AZFb Deletions Research Articles

The significance of Y chromosome microdeletion analysis in subfertile men with clinical variocele.

IntroductionThe aim of study is determining the cost-effectiveness of detection analysis in the presence of exceptional patients who have mild semen disorders, and beware of unnecessary varicocele repairs; and to ascertain whether patients with clinical varicocele should undergo Y chromosome (Yq) microdeletion analysis as a routine procedure.Material and methodsVaricocele with reflux was diagnosed in 51 male patients with subfertility symptoms upon physical examination (PE), confirmed by scrotal colour-Doppler ultrasound (CDU). After cytogenetic examination, Yq microdeletion analysis was performed on the peripheral blood samples using Promega Y Chromosome Deletion Detection System Version 2. Varicocele repair was performed under general anaesthesia with optical magnification (3-fold) through a subinguinal approach.ResultsThe mean age of the patients was 27.9. Values of semen concentration ranged from 0 to 72 million/ml, motility from 0 to 65% (A + B) and Kruger from 0% to 18%. The PE revealed normal size and consistency in the bilateral testicles. All patients were cytogenetically normal. However, Yq microdeletion was detected in 2 patients, 1 with mild oligoteratozoospermia and partial AZFb deletion (sY121) and the second patient with severe oligozoospermia and partial AZFc deletion (sY254 and sY255), and they were not subjected to varicocelectomy.ConclusionsThe routine performance of pre-operative Yq microdeletion analysis in patients with clinical varicocele does not seem to be cost-effective but the omission of patients with mild oligozoospermia would have subjected them to an unnecessary varicocelectomy and/or further ICSI applications and also would have caused the failure of referral for genetic counselling.

Massive deletion in AZFb/b+c and azoospermia with Sertoli cell only and/or maturation arrest

Recent studies have revealed that AZF deletion in Y chromosome is the most common known molecular genetic cause of spermatogenetic failure leading to male infertility. Characteristics of AZFa, AZFb and AZFc deletions and their association with spermatogenic impairment have been reported in a large number of populations. However, the distributions of those larger deletions resulted from P5/proximal-P1, P5/distal-P1 and P4/distal-P1 recombinations are still unclear as the literature on their frequencies is limited, and the contribution of these deletions to spermatogenetic failure remain to be confirmed by population studies. In this study, we investigated such massive deletions in 387 idiopathic azoospermic, 269 oligozoospermic patients and 315 men with normal spermatogenesis using 21 AZFb/c specific sequence-tagged sites. As a result, nine uninterrupted massive deletions were observed exclusively in men with azoospermia caused by either Sertoli cell only (SCO) or maturation arrest (MA). Prevalence of the deletion was 2.33%, in which five deletions arose from non-allelic homologous recombination between the palindromes P5 and P1 and two between P4 and P1. In other two deletions, novel proximal breakpoints in the interval region between P4 and P3 were observed. Our findings strongly support that the massive deletions in the AZFb or AZFb+c regions are important genetic causes of SCO and/or MA resulting in azoospermia and, besides the P5/proximal-P1, P5/distal-P1 and P4/distal-P1 deletions there may be other massive deletions in these regions resulting in severe spermatogenic impairment.

The prevalence of azoospermia factor microdeletion on the Y chromosome of Chinese infertile men detected by multi-analyte suspension array technology

To develop a high-throughput multiplex, fast and simple assay to scan azoospermia factor (AZF) region microdeletions on the Y chromosome and establish the prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. In total, 178 infertile patients with azoospermia (non-obstructed), 134 infertile patients with oligozoospermia as well as 40 fertile man controls were included in the present study. The samples were screened for AZF microdeletion using optimized multi-analyte suspension array (MASA) technology. Of the 312 patients, 36 (11.5%) were found to have deletions in the AZF region. The microdeletion frequency was 14% (25/178) in the azoospermia group and 8.2% (11/134) in the oligospermia group. Among 36 patients with microdeletions, 19 had deletions in the AZFc region, seven had deletions in AZFa and six had deletions in AZFb. In addition, four patients had both AZFb and AZFc deletions. No deletion in the AZF region was found in the 40 fertile controls. There is a high prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. The MASA technology, which has been established in the present study, provides a sensitive and high-throughput method for detecting the deletion of the Y chromosome. And the results suggest that genetic screening should be advised to infertile men before starting assisted reproductive treatments.

