Genetic markers of ovarian follicle number and menopause in women of multiple ethnicities

Enhancing Genomic Prediction Accuracy for Body Conformation Traits in Korean Holstein Cattle

The Holstein breed is the mainstay of dairy production in Korea. In this study, we evaluated the genomic prediction accuracy for body conformation traits in Korean Holstein cattle, using a range of π levels (0.75, 0.90, 0.99, and 0.995) in Bayesian methods (BayesB and BayesC). Focusing on 24 traits, we analyzed the impact of different π levels on prediction accuracy. We observed a general increase in accuracy at higher levels for specific traits, with variations depending on the Bayesian method applied. Notably, the highest accuracy was achieved for rear teat angle when using deregressed estimated breeding values including parent average as a response variable. We further demonstrated that incorporating parent average into deregressed estimated breeding values enhances genomic prediction accuracy, showcasing the effectiveness of the model in integrating both offspring and parental genetic information. Additionally, we identified 18 significant window regions through genome-wide association studies, which are crucial for future fine mapping and discovery of causal mutations. These findings provide valuable insights into the efficiency of genomic selection for body conformation traits in Korean Holstein cattle and highlight the potential for advancements in the prediction accuracy using larger datasets and more sophisticated genomic models.

Multiomics insights into the female reproductive aging

The human female reproductive lifespan significantly diminishes with age, leading to decreased fertility, reduced fertility quality and endocrine function disorders. While many aspects of aging in general have been extensively documented, the precise mechanisms governing programmed aging in the female reproductive system remain elusive. Recent advancements in omics technologies and computational capabilities have facilitated the emergence of multiomics deep phenotyping. Through the application and refinement of various high-throughput omics methods, a substantial volume of omics data has been generated, deepening our comprehension of the pathogenesis and molecular underpinnings of reproductive aging. This review highlights current and emerging multiomics approaches for investigating female reproductive aging, encompassing genomics, epigenomics, transcriptomics, proteomics, metabolomics, and microbiomics. We elucidate their influence on fundamental cell biology and translational research in the context of reproductive aging, address the limitations and current challenges associated with multiomics studies, and offer a glimpse into future prospects.

The Role of Anti-Müllerian Hormone in Ovarian Function

Anti-Müllerian hormone (AMH) is a member of the transforming growth factor β (TGFβ) superfamily, whose actions are restricted to the endocrine-reproductive system. Initially known for its role in male sex differentiation, AMH plays a role in the ovary, acting as a gatekeeper in folliculogenesis by regulating the rate of recruitment and growth of follicles. In the ovary, AMH is predominantly expressed by granulosa cells of preantral and antral follicles (i.e., post primordial follicle recruitment and prior to follicle-stimulating hormone (FSH) selection). AMH signals through a BMP-like signaling pathway in a manner distinct from other TGFβ family members. In this review, the latest insights in AMH processing, signaling, its regulation of spatial and temporal expression pattern, and functioning in folliculogenesis are summarized. In addition, effects of AMH variants on ovarian function are reviewed.

Current Insights in Prolactin Signaling and Ovulatory Function

Prolactin (PRL) is a pleiotropic hormone released from lactotrophic cells of the anterior pituitary gland that also originates from extrapituitary sources and plays an important role in regulating lactation in mammals, as well as other actions. Acting in an endocrine and paracrine/autocrine manner, PRL regulates the hypothalamic-pituitary-ovarian axis, thus influencing the maturation of ovarian follicles and ovulation. This review provides a detailed discussion of the current knowledge on the role of PRL in the context of ovulation and ovulatory disorders, particularly with regard to hyperprolactinemia, which is one of the most common causes of infertility in women. Much attention has been given to the PRL structure and the PRL receptor (PRLR), as well as the diverse functions of PRLR signaling under normal and pathological conditions. The hormonal regulation of the menstrual cycle in connection with folliculogenesis and ovulation, as well as the current classifications of ovulation disorders, are also described. Finally, the state of knowledge regarding the importance of TIDA (tuberoinfundibular dopamine), KNDγ (kisspeptin/neurokinin B/dynorphin), and GnRH (gonadotropin-releasing hormone) neurons in PRL- and kisspeptin (KP)-dependent regulation of the hypothalamic-pituitary-gonadal (HPG) axis in women is reviewed. Based on this review, a rationale for influencing PRL signaling pathways in therapeutic activities accompanying ovulation disorders is presented.

