Bidirectional Mendelian randomization to explore the causal relationships between body mass index and polycystic ovary syndrome

KAT8 beyond Acetylation: A Survey of Its Epigenetic Regulation, Genetic Variability, and Implications for Human Health

Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation. This review presents an overview of KAT8, emphasizing its biological functions, which impact many cellular processes and range from chromatin remodeling to genetic and epigenetic regulation. In many model systems, KAT8's acetylation of histone H4 lysine 16 (H4K16) is critical for chromatin structure modification, which influences gene expression, cell proliferation, differentiation, and apoptosis. Furthermore, this review summarizes the observed genetic variability within the KAT8 gene, underscoring the implications of various single nucleotide polymorphisms (SNPs) that affect its functional efficacy and are linked to diverse phenotypic outcomes, ranging from metabolic traits to neurological disorders. Advanced insights into the structural biology of KAT8 reveal its interaction with multiprotein assemblies, such as the male-specific lethal (MSL) and non-specific lethal (NSL) complexes, which regulate a wide range of transcriptional activities and developmental functions. Additionally, this review focuses on KAT8's roles in cellular homeostasis, stem cell identity, DNA damage repair, and immune response, highlighting its potential as a therapeutic target. The implications of KAT8 in health and disease, as evidenced by recent studies, affirm its importance in cellular physiology and human pathology.

Polycystic ovary syndrome

Despite affecting ~11-13% of women globally, polycystic ovary syndrome (PCOS) is a substantially understudied condition. PCOS, possibly extending to men's health, imposes a considerable health and economic burden worldwide. Diagnosis in adults follows the International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome, requiring two out of three criteria - clinical or biochemical hyperandrogenism, ovulatory dysfunction, and/or specific ovarian morphological characteristics or elevated anti-Müllerian hormone. However, diagnosing adolescents omits ovarian morphology and anti-Müllerian hormone considerations. PCOS, marked by insulin resistance and hyperandrogenism, strongly contributes to early-onset type 2 diabetes, with increased odds for cardiovascular diseases. Reproduction-related implications include irregular menstrual cycles, anovulatory infertility, heightened risks of pregnancy complications and endometrial cancer. Beyond physiological manifestations, PCOS is associated with anxiety, depression, eating disorders, psychosexual dysfunction and negative body image, collectively contributing to diminished health-related quality of life in patients. Despite its high prevalence persisting into menopause, diagnosing PCOS often involves extended timelines and multiple health-care visits. Treatment remains ad hoc owing to limited understanding of underlying mechanisms, highlighting the need for research delineating the aetiology and pathophysiology of the syndrome. Identifying factors contributing to PCOS will pave the way for personalized medicine approaches. Additionally, exploring novel biomarkers, refining diagnostic criteria and advancing treatment modalities will be crucial in enhancing the precision and efficacy of interventions that will positively impact the lives of patients.

PCOS stratification for precision diagnostics and treatment

Globally, polycystic ovarian syndrome (PCOS) affects approximately 10% of fertile women, leading to great health and economic burden. PCOS is a heterogenous illness that can cause infertility, irregular menstrual cycles, acne, and hirsutism, among other symptoms. The clinical diagnosis is primarily a diagnosis of exclusion if one or more of the three primary symptoms, namely, oligo- or anovulation, hyperandrogenism, and polycystic ovarian morphology, are present. Obesity and PCOS are often coexisting disorders that may be bidirectionally causally related. Phenotypic heterogeneity throughout the reproductive lifespan, such as the overlap of PCOS symptoms with regular fluctuations in a woman's menstrual cycle and metabolism during the menarche and menopausal transition, further complicates diagnosis. PCOS etiology is mostly unknown and complex, likely due to the fact that it is a group of disorders with overlapping metabolic and reproductive problems. Evidence-based, common, standardized guidelines for PCOS diagnosis and treatment are urgently needed. Genomics and clinical data from populations across diverse ages and ethnicities are urgently needed to build efficient machine learning models for the stratification of PCOS. PCOS subtype-specific strategies for early screening, an accurate diagnosis, and management throughout life will optimize healthcare resources and reduce unnecessary testing. This will pave the way for women to be able to take the best possible care of their own health using the latest clinical expertise combined with their unique needs and preferences.

Proteomic analysis shows decreased type I fibers and ectopic fat accumulation in skeletal muscle from women with PCOS

Background

Polycystic ovary syndrome's (PCOS) main feature is hyperandrogenism, which is linked to a higher risk of metabolic disorders. Gene expression analyses in adipose tissue and skeletal muscle reveal dysregulated metabolic pathways in women with PCOS, but these differences do not necessarily lead to changes in protein levels and biological function.

Methods

To advance our understanding of the molecular alterations in PCOS, we performed global proteomic and phosphorylation site analysis using tandem mass spectrometry, and analyzed gene expression and methylation. Adipose tissue and skeletal muscle were collected at baseline from 10 women with and without PCOS, and in women with PCOS after 5 weeks of treatment with electrical stimulation.

Results

Perilipin-1, a protein that typically coats the surface of lipid droplets in adipocytes, was increased whereas proteins involved in muscle contraction and type I muscle fiber function were downregulated in PCOS muscle. Proteins in the thick and thin filaments had many altered phosphorylation sites, indicating differences in protein activity and function. A mouse model was used to corroborate that androgen exposure leads to a shift in muscle fiber type in controls but not in skeletal muscle-specific androgen receptor knockout mice. The upregulated proteins in muscle post treatment were enriched in pathways involved in extracellular matrix organization and wound healing, which may reflect a protective adaptation to repeated contractions and tissue damage due to needling. A similar, albeit less pronounced, upregulation in extracellular matrix organization pathways was also seen in adipose tissue.

Conclusions

Our results suggest that hyperandrogenic women with PCOS have higher levels of extra-myocellular lipids and fewer oxidative insulin-sensitive type I muscle fibers. These could be key factors leading to insulin resistance in PCOS muscle while electric stimulation-induced tissue remodeling may be protective.

Funding

Swedish Research Council (2020-02485, 2022-00550, 2020-01463), Novo Nordisk Foundation (NNF22OC0072904), and IngaBritt and Arne Lundberg Foundation. Clinical trial number NTC01457209.

No association effect of genetic polymorphism was observed between polycystic ovary syndrome and cardiovascular diseases risk: a mendelian randomization study

OBJECTIVE

Polycystic ovary syndrome (PCOS) is one of the risk factors for cardiovascular diseases (CVDs). However, the possible association between PCOS and common CVDs remains inconclusive. The aim of this study was to explore the potential relationship between PCOS and CVDs using genetic polymorphisms.

METHODS

We conducted two-sample Mendelian randomization (MR) analyses. In our study, 14 single nucleotide polymorphisms (SNPs) in Europeans and another 13 SNPs in Asians were applied as instrumental variables for PCOS. The largest published meta-genome-wide association studies of European ancestry and the BioBank Japan Project of Asian ancestry were used to collect the outcome data. MR analysis was performed using inverse variance weighting as the primary method. Several sensitivity analyses and instrumental variable strength evaluations were also performed to verify the reliability of results.

RESULTS

Our analysis revealed that any potential causal association between genetically-predicted PCOS and the risk of CVDs do not exist. These CVDs include peripheral artery disease, atrial fibrillation, arrhythmia, cardiovascular diseases, heart failure, peripheral vascular disease, hypertension, ischemic stroke, myocardial infarction and venous thromboembolisms. Associations could not be found even after the SNPs linked to these possible confounders (body mass index, waist-to-hip ratio, and serum testosterone) were deleted. Sensitivity analysis demonstrated no presence of horizontal pleiotropy or heterogeneity.

CONCLUSION

The present mendelian randomization study suggests that genetically-predicted PCOS may not be associated with the risk of CVDs.

Genetic causes of sporadic and recurrent miscarriage

Approximately 80% of miscarriages happen within the first 12 weeks of gestation. More than half of early losses result from genetic defects, usually presenting as abnormal chromosome numbers or gene rearrangements in the embryo. However, the impact of genetics on pregnancy loss goes well beyond embryonic aneuploidy. For example, the use of big data has recently led to the discovery of specific gene mutations that may be implicated in sporadic and recurrent miscarriages. Further, emerging data suggest that genetic factors play a role in conditions for which there is a causative association with recurrent pregnancy loss. Here, we summarize the evidence on the genetics of miscarriage and provide an overview of the diagnosis and prevention of genetic causes associated with sporadic and recurrent pregnancy loss.

SPIOMET4HEALTH-efficacy, tolerability and safety of lifestyle intervention plus a fixed dose combination of spironolactone, pioglitazone and metformin (SPIOMET) for adolescent girls and young women with polycystic ovary syndrome: study protocol for a multicentre, randomised, double-blind, placebo-controlled, four-arm, parallel-group, phase II clinical trial

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most prevalent, chronic endocrine-metabolic disorder of adolescents and young women (AYAs), affecting 5-10% of AYAs worldwide. There is no approved pharmacological therapy for PCOS. Standard off-label treatment with oral contraceptives (OCs) reverts neither the underlying pathophysiology nor the associated co-morbidities. Pilot studies have generated new insights into the pathogenesis of PCOS, leading to the development of a new treatment consisting of a fixed, low-dose combination of two so-called insulin sensitisers [pioglitazone (PIO), metformin (MET)] and one mixed anti-androgen and anti-mineralocorticoid also acting as an activator of brown adipose tissue [spironolactone (SPI)], within a single tablet (SPIOMET). The present trial will evaluate the efficacy, tolerability and safety of SPIOMET, on top of lifestyle measures, for the treatment of PCOS in AYAs.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, four-arm, parallel-group, phase II clinical trial, AYAs with PCOS will be recruited from 7 clinical centres across Europe. Intention is to randomise a total of 364 eligible patients into four arms (1:1:1:1): Placebo, PIO, SPI + PIO (SPIO) and SPI + PIO + MET (SPIOMET). Active treatment over 12 months will consist of lifestyle guidance plus the ingestion of one tablet daily (at dinner time); post-treatment follow-up will span 6 months. Primary endpoint is on- and post-treatment ovulation rate. Secondary endpoints are clinical features (hirsutism, menstrual regularity); endocrine-metabolic variables (androgens, lipids, insulin, inflammatory markers); epigenetic markers; imaging data (carotid intima-media thickness, body composition, abdominal fat partitioning, hepatic fat); safety profile; adherence, tolerability and acceptability of the medication; and quality of life in the study participants. Superiority (in this order) of SPIOMET, SPIO and PIO will be tested over placebo, and if present, subsequently the superiority of SPIOMET versus PIO, and if still present, finally versus SPIO.