Identification of new breakpoints in AZFb and AZFc

Microdeletions in AZFa, AZFb and AZFc regions lead to different patterns of male infertility, from severe oligozoospermia to non-obstructive azoospermia. Intrachromosomal homologous recombination mechanisms were already identified in patients with simultaneous microdeletions in the AZFb and AZFc regions. Ten patients with atypical AZFb and AZFc deletion patterns were studied. The definition of those microdeletions and the fine characterization of the respective breakpoints were performed using sequence tagged sites/single nucleotide variants-PCR and DNA sequencing. Y-chromosome haplogroups were determined to establish a putative association with the patterns obtained. Seven deletion patterns were identified, P5/terminal (30%; 3/10), P5/P1 distal (20%; 2/10), IR4/distal-P2, IR2/proximal-P1, IR4/distal-P1, P4/terminal and complete AZFb/c deletion (10%; 1/10). Breakpoint sequence analysis suggests that only in one patient the P5/P1 distal deletion pattern was due to a homologous recombination mechanism. Sequence alignment of the other deletion patterns suggest that they have resulted from non-homologous recombination mechanisms.

Chromosome Y et infertilité masculine : qu'est-ce qu'un chromosome Y normal ?

The human Y chromosome contains a number of genes and gene families that are essential for germ cell development and maintenance. Many of these genes are located in highly repetitive elements that are subject to rearrangements. Deletion of azoospermia factor (AZF) regions AZFa, AZFb, and AZFc are found in approximately 10-15% of men with severe forms of spermatogenic failure. Several partial AZFc deletions have been described. One of these, which removes around half of all the genes within the AZFc region, appears to be present as an inconsequential polymorphism in populations of northern Eurasia. A second deletion, termed gr/gr, also results in the absence of several AZFc genes and it may be a genetic risk factor for spermatogenic failure. However, the link between these partial deletions and fertility is unclear. The gr/gr deletion is not a single deletion but a combination of deletions that vary in size and complexity and result in the absence of different genes. There are also regional or ethnic differences in the frequency of gr/gr deletions. In some Y-chromosome lineages, these deletions appear to be fixed and may have little influence on spermatogenesis. Most of these data (gene content and Y chromosome structure) have been deduced from the reference Y chromosome sequence deposited in NCBI. However, recently there have been attempts to define these types of structural rearrangements in the general population. These have highlighted the considerable degree of structural diversity that exist. Trying to correlate these changes with the phenotypic variability is a major challenge and it is likely that there will not be a single reference (or normal) Y chromosome sequence but many.

AZF microdeletions and partial deletions of AZFc region on the Y chromosome in Moroccan men

To evaluate for the first time the frequency of Y chromosome microdeletions and the occurrence of the partial deletions of AZFc region in Moroccan men, and to discuss the clinical significance of AZF deletions. We screened Y chromosome microdeletions and partial deletions of the AZFc region of a consecutive group of infertile men (n = 149) and controls (100 fertile men, 76 normospermic men). AZFa, AZFb, AZFc and partial deletions of the AZFc region were analyzed by polymerase chain reaction (PCR) according to established protocols. Among the 127 infertile men screened for microdeletion, four subjects were found to have microdeletions: two AZFc deletions and two AZFb+AZFc deletions. All the deletions were found only in azoospermic subjects (4/48, 8.33%). The overall AZFc deletion frequency was low (4/127, 3.15%). AZF microdeletions were not observed in either oligoasthenoteratozoospermia (OATS) or the control. Partial deletions of AZFc (gr/gr) were observed in a total of 7 of the 149 infertile men (4.70%) and 7 partial AZFc deletions (gr/gr) were found in the control group (7/176, 3.98%). In addition, two b2/b3 deletions were identified in two azoospermic subjects (2/149, 1.34%) but not in the control group. Our results suggest that the frequency of Y chromosome AZF microdeletions is elevated in individuals with severe spermatogenic failure and that gr/gr deletions are not associated with spermatogenic failure.

