DAZ1/DAZ2 cluster deletion mediated by gr/gr recombination per se may not be sufficient for spermatogenesis impairment: a study of Chinese normozoospermic men

Copy number variants within AZF region of Y chromosome and their association with idiopathic male infertility in Serbian population

Results of numerous studies gave contradictory conclusions when analysing associations between copy number variants (CNVs) within the azoospermia factor (AZF) locus of the Y chromosome and idiopathic male infertility. The aim of this study was to identify the presence and possible association of CNVs in the AZF region of Y chromosome with idiopathic male infertility in the Serbian population. Using the multiplex ligation-dependent probe amplification technique, we were able to detect CNVs in 24 of 105 (22.86%) infertile men and in 11 of 112 (9.82%) fertile controls. The results of Fisher's exact test showed a statistically significant difference between cases and controls after merging g(reen)-r(ed)/g(reen)-r(ed) and b(lue)2/b(lue)3 partial deletions identified in the AZFc region (p = 0.024). At the same time, we observed a trend towards statistical significance for a deletion among gr/gr amplicons (p = 0.053). In addition to these, we identified a novel complex CNV involving inversion of r2/r3 amplicons, followed by b2/b3 duplication and b3/b4 deletion, respectively. Additional analyses on a larger study group would be necessary to draw meaningful conclusions about associations among CNVs that presented with higher frequency in the infertile men than the fertile controls.

The association of gr/gr deletion in the Y chromosome and impaired spermatogenesis in Bulgarian males: a pilot study

Background

The microdeletions of the Y chromosome are associated with a decreased number of sperm cells in the ejaculate and male infertility. One such deletion is the gr/gr, which leads to reduction of the alleles in the DAZ gene. In order to evaluate its role, 30 patients with sperm count below 5 × 106/mL and 30 normal fertile men were genotyped for microdeletions in Azoospermia Factor (AZF) region, including gr/gr deletion.

Results

Twenty-one men (70.00%) from the males with impaired fertility had a normal genotype, seven men (23.33%) were carriers of a gr/gr deletion, and two men (6.67%) demonstrated a deletion of the AZFc region. From the control group, there were 22 men (73.33%) with no deletion, seven (23.33%) carried a gr/gr deletion, and one man (3.33%) carried a possible deletion in the b1-b4 region of the Y chromosome. The gr/gr deletion of the Y chromosome showed a statistically nonsignificant difference (p = 0.94, alpha < 0.05) with the control group (chi-square, degrees of freedom 0.006).

Conclusion

The results from the research show no association between this deletion and male infertility in the studied population. Despite the small sample size, the high frequency of the gr/gr deletion, found in the control group, suggests that this variant may not be associated with impaired spermatogenesis.

The Role of Number of Copies, Structure, Behavior and Copy Number Variations (CNV) of the Y Chromosome in Male Infertility

The World Health Organization (WHO) defines infertility as the inability of a sexually active, non-contracepting couple to achieve spontaneous pregnancy within one year. Statistics show that the two sexes are equally at risk. Several causes may be responsible for male infertility; however, in 30–40% of cases a diagnosis of idiopathic male infertility is made in men with normal urogenital anatomy, no history of familial fertility-related diseases and a normal panel of values as for endocrine, genetic and biochemical markers. Idiopathic male infertility may be the result of gene/environment interactions, genetic and epigenetic abnormalities. Numerical and structural anomalies of the Y chromosome represent a minor yet significant proportion and are the topic discussed in this review. We searched the PubMed database and major search engines for reports about Y-linked male infertility. We present cases of Y-linked male infertility in terms of (i) anomalies of the Y chromosome structure/number; (ii) Y chromosome misbehavior in a normal genetic background; (iii) Y chromosome copy number variations (CNVs). We discuss possible explanations of male infertility caused by mutations, lower or higher number of copies of otherwise wild type, Y-linked sequences. Despite Y chromosome structural anomalies are not a major cause of male infertility, in case of negative results and of normal DNA sequencing of the ascertained genes causing infertility and mapping on this chromosome, we recommend an analysis of the karyotype integrity in all cases of idiopathic fertility impairment, with an emphasis on the structure and number of this chromosome.

