Risk of Iron Deficiency in Women With Endometriosis: A Population-Based Prospective Cohort Study

BACKGROUND

Endometriosis may be linked to the risk of iron deficiency through chronic systemic inflammation or heavy menstrual bleeding. No longitudinal studies, however, have examined the relationship between endometriosis and the risk of iron deficiency.

METHODS

This study included 3,294 participants born from 1973 to 1978 and followed as part of the Australian Longitudinal Study on Women's Health from 2000 to 2018. Participants with endometriosis were identified using self-reported longitudinal surveys linked to administrative health records. During each survey, participants were also asked to report the diagnosis of iron deficiency, and we validated diagnoses using an administrative health database. Generalized estimating equations for binary responses with an autoregressive correlation matrix were used to examine the association between endometriosis and the risk of iron deficiency over the seven time points.

FINDINGS

We found that women with endometriosis had a significantly higher risk of iron deficiency than those without endometriosis after adjusting for sociodemographic, lifestyle, reproductive, and nutrition factors (adjusted odds ratio [aOR] = 1.46; 95% confidence interval [CI] [1.29, 1.66]; p < .0001). Women with a surgically confirmed diagnosis and those with clinically suspected endometriosis had a higher risk of iron deficiency (aOR = 1.38; 95% CI [1.17, 1.64] and aOR = 1.53; 95% CI [1.30, 1.81]), respectively. These associations, however, were slightly attenuated (by 8%) when adjusted for the presence of heavy menstrual bleeding.

CONCLUSIONS

Women with endometriosis are at a higher risk of developing iron deficiency than those without endometriosis. The findings suggest that iron deficiency should be concomitantly addressed during initial diagnosis and successive management of endometriosis.

Genome-wide association study meta-analysis of dizygotic twinning illuminates genetic regulation of female fecundity

STUDY QUESTION

Which genetic factors regulate female propensity for giving birth to spontaneous dizygotic (DZ) twins?

SUMMARY ANSWER

We identified four new loci, GNRH1, FSHR, ZFPM1, and IPO8, in addition to previously identified loci, FSHB and SMAD3.

WHAT IS KNOWN ALREADY

The propensity to give birth to DZ twins runs in families. Earlier, we reported that FSHB and SMAD3 as associated with DZ twinning and female fertility measures.

STUDY DESIGN, SIZE, DURATION

We conducted a genome-wide association meta-analysis (GWAMA) of mothers of spontaneous dizygotic (DZ) twins (8265 cases, 264 567 controls) and of independent DZ twin offspring (26 252 cases, 417 433 controls).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Over 700 000 mothers of DZ twins, twin individuals and singletons from large cohorts in Australia/New Zealand, Europe, and the USA were carefully screened to exclude twins born after use of ARTs. Genetic association analyses by cohort were followed by meta-analysis, phenome wide association studies (PheWAS), in silico and in vivo annotations, and Zebrafish functional validation.

MAIN RESULTS AND THE ROLE OF CHANCE

This study enlarges the sample size considerably from previous efforts, finding four genome-wide significant loci, including two novel signals and a further two novel genes that are implicated by gene level enrichment analyses. The novel loci, GNRH1 and FSHR, have well-established roles in female reproduction whereas ZFPM1 and IPO8 have not previously been implicated in female fertility. We found significant genetic correlations with multiple aspects of female reproduction and body size as well as evidence for significant selection against DZ twinning during human evolution. The 26 top single nucleotide polymorphisms (SNPs) from our GWAMA in European-origin participants weakly predicted the crude twinning rates in 47 non-European populations (r = 0.23 between risk score and population prevalence, s.e. 0.11, 1-tail P = 0.058) indicating that genome-wide association studies (GWAS) are needed in African and Asian populations to explore the causes of their respectively high and low DZ twinning rates. In vivo functional tests in zebrafish for IPO8 validated its essential role in female, but not male, fertility. In most regions, risk SNPs linked to known expression quantitative trait loci (eQTLs). Top SNPs were associated with in vivo reproductive hormone levels with the top pathways including hormone ligand binding receptors and the ovulation cycle.

LARGE SCALE DATA

The full DZT GWAS summary statistics will made available after publication through the GWAS catalog (https://www.ebi.ac.uk/gwas/).

LIMITATIONS, REASONS FOR CAUTION

Our study only included European ancestry cohorts. Inclusion of data from Africa (with the highest twining rate) and Asia (with the lowest rate) would illuminate further the biology of twinning and female fertility.

WIDER IMPLICATIONS OF THE FINDINGS

About one in 40 babies born in the world is a twin and there is much speculation on why twinning runs in families. We hope our results will inform investigations of ovarian response in new and existing ARTs and the causes of female infertility.

STUDY FUNDING/COMPETING INTEREST(S)

Support for the Netherlands Twin Register came from the Netherlands Organization for Scientific Research (NWO) and The Netherlands Organization for Health Research and Development (ZonMW) grants, 904-61-193, 480-04-004, 400-05-717, Addiction-31160008, 911-09-032, Biobanking and Biomolecular Resources Research Infrastructure (BBMRI.NL, 184.021.007), Royal Netherlands Academy of Science Professor Award (PAH/6635) to DIB, European Research Council (ERC-230374), Rutgers University Cell and DNA Repository (NIMH U24 MH068457-06), the Avera Institute, Sioux Falls, South Dakota (USA) and the National Institutes of Health (NIH R01 HD042157-01A1) and the Genetic Association Information Network (GAIN) of the Foundation for the National Institutes of Health and Grand Opportunity grants 1RC2 MH089951. The QIMR Berghofer Medical Research Institute (QIMR) study was supported by grants from the National Health and Medical Research Council (NHMRC) of Australia (241944, 339462, 389927, 389875, 389891, 389892, 389938, 443036, 442915, 442981, 496610, 496739, 552485, 552498, 1050208, 1075175). L.Y. is funded by Australian Research Council (Grant number DE200100425). The Minnesota Center for Twin and Family Research (MCTFR) was supported in part by USPHS Grants from the National Institute on Alcohol Abuse and Alcoholism (AA09367 and AA11886) and the National Institute on Drug Abuse (DA05147, DA13240, and DA024417). The Women's Genome Health Study (WGHS) was funded by the National Heart, Lung, and Blood Institute (HL043851 and HL080467) and the National Cancer Institute (CA047988 and UM1CA182913), with support for genotyping provided by Amgen. Data collection in the Finnish Twin Registry has been supported by the Wellcome Trust Sanger Institute, the Broad Institute, ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, AA-09203, AA15416, and K02AA018755) and the Academy of Finland (grants 100499, 205585, 118555, 141054, 264146, 308248, 312073 and 336823 to J. Kaprio). TwinsUK is funded by the Wellcome Trust, Medical Research Council, Versus Arthritis, European Union Horizon 2020, Chronic Disease Research Foundation (CDRF), Zoe Ltd and the National Institute for Health Research (NIHR) Clinical Research Network (CRN) and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. For NESDA, funding was obtained from the Netherlands Organization for Scientific Research (Geestkracht program grant 10000-1002), the Center for Medical Systems Biology (CSMB, NVVO Genomics), Biobanking and Biomolecular Resources Research Infrastructure (BBMRI-NL), VU University's Institutes for Health and Care Research (EMGO+) and Neuroscience Campus Amsterdam, University Medical Center Groningen, Leiden University Medical Center, National Institutes of Health (NIH, ROI D0042157-01A, MH081802, Grand Opportunity grants 1 RC2 Ml-1089951 and IRC2 MH089995). Part of the genotyping and analyses were funded by the Genetic Association Information Network (GAIN) of the Foundation for the National Institutes of Health. Computing was supported by BiG Grid, the Dutch e-Science Grid, which is financially supported by NWO. Work in the Del Bene lab was supported by the Programme Investissements d'Avenir IHU FOReSIGHT (ANR-18-IAHU-01). C.R. was supported by an EU Horizon 2020 Marie Skłodowska-Curie Action fellowship (H2020-MSCA-IF-2014 #661527). H.S. and K.S. are employees of deCODE Genetics/Amgen. The other authors declare no competing financial interests.

