencies of gr/gr deletions and b2/b3 were not significantly different between the azoospermic/severe oligozoospermic men and normozoospermic controls. Our data suggested that gr/gr deletion was not associated with azoospermia/oligozoospermia in an Iranian population.

[Association of the deleted DAZ gene copy related to gr/gr and b2/b3 deletions with spermatogenic impairment].

OBJECTIVE: To investigate the correlation of the deleted azoospermia (DAZ) gene copy related to gr/gr and b2/b3 deletions in the AZFc region with male spermatogenic impairment. METHODS: This study included 121 infertile men with different de- grees of spermatogenic impairment and 95 healthy donors from the sperm bank. Using PCR, PCR-RFLP, and Y chromosome specific sequence tagged sites (STS) , we analyzed the association of DAZ gene copy deletions related to gr/gr and b2/b3 deletions in the AZFc region with spermatogenic impairment. RESULTS: There were 15 cases of gr/gr deletion (12. 40% ) and 6 cases of b2/b3 deletion (4.96%) in the infertility group as compared with 13 cases of gr/gr deletion (13.68%) and 1 case of b2/b3 deletion (1.05%) in the control. Analysis of the DAZ-specific single nucleotide variant (SNV) loci revealed 11 gr/gr-DAZI/DAZ2 deletions (9.09%), 4 gr/gr-DAZ3/DAZ4 deletions (3.31%), and 6 b2/b3-DAZ1/DAZ2 deletions (4.96%) in the infertile men in comparison with 3 gr/ gr-DAZ1/DAZ2 deletions (3.16%), 10 gr/gr-DAZ3/DAZ4 deletions (10.53%), and 1 b2/b3- DAZ3/DAZ4 deletion (1.05%) in the control. CONCLUSION: Partial deletions of gr/gr and b2/b3 exist in both healthy men and male patients with different degrees of spermatogenic impairment and cannot be considered as a risk factor for spermatogenesis impairment. However, deletions of different DAZ duplicons in gr/gr and b2/b3 deletions have different effects on spermatogenesis. DAZ1/DAZ2 instead of DAZ3/DAZ4 deletions might be associated with spermatogenesis impairment.

AZFc deletions do not affect the function of human spermatogonia in vitro.

Azoospermic factor c (AZFc) deletions are the underlying cause in 10% of azoo- or severe oligozoospermia. Through extensive molecular analysis the precise genetic content of the AZFc region and the origin of its deletion have been determined. However, little is known about the effect of AZFc deletions on the functionality of germ cells at various developmental steps. The presence of normal, fertilization-competent sperm in the ejaculate and/or testis of the majority of men with AZFc deletions suggests that the process of differentiation from spermatogonial stem cells (SSCs) to mature spermatozoa can take place in the absence of the AZFc region. To determine the functionality of AZFc-deleted spermatogonia, we compared in vitro propagated spermatogonia from six men with complete AZFc deletions with spermatogonia from three normozoospermic controls. We found that spermatogonia of AZFc-deleted men behave similar to controls during culture. Short-term (18 days) and long-term (48 days) culture of AZFc-deleted spermatogonia showed the same characteristics as non-deleted spermatogonia. This similarity was revealed by the same number of passages, the same germ cell clusters formation and similar level of genes expression of spermatogonial markers including ubiquitin carboxyl-terminal esterase L1 (UCHL1), zinc finger and BTB domain containing 16 (ZBTB16) and glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRA1), as well as germ cell differentiation markers including signal transducer and activator of transcription 3 (STAT3), spermatogenesis and oogenesis specific basic helix-loophelix 2 (SOHLH2), v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) and synaptonemal complex protein 3 (SYCP3). The only exception was melanoma antigen family A4 (MAGEA4) which showed significantly lower expression in AZFc-deleted samples than controls in short-term culture while in long-term culture it was hardly detected in both AZFc-deleted and control spermatogonia. These data suggest that, at least in vitro, spermatogonia of AZFc-deleted men are functionally similar to spermatogonia from non-deleted men. Potentially, this enables treatment of men with AZFc deletions by propagating their SSCs in vitro and autotransplanting these SSCs back to the testes to increase sperm counts and restore fertility.