DISCUSSION

The present study will be the first to evaluate-in a randomised, double-blind, placebo-controlled way-the efficacy, tolerability and safety of SPIOMET treatment for early PCOS, on top of a lifestyle intervention.

TRIAL REGISTRATION

EudraCT 2021-003177-58. Registered on 22 December 2021. https://www.clinicaltrialsregister.eu/ctr-search/search?query=%092021-003177-58 .

Age at menarche and polycystic ovary syndrome: A Mendelian randomization study

OBJECTIVE

The authors aimed to use a large two-sample Mendelian randomization (MR) study to reveal the causality between age at menarche (AAM) and polycystic ovary syndrome (PCOS) incidence.

METHODS

The authors collected summary statistics from the hitherto largest genome-wide association studies conducted in AAM and PCOS in the same ancestry. MR with inverse variance weighting was conducted as the main analysis method, while weighted median and MR-Egger regression were used for comprehensive analysis. As for pleiotropy detection, inverse variance weighting, MR-Egger regression, Mendelian Randomization Pleiotropy Residual Sum and Outlier, as well as leave-one-out analysis were used to detect pleiotropy. Risk factor analysis was conducted to investigate the underlying mechanisms linking AAM to PCOS.

RESULTS

Each standard deviation increment in AAM was associated with a significantly lower incidence of PCOS (odds ratio, 0.86 [95% confidence interval, 0.75-0.98]). After adjustment in horizontal pleiotropy by eliminating four outliers, this pathogenic association was still statistically detected. All pleiotropy indexes were without statistical differences, which suggested the conclusions were robust. It showed the causal association between later AAM and lower body mass index, lower fasting insulin level and insulin resistance.

CONCLUSION

Our MR analysis verified that a slightly later onset age (15 to 18 years) at menarche could reduce the risk of PCOS. A more comprehensive investigation in a prospective setting is strongly advised.

Differential Association of FTO Gene variants and Haplotypes with the Susceptibility to Polycystic Ovary Syndrome According To Obesity in Women with PCOS

We explored the relation between FTO single gene variants (rs1861868, rs9939973, rs1421085, rs1121980, rs17817449, rs8050136, rs9939609, rs9930506, and rs8044769) and polycystic ovary syndrome (PCOS), in particular, according to the obesity status. This retrospective population-based case-control study involved women with PCOS (583) and 713 eumenorrheic control women; genotyping was done by real-time PCR. Significantly higher minor allele frequency (MAF) of rs9939973, rs17817449, rs9939609, and rs9930506 and lower MAF of rs1121980 were seen in PCOS cases. Lower risk of PCOS was associated with rs1121980 and rs8050136 heterozygous and minor allele-homozygous genotypes, while an elevated risk of PCOS was seen with minor allele-homozygous rs9939973, rs17817449, and r9939609 heterozygous and genotypes and minor allele-homozygous rs9930506 and rs8044769 genotype. While none of the tested FTO SNPs variants was associated with PCOS in normal body weight/lean subjects, rs9939973, rs9939609, and rs9930506 were negatively associated with PCOS in overweight subjects. In comparison, rs1861868 was negatively, while rs8044769 was positively associated with PCOS in obese subjects. Haplotype analysis identified haplotypes GACCTCTAT, AACCTCTAT, AACCTATAT and AGTTGCAGC, and GACCTCTAC to be positively associated with PCOS, while haplotypes GGTTGAAGC, GACCTATAT, GGTTGCAGC, and GATCTATAT were negatively associated with PCOS. Apart from GGTTGAAGC, these haplotypes remained associated with altered risk of PCOS after adjusting for covariates. In addition to rs17817449, rs9939609, rs9930506, and rs1121980, this study is the first to demonstrate association of rs9939973 and rs8044769 with altered risk of PCOS and the first to confirm the BMI dependency on the association of FTO variants with PCOS. This underscores the role of FTO gene variants as predisposing factors of PCOS.

Outcome of Gastric Bypass Surgery on Patients with Polycystic Ovary Syndrome: A Review

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is associated with obesity. The most effective method to achieve and maintain long-term weight loss is by the Roux-en-Y gastric bypass (RYGB). In this review, an overview about metabolic and PCOS-specific outcomes after RYGB in obese PCOS women is provided. The RYGB leads to an adequate excess weight loss and reduction in BMI in this patient population. Testosterone levels decline significantly at 6- and 12-months follow-up, as does the incidence of hirsutism and cycle irregularities. Data about fertility are scarce in this patient population. In conclusion, RYGB surgery seems to be an efficient treatment option for obese PCOS patients and leads to weight loss and improvements in metabolic parameters as well as in an improvement of PCOS-specific characteristics. However, larger prospective studies are warranted, which include all PCOS-specific outcome data in one patient population at the same time.

[Polycystic ovary syndrome as a gender-specific cardiometabolic risk factor]

With a prevalence of 15%, polycystic ovary syndrome (PCOS) is the most common endocrinopathy in fertile-aged women. Insulin resistance and obesity play a pivotal role in the pathophysiology of PCOS, modulate the severity of symptoms and are associated with an increased risk for cardiometabolic sequelae such as diabetes, non-alcoholic fatty liver disease and atherosclerotic cardiovascular disease. PCOS should be considered as a gender-specific cardiovascular risk factor. Therefore, if traits indicative for PCOS are present, affected women should undergo PCOS diagnostics as a first step, thereby making it possible to initiate cardiovascular primary prevention strategies in this population of young women at high cardiometabolic risk. In women with known PCOS, screening and treatment of cardiometabolic risk factors and/or diseases should be routinely integrated into the concept of PCOS care. The close link between insulin resistance/obesity and PCOS can be used to improve PCOS-specific symptoms and enhance cardiometabolic health.

American Association of Clinical Endocrinology Consensus Statement: Addressing Stigma and Bias in the Diagnosis and Management of Patients with Obesity/Adiposity-Based Chronic Disease and Assessing Bias and Stigmatization as Determinants of Disease Severity

OBJECTIVE

To focus on the intersection of perception, diagnosis, stigma, and weight bias in the management of obesity and obtain consensus on actionable steps to improve care provided for persons with obesity.

METHODS

The American Association of Clinical Endocrinology (AACE) convened a consensus conference of interdisciplinary health care professionals to discuss the interplay between the diagnosis of obesity using adiposity-based chronic disease (ABCD) nomenclature and staging, weight stigma, and internalized weight bias (IWB) with development of actionable guidance to aid clinicians in mitigating IWB and stigma in that context.

RESULTS

The following affirmed and emergent concepts were proposed: (1) obesity is ABCD, and these terms can be used in differing ways to communicate; (2) classification categories of obesity should have improved nomenclature across the spectrum of body mass index (BMI) using ethnic-specific BMI ranges and waist circumference (WC); (3) staging the clinical severity of obesity based on the presence and severity of ABCD complications may reduce weight-centric contribution to weight stigma and IWB; (4) weight stigma and internalized bias are both drivers and complications of ABCD and can impair quality of life, predispose to psychological disorders, and compromise the effectiveness of therapeutic interventions; (5) the presence and of stigmatization and IWB should be assessed in all patients and be incorporated into the staging of ABCD severity; and (6) optimal care will necessitate increased awareness and the development of educational and interventional tools for health care professionals that address IWB and stigma.

CONCLUSIONS

The consensus panel has proposed an approach for integrating bias and stigmatization, psychological health, and social determinants of health in a staging system for ABCD severity as an aid to patient management. To effectively address stigma and IWB within a chronic care model for patients with obesity, there is a need for health care systems that are prepared to provide evidence-based, person-centered treatments; patients who understand that obesity is a chronic disease and are empowered to seek care and participate in behavioral therapy; and societies that promote policies and infrastructure for bias-free compassionate care, access to evidence-based interventions, and disease prevention.

Understanding the Relationship between Illness Perceptions and Health Behaviour among Women with Polycystic Ovary Syndrome

This paper aims to delineate the cognitive, emotional, and behavioural responses of women with polycystic ovary syndrome (PCOS) to their illness by applying the Common-Sense Model of Self-Regulation (CSM) to their health behaviour. An online cross-sectional design was used to examine the relationship between participants' illness perceptions (illness identity, consequence, timeline, control, and cause) and emotional representations of their PCOS, and their health behaviours (diet, physical activity, and risky contraceptive behaviour). The participants were 252 women between the ages of 18 and 45 years, living in Australia, and self-reporting a diagnosis of PCOS, recruited through social media. Participants completed an online questionnaire regarding illness perceptions as well as their diet, physical activity, and risky contraceptive behaviour. Illness identity was positively associated with the number of maladaptive dietary practices (B = 0.71, 95% CI: 0.003, 0.138; p = 0.04), and perception of longer illness duration was associated with reduced physical activity (OR = 0.898, 95% CI: 0.807, 0.999; p = 0.49) and risky contraceptive behaviour (OR = 0.856, 95% CI: 0.736, 0.997; p = 0.045). The limitations of the study include all data being self-reported (including PCOS diagnosis), and the potential for analyses of physical activity and risky contraceptive use being underpowered due to reduced sample sizes. The sample was also highly educated and restricted to those who use social media. These findings suggest that illness perceptions may play a role in influencing health behaviour in women with PCOS. A better understanding of the illness perceptions of women with PCOS is needed to increase health-promoting behaviour and improve health outcomes for women with PCOS.