The male contribution to recurrent pregnancy loss

There are several known causes of recurrent pregnancy loss (RPL) in a couple, which include endocrine abnormalities, immunologic abnormalities, structural uterine abnormalities and karyotype abnormalities. The evaluation largely focuses on the female. The male contribution to RPL remains understudied. With the exception of the karyotype analysis, there is currently no other recommended testing for the male partner of a woman who has suffered multiple pregnancy losses. Chromosomal abnormalities are well defined causes of pregnancy losses in the literature. However, despite the fact that abnormal DNA fragmentation has been implicated in the pathogenesis of unexplained RPL, it is not routinely checked during the evaluation of RPL. This is likely due to the fact that abnormal DNA fragmentation is the end result of multiple different mechanisms including environmental exposures, varicoceles, gene alteration and epigenetic changes resulting in an inherent susceptibility to DNA damage? We are just beginning to scratch the surface of our understanding of the male contribution to RPL and more studies especially focusing on epigenetic modifications and gene alterations are needed.

Effect of B9 and B12 vitamin intake on semen parameters and fertility of men with MTHFR polymorphisms

The methylenetetrahydrofolate reductase (MTHFR) gene codes a crucial enzyme which involve in folate metabolism. The effect of MTHFR gene polymorphisms on male fertility status is uncertain and controversial. We evaluated the effect of B vitamin family intake on total homocysteine content and semen parameters of men with MTHFR gene polymorphisms. MTHFR genotypes frequency and serum total homocysteine concentration were measured among 280 men with impaired spermatogenesis (asthenospermia, oligospermia, severe oligospermia and azoospermia) and 85 control participants. B vitamin family dietary intakes were assessed using a semi-quantitative food-frequency questionnaire. In addition, concentrations of vitamins B9 and B12 were evaluated in serum samples of some participants (n = 60). We observed significantly higher frequency of TC or TT genotypes in C677T polymorphism among oligospermic, severe oligospermic and azoospermic men. CC genotype of A1298C polymorphism was significantly higher only in azoospermic men. Also, we observed critical effect of vitamin B9 and B12 intake on decreasing of total homocysteine and improving of semen parameters among the men with T allele of MTHFR C677T polymorphism. Our investigation showed that sufficient consumption of vitamins B9 and B12 influences sperm parameters of men with different MTHFR polymorphisms, especially genotypes with T allele.

gr/gr-DAZ2-DAZ4-CDY1b deletion is a high-risk factor for male infertility in Tunisian population

The azoospermia factor c (AZFc) region harbors multi-copy genes that are expressed in the testis. Deletions of this region lead to reduced copy numbers of these genes. In this present study we aimed to determine the frequency of AZFc subdeletion in infertile and fertile men from Tunisia and to identify whether deletions of DAZ and CDY1 gene copies are deleterious on spermatogenesis and on semen quality. We studied a group of 241 infertile men and 115 fertile healthy males using a sequence tagged site (STS)±method. To gain insight into the molecular basis of the heterogeneous phenotype observed in men with the deletion we defined the type of DAZ and CDY1 genes deleted. We reported in the present study and for the first time a new type of AZFc deletion (gr/gr-DAZ2-DAZ4-CDY1b) and hypothesis that this new deletion is the result of two successive events. We also demonstrated that this deletion constitutes a relative high-risk factor for male infertility in Tunisian population.

Gr/gr deletions on Y-chromosome correlate with male infertility: an original study, meta-analyses, and trial sequential analyses

We analyzed the AZFc region of the Y-chromosome for complete (b2/b4) and distinct partial deletions (gr/gr, b1/b3, b2/b3) in 822 infertile and 225 proven fertile men. We observed complete AZFc deletions in 0.97% and partial deletions in 6.20% of the cases. Among partial deletions, the frequency of gr/gr deletions was the highest (5.84%). The comparison of partial deletion data between cases and controls suggested a significant association of the gr/gr deletions with infertility (P = 0.0004); however, the other partial deletions did not correlate with infertility. In cohort analysis, men with gr/gr deletions had a relatively poor sperm count (54.20 ± 57.45 million/ml) in comparison to those without deletions (72.49 ± 60.06), though the difference was not statistically significant (p = 0.071). Meta-analysis also suggested that gr/gr deletions are significantly associated with male infertility risk (OR = 1.821, 95% CI = 1.39–2.37, p = 0.000). We also performed trial sequential analyses that strengthened the evidence for an overall significant association of gr/gr deletions with the risk of male infertility. Another meta-analysis suggested a significant association of the gr/gr deletions with low sperm count. In conclusion, the gr/gr deletions show a strong correlation with male infertility risk and low sperm count, particularly in the Caucasian populations.