TRIAL REGISTRATION NUMBER

N/A.

Polygenic risk score phenome-wide association study reveals an association between endometriosis and testosterone

BACKGROUND

Endometriosis affects 1 in 9 women, yet it is poorly understood with long diagnostic delays, invasive diagnoses, and poor treatment outcomes. Characterised by the presence of endometrial-like tissue outside of the uterus, its main symptoms are pain and infertility. Endometriosis often co-occurs with other conditions, which may provide insights into the origins of endometriosis.

METHODS

Here a polygenic risk score phenome-wide association study of endometriosis was conducted in the UK Biobank to investigate the pleiotropic effects of a genetic liability to endometriosis. The relationship between the polygenic risk score for endometriosis and health conditions, blood and urine biomarkers and reproductive factors were investigated separately in females, males and females without an endometriosis diagnosis. The relationship between endometriosis and the blood and urine biomarkers was further investigated using genetic correlation and Mendelian randomisation approaches to identify causal relationships.

RESULTS

Multiple health conditions, blood and urine biomarkers and reproductive factors were associated with genetic liability to endometriosis in each group, indicating many endometriosis comorbidities are not dependent on the physical manifestation of endometriosis. Differences in the associated traits between males and females highlighted the importance of sex-specific pathways in the overlap of endometriosis with many other traits. Notably, an association of genetic liability to endometriosis with lower testosterone levels was identified. Follow-up analysis utilising Mendelian randomisation approaches suggested lower testosterone may be causal for both endometriosis and clear cell ovarian cancer.

CONCLUSIONS

This study highlights the diversity of the pleiotropic effects of genetic risk to endometriosis irrespective of a diagnosis of endometriosis. A key finding was the identification of a causal effect of the genetic liability to lower testosterone on endometriosis using Mendelian randomisation.

Gene expression profiles separate endometriosis lesion subtypes and indicate a sensitivity of endometrioma to estrogen suppressive treatments through elevated ESR2 expression

BACKGROUND

Endometriosis is a common, gynaecological disease characterised by the presence of endometrial-like cells growing outside the uterus. Lesions appear at multiple locations, present with variation in appearance, size and depth of invasion. Despite hormones being the recommended first-line treatment, their efficacy, success and side effects vary widely amongst study populations. Current, hormonal medication for endometriosis is designed to suppress systemic oestrogen. Whether these hormones can influence the lesions themselves is not yet clear. Evidence of hormone receptor expression in endometriotic lesions and their ability to respond is conflicting. A variation in their expression, activation of transcriptional co-regulators and the potential to respond may contribute to their variation in patient outcomes. Identifying patients who would benefit from hormonal treatments remain an important goal in endometriosis research.

METHODS

Using gene expression data from endometriosis lesions including endometrioma (OMA, n = 28), superficial peritoneal lesions (SUP, n = 72) and deeply infiltrating lesions (DIE, n = 78), we performed principal component analysis, differential gene expression and gene correlation analyses to assess the impact of menstrual stage, lesion subtype and hormonal treatment on the gene expression.

RESULTS

The gene expression profiles did not vary based on menstrual stage, but could distinguish lesion subtypes with OMA significantly differentiating from both SUP and DIE. Additionally, the effect of oestrogen suppression medication altered the gene expression profile in OMA, while such effect was not observed in SUP or DIE. Analysis of the target receptors for hormonal medication indicated ESR2 was differentially expressed in OMA and that genes that correlated with ESR2 varied significantly between medicated and non-medicated OMA samples.

CONCLUSIONS

Our results demonstrate of the different lesion types OMA present with strongest response to hormonal treatment directly through ESR2. The data suggests that there may be the potential to target treatment options to individual patients based on pre-surgical diagnoses.

Evidence of shared genetic factors in the etiology of gastrointestinal disorders and endometriosis and clinical implications for disease management

In clinical practice, the co-existence of endometriosis and gastrointestinal symptoms is often observed. Using large-scale datasets, we report a genetic correlation between endometriosis and irritable bowel syndrome (IBS), peptic ulcer disease (PUD), gastro-esophageal reflux disease (GORD), and a combined GORD/PUD medicated (GPM) phenotype. Mendelian randomization analyses support a causal relationship between genetic predisposition to endometriosis and IBS and GPM. Identification of shared risk loci highlights biological pathways that may contribute to the pathogenesis of both diseases, including estrogen regulation and inflammation, and potential therapeutic drug targets (CCKBR; PDE4B). Higher use of IBS, GORD, and PUD medications in women with endometriosis and higher use of hormone therapies in women with IBS, GORD, and PUD, support the co-occurrence of these conditions and highlight the potential for drug repositioning and drug contraindications. Our results provide evidence of shared disease etiology and have important clinical implications for diagnostic and treatment decisions for both diseases.

Associations between endometriosis and common symptoms: findings from the Australian Longitudinal Study on Women's Health

BACKGROUND

Endometriosis has been linked to higher rates of a variety of symptoms; however, the findings from longitudinal studies are scarce and inconsistent.

OBJECTIVE

This study aimed to examine the association between endometriosis and common symptoms in a prospective cohort study.

STUDY DESIGN

This study included 7606 women born from 1973 to 1978 using data from the Australian Longitudinal Study on Women's Health that were collected every 3 years from 2009 to 2018. We identified women with endometriosis based on self-reported incidence from each survey and linked administrative health data. At each survey, women also completed a checklist on the presence of 24 symptoms. Generalized estimating equations for multinomial responses were used for analyses.

RESULTS

Women with endometriosis had significantly more menstrual symptoms than those without endometriosis with an adjusted odds ratio (95% confidence interval) of 3.61 (3.11-4.19) for severe period pain, 2.40 (2.10-2.74) for heavy menstrual bleeding, 1.76 (1.52-2.03) for irregular bleeding, and 1.52 (1.32-1.76) for premenstrual tension. They also had higher odds of mental health problems with adjusted odds ratios of 1.67 (1.39-2.01) for depression and 1.59 (1.24-2.03) for anxiety and higher odds of allergies and nonspecific symptoms with adjusted odds of 1.62 (1.40-1.89) for allergies or hay fever or sinusitis, 1.79 (1.56-2.05) for severe tiredness, 1.56 (1.35-1.81) for sleep difficulty, and 1.77 (1.37-2.18) for palpitations. There was also a strong association with other forms of pain with an adjusted odds ratio of 1.76 (1.53-2.04) for backpain, 1.50 (1.29-1.74) for headaches or migraines, and 1.65 (1.41-1.93) for stiff or painful joints. Women with endometriosis also had increased odds of developing bowel and urinary symptoms with an adjusted odds ratio (95% confidence interval) of 1.67 (1.35-2.08) for constipation, 1.46 (1.12-1.90) for hemorrhoids or piles, 1.25 (1.03-1.52) for indigestion or heartburn, 2.80 (1.71-4.58) for urine burn or stings, and 1.37 (1.03-1.82) for vaginal discharge or irritation. The association between each symptom and endometriosis was similar whether endometriosis was surgically confirmed or clinically suspected. No association was found between endometriosis and the risk for skin problems, leaking urine, or breathing difficulty.

CONCLUSION

This study suggests that women with endometriosis are more likely to report not only menstrual symptoms but are also at an increased risk for mental health problems, other pain symptoms, bowel and urinary symptoms, and nonspecific symptoms, such as severe tiredness and difficulty sleeping.