Analysis of sex chromosome abnormalities using X and Y chromosome DNA tiling path arrays

Background: Array comparative genomic hybridisation is a powerful tool for the detection of copy number changes in the genome. Methods: A human X and Y chromosome tiling path array was...

Molecular and Clinical Characterization of Y Chromosome Microdeletions in Infertile Men: A 10-Year Experience in Italy

An explosive growth in Y chromosome long arm (Yq) microdeletion testing demand for male infertility occurred in the past few years. However, despite the progresses in the biology of this chromosome, a number of molecular and clinical concerns are not supported by definitive data. The objective was to provide information on the type and prevalence of microdeletions in infertile males, indication for testing, genotype-phenotype correlation, sperm aneuploidies, and genetic counseling. We performed a prospective study from January 1996 to December 2005 in an academic clinic. We studied 3073 consecutive infertile men, of which 625 were affected by nonobstructive azoospermia and 1372 were affected by severe oligozoospermia. Ninety-nine patients with microdeletions are described here. Yq microdeletions, seminal analysis, reproductive hormones, testicular cytology/histology, and sperm sex chromosomes aneuploidies were used as outcome measures. The prevalence of microdeletions was 3.2% in unselected infertile men, 8.3% in men with nonobstructive azoospermia, and 5.5% in men with severe oligozoospermia. Only 2 of 99 deletions were found in men with more than 2 million sperm/ml. No clinical data are useful to identify a priori patients with higher risk of Yq microdeletions. Most deletions are of the AZFc-b2/b4 subtype and are associated with variable spermatogenic phenotype, with sperm present in 72% of the cases. Complete AZFa and AZFb (P5/Proximal P1) deletions are associated with Sertoli cell-only syndrome and alterations in spermatocyte maturation, respectively, whereas partial deletions in these regions are associated with milder phenotype and frequent presence of sperm. Men with AZFc-b2/b4 deletions produce a higher percentage of sperm with nullisomy for the sex chromosomes and XY-disomy. This extensive clinical research expands the knowledge on genotype-phenotype relationships and confirms that the identification of Yq microdeletions has significant diagnostic and prognostic value, adding useful information for genetic counseling in these patients.

Y chromosome microdeletions in idiopathic infertile men from West Azarbaijan.

Although assisted reproduction techniques are used extensively in Iran, screening for Y chromosome microdeletions before intracytoplasmic sperm injection is often undervalued. Our aim was to investigate Y chromosome microdeletions in men with idiopathic azoospermia or severe oligospermia. In 99 selected patients with azoospermia or severe oligospermia and elevated levels of follicle-stimulating hormone and luteinizing hormone in combination with low serum testosterone levels, 20 pairs of sequence-tagged site-based primer sets specific for the Y microdeletion loci were analyzed. Primers were chosen to cover azoospermia factor (AZF) regions as well as deleted in azoospermia (DAZ) and the sex-determining region on Y chromosome (SRY) genes. Also, 100 healthy men served as a control group. Twenty-four patients (24.2%) had microdeletions in AZF genes, but no microdeletions were found in men in the control group. In 15 patients (62.5%), 1 deletion was found. Six patients (25%) had 2, and 3 (12.5%) had 3 deletions. The deletions mainly comprised the AZFc region (in 21 of 24 patients; 87.5%), which corresponds to the DAZ gene. Deletions in AZFb were found in 7 patients (29.2%), and 4 (16.7%) had deletions in the proximal part of AZF regions near SRY gene. No microdeletions were seen in the AZFa or SRY gene. Our results emphasize that Y chromosome microdeletion analysis should be carried out in all patients with idiopathic azoospermia or severe oligospermia who are candidates for intracytoplasmic sperm injection.

