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Male Infertility Caused by a de Novo Partial Deletion of the DAZ Cluster on the Y Chromosome¹

Department of Medical and Surgical Sciences, Clinica Medica 3 (E.M., A.F., C.F.), University of Padova, 35128 Padova, Italy; Department of Pediatrics, Harbor-UCLA Medical Center (P.H.Y.), Torrance, California 90502-2064; and Department of Biomedical Sciences, Section of Medical Genetics (P.G.F., G.P.), University "G. D’Annunzio", 66013 Chieti, Italy

Address all correspondence and requests for reprints to: Prof. Carlo Foresta, University of Padova, Department of Medical and Surgical Sciences, Clinica Medica 3, Via Ospedale 105, 35128 Padova, Italy. E-mail: forestac{at}protec.it

	Abstract

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Deletions in distal Yq interval 6 represent the cause of 10–15% of idiopathic severe male infertility and map to a region defined AZFc (azoospermia factor c). The testis-specific gene DAZ is considered a major AZFc candidate, and its deletion has been associated with a severe disruption in spermatogenesis. However, DAZ is actually a multicopy gene family consisting of seven clustered copies spanning about 1 megabase. Only deletions removing the entire DAZ gene cluster together with other genes have been reported in infertile males. Because no case of spermatogenic failure has been traced to intragenic deletions, point mutations, or even deletions not involving all the DAZ copies, the definitive proof for a requirement of DAZ for spermatogenesis is still debatable. Here we report the first case of a partial deletion of the DAZ cluster removing all but one of the copies. This deletion is present in a patient affected with severe oligozoospermia who had a testicular phenotype characterized by a great quantitative reduction of germ cells (severe hypospermatogenesis). The absence of this deletion in the fertile brother of the patient suggests that this de novo mutation indeed caused the spermatogenic failure.

	Introduction

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DELETIONS IN THE AZFc (azoospermia factor c) region on distal Yq interval 6 represent the cause of 10–15% of idiopathic azoospermia and severe oligozoospermia and most frequently involve the DAZ (deleted in azoospermia) gene family (1, 2, 3, 4, 5, 6). Although DAZ is not the only gene present in this region (7, 8, 9), it is a major AZFc candidate. This possibility is supported by the high homology of DAZ with a Drosophila male infertility gene, boule (10), which mutation causes spermatogenic arrest. Furthermore, more recent proofs of the spermatogenic role of the DAZ gene product arose from the observation that a human DAZ transgene is capable of partially rescuing the sterile phenotype of mouse knockout for the homologous gene Dazl (11). The critical role for DAZ in human male germ cell development is also supported by the evidence that this gene is testis-specific, with transcription limited to germ cells (12, 13, 14), even if its function remains unclear, and the postulated RNA binding property of this gene has not yet been demonstrated (1, 15, 16).

Most difficulties in understanding the biological function of DAZ and the actual genotype-phenotype relationship probably arise from the multicopy nature of this gene, present as a cluster of seven copies spanning about one megabase (8, 15, 17). Because deletions of DAZ in infertile patients are generally assessed by PCR on genomic DNA extracted from peripheral leukocytes, only deletions removing the whole DAZ gene cluster can be detected. Therefore, intragenic deletions, point mutations, or even deletions not involving all the DAZ copies, have not yet been found, and it remains still unknown whether each DAZ copy is effectively expressed and active in the testis. The definitive proof for a requirement of DAZ for spermatogenesis is therefore still debatable.

Here we report the first evidence of a de novo partial deletion of the DAZ cluster, removing all but one of the copies, in a patient affected by severe oligozoospermia and a testicular phenotype of severe hypospermatogenesis. These data further support and elucidate the role of this gene in human spermatogenesis.