A case-control study about markers of stress in normal-/overweight women with polycystic ovary syndrome and in controls

Background

Polycystic ovary syndrome (PCOS) is linked to an elevated risk of psychological disorders, decreased quality of life and emotional distress. Serum cortisol as a potential stress marker has been found to be increased in women with PCOS. The aim of this study was to evaluate both saliva stress markers and subjective psychological distress in women with PCOS.

Methods

In a prospective case-control study, 31 PCOS women and 31 healthy controls were included. Salivary cortisol, and metanephrines were collected in the morning and in the evening. Emotional distress and quality of life were assessed by means of the Perceived Stress Scale (PSS-10) and the Short Form-36 (SF-36). Multivariable generalized linear models were applied to test the influence of various parameters on numerical outcome parameters.

Results

After correction for age and body mass index (BMI), there were no statistically significant differences of salivary biomarkers between PCOS women and healthy controls (p>0.05). PCOS patients revealed significantly higher increased PSS total scores and lower quality of life in all SF-36 modules apart from pain (p< 0.05). The PSS total score was positively correlated to prolactin in PCOS women (r= 0.450; p= 0.011). In overweight/obese PCOS patients, a higher BMI, a higher Ferriman Gallwey score and higher age significantly predicted the PSS total score (p< 0.05).

Conclusion

Stress measured by salivary biomarkers did not differ between PCOS women and healthy controls, whereas stress scores evaluated by questionnaires were significantly greater in women with PCOS. A higher BMI, hirsutism and a higher age seem to be the main modulators of subjective stress in PCOS. Prolactin might serve as a biomarker for chronic stress in PCOS women.

The relationship between polycystic ovary syndrome and coronary heart disease: a bibliometric analysis

Background

Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine diseases for women of puberty and reproductive age. PCOS can affect women's health for the rest of their lives since the incidence of coronary heart disease (CHD) may increase in the perimenopausal and senile periods among PCOS women compared with non-PCOS women.

Method

A literature retrieval based on the Science Citation Index Expanded (SCI-E) database. All obtained records results were downloaded in plain text format for subsequent analysis. VOSviewer v1.6.10, Citespace and Microsoft Excel 2010 software were utilized for analyzing the following terms: countries, institutions, authors, journals, references and keywords.

Results

There were 312 articles retrieved from January 1, 2000 to February 8, 2023, and the frequency of citations was 23,587. The United States, England, and Italy contributed the majority of the records. Harvard University, the University of Athens, and Monash University were the top 3 most productive institutions with publications on the relationship between PCOS and CHD. Journal of clinical endocrinology & metabolism ranked first with the highest publications (24 records), followed by Fertility and sterility (18 records). The keywords were divided into six clusters in the overlay keywords network: (1) the correlation between CHD risk factors and PCOS women; (2) the relationship between cardiovascular disease and female reproductive system hormone secretion; (3) the interaction between CHD and metabolic syndrome; (4) the relationship between c-reactive protein and endothelial function and oxidative stress in PCOS patients; (5) the potential positive effect of metformin on reducing CHD risk factors in PCOS patients; (6) the study of serum cholesterol and body-fat distribution in patients with CHD in PCOS. Oxidative stress, genome-wide association, obesity, primary prevention, and sex difference were main hotspots in this field in recent five years according to the keyword citation burst analysis.

Conclusion

The article obtained the hotspots and trends and provided a reference for subsequent research on the association between PCOS and CHD. Moreover, it is hypothesized that oxidative stress and genome-wide association were frontier hotspots in studies that explore the relationship between PCOS and CHD, and prevention research may be valued in the future.

Combining Mendelian randomization and network deconvolution for inference of causal networks with GWAS summary data

Mendelian randomization (MR) has been increasingly applied for causal inference with observational data by using genetic variants as instrumental variables (IVs). However, the current practice of MR has been largely restricted to investigating the total causal effect between two traits, while it would be useful to infer the direct causal effect between any two of many traits (by accounting for indirect or mediating effects through other traits). For this purpose we propose a two-step approach: we first apply an extended MR method to infer (i.e. both estimate and test) a causal network of total effects among multiple traits, then we modify a graph deconvolution algorithm to infer the corresponding network of direct effects. Simulation studies showed much better performance of our proposed method than existing ones. We applied the method to 17 large-scale GWAS summary datasets (with median N = 256879 and median #IVs = 48) to infer the causal networks of both total and direct effects among 11 common cardiometabolic risk factors, 4 cardiometabolic diseases (coronary artery disease, stroke, type 2 diabetes, atrial fibrillation), Alzheimer's disease and asthma, identifying some interesting causal pathways. We also provide an R Shiny app (https://zhaotongl.shinyapps.io/cMLgraph/) for users to explore any subset of the 17 traits of interest.

The impact of obesity: a narrative review

Obesity is a disease with a major negative impact on human health. However, people with obesity may not perceive their weight to be a significant problem and less than half of patients with obesity are advised by their physicians to lose weight. The purpose of this review is to highlight the importance of managing overweight and obesity by discussing the adverse consequences and impact of obesity. In summary, obesity is strongly related to >50 medical conditions, with many of them having evidence from Mendelian randomisation studies to support causality. The clinical, social and economic burdens of obesity are considerable, with these burdens potentially impacting future generations as well. This review highlights the adverse health and economic consequences of obesity and the importance of an urgent and concerted effort towards the prevention and management of obesity to reduce the burden of obesity.

Deconstructing a Syndrome: Genomic Insights Into PCOS Causal Mechanisms and Classification

Polycystic ovary syndrome (PCOS) is among the most common disorders in women of reproductive age, affecting up to 15% worldwide, depending on the diagnostic criteria. PCOS is characterized by a constellation of interrelated reproductive abnormalities, including disordered gonadotropin secretion, increased androgen production, chronic anovulation, and polycystic ovarian morphology. It is frequently associated with insulin resistance and obesity. These reproductive and metabolic derangements cause major morbidities across the lifespan, including anovulatory infertility and type 2 diabetes (T2D). Despite decades of investigative effort, the etiology of PCOS remains unknown. Familial clustering of PCOS cases has indicated a genetic contribution to PCOS. There are rare Mendelian forms of PCOS associated with extreme phenotypes, but PCOS typically follows a non-Mendelian pattern of inheritance consistent with a complex genetic architecture, analogous to T2D and obesity, that reflects the interaction of susceptibility genes and environmental factors. Genomic studies of PCOS have provided important insights into disease pathways and have indicated that current diagnostic criteria do not capture underlying differences in biology associated with different forms of PCOS. We provide a state-of-the-science review of genetic analyses of PCOS, including an overview of genomic methodologies aimed at a general audience of non-geneticists and clinicians. Applications in PCOS will be discussed, including strengths and limitations of each study. The contributions of environmental factors, including developmental origins, will be reviewed. Insights into the pathogenesis and genetic architecture of PCOS will be summarized. Future directions for PCOS genetic studies will be outlined.

Update on Animal Models of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex disease affecting up to 15% of women of reproductive age. Women with PCOS suffer from reproductive dysfunctions with excessive androgen secretion and irregular ovulation, leading to reduced fertility and pregnancy complications. The syndrome is associated with a wide range of comorbidities including type 2 diabetes, obesity, and psychiatric disorders. Despite the high prevalence of PCOS, its etiology remains unclear. To understand the pathophysiology of PCOS, how it is inherited, and how to predict PCOS, and prevent and treat women with the syndrome, animal models provide an important approach to answering these fundamental questions. This minireview summarizes recent investigative efforts on PCOS-like rodent models aiming to define underlying mechanisms of the disease and provide guidance in model selection. The focus is on new genetic rodent models, on a naturally occurring rodent model, and provides an update on prenatal and peripubertal exposure models.

Why are women with polycystic ovary syndrome obese?

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common condition characterized by reproductive, hyperandrogenic and dysmetabolic features, and often becomes clinically manifest during adolescence, particularly with weight-gain.

SOURCES OF DATA

Pubmed search.

AREAS OF AGREEMENT

PCOS is heritable and closely associates with obesity (based on data from both epidemiological and genetic studies). Furthermore, insulin resistance forms a central cornerstone of the pathogenesis of PCOS and mediates a close association between obesity and the severity of the phenotypic features of PCOS.

AREAS OF CONTROVERSY

Our understanding of the pathogenesis of PCOS remains incomplete, especially regarding its missing heritability (with only a small fraction having been identified from the genome-wide association studies reported to date), and its developmental origins.

GROWING POINTS

A challenge for the future is to explore a role for epigenetic modifications in the development of PCOS, and implications for the in utero environment and novel therapeutic opportunities.

Maternal polycystic ovarian syndrome and pubertal development in daughters and sons: a population-based cohort study

STUDY QUESTION

Does maternal polycystic ovarian syndrome (PCOS) affect the timing of pubertal development in daughters and sons?

SUMMARY ANSWER

Maternal PCOS was associated with earlier adrenarche in daughters.

