Genetic screening in infertile Mexican men: chromosomal abnormalities, Y chromosome deletions, and androgen receptor CAG repeat length

In our study, we analyzed chromosomal abnormalities, Y chromosome deletions, androgen receptor CAG repeat length and their association with defective spermatogenesis in infertile Mexican men. Eighty-two infertile patients and 40 controls were screened for karyotypic abnormalities, Y chromosome microdeletions, and CAG repeats. Nine infertile males (11%) carried chromosomal abnormalities and 10 (12.2%) presented Y chromosome microdeletions. The mean CAG repeat length was 21.6 and 20.88 base pairs in idiopathic infertile males and controls, respectively. Our results suggest that chromosomal aberrations and Y-chromosomal microdeletions are related to male infertility in Mexican men. In addition, expansion of the CAG repeat segments of the androgen receptor is not correlated with male idiopathic infertility.     

Association of oestrogen receptor alpha polymorphisms and androgen receptor CAG trinucleotide repeats with male infertility: a study in 109 Greek infertile men

This study was performed to examine the contribution of genetic polymorphism of oestrogen and androgen receptor (AR) genes in male infertility. We have studied in total 173 Greek men, 109 infertile patients and 64 controls (group A). Patients were divided in to three subgroups: group B (n=29) with idiopathic moderate oligospermia, group C (n=42) with azoospermia or idiopathic severe oligospermia and group D (n=38) with azoospermia or oligospermia of various known aetiologies. All patients and controls were genotyped for two polymorphisms of the oestrogen receptor alpha (ERalpha) gene and also for the (CAG)n repeat length polymorphism of the X-linked androgen receptor (AR)gene. The control group had statistically significant difference from group C regarding the XbaI polymorphism of ERalpha gene. Despite the fact that we did not observe any statistically significant differences in the mean and range of the CAG repeat number, the frequency of the higher repeats of the nucleotide repeat sequence (CAG)n of the AR gene was 2-4 times higher in groups B and C compared with the control group A. Our results indicate that both ERalpha and AR gene play significant role in male fertility. It is possible that a synergy may exist between unfavourable genotypes of these two genes in male infertility.     

CAG repeat expansion in the androgen receptor gene is not associated with male infertility in Indian populations

CAG repeat expansion in exon 1 of the androgen receptor (AR) gene has been reported to be associated with male infertility in some but not all populations. Until now, studies have not been carried out to examine this among Indian populations. For the first time, we have analyzed the CAG repeat motif in the AR gene in 280 men with azoospermia and in 201 men with normal fertility. The mean number of CAG repeats in the AR gene of men with azoospermia was 21.7 +/- 0.18, with a high incidence of repeat number 22. Among fertile-control men, the mean number of CAG repeats was 22.4 +/- 0.19, with a predominance of repeat number 23. The highest number of CAG repeats (32) was found with low frequency in both fertile and azoospermic groups. Comparison of fertile men and those with azoospermia on the basis of CAG repeats revealed that the number of CAG repeats in both groups were similar, as revealed with a paired t test (t = 0.04; P =.967). Expansion of the CAG repeat in the AR gene is therefore not associated with male infertility in Indian populations. This suggests that what is true for one population may not be true for other populations.     

雄激素受体基因CAG重复多态性与男性不育关系的Meta分析

目的:采用Meta分析系统评价雄激素受体(AR)基因CAG串联重复多态性与男性不育的关系。方法:检索Medline、CBM等数据库中有关AR基因CAG重复数与男性不育相关性的病例对照研究,并用RevMan4.2软件进行统计分析。结果:共纳入32篇符合条件的文献,累计特发性不育病例3153例、对照2314例。数据合并结果显示,男性不育、无精子症及中度少精子症者其CAG重复数均数均显著高于对照人群(P<0.01),三者与对照间CAG重复数均数的标准均数差分别为0.27,95%CI:0.17～0.37;0.29,95%CI:0.08～0.50;0.27,95%CI:0.13～0.41。而且,敏感性分析结果也与以上研究结果一致。结论:AR基因CAG重复多态性其重复数增多与精子发生障碍的风险相关。     

No association of androgen receptor GGN repeat length polymorphism with infertility in Indian men