	Materials and Methods

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Clinical analysis

The patient (PD51) was part of a previously selected group of patients in whom we performed a PCR-based screening of Yq microdeletions (18).The study was approved by the Hospital Ethical Committee, and informed consent was obtained from the patient. The patient was 30 yr old and suffered infertility for 3 yr. Semen samples were obtained on three different occasions, separated by a 3-week interval, following a 3-day period of sexual abstinence; and complete semen analyses were performed according to WHO guidelines (19). Plasma concentrations of FSH (Ares-Serono, Milan, Italy), LH (Ares-Serono), and testosterone (Radim, Rome, Italy) were determined by RIA. A comprehensive history and general investigation excluded any possible causes of testicular damage, such as cryptorchidism, varicocele, seminal tract infections, drug use, endocrinopathies, postmumps orchitis, testicular trauma, or torsion (idiopathic infertility). Details of Yq sequence tagged site (STS)-PCR analysis have been given previously (18), as well as details of testicular fine-needle aspiration cytology (FNAC) technique and analysis (20, 21, 22). Briefly, testicular FNAC was performed using 23-gauge (0.6-mm) butterfly needles and aspirating with a 20-mL syringe. The cellular material was placed on microscope slides, air-dried for 24 h, stained with May-Grünwald and Giemsa (Merck KgaA, Darmstadt, Germany), and examined under a light microscope at x125, x400, and x1250 magnifications. At least 200 spermatogenic cells were counted per smear, and the following forms were identified and expressed as relative percentages: spermatogonia, primary and secondary spermatocytes, early and late spermatids, and spermatozoa. The interposed Sertoli cells were expressed as the Sertoli index (the number of Sertoli cells per 100 spermatogenic cells), which as been found to be a reliable index of the tubular germ potential (20, 21, 22). As described in previous studies (20, 21, 22), cytological analysis allowed us to identify the following: 1) complete absence of germ cells, defined as Sertoli cell-only syndrome; 2) quantitative reduction of the germ line, with respect to Sertoli cells, indicating different degrees of hypospermatogenesis; 3) spermatogonia or spermatocytes arrest; 4) spermatids arrest; and 5) normal germ line with increased percentage of mature spermatozoa, indicating an obstruction of the efferent ducts.

DNA probes and Southern blot

Probes from various regions of the DAZ gene were used to define the deletion in patient PD51 (Fig. 1A). Probe A (98.1-ex 2) is a 1.0-kb PCR fragment containing intron 1 and exon 2 sequences. It was amplified from male genomic DNA using primers corresponding to nt 446–470 and nt 1471–1490 of a DAZ cosmid clone 63C9 (GenBank AC000021). Probe B (7A69F/Pst B) is a 1.7-kb PstI genomic fragment containing the entire intron 6, one copy of exon 7, and small segments of exon 6 and intron 7. Probe C (DAZe4-P8/T7) is a 1.0-kb PCR fragment amplified from a DAZ complementary DNA clone e4 and contains the 3' end of the DAZ gene (16). Probe D, used for fiber-fluorescence in situ hybridization (fiber-FISH) analysis (7C46A), is a 6-kb EcoRI genomic fragment containing the 5' end of the gene, including exon 1 and 4 kb of the 5' flanking region. Southern blot experiments were performed using standard methods (23), with ³²P-labeled DNA probes prepared by the random primed method (Boerhinger Mannheim, Milan, Italy). Blots were exposed at -70 C for several days.

View larger version (40K): [in this window] [in a new window]   Figure 1. Genomic structure, probes, and Southern analysis of the DAZ gene cluster in patient PD51. A, The genomic structure of a DAZ gene. The locations of exons, restriction sites for EcoRI and XbaI, and the probes used for Southern blot (probes A, B, and C) and fiber-FISH (probe D) are indicated. B, C, and D, Southern blots with probe A, B, and C, respectively (indicated at the bottom), with the restriction enzymes indicated at the top. The samples are: F, normal female; M; normal male; P, patient PD51; Yq-, a patient with Yq deletion (no. 9, Ref. 18).