A molecular staging model for accurately dating the endometrial biopsy

Natural variability in menstrual cycle length, coupled with rapid changes in endometrial gene expression, makes it difficult to accurately define and compare different stages of the endometrial cycle. Here we develop and validate a method for precisely determining endometrial cycle stage based on global gene expression. Our 'molecular staging model' reveals significant and remarkably synchronised daily changes in expression for over 3400 endometrial genes throughout the cycle, with the most dramatic changes occurring during the secretory phase. Our study significantly extends existing data on the endometrial transcriptome, and for the first time enables identification of differentially expressed endometrial genes with increasing age and different ethnicities. It also allows reinterpretation of all endometrial RNA-seq and array data that has been published to date. Our molecular staging model will significantly advance understanding of endometrial-related disorders that affect nearly all women at some stage of their lives, such as heavy menstrual bleeding, endometriosis, adenomyosis, and recurrent implantation failure.

Insights from Mendelian randomization and genetic correlation analyses into the relationship between endometriosis and its comorbidities

BACKGROUND

Endometriosis remains a poorly understood disease, despite its high prevalence and debilitating symptoms. The overlap in symptoms and the increased risk of multiple other traits in women with endometriosis is becoming increasingly apparent through epidemiological data. Genetic studies offer a method of investigating these comorbid relationships through the assessment of causal relationships with Mendelian randomization (MR), as well as identification of shared genetic variants and genes involved across traits. This has the capacity to identify risk factors for endometriosis as well as provide insight into the aetiology of disease.

OBJECTIVE AND RATIONALE

We aim to review the current literature assessing the relationship between endometriosis and other traits using genomic data, primarily through the methods of MR and genetic correlation. We critically examine the limitations of these studies in accordance with the assumptions of the utilized methods.

SEARCH METHODS

The PubMed database was used to search for peer-reviewed original research articles using the terms 'Mendelian randomization endometriosis' and '"genetic correlation" endometriosis'. Additionally, a Google Scholar search using the terms '"endometriosis" "mendelian randomization" "genetic correlation"' was performed. All relevant publications (n = 21) published up until 7 October 2022 were included in this review. Upon compilation of all traits with published MR and/or genetic correlation with endometriosis, additional epidemiological and genetic information on their comorbidity with endometriosis was sourced by searching for the trait in conjunction with 'endometriosis' on Google Scholar.

OUTCOMES

The association between endometriosis and multiple pain, gynaecological, cancer, inflammatory, gastrointestinal, psychological, and anthropometric traits has been assessed using MR analysis and genetic correlation analysis. Genetic correlation analyses provide evidence that genetic factors contributing to endometriosis are shared with multiple traits: migraine, uterine fibroids, subtypes of ovarian cancer, melanoma, asthma, gastro-oesophageal reflux disease, gastritis/duodenitis, and depression, suggesting the involvement of multiple biological mechanisms in endometriosis. The assessment of causality with MR has revealed several potential causes (e.g. depression) and outcomes (e.g. ovarian cancer and uterine fibroids) of a genetic predisposition to endometriosis; however, interpretation of these results requires consideration of potential violations of the MR assumptions.

WIDER IMPLICATIONS

Genomic studies have demonstrated that there is a molecular basis for the co-occurrence of endometriosis with other traits. Dissection of this overlap has identified shared genes and pathways, which provide insight into the biology of endometriosis. Thoughtful MR studies are necessary to ascertain causality of the comorbidities of endometriosis. Given the significant diagnostic delay of endometriosis of 7-11 years, determining risk factors is necessary to aid diagnosis and reduce the disease burden. Identification of traits for which endometriosis is a risk factor is important for holistic treatment and counselling of the patient. The use of genomic data to disentangle the overlap of endometriosis with other traits has provided insights into the aetiology of endometriosis.

Genomic characterisation of the overlap of endometriosis with 76 comorbidities identifies pleiotropic and causal mechanisms underlying disease risk

Comorbid conditions can be driven by underlying pleiotropic and causal mechanisms that can provide insights into shared molecular and biological processes contributing to disease risk. Endometriosis is a chronic condition affecting one in nine women of reproductive age and poses many challenges including lengthy diagnostic delays and limited treatment efficacy owing to poor understanding of disease aetiology. To shed light on the underlying biological mechanisms and to identify potential risk factors, we examine the epidemiological and genomic relationship between endometriosis and its comorbidities. In the UK Biobank 292 ICD10 codes were epidemiologically correlated with endometriosis diagnosis, including gynaecological, immune, infection, pain, psychiatric, cancer, gastrointestinal, urinary, bone and cardiovascular traits. A subset of the identified comorbidities (n = 76) underwent follow-up genetic analysis. Whilst Mendelian randomisation suggested causality was not responsible for most comorbid relationships, 22 traits were genetically correlated with endometriosis, including pain, gynaecological and gastrointestinal traits, suggestive of a shared genetic background. Pleiotropic genetic variants and genes were identified using gene-based and colocalisation analysis. Shared genetic risk factors and potential target genes suggest a diverse collection of biological systems are involved in these comorbid relationships including coagulation factors, development of the female reproductive tract and cell proliferation. These findings highlight the diversity of traits with epidemiological and genomic overlap with endometriosis and implicate a key role for pleiotropy in the comorbid relationships.

Global endometrial DNA methylation analysis reveals insights into mQTL regulation and associated endometriosis disease risk and endometrial function

Endometriosis is a leading cause of pain and infertility affecting millions of women globally. Herein, we characterize variation in DNA methylation (DNAm) and its association with menstrual cycle phase, endometriosis, and genetic variants through analysis of genotype data and methylation in endometrial samples from 984 deeply-phenotyped participants. We estimate that 15.4% of the variation in endometriosis is captured by DNAm and identify significant differences in DNAm profiles associated with stage III/IV endometriosis, endometriosis sub-phenotypes and menstrual cycle phase, including opening of the window for embryo implantation. Menstrual cycle phase was a major source of DNAm variation suggesting cellular and hormonally-driven changes across the cycle can regulate genes and pathways responsible for endometrial physiology and function. DNAm quantitative trait locus (mQTL) analysis identified 118,185 independent cis-mQTLs including 51 associated with risk of endometriosis, highlighting candidate genes contributing to disease risk. Our work provides functional evidence for epigenetic targets contributing to endometriosis risk and pathogenesis. Data generated serve as a valuable resource for understanding tissue-specific effects of methylation on endometrial biology in health and disease.

A Common Genetic Factor Underlies Genetic Risk for Gynaecological and Reproductive Disorders and Is Correlated with Risk to Depression

INTRODUCTION

Sex steroid hormone fluctuations may underlie both reproductive disorders and sex differences in lifetime depression prevalence. Previous studies report high comorbidity among reproductive disorders and between reproductive disorders and depression. This study sought to assess the multivariate genetic architecture of reproductive disorders and their loading onto a common genetic factor and investigated whether this latent factor shares a common genetic architecture with female depression, including perinatal depression (PND).

METHOD

Using UK Biobank and FinnGen data, genome-wide association meta-analyses were conducted for nine reproductive disorders, and genetic correlation between disorders was estimated. Genomic Structural Equation Modelling identified a latent genetic factor underlying disorders, accounting for their significant genetic correlations. SNPs significantly associated with both latent factor and depression were identified.

RESULTS

Excellent model fit existed between a latent factor underlying five reproductive disorders (χ2 (5) = 6.4; AIC = 26.4; CFI = 1.00; SRMR = 0.03) with high standardised loadings for menorrhagia (0.96, SE = 0.05); ovarian cysts (0.94, SE = 0.05); endometriosis (0.83, SE = 0.05); menopausal symptoms (0.77, SE = 0.10); and uterine fibroids (0.65, SE = 0.05). This latent factor was genetically correlated with PND (rG = 0.37, SE = 0.15, p = 1.4e-03), depression in females only (rG = 0.48, SE = 0.06, p = 7.2e-11), and depression in both males and females (MD) (rG = 0.35, SE = 0.03, p = 1.8e-30), with its top locus associated with FSHB/ARL14EP (rs11031006; p = 9.1e-33). SNPs intronic to ESR1, significantly associated with the latent factor, were also associated with PND, female depression, and MD.