Copy number variation and microdeletions of the Y chromosome linked genes and loci across different categories of Indian infertile males

We analyzed 34 azoospermic (AZ), 43 oligospermic (OS), and 40 infertile males with normal spermiogram (INS) together with 55 normal fertile males (NFM) from the Indian population. AZ showed more microdeletions in the AZFa and AZFb regions whereas oligospermic ones showed more microdeletions in the AZFc region. Frequency of the AZF partial deletions was higher in males with spermatogenic impairments than in INS. Significantly, SRY, DAZ and BPY2 genes showed copy number variation across different categories of the patients and much reduced copies of the DYZ1 repeat arrays compared to that in normal fertile males. Likewise, INS showed microdeletions, sequence and copy number variation of several Y linked genes and loci. In the context of infertility, STS deletions and copy number variations both were statistically significant (p = 0.001). Thus, semen samples used during in vitro fertilization (IVF) and assisted reproductive technology (ART) must be assessed for the microdeletions of AZFa, b and c regions in addition to the affected genes reported herein. Present study is envisaged to be useful for DNA based diagnosis of different categories of the infertile males lending support to genetic counseling to the couples aspiring to avail assisted reproductive technologies.

Combined deletion of DAZ2 and DAZ4 copies of Y chromosome DAZ gene is associated with male infertility in Tunisian men

The relationship between male infertility and AZFc micro-deletions that remove multiple genes of the Y chromosome varies among countries and populations. The purpose of this study was to analyze the prevalence and the characteristics of different Deleted in azoospermia (DAZ) gene copy deletions and their association with spermatogenic failure and male infertility in Tunisian men. 241 infertile men (30.7% azoospermic (n=74), 31.5% oligozoospermic (n=76) and 37.7% normozoospermic (n=91)) and 115 fertile healthy males who fathered at least one child were included in the study. Three DAZ-specific single nucleotide variant loci and six bi-allelic DAZ-SNVs (I-VI) were analyzed using polymerase chain reaction (PCR)-restriction fragment length polymorphism and PCR. Our findings showed high frequencies of infertile men (73.85%) and controls (78.26%) having only three DAZ gene copies (DAZ1/DAZ2/DAZ3 or DAZ1/DAZ3/DAZ4 variants); so deletion of DAZ2 or DAZ4 were frequent both in infertile (36.5% and 37.3%, respectively) and fertile groups (33.9% and 44.3%, respectively) and removing DAZ4 copy was significantly more frequent in oligospermic than in normospermic men (p=0.04) in infertile group. We also report for the first time that simultaneous deletion of both DAZ2 and DAZ4 copies was significantly more common in infertile men (12.4%) than in fertile men (4.3%) (p=0.01). However, deletions of DAZ1/DAZ2 and DAZ3/DAZ4 clusters were very rare. Analysis of DAZ gene copies in Tunisian population, suggested that the simultaneous deletion of DAZ2 and DAZ4 gene copies is associated with male infertility, and that oligospermia seems to be promoted by removing DAZ4 copy.

EAA/EMQN best practice guidelines for molecular diagnosis of Y-chromosomal microdeletions: state-of-the-art 2013