WHAT IS KNOWN ALREADY

Female adolescents with PCOS often experience earlier adrenarche compared to adolescents without PCOS, due to hyperandrogenism. Likewise, they usually have hyperandrogenism during pregnancy, which might potentially affect the development of the foetus, including its future reproductive health.

STUDY DESIGN, SIZE, DURATION

In this population-based cohort study, we included 15 596 mothers-child pairs from the Danish National Birth Cohort (DNBC) Puberty Cohort, who were followed from foetal life until full sexual maturation or 18 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using register-based and self-reported information on maternal PCOS and menstrual irregularities, collected during pregnancy, we categorized the mothers as having PCOS (n = 251), oligomenorhoea (n = 134), 'other menstrual irregularities' (n = 2411) or no menstrual abnormalities (reference group, n = 12 800). The children provided self-reported information on pubertal development every 6 months from the age of 11 years. The main outcome measures were adjusted mean age differences (in months) at attaining several individual pubertal milestones using an interval-censored regression model, as well as the average difference in age at attaining all pubertal milestones combined into a single estimate using Huber-White robust variance estimation.

MAIN RESULTS AND THE ROLE OF CHANCE

We found that maternal PCOS was associated with an accelerated pubertal development in daughters with an overall average difference of -3.3 (95% CI: -6.3; -0.4) months based on all pubertal milestones compared to the reference group. When further looking into the average difference for adrenarche only (pubarche, axillary hair and acne), the average difference was -5.4 (95% CI: -8.7; -2.1) months compared to the reference group; whereas thelarche and menarche did not occur earlier in daughters of mothers with PCOS (average difference: -0.8 (95% CI: -3.9; 2.4) months). Oligomenorrhoea and 'other menstrual irregularities' were not associated with pubertal development in daughters. Neither PCOS, oligomenorrhoea nor 'other menstrual irregularities' were associated with pubertal development in sons.

LIMITATIONS, REASONS FOR CAUTION

We expect some degree of non-differential misclassification of maternal PCOS and menstrual irregularities as well as pubertal development in the children.

WIDER IMPLICATIONS OF THE FINDINGS

Maternal PCOS might accelerate adrenarche in daughters. Whether this is due to genetics, epigenetics or prenatal programming by hyperandrogenism in foetal life remains unsolved. The results from the present study can be generalized to Caucasian populations.

STUDY FUNDING/COMPETING INTEREST(S)

The study is funded by the Faculty of Health at Aarhus University. The authors have no financial relationships or competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects 5-18% of women, and is a reproductive, metabolic, and psychological condition with impacts across the lifespan. The cause is complex, and includes genetic and epigenetic susceptibility, hypothalamic and ovarian dysfunction, excess androgen exposure, insulin resistance, and adiposity-related mechanisms. Diagnosis is recommended based on the 2003 Rotterdam criteria and confirmed with two of three criteria: hyperandrogenism (clinical or biochemical), irregular cycles, and polycystic ovary morphology. In adolescents, both the criteria of hyperandrogenism and irregular cycles are needed, and ovarian morphology is not included due to poor specificity. The diagnostic criteria generates four phenotypes, and clinical features are heterogeneous, with manifestations typically arising in childhood and then evolving across adolescent and adult life. Treatment involves a combination of lifestyle alterations and medical management. Lifestyle optimisation includes a healthy balanced diet and regular exercise to prevent excess weight gain, limit PCOS complications and target weight reduction when needed. Medical management options include metformin to improve insulin resistance and metabolic features, combined oral contraceptive pill for menstrual cycle regulation and hyperandrogenism, and if needed, anti-androgens for refractory hyperandrogenism. In this Review, we provide an update on the pathophysiology, diagnosis, and clinical features of PCOS, and discuss the needs and priorities of those with PCOS, including lifestyle, and medical and infertility treatment. Further we discuss the status of international evidence-based guidelines (EBG) and translation, to support patient self management, healthcare provision, and to set research priorities.

Challenges in diagnosis and understanding of natural history of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting 8%-13% of reproductive-aged women. The aetiology of the syndrome is complex, with genetic susceptibility, androgen exposure in early life and adiposity related dysfunction leading to perturbance in hypothalamic-ovarian function. PCOS clinical features are heterogeneous, with manifestations arising even in early adolescence, developing into multisystem reproductive, metabolic and psychological manifestations in adulthood. In this review, we will discuss challenges in the diagnosis of PCOS and understanding of the natural history of PCOS.

Long-term health outcomes in young women with polycystic ovary syndrome: A narrative review

Polycystic ovary syndrome (PCOS) has long been recognized as a common disorder in young women leading to reproductive and cutaneous sequelae. However, the associated health risks are now known to extend beyond these familiar manifestations to a range of longer-term comorbidities. Here we review the evidence for an association of PCOS with adverse long-term health outcomes, discussing the pathophysiological mechanisms involved in addition to opportunities for therapeutic intervention. Cross-sectional and longitudinal studies point to an increased risk of type 2 diabetes, hypertension and dyslipidaemia, with recent data confirming that these translate to an increased risk of cardiovascular events independently of obesity. Obstructive sleep apnoea, nonalcoholic fatty liver disease and endometrial cancer are also more prevalent, while mental health disorders, notably anxiety and depression, are common but under-appreciated associations. Uncertainties remain as to whether these risks are apparent in all patients with PCOS or are confined to particular subtypes, whether risks persist post-menopausally and how risk may be affected by ethnicity. Further work is also needed in establishing if systematic screening and targeted intervention can lead to improved outcomes. Until such data are available, clinicians managing women with PCOS should counsel patients on long-term health risks and invest in strategies that limit progression to metabolic and non-metabolic morbidities.

Causality of anthropometric markers associated with polycystic ovarian syndrome: Findings of a Mendelian randomization study

Introduction

Using body mass index (BMI) as a proxy, previous Mendelian randomization (MR) studies found total causal effects of general obesity on polycystic ovarian syndrome (PCOS). Hitherto, total and direct causal effects of general- and central obesity on PCOS have not been comprehensively analyzed.

Objectives

To investigate the causality of central- and general obesity on PCOS using surrogate anthropometric markers.

Methods

Summary GWAS data of female-only, large-sample cohorts of European ancestry were retrieved for anthropometric markers of central obesity (waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR)) and general obesity (BMI and its constituent variables–weight and height), from the IEU Open GWAS Project. As the outcome, we acquired summary data from a large-sample GWAS (118870 samples; 642 cases and 118228 controls) within the FinnGen cohort. Total causal effects were assessed via univariable two-sample Mendelian randomization (2SMR). Genetic architectures underlying causal associations were explored. Direct causal effects were analyzed by multivariable MR modelling.

Results

Instrumental variables demonstrated no weak instrument bias (F > 10). Four anthropometric exposures, namely, weight (2.69–77.05), BMI (OR: 2.90–4.06), WC (OR: 6.22–20.27), and HC (OR: 6.22–20.27) demonstrated total causal effects as per univariable 2SMR models. We uncovered shared and non-shared genetic architectures underlying causal associations. Direct causal effects of WC and HC on PCOS were revealed by two multivariable MR models containing exclusively the anthropometric markers of central obesity. Other multivariable MR models containing anthropometric markers of both central- and general obesity showed no direct causal effects on PCOS.

Conclusions

Both and general- and central obesity yield total causal effects on PCOS. Findings also indicated potential direct causal effects of normal weight-central obesity and more complex causal mechanisms when both central- and general obesity are present. Results underscore the importance of addressing both central- and general obesity for optimizing PCOS care.

Polycystic ovary syndrome: a "risk-enhancing" factor for cardiovascular disease

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among women of reproductive age and is hallmarked by hyperandrogenism, oligo-ovulation, and polycystic ovarian morphology. Polycystic ovary syndrome, particularly the hyperandrogenism phenotype, is associated with several cardiometabolic abnormalities, including obesity, dyslipidemia, elevated blood pressure, and prediabetes or type 2 diabetes. Many, but not all, studies have suggested that PCOS is associated with increased risk of cardiovascular disease (CVD), including coronary heart disease and stroke, independent of body mass index and traditional risk factors. Interpretation of the data from these observational studies is limited by the varying definitions and ascertainment of PCOS and CVD across studies. Recent Mendelian randomization studies have challenged the causality of PCOS with coronary heart disease and stroke. Future longitudinal studies with clearly defined PCOS criteria and newer genetic methodologies may help to determine association and causality. Nevertheless, CVD risk screening remains critical in this patient population, as improvements in metabolic profile and reduction in CVD risk are achievable with a combination of lifestyle management and pharmacotherapy. Statin therapy should be implemented in women with PCOS who have elevated atherosclerotic CVD risk. If CVD risk is uncertain, measurement of subclinical atherosclerosis (carotid plaque or coronary artery calcium) may be a useful tool to guide shared decision-making about initiation of statin therapy. Other medications, such as metformin and glucagon-like peptide-1 receptor agonists, also may be useful in reducing CVD risk in insulin-resistant populations. Additional research is needed to determine the best pathways to mitigate PCOS-associated CVD risk.

The role of gonadotropin-releasing hormone neurons in polycystic ovary syndrome

Given the critical central role of gonadotropin-releasing hormone (GnRH) neurons in fertility, it is not surprising that the GnRH neural network is implicated in the pathology of polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility. Although many symptoms of PCOS relate most proximately to ovarian dysfunction, the central reproductive neuroendocrine system ultimately drives ovarian function through its regulation of anterior pituitary gonadotropin release. The typical cyclical changes in frequency of GnRH release are often absent in women with PCOS, resulting in a persistent high-frequency drive promoting gonadotropin changes (i.e., relatively high luteinizing hormone and relatively low follicle-stimulating hormone concentrations) that contribute to ovarian hyperandrogenemia and ovulatory dysfunction. However, the specific mechanisms underpinning GnRH neuron dysfunction in PCOS remain unclear. Here, we summarize several preclinical and clinical studies that explore the causes of aberrant GnRH secretion in PCOS and the role of disordered GnRH secretion in PCOS pathophysiology.