Metaphase chromosomes and interphase nuclei were prepared from peripheral blood lymphocytes, using standard methods. Plasmid probes 7C46A for the DAZ gene (probe D, Fig. 1A) and pHu14 for the SRY gene were labeled with biotinylated deoxy-ATP or digoxigenated deoxyuridine 5-triphosphate (Roche, Molecular Biochemicals, Mannheim, Germany) by nick translation (Life Technologies, Inc.) and hybridized to chromosomes, nuclei, and DNA fibers, as previously described (24). Fiber-FISH analysis was performed using sodium-hydroxide-treated slides (25).

	Results

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While screening infertile men for Y-chromosome deletions, by STS-PCR (18), we identified one severely oligozoospermic patient, PD51, whose DNA gave unclear PCR results. PD51 was first assayed with 38 STSs located within deletion intervals 5 and 6 of the Y chromosome (18). The PCR products of all STSs tested, including those flanking the DAZ region, were of the expected size and intensity, with the exception of five STSs within the AZFc region. In fact, although PD51’s DNA was able to direct the synthesis of sY277, sY254, sY279, sY283, and sY255 (1, 6), the yields were much lower than the normal controls, suggesting partial deletion of the DAZ cluster (data not shown). To further investigate the possible deletion in PD51, Southern hybridization was performed using probes from various regions of the DAZ gene (Fig. 1A). Probe A contained sequences from intron 1 and exon 2. It detected an intense 1.7-kb EcoRI fragment derived from the Y-linked DAZ genes and a 2.2-kb fragment derived from the autosomal DAZL1 gene (26) in a normal male, and only the 2.2-kb fragment in a normal female (Fig. 1B). Probe A also detected a major 3.0-kb fragment of DAZ, in addition to other minor fragments, in the normal male when the genomic DNA was digested with XbaI. The Y-linked EcoRI and XbaI fragments, but not the autosomal fragments, in PD51 were of significantly reduced intensity compared with those in the normal male, indicating that PD51 had a deletion of most of the DAZ genes. Similar reductions in signal intensities of Y-linked fragments in PD51 were also observed using additional probes from either the middle (probe B) or the 3' end (probe C) of the DAZ gene (Fig. 1A). It is noted that there are multiple copies of exon 7, which encodes one DAZ repeat unit, in a given DAZ gene (15, 16). Therefore, probe B, which contained exon 7 and its flanking sequences, detected multiple Y-linked EcoRI fragments of variable intensities in a normal male (Fig. 1C). It also detected an autosomal 2.2-kb fragment, which was present in a normal female and in a patient with complete Yq deletion (patient no. 9, with a deletion breakpoint in interval 5A) (18). PD51 contained only some of the Y-linked fragments detected by probe B, indicating the retaining of the middle portion of some DAZ genes. Probe C contained the 3' end of the gene and detected an intense 4.2-kb band and two weaker bands of 3.4 kb and 2.3 kb in the normal male and two fragments from the autosomal DAZL1 gene that are of similar size as some of the Y-linked fragments but of weaker intensity (Fig. 1D). From the relative intensities of the fragments detected by probe C, it is concluded that PD51 retained some 3' end sequences of the DAZ gene.

Taken together, these results suggested that PD51 lost most of the DAZ copies and that this deletion caused the spermatogenic failure. To test this hypothesis, we performed the same Southern blot experiments in the patient’s brother, who was normally fertile. The brother’s DNA showed the normal presence of all bands; and also, the relative intensity of the fragments was identical to that of the control male (data not shown). Therefore, the deletion was not present in the patient’s brother, allowing us to consider the mutation a de novo event, and therefore the cause of the testiculopathy.

To further characterize the exact copy number of the DAZ genes retained in PD51, we compared signal intensities of the EcoRI fragments detected by probe A (Fig. 1B), because, in this case, there was no overlapping between the Y-linked and autosomal fragments. Using the autosomal 2.2-kb EcoRI fragment as an internal standard, it was determined, from the relative intensities of the 1.7-kb EcoRI fragments in PD51 and in the normal male, that PD51 retained a single DAZ gene, assuming that the normal male had seven DAZ genes (17).