The molecular diagnosis of Y-chromosomal microdeletions is a common routine genetic test which is part of the diagnostic workup of azoospermic and severe oligozoospermic men. Since 1999, the European Academy of Andrology (EAA) and the European Molecular Genetics Quality Network (EMQN) have been actively involved in supporting the improvement of the quality of the diagnostic assays by publication of the laboratory guidelines for molecular diagnosis of Y-chromosomal microdeletions and by offering external quality assessment trials. The present revision of the 2004 laboratory guidelines summarizes all the clinical novelties related to the Y chromosome (classic, partial and gene-specific deletions, genotype-phenotype correlations, methodological issues) and provides an update on the results of the quality control programme. These aspects also reflect the consensus of a large group of specialists present at a round table session during the recent Florence-Utah-Symposium on 'Genetics of male infertility' (Florence, 19-21 September, 2013). During the last 10 years the gr/gr deletion has been demonstrated as a significant risk factor for impaired sperm production. However, the screening for this deletion type in the routine diagnostic setting is still a debated issue among experts. The original basic protocol based on two multiplex polymerase chain reactions remains fully valid and appropriate for accurate diagnosis of complete AZF deletions and it requires only a minor modification in populations with a specific Y chromosome background. However, in light of novel data on genotype-phenotype correlations, the extension analysis for the AZFa and AZFb deletions is now routinely recommended. Novel methods and kits with excessively high number of markers do not improve the sensitivity of the test, may even complicate the interpretation of the results and are not recommended. Annual participation in an external quality control programme is strongly encouraged. The 12-year experience with the EMQN/EAA scheme has shown a steep decline in diagnostic (genotyping) error rate and a simultaneous improvement on reporting practice.

ART do not increase the risk of Y-chromosome microdeletion in 19 candidate genes at AZF regions

Y-chromosome microdeletions (YCMs) have been found at a much higher rate in infertile men than fertile controls. A specific deletion in the azoospermia factor locus (AZF) at Yq11 is significantly associated with male infertility. Whether assisted reproductive technology (ART) increases the risk of YCM in ART-derived offspring remains unclear. In this study the occurrence of YCM in 199 fathers and their 228 sons (Chinese, Han ethnicity), including 85 offspring conceived by IVF, 73 by intra-cytoplasmic sperm injection (ICSI) and 70 by natural conception, was investigated. Nineteen candidate genes related to YCM were analysed by multiplex ligation-dependent probe amplification. We identified one de novo YCM from 70 naturally-conceived offspring and none from 158 ART-conceived offspring and found no statistical significance between these two groups. There was no statistically-significant difference in the detection rate of the father’s Y-chromosome microdeletion group: IVF 10.7% (8/75), ICSI 3.2% (2/63), natural conception 8.2% (5/61). These results suggest that ART does not increase the risk of YCM in male offspring.

Ubiquitin-specific protease (USP26) gene alterations associated with male infertility and recurrent pregnancy loss (RPL) in Iranian infertile patients

BACKGROUND AND PURPOSE

The human X chromosome is enriched with testis-specific genes that may be crucial for male fertility. Mutations in USP26 gene have been proposed to be associated with male infertility. Moreover, the importance of the ubiquitin pathway during different stages of mammalian fertilization and even embryo development has been addressed. Some mutations and haplotypes on this gene have been proposed to be associated with male infertility. In this study, five different mutations on USP26 were investigated: 1737 G > A, 1090 C > T, 370-371ins ACA, 494 T > C and 1423 C > T.

METHODS

The study included 166 infertile men with non-obstructive azoospermia, 72 male partners of couples who had previously experienced ≥3 clinical first trimester spontaneous abortions and 60 fertile men. Besides family history of reproduction, hormonal evaluation and semen analysis were performed. DNA was extracted from blood samples. PCR-SSCP, PCR-RFLP and PCR Product Cloning methods were used and resumed by sequencing to insure about the mutations. Moreover, USP26 gene expression was studied by Real-Time PCR after RNA extraction followed by cDNA synthesis from 24 testis biopsies in obstructive and non-obstructive azoospermia patients.

RESULTS

The results indicate that there is a haplotype between three observed mutations in Iranian population include: 370-371insACA, 1423C > T and 494 T > C. This haplotype was seen in control group as well. Surprisingly, total frequency of mutations in men with history of idiopathic RPL and azoospermic cases were significantly higher than that of in control groups (p < 0.05). Serum testosterone concentrations and testicular volume did not differ in the mutation positive group compared with the non-mutation group. About the USP26 gene expression, there is a significant difference between the expression levels of obstructive azoospermia, complete maturation arrest samples and SCO samples (P < 0.05).

CONCLUSIONS

According to our results, the USP26 gene may play an important role in male reproduction. The alterations of this gene may be involved in male infertility and RPL in Iranian population and may negatively affect testicular function.