Transcriptome analysis of the cancer/testis genes, DAZ1, AURKC, and TEX101, in breast tumors and six breast cancer cell lines.

Breast cancer is the most frequent cancer with second mortality rate in women worldwide. Lack of validated biomarkers for early detection of breast cancer to warranty the diagnosis and effective treatments in early stages has directed to the new therapeutic approach. Cancer/testis antigens which have restricted normal expression in testis and aberrant expression in different cancers are promising targets for generating cancer vaccines, monoclonal antibodies, or dendritic cell-based immunotherapy. In this context, we investigated the expression of two known cancer testis genes, Aurora kinase C (AURKC) and testis expressed 101 (TEX101), and one new candidate, deleted in azoospermia 1 (DAZ1), in six breast cancer cell lines including two ductal carcinomas, T47D and BT-474, and four adenocarcinomas, MDA-MB-231, MDA-MB-468, MCF7, and SKBR3 as well as 50 breast cancer tumors in comparison to normal mammary epithelial cells using quantitative real-time reverse transcription PCR (RT-PCR). Results showed significant overexpression (p = 0.000) of all three genes in BT474, DAZ1 in MDA-MB-231, and AURKC and DAZ1 in SKBR3 and significant downregulation (p = 0.000) of AURKC in MCF7 cell line relative to normal breast epithelial cells. Breast tumors showed significant overexpression of AURKC in comparison to normal breast tissues (p = 0.016). The results are noticeable especially in the case of AURKC; however, there is a little knowledge about the nature, causes, consequences, and effects of cancer/testis antigens activation in different cancers. It is suggested that AURKC has effects on cell division via its serin/threonin kinases activity and organizing microtubules in relation to centrosome/spindle function during mitosis.

Human DAZL, DAZ and BOULE genes modulate primordial germ-cell and haploid gamete formation.

The leading cause of infertility in men and women is quantitative and qualitative defects in human germ-cell (oocyte and sperm) development. Yet, it has not been possible to examine the unique developmental genetics of human germ-cell formation and differentiation owing to inaccessibility of germ cells during fetal development. Although several studies have shown that germ cells can be differentiated from mouse and human embryonic stem cells, human germ cells differentiated in these studies generally did not develop beyond the earliest stages. Here we used a germ-cell reporter to quantify and isolate primordial germ cells derived from both male and female human embryonic stem cells. By silencing and overexpressing genes that encode germ-cell-specific cytoplasmic RNA-binding proteins (not transcription factors), we modulated human germ-cell formation and developmental progression. We observed that human DAZL (deleted in azoospermia-like) functions in primordial germ-cell formation, whereas closely related genes DAZ and BOULE (also called BOLL) promote later stages of meiosis and development of haploid gametes. These results are significant to the generation of gametes for future basic science and potential clinical applications.

Susceptibility of gr/gr rearrangements to azoospermia or oligozoospermia is dependent on DAZ and CDY1 gene copy deletions.

PURPOSE: The purpose of this study was to determine the association of AZFc subdeletions (gr/gr, b1/b3 and b2/b3) and deletion of DAZ and CDY1 gene copies with male infertility METHODS: Three hundred twelve controls, 172 azoospermic and 343 oligozoospermic subjects were subjected to AZFc subdeletion typing by STS PCR. Deletion of DAZ and CDY1 gene copies was done using sequence family variant analysis. Sperm concentration and motility were compared between men with and without AZFc subdeletions. Effect of the AZFc subdeletions on ICSI outcome was evaluated. RESULTS: Amongst the three AZFc subdeletions, the frequency of gr/gr was higher in oligozoospermic (10.5 %) and azoospermic (11.6 %) men as compared to controls (5.1 %). In men with AZFc subdeltions, loss of two DAZ and one CDY1 gene copy made them highly susceptible to azoospermia and severe oligozoospermia with OR of 29.7 and 26, respectively. These subdeletions had no effect on ICSI outcome, albeit there were an increased number of poor quality embryos in AZFc subdeleted group. CONCLUSION: AZFc subdeletions are a major risk factor for male infertility in the Indian population. In the subjects with AZFc subdeletions, the deletion of DAZ and CDY1 gene copies increases its susceptibility to azoospermia or severe oligozoospermia. Since these deletions can be vertically transmitted to the future male offspring by ICSI, it will be essential to counsel the couples for the transmission of the genetic defect in the male offspring born after assisted reproduction and the risk of perpetuating infertility in future generation.

