Azoospermia Factor Genes Research Articles

Azoospermia factor gene microdeletions in infertile men with non-obstructive azoospermia and normal karyotype: First case-control study from Kashmir

BackgroundMicro-deletions in the Y chromosome are recognized as the causative factor for male infertility. The prevalence of Y chromosome micro-deletions exhibits variation among infertile males across different areas and races globally. The study of Y chromosome micro- deletions is crucial among genetic variables owing to their ability to transmit genetic defects to the progeny. Microdeletion of the azoospermia factor (AZF) region associated with the long arm of the Y chromosome (Yq) has three sub-regions (AZFa, AZFb, and AZFc) that play an important role in spermatogenesis. The genes associated with the AZF region of the Y chromosome are believed to play a crucial role in the process of spermatogenesis by performing several activities such as gene silencing, transcription, ubiquitination, and maintenance of microtubule networks. Due to the absence of epidemiological research on Y chromosome micro-deletions in ethnic infertile male population of Kashmir, our study sought to examine the Y chromosome micro-deletions among non-obstructive azospermic infertile men in Kashmir. ObjectiveThe research was aimed to establish the frequency and characteristics of micro-deletions in the AZF region of Y chromosome in infertile males of our population with non-obstructive Azoospermia and normal Karyotype. MethodsA total of 120 subjects were included in the study. Samples from 60 male patients with fertility issues (non-obstructive azoospermia) and an equal number of samples from normal men having established fatherhood (biological fathers) were taken for the study. The average age in years of cases and controls were 32.80 and 34.88 respectively. A total of 26.66 % of cases and 13.33 % of controls were found to be consanguineous, 36.66 % of cases and 40 % of controls were urban while 63.33 % of cases and 60 % of controls were from rural population. Molecular analysis was performed by multiplex polymerase chain reactions (PCR) using sequence tagged sites (STS) from 3 different regions of AZF of Y chromosome. To assess the frequency of AZF micro-deletions, molecular analysis was performed by multiplex polymerase chain reactions (PCR) using sequence tagged sites (STS) from 3 different regions of the Y chromosome (sY84 and sY86 for AZFa region; sY127 and sY134 for AZFb; sY254 and sY255 for AZFc region). ResultsIn the present study a total of 9 out of 60 cases (15 %) were found to have Y chromosome micro- deletions in AZF region of Yq arm. The most frequent micro deletions were observed in AZFb region, 8 out of 60 cases (13.33 %) from AZFb region were found to have deletions.5 out of 60 cases (8.33 %) were reported with deletions associated to AZFc region region and 6.66 % of cases were found to harbor deletions in both AZFb and AZFc region. However no deletion was reported in the AZFa region in all the studied cases. No micro-deletions were reported in the controls during the study. ConclusionThe study represents the first report on the incidence of Y chromosome microdeletions in infertile men from our population. The findings from the present study indicate the prevalence of these gene microdeletions as a major contributing factor to the etiology of infertility in males. This study emphasizes that the multiplex PCR based screening is a reliable method in ruling Y chromosome micro deletions as a factor in the pathogenicity of male infertility and recommends genetic testing prior to planning of any reproductive assistance.

Molecular genetic analysis of 1,980cases of male infertility.

The present study aimed to investigate the occurrence of chromosomal karyotype abnormalities and azoospermia factor (AZF) microdeletion on the long arm of the Y chromosome (Yq) in infertile men, and to determine their association with infertility to ultimately improve clinical outcomes in these patients. A total of 1,980 azoospermic and oligospermic men from the outpatient department of the Fujian Maternity and Child Health Hospital (Fuzhou, China) were recruited between January 2016 and December 2019. Peripheral blood was used for karyotype analysis; AZF microdeletion analysis of the Yq was performed using capillary electrophoresis. Among the 1,980 patients, 178 had chromosomal abnormalities (9.0%; 178/1,980), of whom 98 had an abnormal number of chromosomes. Among the abnormal karyotypes, the most common was 47, XXY (80/178; 44.9%). AZF microdeletion on the Yq occurred at a rate of 10.66% (211/1,980); the most common type was the AZFb/c deletion (sY1192; 140/211; 66.4%). The present findings showed that karyotype abnormalities and AZF gene microdeletion are important drivers of male infertility. Specifically, men with Yqh- and del(Y)(q11) had a higher risk of AZF microdeletion. These results suggested that patient treatment could be personalized based on routine molecular genetic analysis, which could further alleviate the economic and emotional burden of undergoing redundant or ineffective treatments.