Genome-wide association study of anogenital distance and its (co)variances with fertility in growing and lactating Holstein-Friesian dairy cattle

Anogenital distance (AGD) is a moderately heritable trait that can be measured at a young age that may provide an opportunity to indirectly select for improved fertility in dairy cattle. In this study, we characterized AGD and its genetic and phenotypic relationships with a range of body stature and fertility traits. We measured AGD, shoulder height, body length, and body weight in a population of 5,010 Holstein-Friesian and Holstein-Friesian × Jersey crossbred heifers at approximately 11 mo of age (AGD1). These animals were born in 2018 across 54 seasonal calving, pasture-based dairy herds. A second measure of AGD was collected in a subset of herds (n = 17; 1,956 animals) when the animals averaged 29 mo of age (AGD2). Fertility measures included age at puberty (AGEP), then time of calving, breeding, and pregnancy during the first and second lactations. We constructed binary traits reflecting the animal's ability to calve during the first 42 d of their herd's seasonal calving period (CR42), be presented for breeding during the first 21 d of the seasonal breeding period (PB21) and become pregnant during the first 42 d of the seasonal breeding period (PR42). The posterior mean of sampled heritabilities for AGD1 was 0.23, with 90% of samples falling within a credibility interval (90% CRI) of 0.20 to 0.26, whereas the heritability of AGD2 was 0.29 (90% CRI 0.24 to 0.34). The relationship between AGD1 and AGD2 was highly positive, with a genetic correlation of 0.89 (90% CRI 0.82 to 0.94). Using a GWAS analysis of 2,460 genomic windows based on 50k genotype data, we detected a region on chromosome 20 that was highly associated with variation in AGD1, and a second region on chromosome 13 that was moderately associated with variation in AGD1. We did not detect any genomic regions associated with AGD2 which was measured in fewer animals. The genetic correlation between AGD1 and AGEP was 0.10 (90% CRI 0.00 to 0.19), whereas the genetic correlation between AGD2 and AGEP was 0.30 (90% CRI 0.15 to 0.44). The timing of calving, breeding, and pregnancy (CR42, PB21, and PR42) during first or second lactations exhibited moderate genetic relationships with AGD1 (0.19 to 0.52) and AGD2 (0.46 to 0.63). Genetic correlations between AGD and body stature traits were weak (≤0.16). We conclude that AGD is a moderately heritable trait, which may have value as an early-in-life genetic predictor for reproductive success during lactation.

Molecular functions of MCM8 and MCM9 and their associated pathologies

Minichromosome Maintenance 8 Homologous Recombination Repair Factor (MCM8) and Minichromosome Maintenance 9 Homologous Recombination Repair Factor (MCM9) are recently discovered minichromosome maintenance proteins and are implicated in multiple DNA-related processes and pathologies, including DNA replication (initiation), meiosis, homologous recombination and mismatch repair. Consistent with these molecular functions, variants of MCM8/MCM9 may predispose carriers to disorders such as infertility and cancer and should therefore be included in relevant diagnostic testing. In this overview of the (patho)physiological functions of MCM8 and MCM9 and the phenotype of MCM8/MCM9 variant carriers, we explore the potential clinical implications of MCM8/MCM9 variant carriership and highlight important future directions of MCM8 and MCM9 research. With this review, we hope to contribute to better MCM8/MCM9 variant carrier management and the potential utilization of MCM8 and MCM9 in other facets of scientific research and medical care.

Anti-Müllerian Hormone and Cardiometabolic Disease in Women: A Two-Sample Mendelian Randomization Study

Background

Higher age-specific circulating anti-Müllerian hormone (AMH) levels have been linked to a lower risk of cardiometabolic outcomes. However, whether AMH has a casual role in the etiology of these diseases is unknown. The objective of this study was therefore to explore if circulating AMH levels have a causal effect on risk of coronary artery disease (CAD), ischemic stroke and type 2 diabetes (T2D) in women, using a two-sample Mendelian randomization (MR) approach.

Methods

We used four single nucleotide polymorphisms (SNPs) from the most recent AMH GWAS meta-analysis as instrumental variables. Summary-level data for CAD (n = 149,752; 11,802 cases), ischemic stroke (n = 17,541; 4678 cases) and T2D (n = 464,389; 30,052 cases) were extracted from the UK Biobank, the Stroke Genetics Network, and DIAMANTE consortia, respectively. To assess the presence of potential pleiotropy we tested the association of the four AMH SNPs, both individually and combined in a weighted genetic risk score, with a range of cardiovascular risk factors and intermediate traits using UK Biobank data.