CONCLUSION

A common genetic factor, correlated with depression, underlies risk of reproductive disorders, with implications for aetiology and treatment. Genetic variation in ESR1 is associated with reproductive disorders and depression, highlighting the importance of oestrogen signalling for both reproductive and mental health.

Global Analysis of Transcription Start Sites and Enhancers in Endometrial Stromal Cells and Differences Associated with Endometriosis

Identifying tissue-specific molecular signatures of active regulatory elements is critical to understanding gene regulatory mechanisms. In this study, transcription start sites (TSS) and enhancers were identified using Cap analysis of gene expression (CAGE) across endometrial stromal cell (ESC) samples obtained from women with (n = 4) and without endometriosis (n = 4). ESC TSSs and enhancers were compared to those reported in other tissue and cell types in FANTOM5 and were integrated with RNA-seq and ATAC-seq data from the same samples for regulatory activity and network analyses. CAGE tag count differences between women with and without endometriosis were statistically tested and tags within close proximity to genetic variants associated with endometriosis risk were identified. Over 90% of tag clusters mapping to promoters were observed in cells and tissues in FANTOM5. However, some potential cell-type-specific promoters and enhancers were also observed. Regions of open chromatin identified using ATAC-seq provided further evidence of the active transcriptional regions identified by CAGE. Despite the small sample number, there was evidence of differences associated with endometriosis at 210 consensus clusters, including IGFBP5, CALD1 and OXTR. ESC TSSs were also located within loci associated with endometriosis risk from genome-wide association studies. This study provides novel evidence of transcriptional differences in endometrial stromal cells associated with endometriosis and provides a valuable cell-type specific resource of active TSSs and enhancers in endometrial stromal cells.

Impact of endometriosis on women's health-related quality of life: A national prospective cohort study

OBJECTIVE

To examine the association between endometriosis and women's health-related quality of life (HRQoL).

STUDY DESIGN

This study included 3728 women born in 1973-78 using data from the Australian Longitudinal Study on Women's Health. Women with endometriosis were identified using self-reported longitudinal surveys linked to administrative health records. A mixed effect model with only random intercept and generalised estimating equations with binary logistic regressions were used to examine the association between endometriosis and health-related quality of life over eight time points. Each HRQoL scale was analysed in terms of binary outcomes by comparing women who had a lower HRQoL (scoring below the 25th percentile) with those who had a higher HRQoL (scoring above the 25th percentile).

MAIN OUTCOME MEASURES

Women's HRQoL was assessed using the 36-item Short Form Survey every 3 years from 1996 to 2018.

RESULTS

Endometriosis was associated with significantly worse reports of HRQoL over time. In the comparison against women without endometriosis, the following adjusted odds ratios (95 % confidence intervals) were calculated for women with endometriosis having worse scores on the eight domains of the Short Form Survey: physical functioning 1.33 (1.19, 1.50), role physical 1.57 (1.41, 1.74), bodily pain 1.65 (1.48, 1.82), general health 1.61 (1.42, 1.81), vitality 1.38 (1.23, 1.55), social functioning 1.38 (1.25, 1.53), role emotion 1.19 (1.06, 1.33), mental health 1.32 (1.18, 1.48). Women with endometriosis also had significantly lower physical health 1.68 (1.51, 1.88) and mental health components scores 1.28 (1.14, 1.44).

CONCLUSIONS

Endometriosis is associated with worse physical, mental, and social functioning and well-being. Bodily pain was the most affected HRQoL domain.

New concepts on the etiology of endometriosis

Endometriosis is a serious, chronic disorder where endometrial tissue grows outside the uterus, causing severe pelvic pain and infertility. It affects 11% of women. Endometriosis is a multifactorial disorder of unclear etiology, although retrograde menstruation plays a major role. It has a genetic component with over 40 genetic risk factors mapped, although their mechanism of action is still emerging. New evidence suggests a role for retrograde menstruation of endometrial stem/progenitor cells, now that identifying markers of these cells are available. Recent lineage tracing and tissue clearing microscopy and 3D reconstruction has provided new understanding of endometrial glandular structure, particularly the horizontal orientation and interconnection of basalis glands. New sequencing technologies, particularly whole genome DNA sequencing are revealing somatic mutations, including in cancer driver genes, in normal and eutopic endometrium of patients with endometriosis, as well as ectopic endometriotic lesions. Methylome sequencing is offering insight into the regulation of genes and the role of the environmental factors. Single cell RNA sequencing reveals the transcriptome of individual endometrial cells, shedding new light on the diversity and range of cellular subpopulations of the major cell types present in the endometrium and in endometriotic lesions. New endometrial epithelial organoid cultures replicating glandular epithelium are providing tractable models for studying endometriosis. Organoids derived from menstrual fluid offer a non-invasive source of endometrial tissue and a new avenue for testing drugs and developing personalized medicine for treating endometriosis. These new approaches are rapidly advancing our understanding of endometriosis etiology.

An Extremes of Phenotype Approach Confirms Significant Genetic Heterogeneity in Patients with Ulcerative Colitis

BACKGROUND AND AIMS

Ulcerative colitis [UC] is a major form of inflammatory bowel disease globally. Phenotypic heterogeneity is defined by several variables including age of onset and disease extent. The genetics of disease severity remains poorly understood. To further investigate this, we performed a genome wide association [GWA] study using an extremes of phenotype strategy.

METHODS

We conducted GWA analyses in 311 patients with medically refractory UC [MRUC], 287 with non-medically refractory UC [non-MRUC] and 583 controls. Odds ratios [ORs] were calculated for known risk variants comparing MRUC and non-MRUC, and controls.

RESULTS

MRUC-control analysis had the greatest yield of genome-wide significant single nucleotide polymorphisms [SNPs] [2018], including lead SNP = rs111838972 [OR = 1.82, p = 6.28 × 10-9] near MMEL1 and a locus in the human leukocyte antigen [HLA] region [lead SNP = rs144717024, OR = 12.23, p = 1.7 × 10-19]. ORs for the lead SNPs were significantly higher in MRUC compared to non-MRUC [p < 9.0 × 10-6]. No SNPs reached significance in the non-MRUC-control analysis (top SNP, rs7680780 [OR 2.70, p = 5.56 × 10-8). We replicate findings for rs4151651 in the Complement Factor B [CFB] gene and demonstrate significant changes in CFB gene expression in active UC. Detailed HLA analyses support the strong associations with MHC II genes, particularly HLA-DQA1, HLA-DQB1 and HLA-DRB1 in MRUC.

CONCLUSIONS

Our MRUC subgroup replicates multiple known UC risk variants in contrast to non-MRUC and demonstrates significant differences in effect sizes compared to those published. Non-MRUC cases demonstrate lower ORs similar to those published. Additional risk and prognostic loci may be identified by targeted recruitment of individuals with severe disease.

The genetic basis of endometriosis and comorbidity with other pain and inflammatory conditions

Endometriosis is a common condition associated with debilitating pelvic pain and infertility. A genome-wide association study meta-analysis, including 60,674 cases and 701,926 controls of European and East Asian descent, identified 42 genome-wide significant loci comprising 49 distinct association signals. Effect sizes were largest for stage 3/4 disease, driven by ovarian endometriosis. Identified signals explained up to 5.01% of disease variance and regulated expression or methylation of genes in endometrium and blood, many of which were associated with pain perception/maintenance (SRP14/BMF, GDAP1, MLLT10, BSN and NGF). We observed significant genetic correlations between endometriosis and 11 pain conditions, including migraine, back and multisite chronic pain (MCP), as well as inflammatory conditions, including asthma and osteoarthritis. Multitrait genetic analyses identified substantial sharing of variants associated with endometriosis and MCP/migraine. Targeted investigations of genetically regulated mechanisms shared between endometriosis and other pain conditions are needed to aid the development of new treatments and facilitate early symptomatic intervention.