Our initial attempts to detect the presence of the 5' end of the DAZ gene in PD51, by Southern hybridization, were unsuccessful because of weak signals and high backgrounds. To this aim and to directly analyze the copy number of DAZ genes present in PD51, we performed FISH experiments using probe D from the 5' end of the DAZ gene (Fig. 1A). FISH analysis on metaphases and nuclei from PD51 showed the presence of very tiny signals, compared with those on slides from his brother and healthy controls (data not shown). Therefore, we performed fiber-FISH experiments with this probe, and we found a single short array on 20 relaxed chromatin fibers from PD51; whereas, in his brother, a cluster of about 7 arrays was found (Fig. 2), as expected in a normal fertile man (17). These results not only showed the presence of the 5' end of DAZ but also confirmed the single copy of DAZ in PD51. Our findings therefore show that PD51 retained only 1 complete copy of DAZ gene.

View larger version (84K): [in this window] [in a new window]   Figure 2. Fiber-FISH analysis using probe 7C46A (probe D) for the DAZ gene. From the top: three different fibers from patient PD51 show a single short array (number 1 indicates one DAZ copy); whereas, on a fiber from the fertile brother of patient PD51, about seven arrays may be seen (numbers 1–7 indicate seven DAZ copies).

View larger version (122K): [in this window] [in a new window]   Figure 3. Representative picture of the testicular cytology associated with partial deletion of the DAZ cluster in patient PD51. A, Photomicrograph of normal spermatogenesis from a fertile man. Each spermatogenic cell type is present; B, Severe hypospermatogenesis in patient PD51, characterized by a great quantitative reduction of germ cells. Spg, Spermatogonia; Spc, spermatocytes; Spt, spermatids; Sp, mature spermatozoa; SC, Sertoli cells (May Grünwald-Giemsa staining, x1250 magnifications). Bar; 5 µm.

	Discussion

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To support the involvement of DAZ deletions in determining male infertility, we have performed Southern blot and fiber-FISH experiments, in a severely oligozoospermic patient, in which unclear results were obtained by standard PCR technique (18). By using probes from various regions of the DAZ gene, we were able to demonstrate that the patient retained only one complete copy of the DAZ genes, by Southern analysis, and confirmed this finding by fiber-FISH analysis. Furthermore, to clearly support the hypothesis that such deletion was the actual cause of the spermatogenic disruption, we analyzed the fertile brother of the patient, and we found that he carried all the seven DAZ copies. These results showed that the partial deletion of the DAZ cluster was a de novo event arisen in the germ cells of the father and is likely the etiological factor of the testiculopathy in patient PD51. However, we cannot conclude with certainty that this partial deletion actually has determined the spermatogenic. Nevertheless, no other possible causes of testicular damage was evident, and the patient was classified as idiopathic, severely oligozoospermic. Furthermore, the finding that the fertile brother of the patient did not show any alteration in the DAZ genes strongly supports the pathogenic role of the partial deletion.

Oligozoospermia may be related to various spermatogenic alterations, including reduction of germ cells (hypospermatogenesis), maturation arrest at different levels (spermatogonia, spermatocytes, spermatids), or partial obstruction of the seminal pathways (20). Therefore, to look for a phenotype-genotype relationship, we analyzed the testicular structure of patient PD51, other than the seminal parameters. We found that the partial deletion of the DAZ cluster produced important effects on spermatogenesis and caused a severe primary testiculopathy. Semen analysis revealed severe oligozoospermia. The testes were quite small and the basal FSH plasma concentrations were slightly higher than normal, whereas plasma levels of LH and testosterone were in the normal range. Testicular cytology revealed, in both testes, a strong quantitative reduction in the absolute number of germ cells, with the presence of both premeiotic and postmeiotic spermatogenic cells, defining a histologic diagnosis of severe hypospermatogenesis without spermatogenic arrest.