Androgens, acting through the androgen receptor (AR), play a role in secondary sexual differentiation from the prenatal stage to adulthood, including spermatogenesis. The AR gene has 2 polymorphic trinucleotide repeats (CAG and GGN) in exon 1. The CAG repeat length polymorphism has been well studied in a variety of medical conditions, including male infertility. Many of these studies have shown an association of the expanded CAG repeats with male infertility, although this is not true for all populations. The GGN repeat, in contrast, has been less thoroughly studied. Thus far, only 4 reports worldwide have analyzed the GGN repeat, alone or in combination with the CAG repeat, in male infertility cases. No such study has been undertaken on infertile Indian men. Therefore, we have analyzed AR-GGN repeats in a total of 595 Indian males, including 277 azoospemric, 97 oligozoospermic, and 21 oligoteratozoospermic cases, along with 200 normozoospermic controls. The analysis revealed no difference in the mean number or the range of the repeat between cases (mean = 21.51 repeats, range 15-26 repeats) and controls (mean 21.58 repeats, range 15-26 repeats). Furthermore, no difference was observed when azoospermic (mean = 21.53 repeats, range 15-26 repeats), oligozoospermic (mean = 21.46 repeats, range 15-26 repeats), and oligoteratozoospermic cases (mean = 21.48, range 19-26 repeats) were compared individually with the controls.     

The CAG repeat polymorphism of mitochondrial polymerase gamma (POLG) is associated with male infertility in Tunisia

Male fertility largely depends on sperm quality, which may be affected by environmental and genetic factors. Recent data emphasised the implication of the polymorphism of mitochondrial DNA polymerase gamma (POLG) CAG repeats in male infertility. In this report, we explored a possible role of the (POLG) gene polymorphism in male infertility in Tunisian men. The polymorphic CAG repeat in the nuclear POLG gene was studied in 339 male subjects (216 patients with infertility (69 azoospermic, 115 oligoasthenoteratospermic and 32 normospermic) and 123 fertile) after DNA amplification by PCR, followed by genotyping using an automatic sequencer. The heterozygous and the homozygous mutant genotypes (10/ ≠ 10 and ≠ 10/ ≠ 10) were significantly more frequent among infertile patients than among fertile controls (11.2% versus 1.6%, P = 1.3 × 10(-3) and 4.6% versus 0.8%, P = 4.2 × 10(-7) respectively). We also found a significant difference between the frequencies of 10/ ≠ 10 genotype in azoospermic (4.4%) and in oligoasthenoteratospermic (15.6%) infertile patients (P = 2.6 × 10(-2) ). However, the homozygous mutant genotype (≠ 10/ ≠ 10) was seen at similar frequencies in azoospermic, normospermic and oligoasthenospermic men (4.4%, 3.1% and 5.2% respectively). Under our conditions, the findings showed an association between POLG CAG repeat polymorphism and male infertility in Tunisian population.     

CAG repeat length in androgen receptor gene and male infertility in Egyptian patients

The CAG repeat and its association with infertility has been debatable. Therefore, this study was planned to assess the distribution of CAG repeat expansion in Egyptian patients and to investigate its association with male infertility. Forty-five infertile men were eligible for the study in addition to 20 aged-matched fertile males as control. Semen analysis, scrotal sonography, assay of serum testosterone, follicle-stimulating hormone (FSH) and luteinising hormone (LH), and determination of the CAG repeat number within exon 1 of the androgen receptor (AR) gene were carried out. Statistically significant difference was found between infertile and control groups regarding sperm count, sperm motility, serum FSH level and CAG repeats (P < 0.05); statistically insignificant difference for the CAG repeats (P = 1.0) was found between oligozoospermic and asthenospermic groups; negative correlation was found between CAG repeat length and sperm count, and a positive correlation was found between CAG repeat length and serum FSH (P < 0.05). Our results validate the concept that long stretches of CAG repeat may be associated with lower AR function with derangement of sperm production, and this may contribute to male infertility in Egyptian men.     

Cytogenetic and molecular analysis of the Y chromosome: absence of a significant relationship between CAG repeat length in exon 1 of the androgen receptor gene and infertility in Indian men

