The association between sperm sex chromosome disomy and semen concentration, motility and morphology

Assessment of sperm chromosomal abnormalities using fluorescence in situ hybridization (FISH): implications for reproductive potential

PURPOSE

Chromosomal abnormalities play an important role in male infertility, which is becoming a significant issue in human fertility. Aim of this study was to evaluate the incidence of spermatic aneuploidies and diploidies in human sperm, according to semen parameters.

METHODS

We performed semen analysis according to the 6th edition of WHO criteria in 50 male subjects; samples were divided into normozoospermic (n = 23) or those with altered seminal parameters (n = 27). To assess chromosomal numerical alterations of sperm, fluorescence in situ hybridization (FISH) was used.

RESULT

A significant increase in aneuploidies and diploidies was observed in samples with altered seminal parameters. Furthermore, stratifying this group, we observed a significant increase in aneuploidies and total abnormalities in oligozoospermic, asthenoteratozoospermic (AT), and oligoteratoasthenozoospermic (OAT) samples compared to normozoospermic.

CONCLUSION

Our results showed the correlation between altered seminal parameters and numerical chromosomal abnormalities, confirming that sperm FISH analysis could be an additional clinical tool to assess reproductive potential in infertile males. Moreover, our results point to the importance of updating the normality ranges for detecting chromosomal aneuploidies using FISH.

Association of GRP78 promoter polymorphisms and serum GRP78 level with risk of asthenozoospermia

PURPOSE

The aim of this study was undertaken to investigate the association of 78-kDa glucose-regulated protein (GRP78) gene promoter polymorphisms with risk of asthenozoospermia (AZS) men. In addition, we performed association analysis between GRP78 promoter mutations and serum GRP78 level in asthenozoospermia.

METHODS

The study population comprised 400 subjects with AZS patients and 400 healthy controls. We assessed GRP78 rs3216733, rs17840761, and rs17840762 polymorphisms by using Snapshot SNP genotyping assays; serum GRP78 level was measured by enzyme-linked immunosorbent assay (ELISA). Semen quality was assessed by computer-assisted semen analysis.

RESULTS

We found that rs3216733 was associated with increased risk of AZS (Gd vs. dd: adjusted OR = 1.42, 95% CI, 1.06-1.93, P = 0.020; Gd/GG vs. dd: adjusted OR = 1.43, 95% CI, 1.08-1.91, P = 0.013; G vs. d adjusted OR = 1.26, 95% CI, 1.03-1.56, P = 0.027). The haplotype analyses showed the frequency of G-C-C haplotype was significantly higher in AZS (P = 0.026). The percentage of progressive motility sperm was lower in the asthenozoospermic men with Gd and Gd/GG genotypes than dd genotype (P = 0.003). Moreover, the serum GRP78 levels were significantly lower in rs3216733 Gd/GG genotypes compared with the dd genotype (P < 0.001).

CONCLUSION

Our findings suggest that rs3216733 Gd/GG genotypes contribute to poor sperm motility, probably by decreasing the level of GRP78.

Factors associated with aberrant imprint methylation and oligozoospermia

Disturbingly, the number of patients with oligozoospermia (low sperm count) has been gradually increasing in industrialized countries. Epigenetic alterations are believed to be involved in this condition. Recent studies have clarified that intrinsic and extrinsic factors can induce epigenetic transgenerational phenotypes through apparent reprogramming of the male germ line. Here we examined DNA methylation levels of 22 human imprinted loci in a total of 221 purified sperm samples from infertile couples and found methylation alterations in 24.8% of the patients. Structural equation model suggested that the cause of imprint methylation errors in sperm might have been environmental factors. More specifically, aberrant methylation and a particular lifestyle (current smoking, excess consumption of carbonated drinks) were associated with severe oligozoospermia, while aging probably affected this pathology indirectly through the accumulation of PCB in the patients. Next we examined the pregnancy outcomes for patients when the sperm had abnormal imprint methylation. The live-birth rate decreased and the miscarriage rate increased with the methylation errors. Our research will be useful for the prevention of methylation errors in sperm from infertile men, and sperm with normal imprint methylation might increase the safety of assisted reproduction technology (ART) by reducing methylation-induced diseases of children conceived via ART.

Aneuploidy: a common and early evidence-based biomarker for carcinogens and reproductive toxicants

Aneuploidy, defined as structural and numerical aberrations of chromosomes, continues to draw attention as an informative effect biomarker for carcinogens and male reproductive toxicants. It has been well documented that aneuploidy is a hallmark of cancer. Aneuploidies in oocytes and spermatozoa contribute to infertility, pregnancy loss and a number of congenital abnormalities, and sperm aneuploidy is associated with testicular cancer. It is striking that several carcinogens induce aneuploidy in somatic cells, and also adversely affect the chromosome compliment of germ cells. In this paper we review 1) the contributions of aneuploidy to cancer, infertility, and developmental abnormalities; 2) techniques for assessing aneuploidy in precancerous and malignant lesions and in sperm; and 3) the utility of aneuploidy as a biomarker for integrated chemical assessments of carcinogenicity, and reproductive and developmental toxicity.