Downregulation of cold-inducible RNA-binding protein activates mitogen-activated protein kinases and impairs spermatogenic function in mouse testes

Cold-inducible RNA-binding protein (CIRP) is an RNA-binding protein that is expressed in normal testes and downregulated after heat stress caused by cryptorchidism, varicocele or environmental temperatures. The purpose of this study was to investigate the functions of CIRP in the testes. We employed RNAi technique to knock down the expression of CIRP in the testes, and performed haematoxylin and eosin staining to evaluate morphological changes following knockdown. Germ cell apoptosis was examined by terminal deoxynucleotidal transferase-mediated dUTP nick end labelling (TUNEL) assay, and mitogen-activated protein kinase (MAPK) signalling pathways were investigated by Western blotting to determine the possible mechanism of apoptosis. We found that using siRNA is a feasible and reliable method for knocking down gene expression in the testes. Compared to controls, the mean seminiferous tubule diameter (MSTD) and the thickness of the germ cell layers decreased following siRNA treatment, whereas the percentage of apoptotic seminiferous tubules increased. The p44/p42, p38 and SAPK/JNK MAPK pathways were activated after downregulation of CIRP. In conclusion, we discovered that downregulation of CIRP resulted in increased germ cell apoptosis, possibly via the activation of the p44/p42, p38 and SAPK/JNK MAPK pathways.

The Y chromosome-linked copy number variations and male fertility

Since the first definition of the AZoospermia Factor (AZF) regions, the Y chromosome has become an important target for studies aimed to identify genetic factors involved in male infertility. This chromosome is enriched with genes expressed exclusively or prevalently in the testis and their absence or reduction of their dosage is associated with spermatogenic impairment. Due to its peculiar structure, full of repeated homologous sequences, the Y chromosome is predisposed to structural rearrangements, especially deletions/ duplications. This review discusses what is currently known about clinically relevant Y chromosome structural variations in male fertility, mainly focusing on copy number variations (CNVs). These CNVs include classical AZF deletions, gr/gr deletion and TSPY1 CNV. AZF deletions are in a clear-cut causeeffect relationship with spermatogenic failure and they also have a prognostic value for testis biopsy. gr/gr deletion represents the unique example in andrology of a proven genetic risk factor, providing an eight-fold increased risk for oligozoospermia in the Italian population. Studies on TSPY1 CNV have opened new perspectives on the role of this gene in spermatogenic efficiency. Although studies on the Y chromosome have importantly contributed to the identification of new genetic causes and thus to the improvement of the diagnostic work-up for severe male factor infertility, there is still about 50% of infertile men in whom the etiology remains unknown. While searching for new genetic factors on other chromosomes, our work on the Y chromosome still needs to be completed, with special focus on the biological function of the Y genes.

What about gr/gr deletions and male infertility? Systematic review and meta-analysis

BACKGROUND

The impact of gr/gr deletions on male fertility is unclear. These partial deletions of the AZFc region of the Y chromosome have been detected more frequently in infertile patients. However, few individual studies have demonstrated a statistically significant association. This study aims to quantify the strength of association between gr/gr deletions and male infertility, and to explore potential sources of heterogeneity, including ethnicity and geographical location.

METHODS

Medline was searched up to 31 December 2009 for full articles investigating the prevalence of gr/gr deletions in infertile and control men. A pooled odds ratio (OR) was estimated by a random-effects model. Heterogeneity was assessed by the Cochran's Q test, and quantified by I(2) statistic.

RESULTS

A total of 18 case-control studies, including 6388 cases and 6011 controls, met our inclusion criteria and showed that gr/gr deletions were present in 6.86% of cases and 4.69% of controls. The association between gr/gr deletions and infertility was significant (P < 0.001), with a pooled random-effects OR of 1.76 (1.21-2.66) for infertile men versus normozoospermic controls (13 studies). The test for heterogeneity among studies yielded a Q test P = 0.089 with I(2) value of 37%, indicating moderate heterogeneity. The association between gr/gr deletions and infertility was dependent on ethnicity and geographic region.

CONCLUSIONS

Our meta-analysis comprising >12 000 men demonstrates that gr/gr deletions occur more frequently in infertile than control men. The association between gr/gr deletions and infertility varies according to ethnicity and geographic region, with an association reaching significance among Caucasian men, in Europe and the Western Pacific region.

Association of USP26 haplotypes in men in Taiwan, China with severe spermatogenic defect

AIM

To complete comprehensive haplotype analysis of USP26 for both fertile and infertile men.