Results

MR estimates, i.e., inverse variance-weighted odds ratios ( OR IVW ), did not support a causal effect of circulating AMH levels on CAD ( OR IVW = 1.13, 95% CI: 0.95-1.35), ischemic stroke ( OR IVW = 1.11, 95% CI: 0.83-1.49), and T2D ( OR IVW = 0.98, 95% CI: 0.87-1.10). After adjustment for multiple testing, we observed associations between genetically predicted AMH and age at menopause, and age at menarche, but not with intermediate traits on the causal pathway between AMH and cardiometabolic health, such as atherosclerosis or glucose levels.

Conclusions

This study does not provide evidence for a causal effect of circulating AMH levels on CAD, ischemic stroke and T2D in women, although weak instrument bias cannot be excluded.

Genome-wide association study meta-analysis identifies three novel loci for circulating anti-Müllerian hormone levels in women

STUDY QUESTION

Can additional genetic variants for circulating anti-Müllerian hormone (AMH) levels be identified through a genome-wide association study (GWAS) meta-analysis including a large sample of premenopausal women?

SUMMARY ANSWER

We identified four loci associated with AMH levels at P < 5 × 10-8: the previously reported MCM8 locus and three novel signals in or near AMH, TEX41 and CDCA7.

WHAT IS KNOWN ALREADY

AMH is expressed by antral stage ovarian follicles in women, and variation in age-specific circulating AMH levels has been associated with disease outcomes. However, the physiological mechanisms underlying these AMH-disease associations are largely unknown.

STUDY DESIGN, SIZE, DURATION

We performed a GWAS meta-analysis in which we combined summary statistics of a previous AMH GWAS with GWAS data from 3705 additional women from three different cohorts.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, we included data from 7049 premenopausal female participants of European ancestry. The median age of study participants ranged from 15.3 to 48 years across cohorts. Circulating AMH levels were measured in either serum or plasma samples using different ELISA assays. Study-specific analyses were adjusted for age at blood collection and population stratification, and summary statistics were meta-analysed using a standard error-weighted approach. Subsequently, we functionally annotated GWAS variants that reached genome-wide significance (P < 5 × 10-8). We also performed a gene-based GWAS, pathway analysis and linkage disequilibrium score regression and Mendelian randomization (MR) analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified four loci associated with AMH levels at P < 5 × 10-8: the previously reported MCM8 locus and three novel signals in or near AMH, TEX41 and CDCA7. The strongest signal was a missense variant in the AMH gene (rs10417628). Most prioritized genes at the other three identified loci were involved in cell cycle regulation. Genetic correlation analyses indicated a strong positive correlation among single nucleotide polymorphisms for AMH levels and for age at menopause (rg = 0.82, FDR = 0.003). Exploratory two-sample MR analyses did not support causal effects of AMH on breast cancer or polycystic ovary syndrome risk, but should be interpreted with caution as they may be underpowered and the validity of genetic instruments could not be extensively explored.

LARGE SCALE DATA

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

LIMITATIONS, REASONS FOR CAUTION

Whilst this study doubled the sample size of the most recent GWAS, the statistical power is still relatively low. As a result, we may still lack power to identify more genetic variants for AMH and to determine causal effects of AMH on, for example, breast cancer. Also, follow-up studies are needed to investigate whether the signal for the AMH gene is caused by reduced AMH detection by certain assays instead of actual lower circulating AMH levels.

WIDER IMPLICATIONS OF THE FINDINGS

Genes mapped to the MCM8, TEX41 and CDCA7 loci are involved in the cell cycle and processes such as DNA replication and apoptosis. The mechanism underlying their associations with AMH may affect the size of the ovarian follicle pool. Altogether, our results provide more insight into the biology of AMH and, accordingly, the biological processes involved in ovarian ageing.