Causal relationship between polycystic ovary syndrome and coronary artery disease: A Mendelian randomisation study

OBJECTIVE

Polycystic ovary syndrome (PCOS) has been associated with an increased risk of coronary artery disease (CAD). However, it remains uncertain whether this increased risk is the result of PCOS per se or, alternatively, is explained by obesity, a common feature of PCOS. The aim of this study was to assess the causal association between PCOS and CAD and the role of obesity herein.

DESIGN AND METHODS

We conducted two-sample Mendelian randomisation analyses in large-scale, female-specific datasets to study the association between genetically predicted (1) risk of PCOS and risk of CAD, (2) body mass index (BMI) and risk of PCOS and (3) BMI and risk of CAD. Primary analyses were conducted with the inverse-variance weighted (IVW) method. Simple median, penalized weighted median and contamination mixture analyses were performed to assess the robustness of the outcomes.

RESULTS

IVW analyses did not show a statistically significant association between PCOS and CAD (odds ratio [OR]: 0.99, 95% confidence interval [CI]: 0.89, 1.11). In contrast, genetically predicted BMI was statistically significantly associated with an increased odds of PCOS (OR: 3.21, 95% CI: 2.26, 4.56) and CAD (OR: 1.38, 95% CI: 1.14, 1.67). Similar results were obtained when secondary analyses were performed.

CONCLUSION

These sex-specific analyses show that the genetically predicted risk of PCOS is not associated with the risk of CAD. Instead, the genetically predicted risk of obesity (and its downstream metabolic effects) is the common denominator of both PCOS and CAD risk.

Maternal Polycystic Ovary Syndrome and Offspring Birth Weight: A Mendelian Randomization Study

CONTEXT

Observational associations between maternal polycystic ovary syndrome (PCOS) and offspring birth weight (BW) have been inconsistent and the causal relationship is still uncertain.

OBJECTIVE

We conducted a 2-sample Mendelian randomization (MR) study to estimate the causal effect of maternal PCOS on offspring BW.

METHODS

We constructed genetic instruments for PCOS with 14 single nucleotide polymorphisms (SNPs) which were identified in a genome-wide association study (GWAS) meta-analysis including 10 074 PCOS cases and 103 164 controls of European ancestry from 7 cohorts. The genetic associations of these SNPs with the offspring BW were extracted from summary statistics estimated by the Early Growth Genetics consortium (n = 406 063 European ancestry individuals) using the weighted linear model, an approximation method of structural equation model, which separated maternal genetic effects from fetal genetic effects. We used a 2-sample MR design to examine the causal relationship between maternal PCOS and offspring BW. Sensitivity analyses were conducted to assess the robustness of the MR results.

RESULTS

We found little evidence for a causal effect of maternal PCOS on offspring BW (-6.1 g, 95% CI -16.8 g, 4.6 g). Broadly consistent results were found in the sensitivity analyses.

CONCLUSION

Despite the large scale of this study, our results suggested little causal effect of maternal PCOS on offspring BW. MR studies with a larger sample size of women with PCOS or more genetic instruments that would increase the variation of PCOS explained are needed in the future.

Association of FTO gene variants rs9939609 and rs1421085 with polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is among the most common complex genetic endocrinopathy, and its etiology and pathophysiology remain controversial. FTO is a large highly polymorphic gene and was coined as the first locus associated with adiposity. The association of the intronic variant FTO rs9939609 or FTO rs1421085 with PCOS has been controversial and unclear, mainly due to ethnic differences among populations. The present study aims to investigate the association of FTO rs9939609 or FTO rs1421085 polymorphisms with PCOS in Saudi Arabian women.

Results

A total of 98 PCOS patients and 99 healthy females were included in this study. PCR and genotyping (TaqMan®SNP Genotyping Assay) were employed. For FTO rs9939609, the genotype TA and the recessive model (TA + AA) in PCOS patients were significantly different compared with control subjects (p = 0.008 and p = 0.007, respectively). The allele frequency of the FTO rs9939609 gene variant was associated significantly (p = 0.027) with PCOS, suggesting that the A allele is a risk factor for PCOS susceptibility. However, for the FTO rs1421085 variant, the genotype and allele distributions did not differ significantly between PCOS patients and controls (p > 0.05).

Conclusions

This is the first report to study the association of FTO rs9939609 and FTO rs1421085 with PCOS in Saudi women. Results suggest that the FTO rs9939609 gene variant could be a genetic predisposing factor for PCOS Saudi women.

Causes and Consequences of Polycystic Ovary Syndrome: Insights From Mendelian Randomization

CONTEXT

Although polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting women of reproductive age, risk factors that may cause the syndrome are poorly understood. Based on epidemiologic studies, PCOS is thought to cause several adverse outcomes such as cardiovascular disease; however, the common presence of comorbidities such as obesity may be responsible for such associations, rather than PCOS in and of itself. To overcome the limitations of observational studies, investigators have employed Mendelian randomization (MR), which uses genetic variants to interrogate causality between exposures and outcomes.

EVIDENCE ACQUISITION

To clarify causes and consequences of PCOS, this review will describe MR studies involving PCOS, both as an exposure and as an outcome. The literature was searched using the terms "Mendelian randomization," "polycystic ovary syndrome," "polycystic ovarian syndrome," and "PCOS" (to May 2021).

EVIDENCE SYNTHESIS

MR studies have suggested that obesity, testosterone levels, fasting insulin, serum sex hormone-binding globulin concentrations, menopause timing, male-pattern balding, and depression may play a causal role in PCOS. In turn, PCOS may increase the risk of estrogen receptor-positive breast cancer, decrease the risk of endometrioid ovarian cancer, and have no direct causal effect on type 2 diabetes, coronary heart disease, or stroke.

CONCLUSIONS

The accumulation of genome-wide association studies in PCOS has enabled multiple MR analyses identifying factors that may cause PCOS or be caused by PCOS. This knowledge will be critical to future development of measures to prevent PCOS in girls at risk as well as prevent complications in those who have PCOS.

Genomic correlation, shared loci, and causal relationship between obesity and polycystic ovary syndrome: a large-scale genome-wide cross-trait analysis

BACKGROUND

The comorbidity between polycystic ovary syndrome (PCOS) and obesity has long been observed in clinical settings, but their shared genetic basis remains unclear.

METHODS

Leveraging summary statistics of large-scale GWAS(s) conducted in European-ancestry populations on body mass index (adult BMI, Nfemale=434,794; childhood BMI, N=39,620), waist-to-hip ratio (WHR, Nfemale=381,152), WHR adjusted for BMI (WHRadjBMI, Nfemale=379,501), and PCOS (Ncase=10,074, Ncontrol=103,164), we performed a large-scale genome-wide cross-trait analysis to quantify overall and local genetic correlation, to identify shared loci, and to infer causal relationship.

RESULTS

We found positive genetic correlations between PCOS and adult BMI (rg=0.47, P=2.19×10-16), childhood BMI (rg=0.31, P=6.72×10-5), and WHR (rg=0.32, P=1.34×10-10), all withstanding Bonferroni correction. A suggestive significant genetic correlation was found between PCOS and WHRadjBMI (rg=0.09, P=0.04). Partitioning the whole genome into 1703 nearly independent regions, we observed a significant local genetic correlation for adult BMI and PCOS at chromosome 18: 57630483-59020751. We identified 16 shared loci underlying PCOS and obesity-related traits via cross-trait meta-analysis including 9 loci shared between BMI and PCOS (adult BMI and PCOS: 5 loci; childhood BMI and PCOS: 4 loci), 6 loci shared between WHR and PCOS, and 5 loci shared between WHRadjBMI and PCOS. Mendelian randomization (MR) supported the causal roles of both adult BMI (OR=2.92, 95% CI=2.33-3.67) and childhood BMI (OR=2.76, 95% CI=2.09-3.66) in PCOS, but not WHR (OR=1.19, 95% CI=0.93-1.52) or WHRadjBMI (OR=1.03, 95% CI=0.87-1.22). Genetic predisposition to PCOS did not seem to influence the risk of obesity-related traits.

CONCLUSIONS

Our cross-trait analysis suggests a shared genetic basis underlying obesity and PCOS and provides novel insights into the biological mechanisms underlying these complex traits. Our work informs public health intervention by confirming the important role of weight management in PCOS prevention.

Mendelian Randomization: A Review of Methods for the Prevention, Assessment, and Discussion of Pleiotropy in Studies Using the Fat Mass and Obesity-Associated Gene as an Instrument for Adiposity

Pleiotropy assessment is critical for the validity of Mendelian randomization (MR) analyses, and its management remains a challenging task for researchers. This review examines how the authors of MR studies address bias due to pleiotropy in practice. We reviewed Pubmed, Medline, Embase and Web of Science for MR studies published before 21 May 2020 that used at least one single-nucleotide polymorphism (SNP) in the fat mass and obesity-associated (FTO) gene as instrumental variable (IV) for body mass index, irrespective of the outcome. We reviewed: 1) the approaches used to prevent pleiotropy, 2) the methods cited to detect or control the independence or the exclusion restriction assumption highlighting whether pleiotropy assessment was explicitly stated to justify the use of these methods, and 3) the discussion of findings related to pleiotropy. We included 128 studies, of which thirty-three reported one approach to prevent pleiotropy, such as the use of multiple (independent) SNPs combined in a genetic risk score as IVs. One hundred and twenty studies cited at least one method to detect or account for pleiotropy, including robust and other IV estimation methods (n = 70), methods for detection of heterogeneity between estimated causal effects across IVs (n = 72), methods to detect or account associations between IV and outcome outside thought the exposure (n = 85), and other methods (n = 5). Twenty-one studies suspected IV invalidity, of which 16 explicitly referred to pleiotropy, and six incriminating FTO SNPs. Most reviewed MR studies have cited methods to prevent or to detect or control bias due to pleiotropy. These methods are heterogeneous, their triangulation should increase the reliability of causal inference.