METHODS

Two hundred infertile men with severe oligospermia or non-obstructive azoospermia were subjected to sequence analysis for the entire coding sequences of the USP26 gene. Two hundred men with proven fertility were genotyped by primer extension methods. Allele/genotype frequencies, linkage disequilibrium (LD) characteristics and haplotypes of fertile men were compared with infertile men.

RESULTS

The allele frequencies of five single nucleotide polymorphisms (370-371insACA, 494T>C, 576G>A, ss6202791C>T, 1737G>A) were significantly higher in infertile patients than control subjects. The major haplotypes in infertile men were TACCGA (28% of the population), TGCCGA (15%), TACCAA (8%), TGCCAA (6%), TATCAA (5%) and CATCAA (5%). The major haplotypes for the control subjects were TACCGA (58% of the population), CACCGA (7%), CATCGA (6%) and TGCCGA (5%). Haplotypes TGCCGA, TATCAA, CATCAA, CATCGC, TACCAA and TGCCAA were over-transmitted in patients with spermatogenic defect, whereas haplotypes TACCGA, CACCGA, and CATCGA were under-transmitted in these patients.

CONCLUSION

Some USP26 alleles and haplotypes are associated with spermatogenic defect in the Han nationality in Taiwan, China.

Y-chromosome AZFc structural architecture and relationship to male fertility

OBJECTIVE

To determine if there is a relationship between various forms of partial AZFc deletions and spermatogenic failure.

DESIGN

Case-control study.

SETTING

Infertility clinic (Tenon Hospital, Paris).

PATIENT(S)

557 men, comprising 364 infertile men from mixed ethnic backgrounds, and 193 men with known fertility (n = 84) and/or normospermic (n = 109).

INTERVENTION(S)

Characterization of 32 partial AZFc deletions.

MAIN OUTCOME MEASURE(S)

DAZ gene cluster divided into two families (DAZ1/2 and DAZ3/4), CDY1 gene, and Y-chromosome haplogroups.

RESULT(S)

We observed 18 partial AZFc deletions in 364 (4.95%) infertile men compared with 14 out of 193 (7.25%) in the control normospermic/fertile group.

CONCLUSION(S)

The analysis of informative Y-chromosome single nucleotide variants combined with Y-chromosome haplogroup definition enabled us to infer seven deletion classes that occur on a minimum of six Y-chromosome parental architectures. We found no relationship between either the presence or the absence of DAZ1/2, DAZ3/4, CDY1a, or CDY1b with spermatogenic failure at least on one Y-chromosome lineage. The DAZ dosage and Southern blot analyses indicated that the majority of individuals tested carried two copies of the DAZ gene, indicating a partial AZFc deletion. Our data are consistent with the hypothesis that, at least in our study populations, partial AZFc deletions may have a limited impact on fertility.

Gene polymorphisms and male infertility--a meta-analysis and literature review

Many genetic polymorphisms have been studied extensively to elucidate their role in the pathophysiology of male infertility. This article presents a review of the literature following a thorough search of PubMed, a compilation of meta-analyses of studies reporting an association with male fertility where the population(s) could be clearly identified as fertile and/or infertile, and a summary of all polymorphisms that have been investigated in single case-control studies to date. The meta-analyses revealed significant associations between polymorphism and male fertility only for AZF gr/gr deletions (OR 1.81, 1.46-2.24 CI, P<0.00001) and MTHFR 677C-->T (OR 1.39, 1.15-2.69 95% CI, P=0.0006) but not for POLG, DAZL, USP26 or FSHR. The influence of CAG repeat length in AR remains open and debated. Genes encoding nuclear proteins (PRM1/2, TNP1/2) and ER1 are possible candidates for further examination, while the role of TAF7L remains unclear. Polymorphisms in 16 other genes have been investigated in single studies, but the results remain doubtful due to often small and heterogeneous cohorts and in the absence of independent replications. The genetic studies performed so far emphasize the complexity of male infertility as a presumably polygenetic trait amended by environmental, lifestyle or occupational factors.

Novel mutations in ubiquitin-specific protease 26 gene might cause spermatogenesis impairment and male infertility

AIM

To study the incidence of single nucleotide polymorphisms in ubiquitin-specific protease 26 (USP26) gene and its involvement in idiopathic male infertility in China.