Y-chromosomal microdeletions and partial deletions of the Azoospermia Factor c (AZFc) region in normozoospermic, severe oligozoospermic and azoospermic men in Sri Lanka

To assess for the first time the occurrence of Y chromosomal microdeletions and partial deletions of the Azoospermia Factor c (AZFc) region in Sri Lankan men and to correlate them with clinical parameters. In a retrospective study, we analyzed 96 infertile men (78 with non-obstructive azoospermia) and 87 controls with normal spermatogenesis. AZFa, AZFb, AZFc and partial deletions within the AZFc region were analyzed by multiplex polymerase chain reaction (PCR) according to established protocols. No AZFa, AZFb or AZFc deletions were found in the control group. Seven patients in the group of infertile men were found to have deletions as following: one AZFa, two AZFc, two AZFbc and two AZFabc. The relative distribution of these patterns was significantly different compared with that found in the German population. Extension analysis confirmed that the deletions occurred according to the current pathogenic model. gr/gr deletions were found to be equally present both in the patients (n=4) and in the control group (n=4). One b2/b3 deletion was found in the patient group. These results suggest that the frequency and pattern of microdeletions of the Y chromosome in Sri Lankan men are similar to those found in other populations and confirm that gr/gr deletions are not sufficient to cause spermatogenetic failure.

Serum FSH levels and testicular histology in infertile men with non obstructive azoospermia and Y chromosome microdeletions

Objectives: Men with nonobstructive azoospermia may father a child through intracytoplasmic injection of testicular sperms. This can result in transmission of genetic defects such as Y chromosome microdeletions which primarily caused the infertility and occur in up to 55% such men. It may not be feasible to screen all patients for Y chromosome microdeletions due to the cost and technical difficulty. A correlation with existing markers such as follicle stimulating hormone (FSH) and testicular histology may help identify a subgroup for screening. We therefore studied the association between regions of azoospermia factor (AZF) deletion, testicular histology and serum FSH level in men with nonobstructive azoospermia. Materials and Methods: One hundred and nine men presenting with primary infertility and diagnosed as nonobstructive azoospermia based on standard guidelines were included in the study. Fasting blood sugar, serum FSH, testosterone and prolactin estimation was done and testicular fine needle aspiration biopsy was performed where clinically indicated. Patients with normal karyotype on standard Q banding (n=82) were evaluated for microdeletions in the Y chromosome. Eight AZF loci which mapped to interval 5 and 6 of the Y chromosome were evaluated. Results: Microdeletions were found in seven of 82 men with normal karyotype (8.5%). Three patients had deletions in both AZFa and AZFb regions with Sertoli cell only (SCO) histology. Two had AZFc deletion with hypospermatogenesis and maturation arrest in one each. Two patients had cryptorchidism. FSH levels were higher (mean 38.77 mIU/ml) in patients with deletions in the AZFa and AZFb regions than in those with AZFc deletions (mean 5.86 mIU/ml). In patients without a deletion, FSH was higher in the group with SCO (mean 18.28 mIU/ml) compared to those with hypospermatogenesis or maturation arrest (mean 6.83 mIU/ml). Conclusions: Serum FSH is raised in patients with severely depleted germ cell function, irrespective of the presence or absence of a microdeletion. The levels may correlate with the region of deletion in that the patients with AZFa and AZFb deletion had a sertoli cell only picture on histology and raised FSH.