Protocol for the Endometriosis Research Queensland Study (ERQS): an integrated cohort study approach to improve diagnosis and stratify treatment

INTRODUCTION

Endometriosis is a common gynaecological disease associated with pelvic pain and subfertility. There are no non-invasive diagnostic tests, medical management requires suppression of oestrogens and surgical removal is associated with risk. Endometriosis is a complex genetic disease with variants in at least 27 genetic regions associated with susceptibility. Previous research has implicated a variety of biological mechanisms in multiple cell types. Endometrial and endometriotic epithelial cells acquire somatic mutations at frequency higher than expected in normal tissue. Stromal cells have altered adhesive capacity and immune cells show altered cytotoxicity. Understanding the functional consequences of these genetic variants on each cell type requires the collection of patient symptoms, clinical and genetic data and disease-relevant tissue in an integrated program.

METHODS AND ANALYSIS

The aims of this study are to collect tissue associated with endometriosis, chart the genetic architecture related to endometriosis in this tissue, isolate and propagate patient-specific cellular models, understand the functional consequence of these genetic variants and how they interact with environmental factors in pathogenesis and treatment response.We will collect patient information from online questionnaires prior to surgery and at 6 and 12 months postsurgery. Treating physicians will document detailed surgical data. During surgery, we will collect blood, peritoneal fluid, endometrium and endometriotic tissue. Tissue will be used to isolate and propagate in vitro models of individual cells. Genome wide genotyping and gene expression data will be generated. Somatic mutations will be identified via whole genome sequencing.

ETHICS AND DISSEMINATION

The study has been approved and will be monitored by the Metro North Human Research Ethics committee (HREC) and research activities at the University of Queensland (UQ) will be overseen by the UQ HREC with annual reports submitted. Research results will be published in peer-reviewed journals and presented at conferences were appropriate. This study involves human participants and was approved by RBWH Human Research Ethics Committee; HREC/2019/QRBW/56763.The University of Queensland; 2017002744. Participants gave informed consent to participate in the study before taking part.

Clinical characteristics and surgical management of endometriosis-associated infertility: A multicenter prospective cohort study

OBJECTIVE

To study clinical, surgical characteristics and the relationship between endometriosis lesion types and conception rate after surgery in infertile women with endometriosis.

METHODS

A prospective, multicenter cohort of 204 women (age 20-35 years) with endometriosis was followed up post-surgery between November 2017 and February 2020 at three tertiary-care hospitals.

RESULTS

Based on the severity of endometriosis lesion type, deep infiltrating endometriosis (DIE) (81/204, 39.7%) was the most common lesion; followed by ovarian endometriosis (OMA) (64/204, 31.4%), and superficial peritoneal endometriosis (SUP) (59/204, 28.9%). Endometriosis patients had a single lesion type (94/204, 46.1%), two lesion types (77/204, 37.7%), or three lesion types (33/204, 16.2%) with significant differences between regions (P < 0.001). Around 40% (37/95) of obese women had SUP (P = 0.003) whereas 78% (14/18) of underweight women had DIE (P < 0.001). Significant differences in mean Endometriosis Fertility Index scores between endometriosis lesion types and patients with one, two, and three types of lesions were observed (P < 0.001). The majority (22/32, 68.8%) of the women conceived naturally after the surgery. Half (16/32; 50%) of the women with a single lesion type conceived after the surgery; of which most (13/16, 81.2%) had SUP, followed by OMA (2/16, 12.5%), and DIE (1/16, 6.3%).

CONCLUSION

Women with SUP and only one type of endometriotic lesion were more likely to conceive post-surgery.

Pestilence, Plague and Pandemics: A Troubled History

Humankind has lived with the danger of endemic, epidemic and pandemic disease for thousands of years. The effects of these outbreaks have often devastated human populations. Sixteen pandemic events causing an estimated 147 million deaths have occurred since the eighth century, The Black Death and the influenza pandemic of 1918-1920 probably having the greatest impact. Animal populations, both wild and domestic, have similarly suffered devastating outbreaks of disease which, on occasions, have translated into serious effects on human health. The deliberate or accidental introduction of animals into virgin areas has given rise to unforeseen disease events occasionally leading to extinction. Similarly, human intent or negligence and the vagaries of nature itself has resulted in ill health and loss of life. This paper describes the history of pandemics, epidemics and disasters, and the attempts to bring them under control.

A multi-level investigation of the genetic relationship between endometriosis and ovarian cancer histotypes

Endometriosis is associated with increased risk of epithelial ovarian cancers (EOCs). Using data from large endometriosis and EOC genome-wide association meta-analyses, we estimate the genetic correlation and evaluate the causal relationship between genetic liability to endometriosis and EOC histotypes, and identify shared susceptibility loci. We estimate a significant genetic correlation (r_g) between endometriosis and clear cell (r_g = 0.71), endometrioid (r_g = 0.48), and high-grade serous (r_g = 0.19) ovarian cancer, associations supported by Mendelian randomization analyses. Bivariate meta-analysis identified 28 loci associated with both endometriosis and EOC, including 19 with evidence for a shared underlying association signal. Differences in the shared risk suggest different underlying pathways may contribute to the relationship between endometriosis and the different histotypes. Functional annotation using transcriptomic and epigenomic profiles of relevant tissues/cells highlights several target genes. This comprehensive analysis reveals profound genetic overlap between endometriosis and EOC histotypes with valuable genomic targets for understanding the biological mechanisms linking the diseases.

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Endometriosis is genetically correlated with CCOC, ENOC, and HGSOC

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Genetic liability to endometriosis confers risk of these EOC histotypes

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Profound colocalization of genetic associations at endometriosis and EOC risk loci

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Functional annotation highlights shared target genes elucidating the genetic link

Genetic Regulation of Transcription in the Endometrium in Health and Disease

The endometrium is a complex and dynamic tissue essential for fertility and implicated in many reproductive disorders. The tissue consists of glandular epithelium and vascularised stroma and is unique because it is constantly shed and regrown with each menstrual cycle, generating up to 10 mm of new mucosa. Consequently, there are marked changes in cell composition and gene expression across the menstrual cycle. Recent evidence shows expression of many genes is influenced by genetic variation between individuals. We and others have reported evidence for genetic effects on hundreds of genes in endometrium. The genetic factors influencing endometrial gene expression are highly correlated with the genetic effects on expression in other reproductive (e.g., in uterus and ovary) and digestive tissues (e.g., salivary gland and stomach), supporting a shared genetic regulation of gene expression in biologically similar tissues. There is also increasing evidence for cell specific genetic effects for some genes. Sample size for studies in endometrium are modest and results from the larger studies of gene expression in blood report genetic effects for a much higher proportion of genes than currently reported for endometrium. There is also emerging evidence for the importance of genetic variation on RNA splicing. Gene mapping studies for common disease, including diseases associated with endometrium, show most variation maps to intergenic regulatory regions. It is likely that genetic risk factors for disease function through modifying the program of cell specific gene expression. The emerging evidence from our gene mapping studies coupled with tissue specific studies, and the GTEx, eQTLGen and EpiMap projects, show we need to expand our understanding of the complex regulation of gene expression. These data also help to link disease genetic risk factors to specific target genes. Combining our data on genetic regulation of gene expression in endometrium, and cell types within the endometrium with gene mapping data for endometriosis and related diseases is beginning to uncover the specific genes and pathways responsible for increased risk of these diseases.

