Genetic association studies in female reproduction: from candidate-gene approaches to genome-wide mapping

Curcumin Alleviates Hyperandrogenism and Promotes Follicular Proliferation in Polycystic Ovary Syndrome Rats: Insights on IRS1/PI3K/GLUT4 and PTEN Modulations

OBJECTIVE

To explore the effect of curcumin on the insulin receptor substrate 1 (IRS1)/phosphatidylinositol-3-kinase (PI3K)/endometrial expression of glucose 4 (GLUT4) signalling pathway and its regulator, phosphatase and tensin homolog (PTEN), in a rat model of polycystic ovarian syndrome (PCOS).

METHODS

PCOS model was induced by letrozole intragastric administration. Sprague-Dawley rats were randomized into 4 groups according to a random number table: (1) control group; (2) PCOS group, which was subjected to PCOS and received vehicle; (3) curcumin group, which was subjected to PCOS and treated with curcumin (200 mg/kg for 2 weeks); and (4) curcumin+LY294002 group, which was subjected to PCOS, and treated with curcumin and LY294002 (a specific PI3K inhibitor). Serum hormone levels (17 β-estradiol, follicle stimulating hormone, luteinizing hormone, progesterone, and testosterone) were measured by enzyme linked immunosorbent assay, and insulin resistance (IR) was assessed using the homeostasis model assessment of IR. Ovarian tissues were stained with haematoxylin and eosin for pathological and apoptosis examination. Expression levels of key transcriptional regulators and downstream targets, including IRS1, PI3K, protein kinase B (AKT), GLUT4, and PTEN, were measured via reverse transcription polymerase chain reaction and Western blot, respectively.

RESULTS

The PCOS group showed impaired ovarian morphology and function. Compared with the PCOS group, curcumin treatment exerted ovarioprotective effects, down-regulated serum testosterone, restored IR, inhibited inflammatory cell infiltration in ovarian tissues, decreased IRS1, PI3K, and AKT expressions, and up-regulated GLUT4 and PTEN expressions in PCOS rats (P<0.05 or P<0.01). In contrast, IRS1, PI3K, AKT, and PTEN expression levels were not significantly different between PCOS and curcumin+LY294002 groups (P>0.05).

CONCLUSION

The beneficial effects of curcumin on PCOS rats included the alteration of serum hormone levels and recovery of morphological ovarian lesions, in which, PTEN, a new target, may play a role in regulating the IRS1/PI3K/GLUT4 pathway.

Partially purified non-polar phytocomponents from Aloe barbadensis Mill. gel restores metabolic and reproductive comorbidities in letrozole-induced polycystic ovary syndrome rodent model- an "in-vivo" study

ETHNOPHARMACOLOGICAL RELEVANCE

In India, Kumaryasava, a popular Aloe barbadensis Mill. gel preparation has therapeutic value in treatment of female reproductive disorders like menstrual disturbances and menopausal problems. Despite their widespread use, only a limited number of studies have probed into the scientific evidence for their varied bioactivities. In this regard, studies have demonstrated that Aloe vera gel has the potential to modulate steroidogenic activity in letrozole induced polycystic ovary syndrome (PCOS) rat. However, isolation and identification of the bioactive molecule/s from Aloe vera gel and studying their molecular targets will underpin the treatment regime for PCOS.