EVALUATION OF DAZ MICRODELETIONS IN 34 INFERTILE MEN

Microdeletions in Yq11 are a common molecular cause of spermatogenic failure in men and are recurrently detected in about 10-15% of idiopathic azoospermia and severe oligozoospermia. Screening for AZF microdeletions is often performed by multiplex PCR. AZFc deletions, involving the DAZ gene, form the majority of these deletions. The aim of this study was to evaluate in a group of 34 Tunisian infertile patients (16 oligozoospermic and 18 azoospermic men) the prevalence of DAZ microdeletions using a rapid molecular strategy: the PCR-DGGE method based on the high degree of homology between the DAZ gene and its autosomally equivalent DAZLA gene. DAZ microdeletions were detected in 8.8% of patients. The three deleted patients have a 46, XY karyotype. Two of them were azoospermic and the other had an extreme oligo-asthenoteratozoospermia with a predominant abnormality: small round head spermatozoa (Y46). Our findings suggest that PCR-DGGE method, for detection of DAZ gene deletion, could be particularly useful as a first step in the diagnosis workup of nonobstructive azoospermia and severe oligozoospermia for three reasons. First, it is a simple and fast system; second, DAZ microdeletions are the most common Y deletions; and third, partial DAZ microdeletions and mosaicism may be recognized by PCR-DGGE while only deletions removing the whole DAZ gene cluster can be detected by STS-PCR [211]. Nevertheless, this procedure has limitations because other deletions of AZFa and AZFb may go undetected. Therefore, molecular investigation by multiplex PCR must be conducted in a second step according to European guidelines for the molecular diagnosis of Y chromosome microdeletions, particularly before ICSI procedures.

AZF deletions and Y chromosomal haplogroups: history and update based on sequence

AZF deletions are genomic deletions in the euchromatic part of the long arm of the human Y chromosome (Yq11) associated with azoospermia or severe oligozoospermia. Consequently, it can be assumed that these deletions remove Y chromosomal genes required for spermatogenesis. However, these 'classical' or 'complete' AZF deletions, AZFa, AZFb and AZFc, represent only a subset of rearrangements in Yq11. With the benefit of the Y chromosome sequence, more rearrangements (deletions, duplications, inversions) inside and outside the classical AZF deletion intervals have been elucidated and intra-chromosomal non-allelic homologous recombinations (NAHRs) of repetitive sequence blocks have been identified as their major cause. These include duplications in AZFa, AZFb and AZFc and the partial AZFb and AZFc deletions of which some were summarized under the pseudonym 'gr/gr' deletions. At least some of these rearrangements are associated with distinct Y chromosomal haplogroups and are present with similar frequencies in fertile and infertile men. This suggests a functional redundancy of the AZFb/AZFc multi-copy genes. Alternatively, the functional contribution(s) of these genes to human spermatogenesis might be different in men of different Y haplogroups. That raises the question whether, the frequency of Y haplogroups with different AZF gene contents in distinct human populations leads to a male fertility status that varies between populations or whether, the presence of the multiple Y haplogroups implies a balancing selection via genomic deletion/amplification mechanisms.

A deletion of a novel heat shock gene on the Y chromosome associated with azoospermia

Deletions of the Y chromosome are a significant cause of spermatogenic failure. Three major deletion intervals have been defined and termed AZFa, AZFb and AZFc. Here, we report an unusual case of a proximal AZFb deletion that includes the Y chromosome palindromic sequence P4 and a novel heat shock factor (HSFY). This deletion neither include the genes EIF1AY, RPS4Y2 nor copies of the RBMY1 genes. The individual presented with idiopathic azoospermia. We propose that deletions of the testis-specific HSFY gene family may be a cause of unexplained cases of idiopathic male infertility. This deletion would not have been detected using current protocols for Y chromosome microdeletion screens, therefore we recommend that current screening protocols be extended to include this region and other palindrome sequences that contain genes expressed specifically in the testis.