Genetic Relationship Between Endometriosis and Melanoma

Epidemiological studies have observed that risk of endometriosis is associated with history of cutaneous melanoma and vice versa. Evidence for shared biological mechanisms between the two traits is limited. The aim of this study was to investigate the genetic correlation and causal relationship between endometriosis and melanoma. Summary statistics from genome-wide association meta-analyses (GWAS) for endometriosis and melanoma were used to estimate the genetic correlation between the traits and Mendelian randomization was used to test for a causal association. When using summary statistics from separate female and male melanoma cohorts we identified a significant positive genetic correlation between melanoma in females and endometriosis (rg = 0.144, se = 0.065, p = 0.025). However, we find no evidence of a correlation between endometriosis and melanoma in males or a combined melanoma dataset. Endometriosis was not genetically correlated with skin color, red hair, childhood sunburn occasions, ease of skin tanning, or nevus count suggesting that the correlation between endometriosis and melanoma in females is unlikely to be influenced by pigmentary traits. Mendelian Randomization analyses also provided evidence for a relationship between the genetic risk of melanoma in females and endometriosis. Colocalization analysis identified 27 genomic loci jointly associated with the two diseases regions that contain different causal variants influencing each trait independently. This study provides evidence of a small genetic correlation and relationship between the genetic risk of melanoma in females and endometriosis. Genetic risk does not equate to disease occurrence and differences in the pathogenesis and age of onset of both diseases means it is unlikely that occurrence of melanoma causes endometriosis. This study instead provides evidence that having an increased genetic risk for melanoma in females is related to increased risk of endometriosis. Larger GWAS studies with increased power will be required to further investigate these associations.

Genetic analyses of gynecological disease identify genetic relationships between uterine fibroids and endometrial cancer, and a novel endometrial cancer genetic risk region at the WNT4 1p36.12 locus

Endometriosis, polycystic ovary syndrome (PCOS) and uterine fibroids have been proposed as endometrial cancer risk factors; however, disentangling their relationships with endometrial cancer is complicated due to shared risk factors and comorbidities. Using genome-wide association study (GWAS) data, we explored the relationships between these non-cancerous gynecological diseases and endometrial cancer risk by assessing genetic correlation, causal relationships and shared risk loci. We found significant genetic correlation between endometrial cancer and PCOS, and uterine fibroids. Adjustment for genetically predicted body mass index (a risk factor for PCOS, uterine fibroids and endometrial cancer) substantially attenuated the genetic correlation between endometrial cancer and PCOS but did not affect the correlation with uterine fibroids. Mendelian randomization analyses suggested a causal relationship between only uterine fibroids and endometrial cancer. Gene-based analyses revealed risk regions shared between endometrial cancer and endometriosis, and uterine fibroids. Multi-trait GWAS analysis of endometrial cancer and the genetically correlated gynecological diseases identified a novel genome-wide significant endometrial cancer risk locus at 1p36.12, which replicated in an independent endometrial cancer dataset. Interrogation of functional genomic data at 1p36.12 revealed biologically relevant genes, including WNT4 which is necessary for the development of the female reproductive system. In summary, our study provides genetic evidence for a causal relationship between uterine fibroids and endometrial cancer. It further provides evidence that the comorbidity of endometrial cancer, PCOS and uterine fibroids may partly be due to shared genetic architecture. Notably, this shared architecture has revealed a novel genome-wide risk locus for endometrial cancer.

Genetic Regulation of Physiological Reproductive Lifespan and Female Fertility

There is substantial genetic variation for common traits associated with reproductive lifespan and for common diseases influencing female fertility. Progress in high-throughput sequencing and genome-wide association studies (GWAS) have transformed our understanding of common genetic risk factors for complex traits and diseases influencing reproductive lifespan and fertility. The data emerging from GWAS demonstrate the utility of genetics to explain epidemiological observations, revealing shared biological pathways linking puberty timing, fertility, reproductive ageing and health outcomes. The observations also identify unique genetic risk factors specific to different reproductive diseases impacting on female fertility. Sequencing in patients with primary ovarian insufficiency (POI) have identified mutations in a large number of genes while GWAS have revealed shared genetic risk factors for POI and ovarian ageing. Studies on age at menopause implicate DNA damage/repair genes with implications for follicle health and ageing. In addition to the discovery of individual genes and pathways, the increasingly powerful studies on common genetic risk factors help interpret the underlying relationships and direction of causation in the regulation of reproductive lifespan, fertility and related traits.

Elucidating the role of long intergenic non-coding RNA 339 in human endometrium and endometriosis

Endometriosis is a complex disease, influenced by genetic factors. Genetic markers associated with endometriosis exist at chromosome 1p36.12 and lead to altered expression of the long intergenic non-coding RNA 339 (LINC00339), however, the role of LINC00339 in endometriosis pathophysiology remains unknown. The aim of this work was to characterize the expression patterns of LINC00339 mRNA in endometrium and endometriotic lesions in situ and to determine the functional role of LINC00339 in human endometrium. We employed RNA-sequencing (RNA-seq), quantitative RT-PCR and in situ hybridization to investigate the abundance of LINC00339 transcripts in endometrium and endometrial cell lines and to describe the pattern and localization of LINC00339 expression in endometrium and endometriotic lesions. LINC00339 mRNA expression was manipulated (overexpressed and silenced) in endometrial stromal cell lines and RNA-seq data from overexpression models were analysed using online bioinformatics platforms (STRING and Ingenuity Pathway Analysis) to determine functional processes. We demonstrated the expression of LINC00339 in endometriotic lesions for the first time; we found LINC00339 expression was restricted to the lesion foci and absent in surrounding non-lesion tissue. Furthermore, manipulation of LINC00339 expression in endometrial stromal cell lines significantly impacted the expression of genes involved in immune defence pathways. These studies identify a novel mechanism for LINC00339 activity in endometrium and endometriosis, paving the way for future work, which is essential for understanding the pathogenesis of endometriosis.

Genetic risk factors for endometriosis near estrogen receptor 1 and coexpression of genes in this region in endometrium

The etiology and pathogenesis of endometriosis are complex with both genetic and environmental factors contributing to disease risk. Genome-wide association studies (GWAS) have identified multiple signals in the estrogen receptor 1 (ESR1) region associated with endometriosis and other reproductive traits and diseases. In addition, candidate gene association studies identified signals in the ESR1 region associated with endometriosis risk suggesting genetic regulation of genes in this region may be important for reproductive health. This study aimed to investigate hormonal and genetic regulation of genes in the ESR1 region in human endometrium. Changes in serum oestradiol and progesterone concentrations and expression of hormone receptors ESR1 and progesterone receptor (PGR) were assessed in endometrial samples from 135 women collected at various stages of the menstrual cycle. Correlation between hormone concentrations, receptor expression and expression of genes in the ESR1 locus was investigated. The effect of endometriosis risk variants on expression of genes in the region was analyzed to identify gene targets. Hormone concentrations and receptor expression varied significantly across the menstrual cycle. Expression of genes in the ESR1 region correlated with progesterone concentration; however, they were more strongly correlated with expression of ESR1 and PGR suggesting coregulation of genes. There was no evidence that endometriosis risk variants directly regulated expression of genes in the region. Limited sample size and cellular heterogeneity in endometrial tissue may impact the ability to detect significant genetic effects on gene expression. Effects of these variants should be validated in a larger dataset and in relevant individual cell types.

A SHORT HISTORY OF OCCUPATIONAL DISEASE: 1. LABORATORY-ACQUIRED INFECTIONS

Laboratory-acquired infections are as old as laboratories themselves. As soon as the culture of microorganisms was introduced, so too was their transfer to laboratory workers. It is only in relatively recent history that such infections have been fully understood, and methods of spread and their prevention or avoidance developed. This paper endeavours to provide an overview of the history of laboratory-acquired infection and the steps taken, particularly in the UK, for its prevention.

A SHORT HISTORY OF OCCUPATIONAL DISEASE: 2. ASBESTOS, CHEMICALS, RADIUM AND BEYOND

Historically, the weighing out and manipulation of dangerous chemicals frequently occurred without adequate protection from inhalation or accidental ingestion. The use of gloves, eye protection using goggles, masks or visors was scant. From Canary Girls and chimney sweeps to miners, stone cutters and silo fillers, these are classic exemplars of the subtle (and in some cases not so subtle) effects that substances, environments and practices can have on individual health.