MATERIAL AND METHODS

The Partially Purified Non-Polar Phytocomponents (PPNPP)- LP1 and LP3 were isolated from the petroleum ether extract of Aloe vera gel by column chromatography. Based upon the GC-MS analysis, LP1 and LP3 comprised of n-Hexadecanoic acid and Campesterol acetate with an abundance of 97.07%, and 96.07% respectively. For evaluation of their bioactivities, eighty 3-4 months female Balb/c mice were classified as 10 groups with 8 animals in each group. Groups were control (C), PCOS (0.5 mg/kg/day Letrozole orally for 21days), PCOS treated orally for 60 days with Aloe vera gel (AVG) (10 mg/kg/day) (PCOS + AVG), PCOS treated orally for 60 days with petroleum ether extract (PE) of Aloe vera gel (25 μg/kg/day) (PCOS + PE), PCOS treated orally for 60 days with LP1 (0.5 μg/kg/day) (PCOS + LP1), PCOS treated orally for 60 days with commercially available pure compound-n-Hexadecanoic acid (HA) (0.5 μg/kg/day) (PCOS + HA), PCOS treated orally for 60 days with LP3 (0.01 μg/kg/day) (PCOS + LP3), PCOS treated orally for 60 days with commercially available pure compound- Campesterol acetate (CA) (0.01 μg/kg/day) (PCOS + CA), PCOS treated orally for 60 days with Metformin (100 mg/kg/day) (PCOS + Metformin) and PCOS treated orally for 60 days with DMSO (Vehicle) (PCOS + DMSO). Body weight, Oral glucose tolerance test, lipid profile, fasting glucose, insulin, estrus cycle, hormonal profile, gene expression of gonadotropin receptors (Fshr and Lhr), steroid receptors (Ar, Esr1, Esr2 and Pgr) and steroidogenic markers (Star, Hsd3b1, Cyp19a1 and Amh) were analysed in the ovaries. Polycystic ovarian morphology was assessed through histopathological changes of ovary. Toxicity markers- SGOT, SGPT and creatinine were also measured at the end of the study.

RESULTS

Mice treated with letrozole demonstrated significant increase in body weight, glucose intolerance, fasting insulin levels, HOMA-IR, triglycerides levels as well as testosterone levels, and a significant decline in the progesterone levels as compared to the control animals. PCOS animals also exhibited arrested estrus cyclicity, disrupted ovarian histopathology with the presence of multiple peripheral cysts and abnormal gene expression of gonadotropin receptor, steroid receptor and steroid markers. Oral administration of AVG, PE extract of AVG, LP3 and metformin greatly alleviated these complications in PCOS animals.

CONCLUSION

The above findings indicate the effectiveness of LP3, isolated from Aloe vera gel against letrozole induced PCOS in mice and may be used in the treatment of PCOS as an alternative to metformin.

Endometriosis, infertility and MicroRNA's: A review

The review aims to explore circulating small non- coding regulatory Ribonucleic Acids (miRNA) as biomarkers of endometriosis; a reproductive age group disorder. miRNA are linked with genetic, epigenetic and angiogenic factors, hormones, cytokines, chemokines, oxidative stress (OS) markers, mediators of inflammation, hypoxia, angiogenesis and altered immune system contributing to the pathogenesis of endometriosis. Hormonal imbalance occurs by decreased levels of miRNAs -23a and miRNAs -23b and increase in miRNAs -:135a, 135b, 29c and 194-3p. Angiogenesis by vascular endothelial growth factor is attributed to increased miRNAs -126, miRNAs -210, miRNAs -21, miRNAs -199a-5p and miRNAs 20A. OS upregulates miRNAs -302a by increased levels of Tumor Necrosis factor (TNF)-α, TNF- β and Interleukin -1β. Upregulation of miRNAs -199a and miRNAs -16 promotes inflammation and cell proliferation in the endometriotic lesions. The gold standard to diagnose endometriosis is laparoscopy, yet miRNA can be validated as diagnostic tool for detection, progression and prevention of endometriosis in large, independent cohorts of women, with and without endometriosis.

Association between polymorphism in BMP15 and GDF9 genes and impairing female fecundity in diabetes type 2

Background

A shortened reproductive period and earlier menopause have been associated with type 2 diabetes. Growth differentiation factor 9(GDF9) and bone morphogenetic protein 15 (BMP15) gene mutations have been associated with earlier menopause. Therefore, this study aimed to evaluate the association between BMP15 and GDF9 mutations with impairing female fecundity in diabetic patients. The study subjects comprised 90 female diabetic patients and 60 female healthy controls. The physio-biochemical analysis was measured using enzymatic determination. A single-strand conformation polymorphism (SSCP) protocol was utilized to assess the pattern of genetic variations.

Results

Genotyping analysis of the BMP15 gene showed a heterogeneous pattern with the presence of two genotypes: AA and AC genotypes. Five novel missense single nucleotide polymorphisms (SNPs) were identified in the BMP15 gene: four SNPs detected in both genotypes, and Met4Leu, a specific SNP, was detected only in the AC genotype. Cumulative in silico tools indicated a highly deleterious effect for the Met4Leu on the mutant protein structure, function, and stability. Diabetes patients showed a significantly higher frequency of genotype AC. The physio-biochemical analysis of fasting plasma glucose (FBG), glycosylated hemoglobin (HbA1c), and luteinizing hormone (LH) were significantly higher (P < 0.05) in AC genotype than AA genotype.