Obesity and risk of female reproductive conditions: A Mendelian randomisation study

BACKGROUND

Obesity is observationally associated with altered risk of many female reproductive conditions. These include polycystic ovary syndrome (PCOS), abnormal uterine bleeding, endometriosis, infertility, and pregnancy-related disorders. However, the roles and mechanisms of obesity in the aetiology of reproductive disorders remain unclear. Thus, we aimed to estimate observational and genetically predicted causal associations between obesity, metabolic hormones, and female reproductive disorders.

METHODS AND FINDINGS

Logistic regression, generalised additive models, and Mendelian randomisation (MR) (2-sample, non-linear, and multivariable) were applied to obesity and reproductive disease data on up to 257,193 women of European ancestry in UK Biobank and publicly available genome-wide association studies (GWASs). Body mass index (BMI), waist-to-hip ratio (WHR), and WHR adjusted for BMI were observationally (odds ratios [ORs] = 1.02-1.87 per 1-SD increase in obesity trait) and genetically (ORs = 1.06-2.09) associated with uterine fibroids (UF), PCOS, heavy menstrual bleeding (HMB), and pre-eclampsia. Genetically predicted visceral adipose tissue (VAT) mass was associated with the development of HMB (OR [95% CI] per 1-kg increase in predicted VAT mass = 1.32 [1.06-1.64], P = 0.0130), PCOS (OR [95% CI] = 1.15 [1.08-1.23], P = 3.24 × 10-05), and pre-eclampsia (OR [95% CI] = 3.08 [1.98-4.79], P = 6.65 × 10-07). Increased waist circumference posed a higher genetic risk (ORs = 1.16-1.93) for the development of these disorders and UF than did increased hip circumference (ORs = 1.06-1.10). Leptin, fasting insulin, and insulin resistance each mediated between 20% and 50% of the total genetically predicted association of obesity with pre-eclampsia. Reproductive conditions clustered based on shared genetic components of their aetiological relationships with obesity. This study was limited in power by the low prevalence of female reproductive conditions among women in the UK Biobank, with little information on pre-diagnostic anthropometric traits, and by the susceptibility of MR estimates to genetic pleiotropy.

CONCLUSIONS

We found that common indices of overall and central obesity were associated with increased risks of reproductive disorders to heterogenous extents in a systematic, large-scale genetics-based analysis of the aetiological relationships between obesity and female reproductive conditions. Our results suggest the utility of exploring the mechanisms mediating the causal associations of overweight and obesity with gynaecological health to identify targets for disease prevention and treatment.

Leveraging Northern European population history: novel low-frequency variants for polycystic ovary syndrome

STUDY QUESTION

Can we identify novel variants associated with polycystic ovary syndrome (PCOS) by leveraging the unique population history of Northern Europe?

SUMMARY ANSWER

We identified three novel genome-wide significant associations with PCOS, with two putative independent causal variants in the checkpoint kinase 2 (CHEK2) gene and a third in myosin X (MYO10).

WHAT IS KNOWN ALREADY

PCOS is a common, complex disorder with unknown aetiology. While previous genome-wide association studies (GWAS) have mapped several loci associated with PCOS, the analysis of populations with unique population history and genetic makeup has the potential to uncover new low-frequency variants with larger effects.

STUDY DESIGN, SIZE, DURATION

A population-based case-control GWAS was carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We identified PCOS cases from national registers by ICD codes (ICD-10 E28.2, ICD-9 256.4, or ICD-8 256.90), and all remaining women were considered controls. We then conducted a three-stage case-control GWAS: in the discovery phase, we had a total of 797 cases and 140 558 controls from the FinnGen study. For validation, we used an independent dataset from the Estonian Biobank, including 2812 cases and 89 230 controls. Finally, we performed a joint meta-analysis of 3609 cases and 229 788 controls from both cohorts. Additionally, we reran the association analyses including BMI as a covariate, with 2169 cases and 160 321 controls from both cohorts.

MAIN RESULTS AND THE ROLE OF CHANCE

Two out of the three novel genome-wide significant variants associating with PCOS, rs145598156 (P = 3.6×10-8, odds ratio (OR) = 3.01 [2.02-4.50] minor allele frequency (MAF) = 0.005) and rs182075939 (P = 1.9×10-16, OR = 1.69 [1.49-1.91], MAF = 0.04), were found to be enriched in the Finnish and Estonian populations and are tightly linked to a deletion c.1100delC (r2 = 0.95) and a missense I157T (r2 = 0.83) in CHEK2. The third novel association is a common variant near MYO10 (rs9312937, P = 1.7 × 10-8, OR = 1.16 [1.10-1.23], MAF = 0.44). We also replicated four previous reported associations near the genes Erb-B2 Receptor Tyrosine Kinase 4 (ERBB4), DENN Domain Containing 1A (DENND1A), FSH Subunit Beta (FSHB) and Zinc Finger And BTB Domain Containing 16 (ZBTB16). When adding BMI as a covariate only one of the novel variants remained genome-wide significant in the meta-analysis (the EstBB lead signal in CHEK2 rs182075939, P = 1.9×10-16, OR = 1.74 [1.5-2.01]) possibly owing to reduced sample size.

LARGE SCALE DATA

The age- and BMI-adjusted GWAS meta-analysis summary statistics are available for download from the GWAS Catalog with accession numbers GCST90044902 and GCST90044903.

LIMITATIONS, REASONS FOR CAUTION

The main limitation was the low prevalence of PCOS in registers; however, the ones with the diagnosis most likely represent the most severe cases. Also, BMI data were not available for all (63% for FinnGen, 76% for EstBB), and the biobank setting limited the accessibility of PCOS phenotypes and laboratory values.

WIDER IMPLICATIONS OF THE FINDINGS

This study encourages the use of isolated populations to perform genetic association studies for the identification of rare variants contributing to the genetic landscape of complex diseases such as PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

This work has received funding from the European Union's Horizon 2020 research and innovation programme under the MATER Marie Skłodowska-Curie grant agreement No. 813707 (N.P.-G., T.L., T.P.), the Estonian Research Council grant (PRG687, T.L.), the Academy of Finland grants 315921 (T.P.), 321763 (T.P.), 297338 (J.K.), 307247 (J.K.), 344695 (H.L.), Novo Nordisk Foundation grant NNF17OC0026062 (J.K.), the Sigrid Juselius Foundation project grants (T.L., J.K., T.P.), Finska Läkaresällskapet (H.L.) and Jane and Aatos Erkko Foundation (H.L.). The funders had no role in study design, data collection and analysis, publishing or preparation of the manuscript. The authors declare no conflicts of interest.

High-Throughput Sequencing Profiles About lncRNAs and mRNAs of Ovarian Granulosa Cells in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age, which is characterized by ovulatory dysfunction, clinical and/or biochemical androgen excess, polycystic ovaries on ultrasound and genetic heterogeneity. It was well-accepted that many lncRNAs and mRNAs were associated with PCOS, however, remain unclear. Therefore, the purpose of our study was to examine different expression profiles of lncRNAs and mRNAs in ovarian granulosa cells (GCs) in PCOS and Controls, and identify the correlation between lncRNAs, mRNAs and clinical parameters. Sixty five PCOS patients and 65 Controls were enrolled in this study and adopted standard long agonist protocols or GnRH antagonist protocols. Then 6 GCs samples in each group were subjected to high-thoughput sequencing and the remaining samples were used for the further verification by quantitative real-time PCR (qRT-PCR). Gene Oncology (GO), Kyoto Encyclopedia Genes and Genomes (KEGG) enrichment analysis were performed. We predicted the relationship between lncRNAs and mRNAs by Cytoscape software. According to the expression level of lncRNAs, mRNAs and the clinical parameters, we also explored their relationship and evaluate their predictive values for embryos quality and PCOS. We identified 1,049 differential expressed lncRNAs and 3,246 mRNAs (fold-change ≥2, p-value < 0.05). Seven lncRNAs (NONHSAT101926.2, NONHSAT136825.2, NONHSAT227177.1, NONHSAT010538.2, NONHSAT191377.1, NONHSAT230904.1, ENST00000607307) and 3 mRNAs (EREG, ENTPD6, YAP1) were validated consistent with sequence profile. Seven lncRNAs were related to hormone level and follicle counts, 3 mRNAs had connections with lipid metabolism. The area under curve (AUC) of 7 lncRNAs were valuable in distinguishing patients with PCOS from Controls. The AUC of NONHSAT230904.1 and NONHSAT227177.1 were 0.6807 and 0.6410, respectively, for distinguishing whether the rate of high-quality embryos exceeds 50%. Our study showed that the GCs lncRNAs and mRNAs were involved in the occurrence and development of PCOS, which contribute to clarify the pathogenesis mechanism of PCOS.

Dietary Modification for Reproductive Health in Women With Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis

Objective

Diet has been reported as the first-line management of polycystic ovary syndrome (PCOS). However, the relationship between diet and fertility in PCOS is still controversial. This meta-analysis aimed to evaluate whether diet could promote reproductive health in women with PCOS while providing evidence-based nutrition advice for clinical practice.