A SHORT HISTORY OF OCCUPATIONAL DISEASE: 3. LEISURE CAN MAKE YOU SICK

The risk of infection associated with occupations can, and does, extend to certain leisure and sports activities. Generally, such pastimes are regarded as important for human health and mental wellbeing. However, infections may, rarely, be acquired during leisure activities that include water sports and water-related relaxation, and certain sports.

Generation of immortalized human endometrial stromal cell lines with different endometriosis risk genotypes

Endometriotic lesions are composed in part of endometrial-like stromal cells, however, there is a shortage of immortalized human endometrial stromal cultures available for research. As genetic factors play a role in endometriosis risk, it is important that genotype is also incorporated into analysis of pathological mechanisms. Human telomerase reverse transcriptase (hTERT) immortalization (using Lenti-hTERT-green fluorescent protein virus) took place following genotype selection; 13 patients homozygous for either the risk or non-risk 'other' allele for one or more important endometriosis risk single nucleotide polymorphism on chromosome 1p36.12 (rs3820282, rs56318008, rs55938609, rs12037376, rs7521902 or rs12061255). Short tandem repeat DNA profiling validated that donor tissue matched that of the immortalized cell lines and confirmed that cultures were genetically novel. Expression of morphological markers (vimentin and cytokeratin) and key genes of interest (telomerase, estrogen and progesterone receptors and LINC00339) were examined and functional assays for cell proliferation, steroid hormone and inflammatory responses were performed for 7/13 cultures. All endometrial stromal cell lines maintained their fibroblast-like morphology (vimentin-positive) and homozygous endometriosis-risk genotype following introduction of hTERT. Furthermore, the new stromal cultures demonstrated positive and diverse responses to hormones (proliferation and decidualisation changes) and inflammation (dose-dependent response), while maintaining hormone receptor expression. In conclusion, we successfully developed a range of human endometrial stromal cell lines that carry important endometriosis-risk alleles. The wider implications of this approach go beyond advancing endometriosis research; these cell lines will be valuable tools for multiple endometrial pathologies offering a level of genetic and phenotypic diversity not previously available.

Obesity does not alter endometrial gene expression in women with endometriosis

RESEARCH QUESTION

Does obesity affect endometrial gene expression in women with endometriosis, specifically women with stage I disease?

DESIGN

Differential gene expression analysis was conducted on endometrium from women with and without endometriosis (n = 169). Women were diagnosed after surgical visualization and staged according to the revised American Society for Reproductive Medicine (stage I-IV). Women were grouped by body mass index (BMI) (kg/m²) as underweight, normal, pre-obese or obese. After accounting for menstrual cycle stage, endometrial gene expression was analysed by BMI (continuous and grouped) in women with endometriosis, and in non-endometriosis controls.

RESULTS

No significant interaction effect was found between BMI and endometriosis status on endometrial gene expression. We have previously reported that obese women with endometriosis have a reduced incidence of stage I disease; however, stratifying our analysis into stage I endometriosis versus combined II, III and IV endometriosis failed to reveal any differentially expressed endometrial genes between normal, pre-obese and obese patients.

CONCLUSIONS

Despite obesity having deleterious effects on endometrial gene expression in other gynaecological pathologies, e.g. endometrial cancer and polycystic ovary syndrome, our results do not support an association between BMI and altered endometrial gene expression in women with or without endometriosis.

Tissue specific regulation of transcription in endometrium and association with disease

STUDY QUESTION

Are genetic effects on endometrial gene expression tissue specific and/or associated with reproductive traits and diseases?

SUMMARY ANSWER

Analyses of RNA-sequence data and individual genotype data from the endometrium identified novel and disease associated, genetic mechanisms regulating gene expression in the endometrium and showed evidence that these mechanisms are shared across biologically similar tissues.

WHAT IS KNOWN ALREADY

The endometrium is a complex tissue vital for female reproduction and is a hypothesized source of cells initiating endometriosis. Understanding genetic regulation specific to, and shared between, tissue types can aid the identification of genes involved in complex genetic diseases.

STUDY DESIGN, SIZE, DURATION

RNA-sequence and genotype data from 206 individuals was analysed and results were compared with large publicly available datasets.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA-sequencing and genotype data from 206 endometrial samples was used to identify the influence of genetic variants on gene expression, via expression quantitative trait loci (eQTL) analysis and to compare these endometrial eQTLs with those in other tissues. To investigate the association between endometrial gene expression regulation and reproductive traits and diseases, we conducted a tissue enrichment analysis, transcriptome-wide association study (TWAS) and summary data-based Mendelian randomisation (SMR) analyses. Transcriptomic data was used to test differential gene expression between women with and without endometriosis.

MAIN RESULTS AND THE ROLE OF CHANCE

A tissue enrichment analysis with endometriosis genome-wide association study summary statistics showed that genes surrounding endometriosis risk loci were significantly enriched in reproductive tissues. A total of 444 sentinel cis-eQTLs (P < 2.57 × 10-9) and 30 trans-eQTLs (P < 4.65 × 10-13) were detected, including 327 novel cis-eQTLs in endometrium. A large proportion (85%) of endometrial eQTLs are present in other tissues. Genetic effects on endometrial gene expression were highly correlated with the genetic effects on reproductive (e.g. uterus, ovary) and digestive tissues (e.g. salivary gland, stomach), supporting a shared genetic regulation of gene expression in biologically similar tissues. The TWAS analysis indicated that gene expression at 39 loci is associated with endometriosis, including five known endometriosis risk loci. SMR analyses identified potential target genes pleiotropically or causally associated with reproductive traits and diseases including endometriosis. However, without taking account of genetic variants, a direct comparison between women with and without endometriosis showed no significant difference in endometrial gene expression.

LARGE SCALE DATA

The eQTL dataset generated in this study is available at http://reproductivegenomics.com.au/shiny/endo_eqtl_rna/. Additional datasets supporting the conclusions of this article are included within the article and the supplementary information files, or are available on reasonable request.

LIMITATIONS, REASONS FOR CAUTION

Data are derived from fresh tissue samples and expression levels are an average of expression from different cell types within the endometrium. Subtle cell-specifc expression changes may not be detected and differences in cell composition between samples and across the menstrual cycle will contribute to sample variability. Power to detect tissue specific eQTLs and differences between women with and without endometriosis was limited by the sample size in this study. The statistical approaches used in this study identify the likely gene targets for specific genetic risk factors, but not the functional mechanism by which changes in gene expression may influence disease risk.

WIDER IMPLICATIONS OF THE FINDINGS

Our results identify novel genetic variants that regulate gene expression in endometrium and the majority of these are shared across tissues. This allows analysis with large publicly available datasets to identify targets for female reproductive traits and diseases. Much larger studies will be required to identify genetic regulation of gene expression that will be specific to endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Health and Medical Research Council (NHMRC) under project grants GNT1026033, GNT1049472, GNT1046880, GNT1050208, GNT1105321, GNT1083405 and GNT1107258. G.W.M is supported by a NHMRC Fellowship (GNT1078399). J.Y is supported by an ARC Fellowship (FT180100186). There are no competing interests.

Genotype-free demultiplexing of pooled single-cell RNA-seq

A variety of methods have been developed to demultiplex pooled samples in a single cell RNA sequencing (scRNA-seq) experiment which either require hashtag barcodes or sample genotypes prior to pooling. We introduce scSplit which utilizes genetic differences inferred from scRNA-seq data alone to demultiplex pooled samples. scSplit also enables mapping clusters to original samples. Using simulated, merged, and pooled multi-individual datasets, we show that scSplit prediction is highly concordant with demuxlet predictions and is highly consistent with the known truth in cell-hashing dataset. scSplit is ideally suited to samples without external genotype information and is available at: https://github.com/jon-xu/scSplit.

Should Genetics Now Be Considered the Pre-eminent Etiologic Factor in Endometriosis?