The genetic basis of male infertility remains unclear in the majority of cases. Recent studies have indicated an association between microdeletions of the azoospermia factor a (AZFa)-AZFc regions of Yq and severe oligospermia or azoospermia. Increased (CAG)n repeat lengths in the androgen receptor (AR) gene have also been reported in infertile men. Therefore, in order to assess the prevalence of these genetic defects to male infertility, 183 men with non-obstructive azoospermia (n = 70), obstructive azoospermia (n = 33), severe oligospermia (n = 80) and 59 fertile men were examined cytogenetically and at molecular level for Yq deletions, microdeletions, and AR-CAG repeat lengths along with hormonal profiles [luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T)]. We used high resolution cytogenetics to detect chromosome deletions and multiplex polymerase chain reaction (PCR) involving 27 sequence-tagged site (STS) markers on Yq to determine the rate and extent of Yq microdeletions. PCR amplification with primers flanking exon 1 of AR gene was used to determine the AR-(CAG)n repeat lengths. Hormonal profiles (LH, FSH and T levels) were also analysed in infertile and fertile men. Testicular biopsies showed Sertoli cell only (SCO) morphology, maturation arrests (MA) and hypospermatogenesis. No chromosome aberrations were found in infertile men but there was a significant increase (p < 0.001) in the association of acrocentric chromosomes including the Y chromosome. Yq microdeletions were found in 16 non-obstructive azoospermic men (16 of 70; 22%) and seven severe oligospermic individuals (seven of 80; 8.7%) and most of them had deletions in the sY240 locus. No Yq microdeletions were detected in patients with obstructive azoospermia. No statistically significant difference in the mean length of CAG repeats in AR gene was observed between infertile and fertile men (22.2 +/- 1.5 and 21.5 +/- 1.4 respectively). No significant increase or decrease in levels of LH, FSH and T was observed in infertile and fertile men. In some infertile men, significantly elevated levels of FSH alone or in combination with LH were found to be indicative of failure of spermatogenesis and/or suggestive of testicular failure. Y-chromosome microdeletions contribute to infertility in some patients but no relationship could be established with the (CAG)n repeat lengths in exon 1 of the AR gene in infertile Indian men.     

CAG repeat length analysis and mutation screening of the androgen receptor gene in Japanese men with idiopathic azoospermia.

Because androgens are required for normal spermatogenesis, we are investigating abnormalities in the androgen receptor as a possible cause of impaired spermatogenesis in patients with idiopathic male infertility. The CAG repeat length in exon 1 and mutations of the androgen receptor gene were studied in 30 men with idiopathic azoospermia and in 51 fertile men. In men with azoospermia, plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone levels were measured and testicular biopsies were performed. The CAG repeat length ranged from 19 to 30 (mean 23.4 +/- 2.9) and from 17 to 28 (mean 23.7 +/- 3.2) in men with azoospermia and in controls, respectively. There was no significant difference between the 2 groups. In men with azoospermia, the Johnsen testicular biopsy score negatively correlated with plasma FSH (P < .01). However, the Johnsen testicular biopsy score did not correlate with plasma LH and testosterone levels. The CAG repeat length did not correlate with the Johnsen testicular biopsy score, or with plasma concentrations of LH, FSH, and testosterone. No abnormalities in the androgen receptor gene were detected. These facts suggest that the CAG repeat length and alterations in the androgen receptor gene are not associated with the etiology of idiopathic azoospermia.     

CAG repeat variation in the mtDNA polymerase gamma is not associated with oligoasthenozoospermia

Variations in the trinucleotide-CAG repeat number of the catalytic subunit of the mitochondrial DNA polymerase gamma (POLG) have been speculated to be associated with male infertility. The ten CAG repeats (10/10) were found to be the most common allele (88%), absence of which was found to be associated with male infertility. As no study on Indian population was conducted so far to support this view, we investigated the distribution of the POLG -CAG repeats in 509 oligoasthenozoospermic and 241 normozoospermic control Indian men from the same ethnic background. Our study suggested that the distribution of common allele (10/10) was almost similar in both infertile (75%) and normozoospermic (75.5%) men. Further, we had analysed the CAG repeat number in as many as 1306 Indian men belonging to different ethnic, geographical and linguistic backgrounds and found the common allele 10/10 at a frequency of 78.4%. Our study, therefore, suggests that the 10-CAG repeat is the most common allele present in Indian populations, but its absence and the occurrence of the other mutant homozygous (non 10/non 10) genotype should not be understood as being specific to infertility. It, thus, suggests that the POLG -CAG repeat variation is not associated with male infertility in Indian populations, and hence is not a useful marker for screening infertile men.     

Absence of Yq microdeletions in infertile men.