Association of polymorphisms in PATE1 gene with idiopathic asthenozoospermia in Sichuan, China

PURPOSE

Idiopathic Asthenozoospermia (AZS) is a common symptom of male infertility described as reduced forward motility or absence of sperm motility. The PATE1 is generally expressed in male genital tract and related to sperm development, maturation and fertilization. However, the single nucleotide polymorphisms (SNPs) of the PATE1 gene which contribute to AZS were still unknown. For this reason, the possible association between the single nucleotide polymorphisms of the PATE1 gene and idiopathic asthenozoospermia was investigated in this research.

METHODS

108 idiopathic asthenozoospermia were screened by karyotype analysis, detection of Y microdeletions and mutations in 5 other genes from 140 clinical AZS. The sequence analyses of the PATE1 gene were conducted in 108 idiopathic asthenozoospermia and 106 fertile men with normospermic parameters in Sichuan, China.

RESULTS

In this study, a total 108 patients without chromosomal abnormalities, Y microdeletions and selected genes mutation were confirmed. The 1423G (odds ratio [OR] 1.939, 95% confidence interval [CI] 1.320-2.848, P=0.001) was found to be increased significantly in idiopathic asthenozoospermic patients compared with their fertile counterparts. This mutation substitutes a highly conserved glutamic to arginine at the position of the 47th amino acid which was shown to be located on the flank of the pleated sheet domain in PATE1 protein by the 3D model given by the Protein Model Portal (PMP). Moreover, PolyPhen-2 analysis predicted that this variant was "probably damaging".

CONCLUSIONS

These results suggested that PATE1 variant (A1423G) was probably one of the high risk genetic factors for idiopathic asthenozoospermia among males in Sichuan, China.

Sperm Aneuploidy in Faroese Men with Lifetime Exposure to Dichlorodiphenyldichloroethylene (p,p´-DDE) and Polychlorinated Biphenyl (PCB) Pollutants

BACKGROUND

Although it is known that sperm aneuploidy contributes to early pregnancy losses and congenital abnormalities, the causes are unknown and environmental contaminants are suspected.

OBJECTIVES

Our goal was to evaluate associations between lifetime exposure to organochlorines, specifically dichlorodiphenyldicholorethylene (p,p´-DDE) and polychlorinated biphenyls (PCBs), and sperm aneuploidy in men from the general population of the Faroe Islands, a population with a known history of organochlorine exposures.

METHODS

Serum and semen samples from men (n = 90) 22-44 years old who participated in Faroe Islands health studies were analyzed for p,p´-DDE and PCBs 118, 138, 153, and 180 and adjusted for total lipids. Cord blood and age-14 serum were available for a subgroup (n = 40) and were also analyzed for p,p´-DDE and PCBs. Sperm fluorescence in situ hybridization (FISH) for chromosomes X, Y, and 18 was used to determine rates of XX18, XY18, YY18, and total disomy. Multivariable adjusted Poisson models were used to estimate the relationship between organochlorine exposure and sperm disomy outcomes.

RESULTS

Adult p,p´-DDE and total PCB serum concentrations were both associated with significantly increased rates of XX18, XY18, and total disomy. Age-14 p,p´-DDE and PCB concentrations were both associated with significantly increased rates of XX, XY, and total disomy in adulthood. Associations between cord blood concentrations of p,p´-DDE and PCBs and sperm disomy in adulthood were not consistently significant.

CONCLUSIONS

Organochlorine exposures measured at age 14 and in adulthood were associated with sperm disomy in this sample of high-exposure men, suggesting that the impacts of persistent pollutants on testicular maturation and function require further investigation.

CITATION

Perry MJ, Young HA, Grandjean P, Halling J, Petersen MS, Martenies SE, Karimi P, Weihe P. 2016. Sperm aneuploidy in Faroese men with lifetime exposure to dichlorodiphenyldichloroethylene (p,p´-DDE) and polychlorinated biphenyl (PCB) pollutants. Environ Health Perspect 124:951-956; http://dx.doi.org/10.1289/ehp.1509779.