Endometriosis is a common, estrogen-dependent, inflammatory disorder characterized by the growth of endometrial-like tissue at extrauterine locations. Its pathogenesis and mechanisms underlying its pathophysiology are poorly understood, although genetic variation is strongly implicated in these processes. Genetic studies reveal that approximately 50% of risk for endometriosis is due to genetic factors and the other 50% likely owing to environmental factors. As with other complex diseases, genetic variants in the DNA sequence increasing endometriosis risk all have small effects, unlike most single-gene disorders. It is the combinations of these variants adding together that contribute to higher risks for individual women. In addition, recent data on disease lesions demonstrate a high frequency of somatic (likely acquired) mutations, some of which are present in the eutopic endometrium and specifically in the epithelial cell compartment, raising the possibility that abnormal epithelial progenitors in the eutopic endometrium give rise to ectopic disease. Discovery in this field is occurring at a rapid pace, and further definitions of genetic (germline) and environmental (somatic) contributions to the pathogenesis and pathophysiology of this disorder are anticipated soon. These discoveries are expected to increase diagnostic, therapeutic, and preventive strategies to minimize disease and its associated morbidities.

Genome-wide association and epidemiological analyses reveal common genetic origins between uterine leiomyomata and endometriosis

Uterine leiomyomata (UL) are the most common neoplasms of the female reproductive tract and primary cause for hysterectomy, leading to considerable morbidity and high economic burden. Here we conduct a GWAS meta-analysis in 35,474 cases and 267,505 female controls of European ancestry, identifying eight novel genome-wide significant (P < 5 × 10^-8) loci, in addition to confirming 21 previously reported loci, including multiple independent signals at 10 loci. Phenotypic stratification of UL by heavy menstrual bleeding in 3409 cases and 199,171 female controls reveals genome-wide significant associations at three of the 29 UL loci: 5p15.33 (TERT), 5q35.2 (FGFR4) and 11q22.3 (ATM). Four loci identified in the meta-analysis are also associated with endometriosis risk; an epidemiological meta-analysis across 402,868 women suggests at least a doubling of risk for UL diagnosis among those with a history of endometriosis. These findings increase our understanding of genetic contribution and biology underlying UL development, and suggest overlapping genetic origins with endometriosis.

Genetic regulation of methylation in human endometrium and blood and gene targets for reproductive diseases

Background

Major challenges in understanding the functional consequences of genetic risk factors for human disease are which tissues and cell types are affected and the limited availability of suitable tissue. The aim of this study was to evaluate tissue-specific genotype-epigenetic characteristics in DNA samples from both endometrium and blood collected from women at different stages of the menstrual cycle and relate results to genetic risk factors for reproductive traits and diseases.

Results

We analysed DNA methylation (DNAm) data from endometrium and blood samples from 66 European women. Methylation profiles were compared between stages of the menstrual cycle, and changes in methylation overlaid with changes in transcription and genotypes. We observed large changes in methylation (27,262 DNAm probes) across the menstrual cycle in endometrium that were not observed in blood. Individual genotype data was tested for association with methylation at 443,016 and 443,101 DNAm probes in endometrium and blood respectively to identify methylation quantitative trait loci (mQTLs). A total of 4546 sentinel cis-mQTLs (P < 1.13 × 10⁻¹⁰) and 434 sentinel trans-mQTLs (P < 2.29 × 10⁻¹²) were detected in endometrium and 6615 sentinel cis-mQTLs (P < 1.13 × 10⁻¹⁰) and 590 sentinel trans-mQTLs (P < 2.29 × 10⁻¹²) were detected in blood. Following secondary analyses, conducted to test for overlap between mQTLs in the two tissues, we found that 62% of endometrial cis-mQTLs were also observed in blood and the genetic effects between tissues were highly correlated. A number of mQTL SNPs were associated with reproductive traits and diseases, including one mQTL located in a known risk region for endometriosis (near GREB1).

Conclusions

We report novel findings characterising genetic regulation of methylation in endometrium and the association of endometrial mQTLs with endometriosis risk and other reproductive traits and diseases. The high correlation of genetic effects between tissues highlights the potential to exploit the power of large mQTL datasets in endometrial research and identify target genes for functional studies. However, tissue-specific methylation profiles and genetic effects also highlight the importance of also using disease-relevant tissues when investigating molecular mechanisms of disease risk.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0648-7) contains supplementary material, which is available to authorized users.

Genetic Variation at Chromosome 2q13 and Its Potential Influence on Endometriosis Susceptibility Through Effects on the IL-1 Family

Endometriosis is characterized by the growth of epithelial and stromal cells outside the uterine cavity. It has a complex etiology and affects ∼10% of reproductive age women. It is accompanied by a chronic inflammatory response with substantial evidence to indicate genetic susceptibility. The causal genes and their pathways leading to endometriosis, however, are still unknown. Recently, genomewide association studies on endometriosis identified 14 genomic risk loci in women of European and Japanese ancestry. It is becoming increasingly clear that these risk regions are intergenic and thus contribute to disease susceptibility through regulatory mechanisms, most likely mediated through regulation of genes within a restricted distance from the risk variants. One endometriosis risk locus has been detected at chromosome 2q13 within an inflammatory-rich region of gene transcripts and thus may play a role in the inflammation component of the disease. We carried out detailed analysis of the genomic region 250 kb on either side of sentinel SNP rs10167914 and identified 21 transcripts which contained 6 interleukin (IL)-1 family genes, 3 previously reported coding genes that have a relationship to inflammation, 4 novel coding, or pseudogenes, and 8 noncoding RNA transcripts. Through an extensive literature search, we examined the roles these genes and their resultant proteins play in endometriosis pathogenesis. The results suggest alteration in the expression the IL-1 family transcripts either alone or as a complex milieu could have a significant influence on endometriosis and should be prioritized for future study on the implications of inflammation on endometriotic lesions.

Rubella antibody status of patients attending a south-west London antenatal clinic, 2007-2012

Mass vaccination with the measles-mumps-rubella (MMR) vaccine for children aged 12-15 months was introduced in 1988; schoolgirl vaccination was discontinued in 1996 and replaced by a second dose of MMR for preschool children and post-partum vaccination of susceptible women identified through antenatal testing. In the UK, declining uptake rates due to concerns about the MMR vaccine, and increasing numbers of cases in some European countries where rubella surveillance and preconceptional vaccination are inadequate, coupled with poor uptake rates, has started to show in the number of rubella-susceptible patients presenting at antenatal clinics (ANCs). In this study, samples were collected in serum separator tubes at the West Middlesex University Hospital (WMUH) ANC and sent to the laboratory. Rubella status was determined using a third-generation rubella IgG enzyme immunoassay. Any negative results were retested and confirmed using an alternative method. The concentrations were expressed as iu/mL (World Health Organization [WHO] standard). Over a five-year period, the number of rubella-susceptible patients increased from 4.1% to 6.8% of the total number of specimens tested. The current population susceptibility levels seem to be influenced by a number of factors: the target population, age at vaccination and the level of coverage, and exposure to wild virus.

Hybrid capture as a means of detecting human papillomavirus DNA from liquid-based cytology specimens: a preliminary evaluation

The connection between human papillomavirus (HPV) and cervical cancer is well documented, as is the benefit of an adjunctive, standardised objective test to complement cervical screening. Here, 197 liquid-based cytology (LBC) specimens previously processed for cytological examination (75 negative, 108 borderline/mild dyskaryosis, and 14 moderate/severe dyskaryosis) are examined for the presence of HPV using a hybrid capture assay. Of the 197 specimens tested for HPV DNA, 97 (49.2%) were positive using the combined high/low-risk probe, and 59 (29.9%) were negative cytologically and with the hybrid capture HPV test; however, 16/175 (21.3%) specimens classified as negative cytologically with LBC proved positive for HPV by hybrid capture. Of the 122 samples that showed abnormal cytology, 81 (66.4%) were positive for HPV. Although the number of samples tested is small, the results show that the use of LBC technology for both cervical cytological screening and the hybrid capture test has the potential to reduce both false-negative and -positive rates associated with cytological screening alone.