Methods

Seven databases, including Cochrane Central Register of Controlled Trials, PubMed, Embase, Web of Science, and some Chinese database, were searched up to January 31, 2021. Randomized controlled trials evaluating the effects of diet in women with PCOS were included. Based on a preregistered protocol (PROSPERO CRD42019140454), the systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Two reviewers made study selection, data extraction and bias assessment independently. Risk ratios and mean difference with 95% confidence intervals were assessed by a random-effects model. Statistical heterogeneity within comparisons was evaluated by Cochran's Q test and quantified by the I-squared (I2 ) statistic.

Results

Twenty RCTs with 1113 participants were included. Results showed diet significantly related to improved fertility outcomes (increasing clinical pregnancy, ovulation and menstrual regularity rate; reducing miscarriage rate), reproductive endocrine [increasing sex hormone-binding globulin (SHBG); decreasing Anti-Müllerian Hormone (AMH), free androgen index (FAI), total testosterone (T)] and clinical hyperandrogenism (hirsutism assessed by Ferriman-Gallwey score) in PCOS. Specifically, subgroup analyses indicated low-carbohydrate diets were superior in optimizing reproductive outcomes and calorie restriction was critical in ameliorating hyperandrogenism. Additionally, the positive effects were associated with the treatment duration. The longer the duration, the greater the improvement was.

Conclusion

Overall, diet is an effective intervention for improving fertility health, thus professional and dynamic dietary advice should be offered to all PCOS patients, based on the changeable circumstances, personal needs and expectations of the individuals.

Dietary Interventions: A Promising Treatment for Polycystic Ovary Syndrome

BACKGROUND

Dietary interventions as a first-line treatment for patients with polycystic ovary syndrome (PCOS) have been evaluated, but the optimal diet has not been determined. Proper diet and the maintenance of adequate nutritional status are of great importance in the prevention of this disorder, and therapeutics and dietary habits play an important role in the recovery of patients with PCOS.

SUMMARY

A range of dietary patterns have been shown to impact weight loss and insulin resistance (IR) and improve reproductive function, including the Mediterranean diet, the ketogenic diet, Dietary Approaches to Stop Hypertension, and other dietary patterns. Key Messages: Diets that can reduce rates of obesity and IR are beneficial to women with PCOS, the status of obesity and IR should be determined at the early stage of the disease, so as to develop individualized and sustainable dietary intervention. The long-term efficacy, safety, and health benefits of diet management in patients with PCOS need to be tested by further researches.

Is there a shared genetic basis and causal relationship between polycystic ovary syndrome and psychiatric disorders: evidence from a comprehensive genetic analysis

STUDY QUESTION

Is there a shared genetic basis or causal relationship between polycystic ovary syndrome (PCOS) and a range of psychiatric disorders?

SUMMARY ANSWER

Genome-wide genetic correlation analysis and bidirectional Mendelian randomisation (MR) analysis suggest no shared genetic basis or causal relationship of PCOS with psychiatric disorders including depression, anxiety, schizophrenia and bipolar disorder.

WHAT IS KNOWN ALREADY

The comorbidity of PCOS with a range of psychiatric disorders has been recognised by epidemiological investigations yet a causal relationship remains unclear. Understanding of how genetic variations contribute to the susceptibility to PCOS and psychiatry disorders could provide meaningful insights into disease mechanisms.

STUDY DESIGN, SIZE, DURATION

We incorporated summary statistics from the hitherto largest genome-wide association studies (GWAS) conducted in subjects with PCOS (Ncase = 9322) or four common psychiatric disorders (depression, anxiety, schizophrenia and bipolar disorder) (Ncase ranges between 20 352 and 246 363), all of European ancestry.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We quantified pairwise genetic correlation to understand the shared genetic predisposition using genome-wide genetic variants. We performed a two-sample bidirectional Mendelian randomisation analysis to make causal inferences, using GWAS-identified 102 depression-associated genetic instruments, 6 anxiety-associated instruments, 179 schizophrenia-associated instruments, 30 bipolar disorder-associated instruments and 14 PCOS-associated instruments. We performed several important sensitivity analyses examining sex hormones and utilising different MR approaches.

MAIN RESULTS AND THE ROLE OF CHANCE

We did not find significant genetic correlations (rg) for PCOS with psychiatric disorders (depression (rg = 0.09, P = 0.06), anxiety (rg = 0.15, P = 0.06), schizophrenia (rg = 0.02, P = 0.59), bipolar disorder (rg = 0.08, P = 0.19)). Genetic predisposition to PCOS was associated with depression in some of our MR approaches, without any evidence of pleiotropy (PMR-Egger intercept = 0.60). However, this weak PCOS-depression causal association attenuated to null after adjusting for BMI (1.00 (0.99-1.02), P = 0.28). On the contrary, we did not observe any statistically significant association between genetically instrumented PCOS with other psychiatric disorders (anxiety 1.01 (0.93-1.08), P = 0.89; schizophrenia 1.03 (0.97-1.10), P = 0.37; bipolar disorder 0.96 (0.90-1.03), P = 0.26). Bidirectional MR did not reveal an effect by which mental health conditions influenced PCOS risk.

LIMITATIONS, REASONS FOR CAUTION

Despite our study being the largest in sample size of its kind, the overall negligible causal relationship between PCOS and psychiatric outcomes may reflect a true null association but may also be due to a true effect too modest to be detected. We were not able to investigate PCOS subtypes and used an overall heterogenous PCOS sample due to limited availability of data.

WIDER IMPLICATIONS OF THE FINDINGS

Our comprehensive analysis does not identify a shared genetic basis of PCOS with psychiatric diseases. Although genetically instrumented PCOS appears to correlate with depression, such an effect is likely mediated by BMI, suggesting a role of non-genetic exposures underlying the observed comorbidity.

STUDY FUNDING/COMPETING INTEREST(S)

The work was supported by the Swedish Medical Research Council 2018-02435 (to E.S.V.), Novo Nordisk Foundation NNF19OC0056647 (to E.S.V.), the Adlerbert Research Foundation (to E.S.V.), the SRP in Diabetes at Karolinska Institutet (to E.S.V.) and the Swedish Research Council VR 2018-02247 (to X.J.). The funders had no influence on the data collection, analyses or conclusions of the study. No conflict of interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

Association of maternal polycystic ovary syndrome or anovulatory infertility with obesity and diabetes in offspring: a population-based cohort study

STUDY QUESTION

Are children of mothers with polycystic ovary syndrome (PCOS) or anovulatory infertility at increased risks of obesity or diabetes?

SUMMARY ANSWER

Maternal PCOS/anovulatory infertility is associated with an increased risk of offspring obesity from early age and diabetes in female offspring from late adolescence.

WHAT IS KNOWN ALREADY

Women with PCOS often have comorbid metabolic disorders such as obesity and diabetes, and children of mothers with PCOS have an increased risk of subtle signs of cardiometabolic alterations.

STUDY DESIGN, SIZE, DURATION

This was a nationwide cohort study of all live births (n = 1 105 997) during 1996-2014 in Finland, excluding those with maternal diagnoses sharing signs and symptoms with PCOS (n = 8244). A total of 1 097 753 births were included and followed up until 31 December 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

National registries were linked to identify births with maternal PCOS or anovulatory infertility (n = 24 682). The primary outcomes were diagnoses of obesity (ICD-10: E65, E66) and diabetes (ICD-10: E10-E14) in offspring recorded in the Finnish Care Register for Health Care. Cox proportional hazards regression was modeled to analyze the risk of offspring obesity and diabetes in relation to prenatal exposure to maternal PCOS/anovulatory infertility. Differently adjusted models and stratified analyses were used to assess whether the risk was modified by maternal obesity or diabetes diagnoses, pre-pregnancy BMI, fertility treatment or perinatal problems.

MAIN RESULTS AND THE ROLE OF CHANCE

Exposure to maternal PCOS/anovulatory infertility was associated with a higher cumulative incidence of obesity in the children (exposed: 1.83%; 95% CI 1.66-2.00% vs unexposed: 1.24%; 95% CI 1.22-1.26%). Accounting for birth factors and maternal characteristics such as obesity and diabetes diagnoses, the hazard ratio (HR) for obesity was increased in offspring below 9 years of age (HR 1.58; 95% CI 1.30-1.81), and in those 10-16 years of age (HR 1.37; 95% CI 1.19-1.57), but not in those aged 17-22 years (HR 1.24; 95% CI 0.73-2.11). Sex-stratified analyses revealed similar risk estimates for boys (HR 1.48; 95% CI 1.31-1.68) and girls (HR 1.45; 95% CI 1.26-1.68). Notably, the joint effect of PCOS/anovulatory infertility and BMI-based pre-pregnancy obesity on offspring obesity (HR 8.89; 95% CI 7.06-11.20) was larger than that of either PCOS/anovulatory infertility or obesity alone. Furthermore, PCOS/anovulatory infertility was associated with offspring obesity in children without perinatal problems (HR 1.27; 95% CI 1.17-1.39), with larger effect size for maternal PCOS/anovulatory infertility and joint perinatal problems (HR 1.61; 95% CI 1.35-1.91). However, the risk estimates were comparable between maternal PCOS/anovulatory infertility with (HR 1.54; 95% CI 1.17-2.03) and without fertility treatment (HR 1.46; 95% CI 1.32-1.61). For offspring diabetes, the HR was increased only between 17 and 22 years of age (HR 2.06; 95% CI 1.23-3.46), and specifically for Type 1 diabetes in females (HR 3.23; 95% CI 1.41-7.40).