Conclusions

The current research provides the first indication regarding the tight association of BMP15 polymorphism with the impairing female fecundity in the diabetic. A pivotal role is played by the novel (Met4Leu) SNP that can be used as a predictor for the impairing female fecundity of diabetes, while no polymorphism was found in exon 4 of the GDF9 gene.

Genetic, Epigenetic, and Steroidogenic Modulation Mechanisms in Endometriosis

Endometriosis is a chronic gynecological disease, affecting up to 10% of reproductive-age women. The exact cause of the disease is unknown; however, it is a heritable condition affected by multiple genetic, epigenetic, and environmental factors. Previous studies reported variations in the epigenetic patterns of numerous genes known to be involved in the aberrant modulation of cell cycle steroidogenesis, abnormal hormonal, immune and inflammatory status in endometriosis, apoptosis, adhesion, angiogenesis, proliferation, immune and inflammatory processes, response to hypoxia, steroidogenic pathway and hormone signaling are involved in the pathogenesis of endometriosis. Accumulating evidence suggest that various epigenetic aberrations may contribute to the pathogenesis of endometriosis. Among them, DNA methyltransferases, histone deacetylators, and non-coding microRNAs demonstrate differential expression within endometriotic lesions and in the endometrium of patients with endometriosis. It has been indicated that the identification of epigenetic differences within the DNA or histone proteins may contribute to the discovery of a useful prognostic biomarker, which could aid in the future earlier detection, timely diagnosis, and initiation of a new approach to the treatment of endometriosis, as well as inform us about the effectiveness of treatment and the stage of the disease. As the etiology of endometriosis is highly complex and still far from being fully elucidated, the presented review focuses on different approaches to identify the genetic and epigenetic links of endometriosis and its pathogenesis.

MicroRNA-141 and MicroRNA-200c Are Overexpressed in Granulosa Cells of Polycystic Ovary Syndrome Patients

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in reproductive-aged women, affecting 6–8% of women and characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology. Accumulating evidence demonstrates that different microRNAs (miRNAs) expressions may contribute to the pathogenesis of PCOS. Therefore, the goal of this study is to compare the expression levels of miR-141 and miR-200c in granulosa cells isolated from PCOS patients and also evaluate their predictive values for pregnancy complications. First, RNA extraction, reverse transcription, and reverse transcription-polymerase chain reaction (RT-PCR) were performed to assess the expression levels of miR-141 and miR-200c in granulosa cells isolated from 62 PCOS patients and 61 controls. Second, according to each mean of miR-141 and miR-200c measured values in all patients, PCOS, and controls were divided into low-expression group and high-expression group to better evaluate their predictive values for pregnancy complications. Significantly elevated expressions of miR-141 and miR-200c were observed in PCOS patients compared with the controls (p < 0.001 and p = 0.002, respectively). Furthermore, PCOS patients had a significantly increased incidence of pregnancy complications in low-expression groups of miR-141 and miR-200c (p = 0.007 and p = 0.002, respectively). Our findings demonstrated that the expressions of both miR-141 and miR-200c were significantly increased in PCOS patients, which might contribute to the pathogenesis of PCOS. PCOS patients had an increased risk of pregnancy complications in low-expression groups of both miR-141 and miR-200c.

New MCM8 mutation associated with premature ovarian insufficiency and chromosomal instability in a highly consanguineous Tunisian family

OBJECTIVE

To identify the gene(s) involved in the etiology of premature ovarian insufficiency in a highly consanguineous Tunisian family.

DESIGN

Genetic analysis of a large consanguineous family with several affected siblings.

SETTING

University hospital-based cytogenetics and molecular genetics laboratories.

PATIENT(S)

A highly consanguineous Tunisian family with several affected siblings born to healthy second-degree cousins.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Targeted exome sequencing was performed by next-generation sequencing for affected family members. Mutations were validated by Sanger sequencing. Functional experiments were performed to explore the deleterious effects of the identified mutation. DNA damage was induced by increasing mitomycin C (MMC) concentrations on cultured peripheral lymphocytes.