A clear phenotype-genotype relationship in patients with deletion of the entirety of the DAZ cluster has not yet been demonstrated, and AZFc deletions may be found both in azoospermic and oligozoospermic men (1, 2, 4, 5, 6, 18, 23). Furthermore, different testicular histologies may be found in these patients. The spermatogenic failure observed in patient PD51 seems to suggest that the loss of most copies of DAZ produces a depopulation of germ cells, rather than their complete absence, and that DAZ probably acts during the first phases of the spermatogenic process. Therefore, it could be speculated that, in patients with deletion of the entirety of the DAZ cluster, the loss of other possible gene(s) in the AZFc region may exacerbate the spermatogenic disruption, leading to more severe phenotypes, as observed in patients with, for example, Sertoli cell-only syndrome. The recent findings of other genes, such as BPY2 (7) and CDY (7, 8, 27), as well as new exons (9) in the vicinity or within the DAZ cluster, seem to support this idea.

Another area of interest is the number of DAZ genes that are transcribed and active in the testis. Unfortunately, we could not determine whether DAZ was expressed at some level in the spermatogenic cells of PD51, because DAZ messenger RNAs have not been detected in ejaculated sperm but only in more immature spermatogenic cells (spermatogonia and spermatocytes) (12, 14). Furthermore, we had no testicular material for expression analysis, because FNA was performed during the diagnostic workup of the patient before molecular experiments, and the patient denied any further analysis.

	Acknowledgments

 
We thank Dr. G. Calabrese and L. Stuppia for support and comments.

	Footnotes

 
¹ The financial support of Telethon-Italy (to C.F., Grant E.C0988), Ministero dell’ Universitá e della Ricerca Scientifica 1999 (to C.F. and G.P.), and the NIH (to P.H.Y., Grant HD-28009) are gratefully acknowledged.

Received March 3, 2000.

Revised May 15, 2000.

Revised July 11, 2000.