Frequency of Y Chromosome Microdeletions in Azoospermic and Oligospermic Iranian Infertile Men

Background and Aims: Azoospermia factor (AZF) region of the Ychromosome has several genes which are responsible for normal spermatogenesis. Microdeletions of these genes are associated with azoospermia and oligospermia. These microdeletions are too small to be detected by karyotyping. They can be easily identified using polymerase chain reaction. The aim of this study is to determine the frequencies of Ychromosome microdeletions in azoospermic and oligospermic Iranian infertile men and compare them with other studies in different ethnic groups. Materials and Methods: At first, karyotype analysis was performed in 80 infertile men and 30 healthy age-matched counterparts as control group using standard cytogenetic methods. Second, genomic DNA was extracted from all cases and genetic screening was conducted for Y chromosome microdeletions by multiplex polymerase chain reaction for AZF genes on both infertile and control men using 6 STS markers on the long arm of the Y chromosome. Results: Totally, 49 infertile men were azoospermic and 31 were oligospermic. Y-chromosome microdeletions in the AZFc region were detected in 4 of azoospermic patients. Y-chromosome microdeletions was not detected in any of the oligospermic patients and the control group. Conclusions: This finding recommends that genetic counseling and screening before starting assisted reproductive techniques such as in vitro fertilisation and intracytoplasmic sperm injection can prevent unnecessary treatment and transmission of genetic defects to offspring

Consequences of Y chromosome microdeletions beyond male infertility

The human Y chromosome plays a central role in sex determination and spermatogenesis. The azoospermia factor (AZF) loci on the Y chromosome contain genes that were thought to be testis specific with their deletions leading to spermatogenic failure. However, beyond the testis, the AZF genes (mainly those in AZFa and AZFb loci) are widely expressed in multiple tissues. Further, these genes are predicted to play roles in processes such as gene regulation and protein synthesis. These observations suggest that the AZF genes may have functions beyond regulation of fertility. Three major areas have emerged where alternations in AZF genes have effects beyond infertility. (1) Poor-quality embryos are generated in assisted reproduction when sperm from men harboring Y chromosome microdeletions are used, (2) a higher preponderance of neuropsychiatry disorders is observed in men with deletions in AZF genes, and (3) copy number variations and altered expression of AZF genes are found in several cancers. While ourdata is preliminary and observational in nature, systematic studies are required to address how genetic alterations in the Y chromosome can affect the health of men beyond infertility. This information will provide a different perspective in the area of androgenetics and have implications in devising strategies for maintaining the overall well-being of infertile males.

Analysis of microdeletions of azoospermia factor genes on Y chromosome in infertile males

To investigate the location and characteristics of microdeletions of Y chromosome azoospermia factor (AZF) genes in infertile males with azoospermia and severe oligozoospermia in southern Sichuan. Multiplex PCR was used to detect 18 sequence tagged sites (STS) involved in Y chromosome AZF microdeletions among 224 infertile males (including 134 azoospermia cases and 90 severe oligozoospermia cases) and 70 healthy males. Among the 224 infertile males, the overall frequency of microdeletions was 12.1% (27/224), and were 13.4% (18/134) in those with azoospermia and 10.0% (9/90) in those with severe oligozoospermia. The most frequent microdeletions have occurred in the AZFc region (51.9%). Compared with the 6 STS loci recommended by European Academy of Andrology and European Molecular Genetics Quality Network, 22.7% more deletions were detected based on the 18 STS loci selected from the AZF region. Identification of Y chromosome microdeletions has a significant implication on the diagnosis of male infertility. The most frequent microdeletions have occurred in the AZFc region in southern Sichuan. To use more sequence tagged sites for the screening can improve the reliability and detection rate of Y chromosome microdeletions.