RESULT(S)

Analysis of the next-generation sequencing data revealed a new homozygous missense mutation in the minichromosome maintenance 8 gene (MCM8).This homozygous mutation (c. 482A>C; p.His161Pro) was predicted to be deleterious and segregated with the disease in the family. MCM8 participates in homologous recombination during meiosis and DNA double-stranded break repair by dimerizing with MCM9. Mcm8 knock out results in an early block in follicle development and small gonads. Given this, we tested the chromosomal breakage repair capacity of homozygous and heterozygous MCM8 p.His161Pro mutation on cultured peripheral lymphocytes exposed to increasing MMC concentrations. We found that chromosomal breakage after MMC exposure was significantly higher in cells from homozygously affected individuals than in those from a healthy control.

CONCLUSION(S)

Our findings provide additional support to the view that MCM8 mutations are involved in the primary ovarian insufficiency phenotype.

A network-based method for the identification of putative genes related to infertility

BACKGROUND

Infertility has become one of the major health problems worldwide, with its incidence having risen markedly in recent decades. There is an urgent need to investigate the pathological mechanisms behind infertility and to design effective treatments. However, this is made difficult by the fact that various biological factors have been identified to be related to infertility, including genetic factors.

METHODS

A network-based method was established to identify new genes potentially related to infertility. A network constructed using human protein-protein interactions based on previously validated infertility-related genes enabled the identification of some novel candidate genes. These genes were then filtered by a permutation test and their functional and structural associations with infertility-related genes.

RESULTS

Our method identified 23 novel genes, which have strong functional and structural associations with previously validated infertility-related genes.

CONCLUSIONS

Substantial evidence indicates that the identified genes are strongly related to dysfunction of the four main biological processes of fertility: reproductive development and physiology, gametogenesis, meiosis and recombination, and hormone regulation.

GENERAL SIGNIFICANCE

The newly discovered genes may provide new directions for investigating infertility. This article is part of a Special Issue entitled "System Genetics" Guest Editor: Dr. Yudong Cai and Dr. Tao Huang.

Environmentally Induced Epigenetic Transgenerational Inheritance of Reproductive Disease

Reproductive disease and fertility issues have dramatically increased in the human population over the last several decades, suggesting environmental impacts. Epigenetics provides a mechanistic link by which an organism can respond to environmental factors. Interestingly, environmentally induced epigenetic alterations in the germ line can promote aberrant gene expression and disease generationally. Environmentally induced epigenetic transgenerational inheritance is defined as germ-line transmission of altered epigenetic information between generations in the absence of continued environmental exposures. This form of nongenetic inheritance has been shown to directly influence fertility and reproductive disease. This review describes the studies in a variety of species that impact reproductive disease and abnormalities. Observations suggest serious attention be paid to the possibility that ancestral exposures to environmental insults promotes transgenerational inheritance of reproductive disease susceptibility. Environmentally induced epigenetic transgenerational inheritance appears to be an important contributing factor to reproductive disease in many organisms, including humans.

Family-based analysis of eight susceptibility loci in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder that is proposed to have a genetic basis. A recent genome-wide association study (GWAS) identified eight new risk loci that are independently associated with PCOS. To further validate the findings, a total of 321 case-parent trios (963 participants) who had a proband affected with PCOS were recruited for the family-based study. The transmission disequilibrium test (TDT) was used to analyze associations between PCOS and ten single nucleotide polymorphisms (SNPs) mapped to eight new susceptibility loci. Significant differences in transmission were observed for the SNPs rs2349415 (located in the FSHR gene, P = 0.0001) and rs3802457 (located in the C9orf3 gene, P = 0.0001), even after correction for multiple testing bias. The present data provides further evidence for an association between two susceptibility loci, 2p16.3 and 9q22.32, and PCOS. Follow-up functional studies on the FSHR and C9orf3 genes are required to understand their roles in PCOS development.

Current Concepts in Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is a life-changing diagnosis, with profound physical and psychological consequences. Unfortunately, there are many deficiencies in our understanding of the condition as the underlying etiology and optimum management strategies are poorly understood. Improved awareness of POI and its long-term implications has led to increased research interest in recent years. Current research has allowed a greater understanding of the changing epidemiology in POI, genetic factors in its etiology and randomized controlled trials of hormone therapy are underway to provide evidence for treatment. This article reviews the latest literature on POI to summarize current understanding and future directions.