Gene copy number alterations in the azoospermia-associated AZFc region and their effect on spermatogenic impairment.

The azoospermia factor c (AZFc) region in the long arm of human Y chromosome is characterized by massive palindromes. It harbors eight multi-copy gene families that are expressed exclusively or predominantly in testis. To assess systematically the role of the AZFc region and these eight gene families in spermatogenesis, we conducted a comprehensive molecular analysis (including Y chromosome haplogrouping, AZFc deletion typing and gene copy quantification) in 654 idiopathic infertile men and 781 healthy controls in a Han Chinese population. The b2/b3 partial deletion (including both deletion-only and deletion-duplication) was consistently associated with spermatogenic impairment. In the subjects without partial AZFc deletions, a notable finding was that the frequency of DAZ and/or BPY2 copy number alterations in the infertile group was significantly higher than in the controls. Combined patterns of DAZ and/or BPY2 copy number abnormality were associated with spermatogenic impairment when compared with the pattern of all AZFc genes with common level copies. In addition, in Y chromosome haplogroup O1 (Y-hg O1), the frequency of copy number alterations of all eight gene families was significantly higher in the case group than that in the control group. Our findings indicate that the DAZ, BPY2 genes may be prominent players in spermatogenesis, and genomic rearrangements may be enriched in individuals belonging to Y-hg O1. Our findings emphasize the necessity of routine molecular analysis of AZFc structural variation during the workup of azoospermia and/or oligozoospermia, which may diminish the genetic risk of assisted reproduction.

Analysis of DAZ gene expression in a partial AZFc deletion of the human Y chromosome.

The azoospermia factor c (AZFc) region of the Y chromosome consists of repetitive amplicons and is therefore highly susceptible to structural rearrangements, such as deletions and duplications. The b2/b3 deletion is a partial AZFc deletion that is conventionally determined by the selective absence of sY1191 in sequence-tagged site polymerase chain reaction (PCR) and is generally believed to retain two of the four deleted in azoospermia (DAZ) genes on the Y chromosome. In the present study we determined the copy number and expression of DAZ genes in sY1191-negative individuals. Using a DAZ dosage PCR assay and Southern blot analysis we evaluated the expression of four DAZ genes in five of six sY1191-negative individuals. Furthermore, cloning and immunoblot analyses revealed that three or more DAZ genes are expressed in sY1191-negative testes with germ cells. The results indicate that the selective absence of sY1191 not only means b2/b3 deletion with two DAZ genes, but also includes another AZFc configuration with four DAZ genes. These results exemplify the prevalence of variations in the AZFc region of the human Y chromosome.

Sequencing of rhesus macaque Y chromosome clarifies origins and evolution of the DAZ (Deleted in AZoospermia) genes.

Studies of Y chromosome evolution often emphasize gene loss, but this loss has been counterbalanced by addition of new genes. The DAZ genes, which are critical to human spermatogenesis, were acquired by the Y chromosome in the ancestor of Old World monkeys and apes. We and our colleagues recently sequenced the rhesus macaque Y chromosome, and comparison of this sequence to human and chimpanzee enables us to reconstruct much of the evolutionary history of DAZ. We report that DAZ arrived on the Y chromosome about 38 million years ago via the transposition of at least 1.1 megabases of autosomal DNA. This transposition also brought five additional genes to the Y chromosome, but all five genes were subsequently lost through mutation or deletion. As the only surviving gene, DAZ experienced extensive restructuring, including intragenic amplification and gene duplication, and has been the target of positive selection in the chimpanzee lineage. Editor's suggested further reading in BioEssays Should Y stay or should Y go: The evolution of non-recombining sex chromosomes Abstract.

Molecular analysis of testis biopsy and semen pellet as complementary methods with histopathological analysis of testis in non-obstructive azoospermia.