Genomic integrity of the Y chromosome sequence-tagged-sites in infertile and Down syndrome Jordanian males

The long arm of the Y chromosome contains nonoverlapping regions termed azoospermia factor (AZF) with great influence on male fertility. Microdeletions at these regions minimise the males' ability to father offsprings. In this preliminary study, we attempted to screen the presence or absence of twenty Y chromosome's sequence-tagged sites (STS) associated with fertility in infertile and Down syndrome (DS) males. Genomic DNA from 35 fertile, 74 infertile and 22 karyotyped DS males was extracted and amplified in multiplex polymerase chain reaction (PCR) containing 20 primer pairs that amplify Y-specific STS that cover functional regions associated with AZF and spermatogenesis-related genes. Our results indicated the integrity of the Y chromosome at the 20 fertility markers for both the fertile and Down syndrome males. However, the results of the infertile males showed the presence of microdeletions at these Y-specific STS. Three samples showed Y chromosome microdeletion when blood and seminal fluid genomic DNA were assayed, while two samples showed microdeletion only when seminal fluid genomic DNA was assayed. The current study demonstrated that the molecular genetic aspect of infertility should be given proper attention when dealing with infertility cases. Furthermore, our results indicate the importance of genetic counselling in managing infertility cases.

Cytogenetic abnormalities and Y-chromosome microdeletions in infertile Syrian males

Infertility is an important health issue affecting numerous couples. Approximately 30-50% of the cases of male infertility is due to unknown reasons. The main genetic factors involved in male infertility are chromosomal abnormalities and Y chromosome microdeletions within the Yq11 region. The genes controlling spermatogenesis located in the Yq11 region are termed azoospermia factor genes (AZF). Klinefelter syndrome (KS) is the most common of the chromosomal anomalies in the infertile male. AZF microdeletions on the Y chromosome are the most frequent genetic cause of male infertility. Screening for microdeletions in the AZFa, b and c regions of the Y chromosome showed a marked variation among different studies. The present study aimed to investigate the prevalence of such deletions in Syrian men. A total of 162 infertile males (97 azoospermic, 49 oligospermic and 16 severely oligospermic) were screened for chromosomal abnormalities and Y chromosome microdeletions using 28 markers in the AZF region. Twenty (12.34%) patients had chromosomal rearrangements, 17 of them showed sex chromosome abnormalities (11 of 17 patients within the azoospermic group had a KS of 64.7%), 2 patients had apparently balanced autosomal rearrangements, while 1 patient had an inversion. Of the 162 infertile men, 46 patients (28.4%) had Y chromosome microdeletions within the AZF-regions. Most frequently hit were the AZFc (34.8%), followed by the AZFbc, AZFa, AZFac, AZFbc, AZFb, AZFd, AZFab, AZFad, AZFbd, AZFabc and the AZFbcd. Combined AZF deletions involving three regions with chromosomal abnormalities were observed in one case. The higher frequency of AZF deletions in our study was comparable with frequencies in other countries and regions of the world, possibly due to the elevated number of the sequence-tagged site (STS) markers used for this screening.

Genetic Dissection of the AZF Regions of the Human Y Chromosome: Thriller or Filler for Male (In)fertility?

The azoospermia factor (AZF) regions consist of three genetic domains in the long arm of the human Y chromosome referred to as AZFa, AZFb and AZFc. These are of importance for male fertility since they are home to genes required for spermatogenesis. In this paper a comprehensive analysis of AZF structure and gene content will be undertaken. Particular care will be given to the molecular mechanisms underlying the spermatogenic impairment phenotypes associated to AZF deletions. Analysis of the 14 different AZF genes or gene families argues for the existence of functional asymmetries between the determinants; while some are prominent players in spermatogenesis, others seem to modulate more subtly the program. In this regard, evidence supporting the notion that DDX3Y, KDM5D, RBMY1A1, DAZ, and CDY represent key AZF spermatogenic determinants will be discussed.

Rapid screening of the Y chromosome in idiopathic sterile men, diagnostic for deletions in AZF, a genetic Y factor expressed during spermatogenesis.

A rapid molecular screening programme has been established for the long arm of the human Y chromosome in Yq11 in order to quickly detect small interstitial deletions in this chromosome region. They have been observed in idiopathic sterile males with azoospermia and a severe oligozoospermia and are therefore indicative for deletion of AZF gene sequences. AZF (i.e. azoospermia factor) is a genetic factor located in Yq11 which controls human spermatogenesis. The screening programme is based mainly on a multiplex PCR approach using a series of Y-specific primers amplifying single DNA loci in Yq11. The order of all Y-DNA loci can be unequivocally arranged along the whole long Y arm. Therefore, any detected deletion can be quickly mapped in relation to the proposed position of AZF. Benefits and pitfalls of this new diagnostic Y screening method will be discussed.