Persistent organic pollutants and semen quality: The LIFE Study

Growing evidence suggests that persistent environmental chemicals such as polychlorinated biphenyls may adversely affect human fecundity. The purpose of this study was to evaluate associations between persistent environmental chemicals and semen quality among 501 male partners of couples discontinuing contraception for purposes of becoming pregnant. Men provided a blood specimen and two fresh semen samples collected approximately a month apart that underwent next day analysis for 35 semen quality endpoints. Serum samples were analyzed for 36 polychlorinated biphenyls (congeners #18, 28, 44, 49, 52, 66, 74, 87, 99, 101, 114, 118, 128, 138, 146, 149, 151, 153, 156, 157, 167, 170, 172, 177, 178, 180, 183, 187, 189, 194, 195, 196, 201, 206, 209); 1 polybrominated biphenyl (#153); 9 organochlorine pesticides; and 10 polybrominated diphenyl ethers (congeners #17, 28, 47, 66, 85, 99, 100, 153, 154183) using high resolution mass spectrometry. To estimate the effect of chemicals on semen quality, we regressed each semen marker on each chemical while adjusting for research site, age, body mass index, serum lipids, and cotinine levels. Males with chemical concentrations in the fourth quartile, as compared to the first quartile, showed significant associations for several individual chemicals in each chemical class and type of semen quality parameter indicating negative and positive associations with semen quality. Polybrominated diphenyl ethers in particular were associated with several measures of increased abnormal morphology. These exploratory results highlight the role of environmental influences on male fecundity, and are of particular interest given the ubiquitous exposures to these compounds.

Epigenetic alterations in sperm associated with male infertility

The most common form of male infertility is a low sperm count, known as oligozoospermia. Studies suggest that oligozoospermia is associated with epigenetic alterations. Epigenetic alterations in sperm, which may arise due to the exposure of gametes to environmental factors or those that pre-exist in the sperm of infertile individuals, may contribute to the increased incidence of normally rare imprinting disorders in babies conceived after assisted reproductive technology using the sperm of infertile men. Genomic imprinting is an important developmental process whereby the allelic activity of certain genes is regulated by DNA methylation established during gametogenesis. The aberrant expression of several imprinted genes has been linked to various diseases, malignant tumors, lifestyle and mental disorders in humans. Understanding how infertility and environmental factors such as reproductive toxicants, certain foods, and drug exposures during gametogenesis contribute to the origins of these disorders via defects in sperm is of paramount importance. In this review, we discuss the association of epigenetic alterations with abnormal spermatogenesis and the evidence that epigenetic processes, including those required for genomic imprinting, may be sensitive to environmental exposures during gametogenesis, fertilization and early embryonic development. In addition, we review imprinting diseases and their relationships with environmental factors. While the plasticity of epigenetic marks may make these more susceptible to modification by the environment, this also suggests that aberrant epigenetic marks may be reversible. A greater understanding of this process and the function of epidrugs may lead to the development of new treatment methods for many adult diseases in the future.

Sperm aneuploidy in infertile male patients: a systematic review of the literature

Males with abnormal karyotypes and subgroups of fertile and infertile males with normal karyotypes may be at risk of producing unbalanced or aneuploid spermatozoa. Biological, clinical, environmental and other factors may also cause additional sperm aneuploidy. However, increased risk of sperm aneuploidy is directly related to chromosomally abnormal embryo production and hence to poor reproductive potential. This systemic literature review focuses on the identification of these males because this is an essential step in the context of assisted reproduction. This research may allow for a more personalised and, hence, more accurate estimation of the risk involved in each case, which in turn will aid genetic counselling for affected couples and help with informed decision-making.

Smoking-induced chromosomal segregation anomalies identified by FISH analysis of sperm

Background

Numerical chromosome aberrations in gametes are directly related to infertility and aneuploid embryos. Previous studies have shown that toxic substances from cigarette smoke induce structural and numerical chromosomal aberrations in vitro and could potentially increase levels of aneusomy in sperm. Moreover, increased levels of aneusomy in sperm are correlated with low implantation rates, spontaneous abortions and fetal losses. Studies of chromosome 3 in sperm suggest it may be more prone to segregation anomalies than other autosomes, but there has been no systematic investigation of the incidence of disomy for chromosome 3 in sperm derived from donor male smokers. The objective of this study was to use FISH to evaluate the influence of smoking on the levels of disomy for chromosomes X and Y, and to determine whether disomy levels for chromosome 3 were elevated in sperm derived from male smokers.

Results

FISH analysis was used to evaluate the frequency of disomies of chromosomes 3, X, and Y in sperm of 10 smokers, compared to a control group of 7 non-smoking fertile men. All the subjects presented a normal somatic karyotype. There was a significant increase in the overall frequency of disomies in sperm derived from the smoking group (P< 0.0001). When each chromosome pair was analyzed individually, disomy of chromosome 3 in smokers was found to be more than twice that observed in the matched non-smoker control group. In addition we observed a higher frequencies of disomy of the X and Y chromosomes, indicating elevated levels of diploidy in the sperm from the smoking group.

Conclusions

In this study we have shown that chromosome 3 may be susceptible to smoking-related segregation anomalies. Our results also suggest that errors can occur in both meiosis I and II, confirming the emerging literature that the male meiotic process may generally be affected by the genotoxic damage from tobacco use. Collectively, these findings provide additional evidence for enhancing tobacco control measures, and suggest that FISH analysis of chromosome 3 in sperm may be useful for monitoring smoking–induced segregation damage as part of the evaluation of infertile males.