STUDY FUNDING/COMPETING INTEREST(S)

Nurses' Health Study and Nurses' Health Study II were supported by research grants from the National Institutes of Health (CA172726, CA186107, CA50385, CA87969, CA49449, CA67262, CA178949). The UK Medical Research Council and Wellcome (217065/Z/19/Z) and the University of Bristol provide core support for ALSPAC. This publication is the work of the listed authors, who will serve as guarantors for the contents of this article. A comprehensive list of grants funding is available on the ALSPAC website (http://www.bristol.ac.uk/alspac/external/documents/grant-acknowledgements.pdf). Funding for the collection of genotype and phenotype data used here was provided by the British Heart Foundation (SP/07/008/24066), Wellcome (WT092830M and WT08806) and UK Medical Research Council (G1001357). M.C.B., A.L.G.S. and D.A.L. work in a unit that is funded by the University of Bristol and UK Medical Research Council (MC_UU_00011/6). M.C.B.'s contribution to this work was funded by a UK Medical Research Council Skills Development Fellowship (MR/P014054/1) and D.A.L. is a National Institute of Health Research Senior Investigator (NF-0616-10102). A.L.G.S. was supported by the study of Dynamic longitudinal exposome trajectories in cardiovascular and metabolic non-communicable diseases (H2020-SC1-2019-Single-Stage-RTD, project ID 874739). The Doetinchem Cohort Study was financially supported by the Ministry of Health, Welfare and Sports of the Netherlands. The funder had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. Ansh Labs performed the AMH measurements for the Doetinchem Cohort Study free of charge. Ansh Labs was not involved in the data analysis, interpretation or reporting, nor was it financially involved in any aspect of the study. R.M.G.V. was funded by the Honours Track of MSc Epidemiology, University Medical Center Utrecht with a grant from the Netherlands Organization for Scientific Research (NWO) (022.005.021). The Study of Women's Health Across the Nation (SWAN) has grant support from the National Institutes of Health (NIH), DHHS, through the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR) and the NIH Office of Research on Women's Health (ORWH) (U01NR004061; U01AG012505, U01AG012535, U01AG012531, U01AG012539, U01AG012546, U01AG012553, U01AG012554, U01AG012495). The SWAN Genomic Analyses and SWAN Legacy have grant support from the NIA (U01AG017719). The Generations Study was funded by Breast Cancer Now and the Institute of Cancer Research (ICR). The ICR acknowledges NHS funding to the NIHR Biomedical Research Centre. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent official views of the funders. The Sister Study was funded by the Intramural Research Program of the National Institutes of Health (NIH), National Institute of Environmental Health Sciences (Z01-ES044005 to D.P.S.); the AMH assays were supported by the Avon Foundation (02-2012-065 to H.B. Nichols and D.P.S.). The breast cancer genome-wide association analyses were supported by the Government of Canada through Genome Canada and the Canadian Institutes of Health Research, the 'Ministère de l'Économie, de la Science et de l'Innovation du Québec' through Genome Québec and grant PSR-SIIRI-701, The National Institutes of Health (U19 CA148065, X01HG007492), Cancer Research UK (C1287/A10118, C1287/A16563, C1287/A10710) and The European Union (HEALTH-F2-2009-223175 and H2020 633784 and 634935). All studies and funders are listed in Michailidou et al. (Nature, 2017). F.J.M.B. has received fees and grant support from Merck Serono and Ferring BV. D.A.L. has received financial support from several national and international government and charitable funders as well as from Medtronic Ltd and Roche Diagnostics for research that is unrelated to this study. N.S. is scientific consultant for Ansh Laboratories. The other authors declare no competing interests.

Effect of cigarette smoking on serum anti-Mullerian hormone and antral follicle count in women seeking fertility treatment: a prospective cross-sectional study

OBJECTIVES

The relationship between smoking and ovarian reserve markers is inconclusive. The primary objective of our study was to assess the effect of cigarette smoking on the quantitative ovarian reserve parameters, serum anti-Mullerian hormone (AMH) and antral follicle count (AFC) as relevant to prediction of fertility outcomes in women seeking fertility treatment. Our secondary aims were to validate self-reported smoking behaviour using biomarkers and evaluate the association between biomarkers of ovarian reserve (serum AMH and AFC) with biomarkers of smoking exposure (breath carbon monoxide (CO) and urine cotinine levels).

DESIGN

Prospective, cross-sectional study.

SETTING

Single tertiary care fertility centre.

PARTICIPANTS

Women ≤35 years seeking fertility treatment.

PRIMARY OUTCOME MEASURES

Serum AMH and AFC.