The AZF proteins

The azoospermia factor (AZF) locus in Yq11 is now functionally subdivided in three distinct spermatogenesis loci: AZFa, AZFb and AZFc. After knowledge of the complete genomic Y sequence in Yq11, 14 Y genes encoding putatively functional proteins and expressed in human testis are found to be located in one of the three AZF intervals. Therefore, a major question for each infertility clinic performing molecular screening for AZF deletions has now raised concerning the functional contribution of the encoded AZF proteins to human spermatogenesis. Additionally, it has been shown that distinct chromatin regions in Yq11 overlapping with the genomic AZFb and AZFc intervals are probably involved in the pre-meiotic X and Y chromosome pairing process. An old hypothesis on the germ line function of AZF becomes therefore revitalized. It proposed a specific chromatin folding code in Yq11, which controls the condensation cycle of the Y chromosome in the male germ line. Thus, with the exception of AZF proteins functionally expressed during the pre-meiotic differentiation and proliferation of spermatogonia, the need for AZF proteins functionally expressed at meiosis or during the post-meiotic spermatid maturation process is difficult to assess before the identification of specific mutations in the corresponding AZF gene causing male infertility.

Genes involved in spermatogenesis

During mammalian spermatogenesis, primordial germ cells develop into spermatogonia, giving rise to spermatocytes that undergo two meiotic divisions to become round spermatids. These cells differentiate into spermatozoa during spermiogenesis. Spermatogenesis is a complex process of cell differentiation controlled by many factors, among which gene regulation in the spermatogenic cells plays a pivotal role. Genes important for male gametogenesis involved in highly con-served landmark events such as meiotic recombination, formation of the synaptonemal complex, sister chromatid cohesion, spermiogenesis during postmeiotic stages, and checkpoints and factors required for the meiotic cell cycle. Spermatogenesis is characterized by phase-specific expression of many genes exclusively expressed in the spermatogenic cells. With the development and application of technologies like gene cloning, gene expression and functional characterization, many spermatogenesis-related genes have been found in the past few years, and some of them have been proved to play an important role in spermatogenesis. Here, we review the advances in this field with an emphasis on spermatogenesis-associated genes such as cyclins, proto-oncogenes, azoospermia factor genes, cytoskeleton genes, heat shock genes, nucleoprotein transition genes, centrin genes and apoptosis genes.

SRY and AZF gene variation in male infertility: a cytogenetic and molecular approach

The aim of this study was to identify the genetic effects of Y chromosome and azoospermia factor (AZF) gene variation in men with infertility and to elucidate the molecular mechanism responsible for the identified point mutation. Chromosome analysis was performed according to standard methods on lymphocyte cultured cells and genomic DNA was extracted from the peripheral blood. Three sets of primers were used encompassing the AZFb, AZFc and SRY14 gene regions. Products were genotyped with single-strand comformational polymorphisim (SSCP) analysis. The profiles of the mutated genes were detected in five of three azoospermic and two oligoasthenozoospermic infertile males. The SSCP variability of the AZFc gene was detected in all of the cases, while sex-determining region Y (SRY) gene variation was detected in two of the current cases. Three cases with oligoasthenozoospermia showed mutated SSCP profiles in both their SRY and AZFc gene regions. No AZFb variation was detected in the presented cases. The AZF locus is assumed to contain the genes responsible for spermatogenesis in human. Deletions in these genes are thought to be involved in male infertility associated with azoospermia, oligozoospermia and/or both. AZF microdeletions and variations that are seen in infertile males suggest the need for molecular screening of such cases. Advance studies are also needed to detect of these variations and their relevance to male infertility before using assisted reproduction techniques in such cases.

Natural transmission of USP9Y gene mutations: a new perspective on the role of AZFa genes in male fertility

Deletions of the azoospermia factor (AZF) regions of the Y chromosome are associated with severe spermatogenic failure and represent the most frequent molecular genetic cause of azoospermia and severe oligozoospermia. The exact role of the candidate AZF genes is largely unknown due to both the extreme rarity of naturally occurring AZF gene-specific mutations and the lack of functional assays. Here, we report the fine characterization of two different deletions in the USP9Y gene (one of the two candidate genes in the AZFa region), which have been transmitted through natural conception in two unrelated families. The associated mild testicular phenotype, in both cases, is in sharp contrast with that of the two previously reported infertile patients bearing a mutation of the same gene. In conclusion, to date, the USP9Y gene has been considered as one of the major Y-linked spermatogenesis genes, based on both its position within the AZFa region and previous reports that correlated USP9Y mutation to severe spermatogenic failure and infertility. This view is now substantially changed because our findings clearly demonstrate that during human spermatogenesis, USP9Y is more likely a fine tuner that improves efficiency, rather than a provider of an essential function. More importantly, the observed natural conceptions suggest that the protein is not required for the final sperm maturation process or for the acquisition of sperm fertilizing ability, providing a new perspective on the role played by the USP9Y gene in male fertility.