Molecular and cytogenetic characterization of a structural rearrangement of the Y chromosome in an azoospermic man

Objective To better define an abnormal karyotype found in a male with primary infertility. Design Case report. Setting Molecular and cytogenetics unit in a university-affiliated hospital. Patient(s) A 41-year-old, azoospermic, but otherwise healthy male. Intervention(s) Lymphocytic karyotype and genetic counseling. Main outcome measure(s) Metaphases were studied by standard G- and Q-banding, followed by fluorescence in situ hybridization (FISH) and polymerase chain reaction to analyze specific Y chromosome regions. Result(s) Chromosomal analysis and FISH allowed us to define the propositus's karyotype as 45,X/46,X,idic(Yp)/46,XY (71%, 26%, and 3% of analyzed metaphases, respectively). Molecular analysis of azoospermic factor (AZF) regions showed deletion of AZFb and AZFc. Conclusion(s) A 45,X/46,X,idic(Yp) mosaicism is associated with a very broad spectrum of phenotypes, including patients with Ullrich-Turner syndrome, patients with various degrees of genital ambiguity, or normal males. In the presence of a normal masculinization in otherwise healthy males azoospermia is a distinct feature that can be explained by partial deletion of AZF regions.

1562: Erroneous Diagnosis of AZFB Deletion: Discovery of a Point Mutation Simulating Positive Results

1562: Erroneous Diagnosis of AZFB Deletion: Discovery of a Point Mutation Simulating Positive Results

Y-chromosome haplotypes in azoospermic Israeli men.

Among azoospermic and severely oligozoospermic men, 7-15% present microdeletions of a region on the long arm of the Y chromosome that has been called AZF (azoospermia factor). Because these deletions present varying relative frequencies in different populations, we decided to ascertain whether their presence was correlated with specific Y-chromosome haplotypes. For that, we evaluated 51 infertile Israeli men, 9 of whom had microdeletions in AZF. Haplotypes were identified using a hierarchical system with eight biallelic DNA markers. We also checked for the presence of the deletion marker 50f2/C, which was absent in all seven patients with isolated AZFc deletion and also in the one patient with isolated AZFb deletion, suggesting that these microdeletions overlap. As expected, haplogroup J was the most common (47%), followed by equal frequencies of haplogroups Y* (xDE, J, K), P* (xR1a, R1b8), K* (xP), and E. In six patients with AZFc deficiencies of comparable size, three belonged to haplogroup J, two belonged to haplogroup P* (xR1a, R1b8), and one belonged to haplogroup R1a. Also, there were no significant differences in the haplotype frequencies between the groups with and without microdeletions. Thus we did not identify any association of a specific haplogroup with predisposition to de novo deletion of the AZF region in the Israeli population.

The pituitary–testicular axis in Klinefelter's syndrome and in oligo‐azoospermic patients with and without deletions of the Y chromosome long arm

The most frequent known genetic causes of severe oligospermia (< 5 million sperm/ml) or azoospermia in men are Klinefelter's syndrome (KS), and deletions in the Y chromosome long arm (Yq). We aimed to compare the function of the pituitary-testicular axis in patients with severe oligospermia or azoospermia, idiopathic or associated with Y chromosome deletions or Klinefelter's syndrome (KS) and in control subjects. We studied 47 men with idiopathic oligo-azoospermia, 42 with Yq deletions (27 AZFc, 13 AZFb and two AZFa) and oligo-azoospermia, 14 with KS and 39 control subjects (total 143). We analysed levels of FSH, inhibin-B, LH, free testosterone and oestradiol in all subjects, and we calculated indexes based on those hormones. Inhibin-B levels were indistinguishable between patients with idiopathic and Y deletion-associated oligo-azoospermia, lowest in the Klinefelter's patients and highest in controls. FSH levels followed the reverse pattern: indistinguishable between patients with idiopathic and deletion-associated oligo-azoospermia, highest in Klinefelter's patients and lowest in controls. Oestradiol, free testosterone and the derived indeces were not different in subjects with Yq deletions compared to those with idiopathic oligo-azoospermia. Among the Yq-deleted patients, no measured or derived parameter differed between the subjects with AZFc deletion and those with AZFb deletion. When non-KS oligo-azoospermic patients were classified according to histology [Sertoli cell-only (SCO), n = 18 or non-Sertoli cell only (non-SCO), n= 18] and compared to KS patients, the hormonal pattern did not differ between SCO and non-SCO subjects, but levels in KS patients were significantly different for FSH, inhibin-B and the FSH/inhibin-B ratio. KS patients not only had lower inhibin-B than SCO and non-SCO oligo-azoospermic men, but also higher FSH levels for any given inhibin-B concentration. Our data show that Y-deleted patients do not have a lesser impairment of Sertoli cell function than patients with idiopathic oligo-azoospermia, and support the concept that the main determinant of inhibin-B production is the germ cell mass. Also, our results suggest that one or more other factors, apart from inhibin-B, may contribute to increased pituitary secretion of FSH in KS patients.