Microdeletions of the long arm of the Y chromosome (Yq) were described in men with idiopathic azoo- or oligozoospermia and seem to cause impairment of spermatogenesis. Deletion frequencies differ considerably among selected infertile men. The aim of this study was to investigate the prevalence of Yq microdeletions in patients with idiopathic infertility. Men with azoospermia or oligozoospermia resulting from endocrine or obstructive causes or with a constitutional cytogenetic anomaly were excluded. Ninety-seven patients presenting at infertility centers in Leipzig and Zurich were included in the study. Sixty-four (66%) of them were severely oligozoospermic (sperm concentrations < 5 x 10(6)/mL) and 33 (36%) were azoospermic. A sequence-tagged site (STS) PCR strategy was applied for the microdeletion screening. Thirteen STS markers spanning the whole euchromatic region of Yq were used. No Y-chromosomal microdeletion could be detected in these 97 infertile men. This result suggests a much lower Yq deletion frequency than previously thought, even among strictly selected patients with idiopathic azoo- or oligozoospermia.     

Absence of association of androgen receptor trinucleotide expansion and poor semen quality

This study investigated the relationship between variation in the polymorphic CAG trinucleotide repeat (TNR) region of the human androgen receptor (AR) gene and semen quality in a Caucasian sample population. These men were patients attending the New Zealand Centre for Reproductive Medicine in Christchurch. The AR TNR region was amplified by polymerase chain reaction and then DNA sequenced to determine exact numbers of CAG repeats for each sample. In addition, the samples were screened for microdeletions within the AZFc region of the Y-chromosome. A total of 105 men with poor semen quality were compared with a group of 93 men with normal semen quality. Men with poor semen quality had similar CAG repeat number to men with normal semen quality (21.46 +/- 0.30 vs. 20.99 +/- 0.28, p = 0.126). Y-chromosome microdeletions were only detected in men with suboptimal semen parameters (7.4%). However, the presence of a deletion was not related to CAG repeat number. The CAG repeat number in the men with normal semen quality in the present study is similar to the Australian and German samples, but lower than those reported for the Swedes, Dutch and Danes. These results are contrary to the hypothesis that higher CAG repeats are associated with infertility in men, but strongly suggest that different populations may show different numbers of CAG repeats in addition to racial variation reported in previous studies.     

Y染色体上热休克转录因子在无、少精子症患者精液、睾丸中的缺失研究

目的 通过检测无、少精子症不育患者睾丸、精液基因组HSFY基因缺失情况,探讨其病因的基因诊断方法.方法 选择35例特发性无、少精子症患者作为研究对象,其中少精子症18例、严重少精子症12例、无精子症5例;10例正常已生育健康男性作为正常对照.应用PCR技术,检测每例患者睾丸、精液中精子基因组中的Y染色体上特异性序列标签位点(STS)的引物扩增了解基因缺失情况.结果 35例患者中5例表现睾丸、精液中精子基因组微缺失,其中少精子症2例,严重少精子症3例;其余30例患者和10例正常对照睾丸、精液中精子基因组未见基因微缺失.结论 AZFb区热休克转录因子基因的部分缺失将会使精子数量明显减少.     

Whole cell and nuclear androgen uptake in skin fibroblasts from infertile men

In order to reexamine the hypothesis that a high percentage of infertile men with oligo/azoospermia have androgen resistance due to androgen receptor abnormalities, both whole cell and nuclear uptake of [3H]R1881 (a synthetic, nonmetabolizable androgen) were measured in intact, dispersed fibroblasts cultured from pubic skin biopsy specimens of 15 men selected because of infertility associated with varying degrees of oligozoospermia. Eight men had sperm densities less than or equal to 2 X 10(6)/ml; 7 were greater than 2 X 10(6)/ml. Serum levels of FSH and LH were elevated in the severely oligo/azoospermic group, but normal in the other infertile men; concentrations of testosterone, estradiol, and prolactin were normal in both groups. The controls were six normal, age-matched, fertile males. There was no difference in binding capacity or dissociation constant for androgen uptake either into whole cells (3940 +/- 940 [mean +/- SE] sites/cell vs. 4700 +/- 1120 sites/cell, P = NS) or into nuclei (1360 +/- 340 sites/cell vs. 1460 +/- 340 sites/cell, P = NS) of the fibroblasts from the patients vs. the controls, respectively. Furthermore, there was no correlation between patient sperm densities and fibroblast whole cell or nuclear uptake binding capacities. Finally, there was no difference in any androgen binding parameter when only the fibroblasts from the men with severe oligozoospermia or azoospermia were compared with the controls. The authors conclude that the infertility of men with severe testicular germ cell depletion cannot be accounted for by a quantitative androgen receptor abnormality in their pubic skin fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)     