Somatic cytogenetic and azoospermia factor gene microdeletion studies in infertile men

The objective of the present study was to determine the frequency of somatic chromosomal anomalies and Y chromosomal microdeletions (azoospermia factor genes, AZF) in infertile males who seek assisted reproduction. These studies are very important because the assisted reproduction techniques (mainly intracytoplasmic sperm injection) bypass the natural selection process and some classical chromosomal abnormalities, microdeletions of AZF genes or some deleterious genic mutations could pass through generations. These genetic abnormalities can cause in the offspring of these patients male infertility, ambiguous external genitalia, mental retardation, and other birth defects. We studied 165 infertile men whose infertility was attributable to testicular problems (60 were azoospermic, 100 were oligospermic and 5 were asthenospermic). We studied 100 metaphases per patient with GTG banding obtained from temporary lymphocyte culture for chromosomal abnormality detection and performed a genomic DNA analysis using 28 Y chromosome-specific sequence-tagged sites for Y AZF microdeletion detection. Karyotyping revealed somatic anomalies in 16 subjects (16/165 = 9.6%). Of these 16, 12 were in the azoospermic group (12/60 = 20%) and 4 were in the oligospermic group (4/100 = 4%). The most common chromosomal anomaly was Klinefelter syndrome (10/165 = 6%). Microdeletions of AZF genes were detected in 12 subjects (12/160 = 7.5%). The frequencies detected are similar to those described previously. These results show the importance of genetic evaluation of infertile males prior to assisted reproduction. Such evaluation can lead to genetic counseling and, consequently, to primary and secondary prevention of mental retardation and birth defects.

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 chromosome and male infertility: Update, 2006

Male factor infertility accounts for about half the cases of couple infertility and in around 50% of cases its etiology remains unknown. Molecular genetic techniques have unveiled a number of etiopathogenetic factors, including microdeletions of the Yq. Y chromosome microdeletions removing the AZoospermia Factor (AZF) regions are the most frequent molecular genetic causes of oligo/azoospermia. The intense effort of many laboratories contributed to a better understanding of the clinical significance of this genetic anomaly and to the identification of fertility candidate genes in the AZF regions. Important progress has been made on the structure of the Y chromosome and the mechanism of deletion. Studies aimed to define a predisposing genetic background for Yq deletions were not successful, perhaps due to the low number of patients analyzed so far. The screening for Yq deletions became a routine diagnostic test that provides an etiology for spermatogenic disturbances, and assess in the prognosis for testicular sperm retrieval according to the type of deletion. Assisted reproductive techniques represent an efficient symptomatic therapy for men bearing Y microdeletions, however, this genetic defect is transmitted to the male offsprings, affecting their fertility. Future studies should focus on understanding the biological function of AZF genes which is an essential step for the development of more appropriate and knowledge-based therapies.

Azoospermia factor (AZF) in Yq11: towards a molecular understanding of its function for human male fertility and spermatogenesis

The Y chromosomal azoospermia factor (AZF) is essential for human spermatogenesis. It has been mapped by molecular deletion analyses to three subintervals in Yq11, AZFa, AZFb, and AZFc, containing a number of genes of which at least some control, post-transcriptionally, the RNA metabolism of other spermatogenesis genes, functionally expressed at different phases of the spermatogenic cycle. Intrachromosomal recombination events between homologous large repetitive sequence block in Yq11 are now recognized as the major cause of the AZFa, AZFb and AZFc microdeletions, and an overlap of the AZFb and AZFc regions was revealed by sequence analysis of the complete Yq11 region. The increasing knowledge of the expression patterns of AZF genes in human germ cells suggests that the DBY gene is the major AZFa gene, the RBMY gene the major AZFb gene, although a functional expression of the other AZFa/b genes in the male germ line is also most likely. Genetic redundancy might exist in AZFc because a number of gene copies in the large P1 palindrome structure in distal AZFc were found to be deleted also in fertile men.