Recombination between Palindromes P5 and P1 on the Human Y Chromosome Causes Massive Deletions and Spermatogenic Failure

It is widely believed that at least three nonoverlapping regions of the human Y chromosome-AZFa, AZFb, and AZFc ("azoospermia factors" a, b, and c)-are essential for normal spermatogenesis. These intervals are defined by interstitial Y-chromosome deletions that impair or extinguish spermatogenesis. Deletion breakpoints, mechanisms, and lengths, as well as inventories of affected genes, have been elucidated for deletions of AZFa and of AZFc but not for deletions of AZFb or of AZFb plus AZFc. We studied three deletions of AZFb and eight deletions of AZFb plus AZFc, as assayed by the STSs defining these intervals. Guided by Y-chromosome sequence, we localized breakpoints precisely and were able to sequence nine of the deletion junctions. Homologous recombination can explain seven of these deletions but not the remaining two. This fact and our discovery of breakpoint hotspots suggest that factors in addition to homology underlie these deletions. The deletions previously thought to define AZFb were found to extend from palindrome P5 to the proximal arm of palindrome P1, 1.5 Mb within AZFc. Thus, they do not define a genomic region separate from AZFc. We also found that the deletions of AZFb plus AZFc, as assayed by standard STSs heretofore available, in fact extend from P5 to the distal arm of P1 and spare distal AZFc. Both classes of deletions are massive: P5/proximal-P1 deletions encompass up to 6.2 Mb and remove 32 genes and transcripts; P5/distal-P1 deletions encompass up to 7.7 Mb and remove 42 genes and transcripts. To our knowledge, these are the largest of all human interstitial deletions for which deletion junctions and complete intervening sequence are available. The restriction of the associated phenotype to spermatogenic failure indicates the remarkable functional specialization of the affected regions of the Y chromosome.

Reduced copy number of DAZ genes in subfertile and infertile men

Objective(s): To determine the copy number and identity of the DAZ genes on the Y chromosomes of infertile patients. Design: Prospective study. Setting: University medical center. Patient(s): One hundred and thirty-nine patients with male factor infertility. Intervention(s): The separate genes were detected by polymerase chain reaction (PCR) digestion assays of sequence family variants in leukocyte DNA and by fluorescence in situ hybridization of interphase nuclei and chromatin fibers. Main Outcome Measure(s): Number of DAZ genes present. Result(s): One hundred twenty-nine patients had four genes, 6 patients had two genes, and 4 patients had none. Three patients had a deletion of the two proximal DAZ genes, and three were missing both distal genes. Semen analysis showed a less severe phenotype in patients with only two DAZ genes compared with patients missing all four genes. Conclusion(s): In six patients, two different partial deletions were found that were not detected by PCR with conventional markers. One patient with an AZFb deletion appeared to also have a partial AZFc deletion that was not detected by routine PCR. Phenotypic differences between patients with different deletions suggest a dose effect of the DAZ genes.