PURPOSE: Non-obstructive azoospermia (NOA) is one the many causes of male infertility (10 %) resulting from testicular failure. Multiple testicular biopsies fail to find mature sperm in at least 50 % of cases Therefore; hunting for sensitive and specific biomarkers of spermatogenesis that could better determine the fertility status in NOA can lead to improved management of male infertility. Therefore, we evaluated sperm production through analyses of germ cell-specific transcripts (DAZ, TSPY1, SPTRX3 and SPTRX1) in semen and testicular biopsies of men with azoospermia. METHODS: We collected semen (N=83) and testis biopsies (N=31) from men with non-obstructive azoospermia. We later extracted RNA and synthesized cDNA using washed semen precipitate and testicular tissues. We also performed semi-nested PCR with designed specific primers. Using H&E method, an expert pathologist performed the histopathological evaluation. Having categorized the patients into three groups based on histopathological results, we calculated the agreement between molecular results of semen and tissues with histopathological findings for each patient using Kappa statistical test. RESULTS: Molecular findings of precipitated semen and testicular tissues were in disagreement with histopathological results in most cases. Molecular analysis of testis biopsies showed significant difference (Kappa coefficient=0.009, P value=0.894) with histopathological results; TSPY1, DAZ, SPTRX3 and SPTRX1 were respectively detected in 94 %, 94 %, 17.6 % and 52.9 % of men diagnosed with germ cell aplasia. CONCLUSIONS: Molecular analysis of semen does not provide sufficient sensitivity and specificity to be used as a screening test at the present time, but it is a useful adjunct to histopathological methods in men with NOA. Spermatid/sperm specific transcripts indicated the possibility to find mature sperm following repeated multiple testicular sperm extraction (TESE) or microdisection TESE (mTESE).

DAZ duplications confer the predisposition of Y chromosome haplogroup K* to non-obstructive azoospermia in Han Chinese populations.

STUDY QUESTION: What are the genetic causes for the predisposition of certain Y chromosome haplogroups (Y-hgs) to spermatogenic impairment? SUMMARY ANSWER: The AZFc(azoospermia factor c)/DAZ (deleted in azoospermia) duplications might underlie the susceptibility of Y-hg K* to spermatogenic impairment. WHAT IS KNOWN ALREADY: The roles of Y chromosomal genetic background in spermatogenesis are controversial and vary among human populations. Individuals in predisposed Y-hgs may carry some genetic factors, which might be a potential genetic modifier for the Y-hg-specific susceptibility to spermatogenic impairment. STUDY DESIGN, SIZE, DURATION: A total of 2444 individuals with azoospermia or oligozoospermia and 2456 healthy controls were recruited to this study from March 2004 and January 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS: We performed a two-stage association study to investigate the risk and/or protective Y-hgs for spermatogenic impairment. In addition, the genetic causes for the predisposition of certain Y-hg to spermatogenic impairment were investigated. Deletion typing and DAZ gene copy number quantification were performed for individuals in predisposed Y-hgs. MAIN RESULTS AND THE ROLE OF CHANCE: Y-hgs K* and O3e* showed significantly different distribution between cases and controls consistently in two-stage studies. Combined analyses identified significant predisposition to non-obstructive azoospermia in Y-hg K* [odds ratio (OR) 8.58; 95% confidence interval (CI) 3.31-22.28; P = 1.40 × 10⁻5], but a protecting effect in Y-hg O3e* (OR 0.64; 95% CI 0.53-0.78; P = 4.20 × 10⁻5). Based on the dynamic nature of the Y chromosome, we hypothesized that Y-hgs K* and O3e* may be accompanied by modifying genetic factors for their predisposing or protecting effects in spermatogenesis. Accordingly, we quantified the multi-copy DAZ gene, which has variable copy numbers between individuals and plays an important role in spermatogenesis. In combined analysis, we found that the over-dosage of DAZ was significantly more frequent in Y-hg K* than in O3e* (OR 4.79; 95% CI 1.67-13.70; P = 6 × 10⁻³). LIMITATIONS, REASONS FOR CAUTION: Owing to the inconsistency of genetic background, it remains to be determined whether the results derived from Han Chinese populations are applicable to other ethnic groups. WIDER IMPLICATIONS OF THE FINDINGS: The findings of this study can advance the etiology of spermatogenic impairment, and also shed new light on Y chromosome evolution in human populations. Y-hg-specific genetic factors of modifying spermatogenic phenotypes deserve further investigation in larger and diverse populations.