DNA extraction and quantification from touch and scrape preparations obtained from autopsy liver cells

The objective of the present study was to develop a simplified low cost method for the collection and fixation of pediatric autopsy cells and to determine the quantitative and qualitative adequacy of extracted DNA. Touch and scrape preparations of pediatric liver cells were obtained from 15 cadavers at autopsy and fixed in 95% ethanol or 3:1 methanol:acetic acid. Material prepared by each fixation procedure was submitted to DNA extraction with the Wizard genomic DNA purification kit for DNA quantification and five of the preparations were amplified by multiplex PCR (azoospermia factor genes). The amount of DNA extracted varied from 20 to 8,640 microg, with significant differences between fixation methods. Scrape preparation fixed in 95% ethanol provided larger amount of extracted DNA. However, the mean for all groups was higher than the quantity needed for PCR (50 ng) or Southern blot (500 ng). There were no qualitative differences among the different material and fixatives. The same results were also obtained for glass slides stored at room temperature for 6, 12, 18 and 24 months. We conclude that touch and scrape preparations fixed in 95% ethanol are a good source of DNA and present fewer limitations than cell culture, tissue paraffin embedding or freezing that require sterile material, culture medium, laboratory equipment and trained technicians. In addition, they are more practical and less labor intensive and can be obtained and stored for a long time at low cost.

Transcriptional levels of four Y chromosome-linked AZF genes in azoospermic men and their association with successful sperm retrieval

Objectives To investigate the transcriptional levels of four azoospermia factor genes in the testis of azoospermic men and to investigate the association between transcriptional levels and the results of sperm retrieval. Methods Thirty-eight azoospermic men with normal karyotype and without Y chromosome gene deletions were enrolled. The amounts of USP9Y (ubiquitin specific protease 9, Y chromosome), DBY (dead box on the Y), RBMY1 (RNA-binding motif on the Y, 1), and DAZ (deleted in azoospermia) transcripts were examined by quantitative competitive-reverse transcriptase-polymerase chain reaction. The steady-state concentrations of mRNA encoding for each gene in each testicular sample were normalized by the amounts of a housekeeping gene (glyceraldehyde phosphate dehydrogenase [GAPDH]). Differences in the transcript ratios (gene transcript/GAPDH transcript) among patients with different testicular histologic findings (normal spermatogenesis, hypospermatogenesis, maturation arrest, Sertoli cell-only syndrome) were analyzed. For each gene, the association between the transcript ratios and the results of sperm retrieval was evaluated. Results No statistically significant difference was found in the transcript ratios of USP9Y and DBY among the four histologic patient groups ( P = 0.33 and P = 0.21, respectively). In contrast, statistically significant decreases were found in the transcript ratios of RBMY1 and DAZ in patients with spermatogenic failure ( P = 0.0002 and P = 0.002, respectively). The transcript ratios of USP9Y and DBY were not associated with the results of sperm retrieval, and the transcript ratios of RBMY1 and DAZ revealed a positive association with successful sperm retrieval. Conclusions The decreased transcriptional levels of RBMY1 and DAZ in patients with spermatogenic failure may reflect the generalized loss of germ cells. The transcriptional levels of RBMY1 and DAZ may have the potential of becoming useful parameters in the prediction of successful sperm retrieval.

An evolutionarily conserved germ cell-specific hnRNP is encoded by a retrotransposed gene.

The gene encoding heterogeneous ribonucleoprotein (hnRNP) G recently has been mapped to the X chromosome. All mammals have a Y chromosome-encoded homologue of HNRNP G called RBMY, which is implicated with a role in male fertility and is a candidate for the azoospermia factor gene. We have identified a new member of this gene family, HNRNP G-T, and have mapped it as a single-copy gene on chromosome 11. This gene contains an uninterrupted open reading frame and no introns, consistent with derivation from a retroposon. However, unlike many retroposon-derived genes, HNRNP G-T is not a pseudogene. An antiserum raised to the conceptual reading frame of HNRNP G-T showed that it encodes a protein that is highly expressed in germ cells and in particular in the nuclei of meiotic spermatocytes. Surprisingly, although this antiserum was raised against human hnRNP G-T protein, it can also detect a similar protein in the testis of several mammals. This suggests that the protein is highly conserved and that the retrotransposition event generating the HNRNP G-T gene pre-dated at least the common ancestor of mouse and man. The existence of an additional testis-specific hnRNP G family member provides evidence for the importance of these proteins in normal germ cell development.