Accepted July 24, 2000.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Reijo R, Lee T, Salo P, et al. 1995 Diverse spermatogenic defects in humans caused by Y chromosome deletions encompassing a novel RNA-binding protein gene. Nat Genet. 10:383–393.[CrossRef][Medline]
2. Vogt PH, Edelmann E, Kirsch S, et al. 1996 Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11. Hum Mol Genet. 5:933–943.[Abstract/Free Full Text]
3. Vogt PH, Affara N, Davey P, et al. 1997 Report of the Third International Workshop on Y Chromosome Mapping 1997. Cytogenet Cell Genet. 79:1–20.[Medline]
4. Hargreave TB. 2000 Understanding the Y chromosome. Lancet. 354:1746–1747.
5. Foresta C, Ferlin A, Moro E, Scandellari C. 2000 Y chromosome. Lancet. 355:234–235.[Medline]
6. Reijo R, Alagappan RK, Patrizio P, Page DC. 1996 Severe oligozoospermia resulting from deletions of azoospermia factor gene on Y chromosome. Lancet. 347:1290–1293.[CrossRef][Medline]
7. Lahn BT, Page DC. 1997 Functional coherence of the human Y chromosome. Science. 278:675–680.[Abstract/Free Full Text]
8. Yen PH. 1998 A long-range restriction map of deletion interval 6 of the human Y chromosome: a region frequently deleted in azoospermic males. Genomics. 54:5–12.[CrossRef][Medline]
9. Wong J, Blanco P, Affara NA. 1999 An exon map of the AZFc male infertility region of the human Y chromosome. Mamm Genome. 10:57–61.[CrossRef][Medline]
10. Eberhart CG, Maines JZ, Wasserman SA. 1996 Meiotic cell cycle requirement for a fly homologue of human deleted in azoospermia. Nature. 38:783–785.
11. Slee R, Grimes B, Speed RM, et al. 1999 A human DAZ transgene confers partial rescue of the mouse Dazl null phenotype. Proc Natl Acad Sci USA. 96:8040–8045.[Abstract/Free Full Text]
12. Menke DB, Mutter GL, Page DC. 1997 Expression of DAZ, an azoospermia factor candidate, in human spermatogonia. Am J Hum Genet. 60:237–241.[Medline]
13. Habermann B, Mi HF, Edelmann A, et al. 1998 DAZ (deleted in azoospermia) genes encode proteins located in human late spermatids and in sperm tails. Hum Reprod. 13:363–369.
14. Ferlin A, Moro E, Onisto M, Toscano E, Bettella A, Foresta C. 1999 Absence of testicular DAZ gene expression in idiopathic severe testiculopathies. Hum Reprod. 14:2286–2292.[Abstract/Free Full Text]
15. Saxena R, Brown L, Hawkins T, et al. 1996 The DAZ gene cluster on the human Y chromosome arose from an autosomal gene that was transposed, repeatedly amplified and pruned. Nat Genet. 14:292–299.[CrossRef][Medline]
16. Yen PH, Chai NN, Salido EC. 1997 The human DAZ genes, a putative male infertility factor on the Y chromosome, are highly polymorphic in the DAZ repeat regions. Mamm Genome. 8:756–759.[CrossRef][Medline]
17. Glaser B, Yen PH, Schempp W. 1998 Fibre-fluorescence in situ hybridization unravels apparently seven DAZ genes or pseudogenes clustered within a Y-chromosome region frequently deleted in azoospermic males. Chromosome Res. 6:481–486.[CrossRef][Medline]
18. Ferlin A, Moro E, Garolla A, Foresta C. 1999 Human male infertility and Y chromosome deletions: role of the AZF-candidate genes DAZ, RBM and DFFRY. Hum Reprod. 14:1710–1716.[Abstract/Free Full Text]
19. World Health Organization. 1992 WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. ed 3. Cambridge: CambridgeUniversity Press.
20. Foresta C, Varotto A. 1992 Assessment of testicular cytology by fine needle aspiration as a diagnostic parameter in the evaluation of the oligozoospermic subject. Fertil Steril. 58:1028–1033.[Medline]
21. Foresta C, Varotto A, Scandellari C. 1992 Assessment of testicular cytology by fine needle aspiration as a diagnostic parameter in the evaluation of the azoospermic subject. Fertil Steril. 57:858–865.[Medline]
22. Foresta C, Ferlin A, Bettella A, Rossato M, Varotto A. 1995 Diagnostic and clinical features in azoospermia. Clin Endocrinol (Oxf). 43:537–543.[Medline]
23. Foresta C, Moro E, Garolla A, Onisto M, Ferlin A. 1999 Y chromosome microdeletions in cryptorchidism and idiopathic infertility. J Clin Endocrinol Metab. 84:3660–3665.[Abstract/Free Full Text]
24. Calabrese G, Sallese M, Stornaiuolo A, Stuppia L, Palka G, De Blasi A. 1994 Chromosome mapping of the human arrestin (SAG), ß-arrestin 2 (ARRB2), and ß-adrenergic receptor kinase 2 (ADRBK2). Genomics. 23:286–288.[CrossRef][Medline]
25. Fidlerova H, Senger G, Kost M, Sanseau P, Sheer D. 1994 Two simple procedures for releasing chromatin from routinely fixed cells for fluorescence in situ hybridization. Cytogenet Cell Genet. 65:203–205.[Medline]
26. Yen PH, Chai NN, Salido EC. 1996 The human autosomal gene DAZLA: testis specificity and a candidate for male infertility. Hum Mol Genet. 5:2013–2017.[Abstract/Free Full Text]
27. Lahn BT, Page DC. 1999 Retroposition of autosomal mRNA yielded testis-specific gene family on human Y chromosome. Nat Genet. 21:429–433.[CrossRef][Medline]

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