METHODS

Routine semen analysis was performed. Infertility factors such as immunological, infectious and biochemical disorders were examined to select patients with idiopathic infertility. DNA was isolated from peripheral blood of the selected patients and control population, which were examined for mutations using polymerase chain reaction-single strand conformation polymorphism analysis. Furthermore, nucleotide sequences were sequenced in some patients and controls.

RESULTS

Of 41 infertile men, 9 (22.0%, P = 0.01) had changes in USP26 gene on the X chromosome. A compound mutation (364insACA; 460G right triple arrow A) was detected in 8 patients (19.5%, P = 0.01) and a 1044T right triple arrow A substitution was found in 1 patient (2.4%, P > 0.05). All three variations led to changes in the coding amino acids. Two substitutions predict some changes: 460G right triple arrow A changes a valine into an isoleucine, and 1044T right triple arrow A substitutes a leucine for a phenylalanine. Another insertion of three nucleotides ACA causes an insertion of threonine. No other changes were found in the remaining patients and fertile controls.

CONCLUSION

The USP26 gene might be of importance in male reproduction. Mutations in this gene might be associated with male infertility, and might negatively affect testicular function. Further research on this issue is in progress.

Characterizing partial AZFc deletions of the Y chromosome with amplicon-specific sequence markers

BACKGROUND

The AZFc region of the human Y chromosome is a highly recombinogenic locus containing multi-copy male fertility genes located in repeated DNA blocks (amplicons). These AZFc gene families exhibit slight sequence variations between copies which are considered to have functional relevance. Yet, partial AZFc deletions yield phenotypes ranging from normospermia to azoospermia, thwarting definite conclusions on their real impact on fertility.

RESULTS

The amplicon content of partial AZFc deletion products was characterized with novel amplicon-specific sequence markers. Data indicate that partial AZFc deletions are a male infertility risk [odds ratio: 5.6 (95% CI: 1.6-30.1)] and although high diversity of partial deletion products and sequence conversion profiles were recorded, the AZFc marker profiles detected in fertile men were also observed in infertile men. Additionally, the assessment of rearrangement recurrence by Y-lineage analysis indicated that while partial AZFc deletions occurred in highly diverse samples, haplotype diversity was minimal in fertile men sharing identical marker profiles.

CONCLUSION

Although partial AZFc deletion products are highly heterogeneous in terms of amplicon content, this plasticity is not sufficient to account for the observed phenotypical variance. The lack of causative association between the deletion of specific gene copies and infertility suggests that AZFc gene content might be part of a multifactorial network, with Y-lineage evolution emerging as a possible phenotype modulator.

AZFc partial deletions in Chilean men with severe spermatogenic failure

OBJECTIVE

To determine the prevalence of AZFc subdeletions in infertile Chilean men with severe spermatogenic impairment.

DESIGN

Prospective analysis.

SETTING

University infertility clinic.

PATIENT(S)

Ninety-five secretory azo/oligozoospermic men without AZFc Y chromosome microdeletions: 71 whose testicular histology showed severe spermatogenic impairment and 24 who exhibited reduced testicular volume and elevated serum FSH levels. As controls, we studied 77 men (50 fertile and/or normozoospermic, and 27 with azoospermia and normal spermatogenesis).

INTERVENTION(S)

Peripheral blood was drawn to obtain genomic DNA for polymerase chain reaction (PCR) digestion assays of DAZ-sequence nucleotide variants and for AZFc-STS PCR after a complete testicular characterization (biopsy, hormonal, and physical evaluation).

MAIN OUTCOME MEASURE(S)

DAZ genes and AZFc subdeletion types.

RESULT(S)

In cases we observed two "gr/gr" subdeletions (2.1%), one with absence of DAZ1/DAZ2 (g1/g2 subtype), and the other with absence of DAZ3/DAZ4 (r2/r4 subtype). Additionally, we found a g1/g3 subdeletion in a patient with Sertoli-cell-only syndrome. In controls, we observed two gr/gr subdeletions with absence of DAZ1/DAZ2 (2.6%) in a fertile/normozoospermic and in an obstructive azoospermic man.

CONCLUSION(S)

AZFc subdeletions do not seem to cause severe impairment of spermatogenesis. Moreover, gr/gr-DAZ1/DAZ2 subdeletions do not appear to affect fertility in Chilean men.