LIMITATIONS, REASONS FOR CAUTION

The prevalence of PCOS/anovulatory infertility in this study was 2.2%, lower than that reported in previous studies. In addition, the incidence of obesity in offspring was lower than that reported in studies based on measured or self-reported weight and height and may include mainly moderate and severe obesity cases who needed and/or actively sought medical care. Moreover, mothers with PCOS/anovulatory infertility were identified based on ICD codes, with no information on PCOS phenotypes. Furthermore, maternal pre-pregnancy BMI was available only from 2004. The PCOS/anovulatory infertility association with female offspring diabetes was based on only a few cases. Mothers' weight gain during pregnancy, use of fertility treatment other than fresh or frozen IVF/ICSI, offspring lifestyle, as well as fathers' age, medical disorders or medication prescriptions were not available for this study.

WIDER IMPLICATIONS OF THE FINDINGS

These findings support that prenatal PCOS/anovulatory infertility exposure influences metabolic health in the offspring from early age.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Shandong Provincial Natural Science Foundation, China [ZR2020MH064 to X.C.], Shandong Province Medical and Health Technology Development Plan [2018WS338 to X.C.], the joint research funding of Shandong University and Karolinska Institute [SDU-KI-2019-08 to X.C. and C.L.], the Finnish Institute for Health and Welfare: Drug and Pregnancy Project [M.G.], the Swedish Research Council [2014-10171 to C.L.], the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institute Stockholm County Council [SLL20170292 and SLL20190589 to C.L.], the Swedish Brain Foundation [FO2018-0141 and FO2019-0201 to C.L.]. X.C. received grants from the China Scholarship Council at the beginning of the study. The authors have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Polycystic Ovary Syndrome Susceptibility Loci Inform Disease Etiological Heterogeneity

Polycystic ovary syndrome (PCOS) is a complex disorder with heterogenous phenotypes and unclear etiology. A recent phenotypic clustering study identified metabolic and reproductive subtypes of PCOS. We hypothesize that the heterogeneity of PCOS manifestations reflects different mechanistic pathways and can be identified using a genetic approach. We applied k-means clustering to categorize the genome-wide significant PCOS variants into clusters based on their associations with selected quantitative traits that likely reflect PCOS etiological pathways. We evaluated the association of each cluster with PCOS-related traits and disease outcomes. We then applied Mendelian randomization to estimate the causal effects between the traits and PCOS. Three categories of variants were identified: adiposity, insulin resistant, and reproductive. Significant associations were observed for variants in the adiposity cluster with body mass index (BMI), waist circumference and breast cancer, and variants in the insulin-resistant cluster with fasting insulin, glucose values, and homeostatic model assessment of insulin resistance (HOMA-IR). Sex hormone binding globulin (SHBG) has strong association with all three clusters. Mendelian randomization suggested a causal role of BMI and SHBG on PCOS. No causal associations were observed for PCOS on disease outcomes.

Genetics of Polycystic Ovary Syndrome: What is New?

Polycystic ovary syndrome (PCOS) is a complex genetic disorder with many genetic loci contributing small risk. Large genome-wide association studies identified 21 genetic risk loci for PCOS in European and Han Chinese women. The genetic architecture is similar across PCOS diagnostic categories. The next wave of analysis will incorporate large genotyped datasets linked to medical records, increasing numbers and ethnic subsets. The resulting genetic risk loci can then be used to create robust genetic risk scores enhanced with clinical information, environment and lifestyle data for a precision medicine approach to PCOS diagnosis and treatment.

Polycystic Ovary Syndrome: Ontogeny in Adolescence

The pathophysiology of symptomatic polycystic ovary syndrome (PCOS) often unfolds across puberty, but the ontogeny of PCOS is difficult to study because, in general, its pathophysiology is well entrenched before the diagnosis can be confirmed. However, the study of high-risk groups (daughters of women with PCOS, girls with premature pubarche, and girls with obesity) can offer insight in this regard. Available data support the hypothesis that the pubertal development of PCOS involves various combinations of genetic predisposition, intrauterine programming, hyperinsulinism, and numerous other abnormalities that provoke reproductive symptoms (eg, hyperandrogenism, ovulatory dysfunction) in response to the pubertal increase in gonadotropin secretion.

Insulin resistance and PCOS: chicken or egg?

PCOS is a common and heterogeneous endocrine disorder in women of reproductive age, frequently associated with metabolic abnormalities. It was estimated that about 75% of these subjects have an impairment of insulin action, as measured by gold standard methods. While the relationship between insulin resistance and PCOS is consistently shown by a number of studies, the mechanisms underlying its primary origin still remains an unsolved issue. Insulin resistance and the associated hyperinsulinemia can induce both the endocrine and reproductive traits of PCOS. However, androgen excess, in turn, can impair insulin action, directly and/or through several changes occurring in different tissues. Body fat excess, which is another common feature in these women, can contribute to worsening the whole picture. Nevertheless, insulin resistance may also be found in many normal-weight individuals. Endocrine and metabolic abnormalities can develop in different moments, and probably there is fetal programming of these alterations. However, a number of vicious circles, with bidirectional relationships between androgen excess and insulin resistance, and with the contribution of several other factors, make it extremely difficult to understand where this process really originates. This review summarizes available evidence on this topic, in order to better understand the complex relationships linking hyperandrogenism and impaired insulin action in women with PCOS.

The Genetic Association of Polycystic Ovary Syndrome and the Risk of Endometrial Cancer: A Mendelian Randomization Study

The association between polycystic ovary syndrome (PCOS) and endometrial cancer remains unclear. We aimed to investigate the causal association between genetically predicted PCOS and endometrial cancer risk in two ethnic groups through a two-sample Mendelian randomization (MR) approach. Our study includes 13 single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for PCOS in Europeans, and another 13 SNPs are used as IVs for PCOS in Asians. Outcome data were obtained from the largest published meta-GWAS of European ancestry to date, as well as from the BioBank Japan Project of Asian ancestry. Our study demonstrates that genetically predicted PCOS is not causally associated with the risk of overall endometrial cancer in either Europeans or Asians (odds ratio (OR) = 0.93, 95% confidence interval (CI) = 0.85-1.01, p = 0.09 and OR = 0.98, 95% CI 0.84-1.13, p = 0.75, respectively). Subgroup analyses according to histotype further illustrate that PCOS might not be associated with the risk of either endometrioid endometrial cancer or non-endometrioid endometrial cancer in European ancestry. No pleiotropy is found in our study, and a sensitivity analysis shows similar results. Our results indicate that genetically predicted PCOS might not be associated with the risk of endometrial cancer.

Proteome analysis of endometrial tissue from patients with PCOS reveals proteins predicted to impact the disease

Polycystic ovary syndrome (PCOS) is a complex disease that causes an ovulatory infertility in approximately 10% of reproductive-age women. We searched for candidate proteins that might contribute to endometrial receptivity defects in PCOS patients, and result in adverse reproductive outcomes. Shotgun proteomics approach was used to investigate the proteome profile of the endometrium at the luteal phase in PCOS patients compared to healthy fertile individuals. Biological process and pathway analyses were conducted to categorize the proteins with differential expressions. Confirmation was performed for a number of proteins via immunoblotting in new samples. 150 proteins with higher abundance, and 46 proteins with lower abundance were identified in the endometrial tissue from PCOS patients compared to healthy fertile individuals. The proteins with higher abundance were enriched in protein degradation, cell cycle, and signaling cascades. Proteins with lower abundance in PCOS patients were enriched in extracellular matrix (ECM) composition and function, as well as the salvage pathway of purine biosynthesis. Metabolism was the most affected biological process with over 100 up-regulated, and approximately 30 down-regulated proteins. Our results indicate significant imbalances in metabolism, proteasome, cell cycle, ECM related proteins, and signaling cascades in endometrial tissue of PCOS, which may contribute to poor reproductive outcomes in these patients. We postulate that the endometria in PCOS patients may not be well-differentiated and synchronized for implantation. Possible roles of the above-mentioned pathways that underlie implantation failure in PCOS will be discussed. Our findings need to be confirmed in larger populations.

Effect of Diet on Insulin Resistance in Polycystic Ovary Syndrome

OBJECTIVE

The effect of diet on insulin resistance (IR) in polycystic ovary syndrome (PCOS) is controversial. Thus, we conducted this systematic review and meta-analysis to evaluate whether diet could reduce IR in women with PCOS while providing optimal and precise nutrition advice for clinical practice.

DESIGN

The search was conducted in 8 databases through June 30, 2019. The systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A random-effects model was adopted to calculate the overall effects.

RESULTS

A total of 19 trials (1193 participants) were included. The analysis showed that diet was significantly related to improvements in IR and body composition (eg, homeostasis model assessment of insulin resistance, fasting insulin, fasting plasma glucose, body mass index [BMI], weight, and waist circumference) in PCOS patients. The Dietary Approaches to Stop Hypertension diet and calorie-restricted diets might be the optimal choices for reducing IR and improving body composition, respectively, in the PCOS population. Additionally, the effects were associated with the course of treatment. The longer the duration, the greater the improvement was. Compared with metformin, diet was also advantageous for weight loss (including BMI and weight) and had the same effects on insulin regulation.

CONCLUSION

Overall, our findings suggest that diet is an effective, acceptable and safe intervention for relieving IR, and professional dietary advice should be offered to all PCOS patients.

Intertwined reproductive endocrinology: Puberty and polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a heterogeneous familial disorder often emerging during the peri-pubertal years concomitantly with the onset of gonadarche and adrenarche. Both gonadarche and PCOS reflect functional changes in the hypothalamic-pituitary-ovarian axis. During this transition, normal girls manifest features consistent with PCOS such as irregular menses, mild hyperandrogenism, and multi-follicular ovary morphology. Themes common to puberty and PCOS, neuroendocrine features, androgen exposure, and insulin sensitivity, will be considered to address the possibility that PCOS interferes with the normal pubertal transition.