Gap junction connexins in female reproductive organs: implications for women's reproductive health

BACKGROUND

Connexins comprise a family of ~20 proteins that form intercellular membrane channels (gap junction channels) providing a direct route for metabolites and signalling molecules to pass between cells. This review provides a critical analysis of the evidence for essential roles of individual connexins in female reproductive function, highlighting implications for women's reproductive health.

METHODS

No systematic review has been carried out. Published literature from the past 35 years was surveyed for research related to connexin involvement in development and function of the female reproductive system. Because of the demonstrated utility of genetic manipulation for elucidating connexin functions in various organs, much of the cited information comes from research with genetically modified mice. In some cases, a distinction is drawn between connexin functions clearly related to the formation of gap junction channels and those possibly linked to non-channel roles.

RESULTS AND CONCLUSIONS

Based on work with mice, several connexins are known to be required for female reproductive functions. Loss of connexin43 (CX43) causes an oocyte deficiency, and follicles lacking or expressing less CX43 in granulosa cells exhibit reduced growth, impairing fertility. CX43 is also expressed in human cumulus cells and, in the context of IVF, has been correlated with pregnancy outcome, suggesting that this connexin may be a determinant of oocyte and embryo quality in women. Loss of CX37, which exclusively connects oocytes with granulosa cells in the mouse, caused oocytes to cease growing without acquiring meiotic competence. Blocking of CX26 channels in the uterine epithelium disrupted implantation whereas loss or reduction of CX43 expression in the uterine stroma impaired decidualization and vascularization in mouse and human. Several connexins are important in placentation and, in the human, CX43 is a key regulator of the fusogenic pathway from the cytotrophoblast to the syncytiotrophoblast, ensuring placental growth. CX40, which characterizes the extravillous trophoblast (EVT), supports proliferation of the proximal EVTs while preventing them from differentiating into the invasive pathway. Furthermore, women with recurrent early pregnancy loss as well as those with endometriosis exhibit reduced levels of CX43 in their decidua. The antimalaria drug mefloquine, which blocks gap junction function, is responsible for increased risk of early pregnancy loss and stillbirth, probably due to inhibition of intercellular communication in the decidua or between trophoblast layers followed by an impairment of placental growth. Gap junctions also play a critical role in regulating uterine blood flow, contributing to the adaptive response to pregnancy. Given that reproductive impairment can result from connexin mutations in mice, it is advised that women suffering from somatic disease symptoms associated with connexin gene mutations be additionally tested for impacts on reproductive function. Better knowledge of these essential connexin functions in human female reproductive organs is important for safeguarding women's reproductive health.

Intraovarian control of early folliculogenesis

Although hormonal regulation of ovarian follicle development has been extensively investigated, most studies concentrate on the development of early antral follicles to the preovulatory stage, leading to the successful use of exogenous FSH for infertility treatment. Accumulating data indicate that preantral follicles are under stringent regulation by FSH and local intraovarian factors, thus providing the possibility to develop new therapeutic approaches. Granulosa cell-derived C-type natriuretic factor not only suppresses the final maturation of oocytes to undergo germinal vesicle breakdown before ovulation but also promotes preantral and antral follicle growth. In addition, several oocyte- and granulosa cell-derived factors stimulate preantral follicle growth by acting through wingless, receptor tyrosine kinase, receptor serine kinase, and other signaling pathways. In contrast, the ovarian Hippo signaling pathway constrains follicle growth and disruption of Hippo signaling promotes the secretion of downstream CCN growth factors capable of promoting follicle growth. Although the exact hormonal factors involved in primordial follicle activation has yet to be elucidated, the protein kinase B (AKT) and mammalian target of rapamycin signaling pathways are important for the activation of dormant primordial follicles. Hippo signaling disruption after ovarian fragmentation, combined with treating ovarian fragments with phosphatase and tensin homolog (PTEN) inhibitors and phosphoinositide-3-kinase stimulators to augment AKT signaling, promote the growth of preantral follicles in patients with primary ovarian insufficiency, leading to a new infertility intervention for such patients. Elucidation of intraovarian mechanisms underlying early folliculogenesis may allow the development of novel therapeutic strategies for patients diagnosed with primary ovarian insufficiency, polycystic ovary syndrome, and poor ovarian response to FSH stimulation, as well as for infertile women of advanced reproductive age.