中国特发性无精子症和少精子症患者雄激素受体基因CAG重复多态性研究

目的分析中国特发性无精子症和少精子症患者雄激素受体(AR)基因(CAG)n微卫星多态性并探讨该多态性与精子生成障碍发生的关系。方法应用PCR和变性聚丙烯酰胺凝胶电泳分析技术对52例少精子症患者和31例无精子症患者的外周血标本进行CAG重复数测定,分析该微卫星多态性和精子生成障碍发生的关系。结果少精子症患者组和无精子症患者组CAG重复数均数分别为22.19和22.13,CAG重复数≥28的百分率分别为1.9%和3.2%,比例逐渐升高。结论AR基因(CAG)n微卫星的CAG重复数在中国男性不育患者中呈现多态性,与精子生成障碍发生的关系有待进一步研究。     

Oxidative stress in normospermic men undergoing infertility evaluation

The purpose of this study was to determine whether normospermic infertile men have high seminal oxidative stress, using 3 measures of oxidative stress: reactive oxygen species (ROS), total antioxidant capacity (TAC), and a composite ROS-TAC score. Forty-three normospermic men without leukocytospermia and 19 healthy donors who came to our infertility clinic were included. Patients were categorized into 3 groups: group I, varicocele and no female factor (n = 16); group II, positive female factor (n = 16); and group III, idiopathic infertility (n = 11). In addition, 52 treated male factor patients and 19 donors were included as reference groups. We measured seminal ROS, TAC, and the ROS-TAC score in the patient groups and the controls. Normospermic infertile patients as a group had higher ROS levels (mean log [ROS + 1] 1.76 +/- 0.13) compared with controls (1.39 +/- 0.16; P = .03). Patients in the idiopathic subgroup had significantly higher ROS levels (2.29 +/- 0.25; P = .004) than controls. Normospermic infertile patients as a group not only had reduced TAC levels (970.18 +/- 73.95 Trolox equivalents), but each subgroup also had significantly lower TAC than controls (1650.93 +/- 95.87; P < .003). The ROS-TAC scores in all normospermic infertile patients as a group (35.7 +/- 1.8) as well as in each subgroup was significantly reduced compared with the ROS-TAC levels in the controls (50.0 +/- 2.1; P < .005). We conclude that oxidative stress is associated with male factor infertility. The presence of oxidative stress in infertile normospermic men may explain previously unexplained cases of infertility otherwise attributed to female factors.     

An increased CAG repeat length in the androgen receptor gene in azoospermic ICSI candidates

The androgen receptor gene has a polymorphic trinucleotide repeat that encodes a polyglutamine tract in its N-terminal transactivation domain. We started this study in order to find out whether a correlation existed between the length of this polymorphic tract and the presence of azoospermia in candidates for intracytoplasmic sperm injection (ICSI). The CAG repeat length in exon 1 of the androgen receptor (AR) gene was directly sequenced in 102 patients with azoospermia and in 96 fertile controls. Hormone levels were also measured in patients with azoospermia. The mean AR gene CAG repeat length was significantly larger in azoospermic subjects than it was in control fertile men (23.25 +/- 2.7 versus 22.42 +/- 2.8; P =.033). A receiver operating characteristic analysis evidenced a cutoff point at 22/23 CAG repeats at which the probability of being azoospermic increased 2.2 times. Subsequent logistic regression analysis of the data showed that the odds for azoospermia increased with the number of CAG repeats. Men with more than 26 CAG repeats have a 4.09 greater risk of being azoospermic. Therefore, in our candidates for ICSI, a direct correlation exists between the CAG repeat length in the exon 1 of the AR gene and the risk of being azoospermic.     

CAG repeat length in the androgen receptor gene is enhanced in patients with idiopathic azoospermia

Objectives. To determine whether the number of CAG repeats in the androgen receptor gene is enhanced in patients with idiopathic azoospermia.Methods. Using the polymerase chain reaction, the number of CAG repeats was assayed in 41 patients with idiopathic azoospermia and in 48 normozoospermic fertile men.Results. In the control group, the CAG repeat length ranged from 17 to 30 (mean 23.9 ± 2.9); in the azoospermic group, the CAG repeat length ranged from 20 to 34 (mean 26.5 ± 3.5). The difference between the two groups was statistically significant (P = 0.0013). None of the men in the control group had a CAG repeat length greater than 31; four of the azoospermic men had 34 CAG repeats.Conclusions. Results suggest that an increase in the number of CAG repeats in the androgen receptor gene to 31 or greater may be associated with the etiology of at least some cases of idiopathic azoospermia.