Association of DAZ1/DAZ2 deletion with spermatogenic impairment and male infertility in the South Chinese population.

PURPOSE: To investigate the effect of the deleted in azoospermia (DAZ) copy cluster deletion on spermatogenesis in the South Chinese population. METHODS: In this study, the prevalence and characteristics of different DAZ copy cluster deletions and their association with spermatogenic failure were analyzed. A total of 186 infertile men with different spermatogenic impairments and 190 normozoospermic fertile men were studied. Three DAZ-specific single nucleotide variant loci and seven AZFc-specific sequence-tagged sites were examined using polymerase chain reaction (PCR)-restriction fragment length polymorphism and routine PCR. RESULTS: Gr/gr deletions were observed in a total of 9 of the 190 normozoospermic fertile men, and 11 gr/gr deletions were found in 186 infertile men. In addition, 3 b2/b3 deletions were identified in the infertile, but not in the fertile men. DAZ-SNV loci analysis revealed 4 DAZ copies that had 8 gr/gr-DAZ3/DAZ4 deletions and 1 gr/gr-DAZ1/DAZ2 deletion in the fertile men (8/190 vs. 1/190, p = 0.037). Analysis of DAZ deletion copies in infertile men revealed 10 gr/gr-DAZ1/DAZ2 deletions, 1 gr/gr-DAZ3/DAZ4 deletion (10/186 vs. 1/186, p = 0.011) and 3 b2/b3-DAZ1/DAZ2 deletions (13/186 vs. 1/186, p = 0.002). CONCLUSIONS: Analysis of DAZ gene copies in AZFc microdeletions suggests that the contribution of the different deletions to male infertility varies. Removing DAZ1/DAZ2 seems to be associated with spermatogenic impairment, whereas removing DAZ3/DAZ4 seems to have little or no effect on fertility in the South Chinese population.

The DAZ gene cluster on the human Y chromosome arose from an autosomal gene that was transposed, repeatedly amplified and pruned.

It is widely believed that most or all Y-chromosomal genes were once shared with the X chromosome. The DAZ gene is a candidate for the human Y-chromosomal Azoospermia Factor (AZF). We report multiple copies of DAZ (> 99% identical in DNA sequence) clustered in the AZF region and a functional DAZ homologue (DAZH) on human chromosome 3. The entire gene family appears to be expressed in germ cells. Sequence analysis indicates that the Y-chromosomal DAZ cluster arose during primate evolution by (i) transposing the autosomal gene to the Y, (ii) amplifying and pruning exons within the transposed gene and (iii) amplifying the modified gene. These results challenge prevailing views of sex chromosome evolution, suggesting that acquisition of autosomal fertility genes is an important process in Y chromosome evolution.

Diverse spermatogenic defects in humans caused by Y chromosome deletions encompassing a novel RNA-binding protein gene.

We have detected deletions of portions of the Y chromosome long arm in 12 of 89 men with azoospermia (no sperm in semen). No Y deletions were detected in their male relatives or in 90 other fertile males. The 12 deletions overlap, defining a region likely to contain one or more genes required for spermatogenesis (the Azoospermia Factor, AZF). Deletion of the AZF region is associated with highly variable testicular defects, ranging from complete absence of germ cells to spermatogenic arrest with occasional production of condensed spermatids. We find no evidence of YRRM genes, recently proposed as AZF candidates, in the AZF region. The region contains a single-copy gene, DAZ (Deleted in AZoospermia), which is transcribed in the adult testis and appears to encode an RNA binding protein. The possibility that DAZ is AZF should now be explored.

A human candidate spermatogenesis gene, RBM1, is conserved and amplified on the marsupial Y chromosome.

Three genes, RBM1, DAZ and TSPY, map to a small region of the long arm of the human Y chromosome which is deleted in azoospermic men. RBM1, but not DAZ or TSPY, has a Y-linked homologue in marsupials which is transcribed in the testis. This suggests that RBM1 has been retained on the Y chromosome because of a critical male-specific function. Marsupial RBM1 is closely related to human RBM1, but, like the related autosomal gene hnRNPG, lacks the amplification of an exon. This suggests that RBM1 evolved from hnRNPG at least 130 million years ago and has undergone internal amplification in primates, as well as independent amplification in several therian [corrected] lineages.