Association of luteinizing hormone chorionic gonadotropin receptor gene polymorphism (rs2293275) with polycystic ovarian syndrome

BACKGROUND

Polycystic ovaries and irregular menstruation/anovulation are important diagnostic criteria along with hyperandrogenism as per the Androgen Excess Society-2006 criteria for polycystic ovarian syndrome (PCOS). In the etiopathogenesis of PCOS, one of the candidate genes causing ovarian failure is the luteinizing hormone (LH) chorionic gonadotropin hormone receptor (LHCGR). Our aim was to study the association of LHCGR polymorphism (rs2293275) with PCOS in our study population.

MATERIALS AND METHODS

Genetic case-control study from multiple gynecological centers from Hyderabad, a cosmopolitan city in South India. The study involved 204 women with PCOS and 204 healthy, sex-, and age-matched controls. Anthropometric and biochemical profiles were taken in a well-designed pro forma. Isolation of deoxyribonucleic acid (DNA) and genotype analysis were done for the entire study population using the polymerase chain reaction-restriction fragment length polymorphism method followed by 12% polyacrylamide gel electrophoresis.

RESULTS

In this study, we have demonstrated an association between LHCGR (rs2293275) polymorphism and PCOS. The frequency of the G allele was 0.60 in PCOS and 0.49 in controls (odds ratio [OR] 1.531, confidence interval [CI] 1.16-2.01, and p-value=0.0026), which indicates that the G allele is associated with PCOS in our population. The GG genotype conferred a significant risk of developing PCOS (OR 3.36, CI 1.96-5.75, and p-value<0.0001). We found a significant association of the GG allele with body-mass index, waist to hip ratio, insulin resistance, LH, and LH/follicle-stimulating hormone (FSH) ratio in PCOS when compared with controls. The AA allele showed high basal FSH levels.

CONCLUSIONS

This study suggests that LHCGR (rs2293275) polymorphism is associated with PCOS and could be used as a relevant molecular marker to identify women with the risk of developing PCOS in our population and may provide an understanding about the etiology of PCOS.

The Biodemography of Fertility: A Review and Future Research Frontiers

The social sciences have been reticent to integrate a biodemographic approach to the study of fertility choice and behaviour, resulting in theories and findings that are largely socially-deterministic. The aim of this paper is to first reflect on reasons for this lack of integration, provide a review of previous examinations, take stock of what we have learned until now and propose future research frontiers. We review the early foundations of proximate determinants followed by behavioural genetic (family and twin) studies that isolated the extent of genetic influence on fertility traits. We then discuss research that considers gene and environment interaction and the importance of cohort and country-specific estimates, followed by multivariate models that explore motivational precursors to fertility and education. The next section on molecular genetics reviews fertility-related candidate gene studies and their shortcomings and on-going work on genome wide association studies. Work in evolutionary anthropology and biology is then briefly examined, focusing on evidence for natural selection. Biological and genetic factors are relevant in explaining and predicting fertility traits, with socio-environmental factors and their interaction still key in understanding outcomes. Studying the interplay between genes and the environment, new data sources and integration of new methods will be central to understanding and predicting future fertility trends.

Endocrine disruptor induction of epigenetic transgenerational inheritance of disease

Environmental exposures such as toxicants, nutrition and stress have been shown to promote the epigenetic transgenerational inheritance of disease susceptibility. Endocrine disruptors are one of the largest groups of specific toxicants shown to promote this form of epigenetic inheritance. These environmental compounds that interfere with normal endocrine signaling are one of the largest classes of toxicants we are exposed to on a daily level. The ability of ancestral exposures to promote disease susceptibility significantly increases the potential biohazards of these toxicants. Therefore, what your great-grandmother was exposed to during pregnancy may influence your disease development, even in the absence of any exposure, and you are going to pass this on to your grandchildren. This non-genetic form of inheritance significantly impacts our understanding of biology from the origins of disease to evolutionary biology. The current review will describe the previous studies and endocrine disruptors shown to promote the epigenetic transgenerational inheritance of disease.

Mutant cohesin in premature ovarian failure

Premature ovarian failure is a major cause of female infertility. The genetic causes of this disorder remain unknown in most patients. Using whole-exome sequence analysis of a large consanguineous family with inherited premature ovarian failure, we identified a homozygous 1-bp deletion inducing a frameshift mutation in STAG3 on chromosome 7. STAG3 encodes a meiosis-specific subunit of the cohesin ring, which ensures correct sister chromatid cohesion. Female mice devoid of Stag3 are sterile, and their fetal oocytes are arrested at early prophase I, leading to oocyte depletion at 1 week of age.

A possible new mechanism in the pathophysiology of polycystic ovary syndrome (PCOS): the discovery that leukocyte telomere length is strongly associated with PCOS

CONTEXT

Telomeres are specialized chromatin structures located at the ends of eukaryotic chromosomes, and telomere length plays a clear role in various diseases. However, it is not known whether telomere length is related to polycystic ovary syndrome (PCOS).

OBJECTIVE

We hypothesized that leukocyte telomere length (LTL) plays an important role in the pathophysiology of PCOS.

DESIGN

We used an established and validated quantitative PCR technique to measure the mean LTL in a large sample of PCOS patients and controls. We used logistic regression and multiple linear regression to analyze the association of PCOS and several related clinical parameters with the age-adjusted ratio of the telomere repeat length to the copy number of a single-copy gene (T/S).

RESULTS

Individuals with PCOS (n = 698) exhibited significantly shorter LTLs than the controls (n = 611) after adjusting for age (0.764 ± 0.016 vs 0.876 ± 0.023; P = .001; odds ratio = 1.403; 95% confidence interval, 1.150-1.712). The mean telomere length in the leukocytes of PCOS patients was comparable to that of control individuals who were on average 6.16 years older. Individuals having shorter telomere lengths (middle and lowest tertile) had significantly higher disease risk than those having the longest telomere length (highest tertile) (odds ratio = 1.614; 95% confidence interval, 1.262-2.066; P = .0001) after adjusting for age. In addition, a significant correlation between the LTL and the level of dehydroepiandrosterone sulfate was observed in controls (r = -0.185; P = .01).

CONCLUSION

We provide the first report that LTL is strongly associated with PCOS. This study suggests a new role for LTL in the pathophysiology of PCOS and might have important implications for our understanding of the etiology of the disease.

Common polymorphisms in the CYP1A1 and CYP11A1 genes and polycystic ovary syndrome risk: a meta-analysis and meta-regression

AIM

Increasing scientific evidences suggest that common polymorphisms in the CYP1A1 and CYP11A1 genes may contribute to the development and progression of polycystic ovary syndrome (PCOS), but many existing studies have yielded inconclusive results. The aim of this study was to perform a meta-analysis of published studies on the associations between common polymorphisms in the CYP1A1 and CYP11A1 genes and susceptibility to PCOS.

METHODS

An extensive literature search for relevant studies was conducted on PubMed, Embase, Web of Science, Cochrane Library, and CBM databases from their inception through 1 June, 2013. This meta-analysis was performed using the STATA 12.0 software. The crude risk ratio (RR) with 95% confidence interval was calculated.

RESULTS

Thirteen case-control studies were included in this meta-analysis with a total of 1,571 PCOS cases and 1,918 healthy controls. Our meta-analysis revealed that CYP1A1 MspI (rs4646903 T > C) polymorphism may increase the risk of PCOS, especially among Caucasian populations. Furthermore, CYP11A1 microsatellite [TTTA]n repeat polymorphism also showed significant associations with increased risk of PCOS among Caucasian populations. However, there was no statistically significant association between CYP1A1 Ile462Val (rs1048943 A > G) polymorphism and PCOS risk.

CONCLUSION

Our meta-analysis suggests that CYP1A1 MspI and CYP11A1 microsatellite [TTTA]n repeat polymorphisms may contribute to increasing susceptibility to PCOS among Caucasian populations. Detection of common polymorphisms in the CYP1A1 and CYP11A1 genes might be promising biomarkers for the diagnosis and prognosis of PCOS.