RESULTS

Significant differences were found among current smokers, ex-smokers and never smokers for breath CO (F(2,97)=33.32, p<0.0001) and urine cotinine levels (p<0.001). However, no significant differences were found either for serum AMH (F(2,91)=1.19, p=0.309) or total AFC (F(2,81)=0.403, p=0.670) among the three groups. There was no significant correlation between pack years of smoking and serum AMH (r=-0.212, n=23, p=0.166) or total AFC (r=-0.276, n=19, p=0.126). No significant correlation was demonstrated between breath CO and serum AMH (r=0.082, n=94, p=0.216) or total AFC (r=0.096, n=83, p=0.195). Similarly, no significant correlation was demonstrated between urine cotinine levels and serum AMH (r=0.146, n=83, p=0.095) or total AFC (r=-0.027, n=77, p=0.386).

CONCLUSION

We did not find a statistically significant difference in quantitative ovarian reserve markers between current smokers, ex-smokers and never smokers which would be clinically meaningful in our study population. We confirmed that self-reported smoking correlates well with quantitatively measured biomarkers of smoking. This validated the self-reported comparison groups to ensure a valid comparison of outcome measures. There was no significant association between biomarkers of smoking and biomarkers of ovarian reserve. We were also unable to demonstrate a correlation between the lifetime smoking exposure and ovarian reserve.

A kaleidoscopic view of ovarian genes associated with premature ovarian insufficiency and senescence

Ovarian infertility and subfertility presenting with premature ovarian insufficiency (POI) and diminished ovarian reserve are major issues facing the developed world due to the trend of delaying childbirth. Ovarian senescence and POI represent a continuum of physiological/pathophysiological changes in ovarian follicle functions. Based on advances in whole exome sequencing, evaluation of gene copy variants, together with family-based and genome-wide association studies, we discussed genes responsible for POI and ovarian senescence. We used a gene-centric approach to sort out literature deposited in the Ovarian Kaleidoscope database (http://okdb.appliedbioinfo.net) by sub-categorizing candidate genes as ligand-receptor signaling, meiosis and DNA repair, transcriptional factors, RNA metabolism, enzymes, and others. We discussed individual gene mutations found in POI patients and verification of gene functions in gene-deleted model organisms. Decreased expression of some of the POI genes could be responsible for ovarian senescence, especially those essential for DNA repair, meiosis and mitochondrial functions. We propose to set up a candidate gene panel for targeted sequencing in POI patients together with studies on mitochondria-associated genes in middle-aged subfertile patients.

Structural study of the N-terminal domain of human MCM8/9 complex

MCM8/9 is a complex involved in homologous recombination (HR) repair pathway. MCM8/9 dysfunction can cause genome instability and result in primary ovarian insufficiency (POI). However, the mechanism underlying these effects is largely unknown. Here, we report crystal structures of the N-terminal domains (NTDs) of MCM8 and MCM9, and build a ring-shaped NTD structure based on a 6.6 Å resolution cryoelectron microscopy map. This shows that the MCM8/9 complex forms a 3:3 heterohexamer in an alternating pattern. A positively charged DNA binding channel and a putative ssDNA exit pathway for fork DNA unwinding are revealed. Based on the atomic model, the potential effects of the clinical POI mutants are interpreted. Surprisingly, the zinc-finger motifs are found to be capable of binding an iron atom as well. Overall, our results provide a model for the formation of the MCM8/9 complex and provide a path for further studies.

Current Approaches to Fertility Preservation

The 5 principal reasons a patient may consider fertility preservation are: treatment for cancer that may affect fertility, treatment for nonmalignant medical conditions that may affect fertility, planned indications, planned gender-affirming hormone therapy or surgery, or in the setting of genetic conditions that may increase the risks of premature ovarian insufficiency or early menopause. This paper will focus on describing who may consider preserving their fertility, how to provide the best clinical evaluation of those seeking fertility preservation, and current and future fertility preservation techniques. Last, we will highlight a need to continue to expand access to fertility preservation technologies.

Genome-wide association study meta-analysis identifies three novel loci for circulating anti-Müllerian hormone levels in women

Anti-Müllerian hormone (AMH) is expressed by antral stage ovarian follicles in women. Consequently, circulating AMH levels are detectable until menopause. Variation in age-specific AMH levels has been associated with breast cancer and polycystic ovary syndrome (PCOS), amongst other diseases. Identification of genetic variants underlying variation in AMH levels could provide clues about the physiological mechanisms that explain these AMH-disease associations. To date, only one variant in MCM8 has been identified to be associated with circulating AMH levels in women. We aimed to identify additional variants for AMH through a GWAS meta-analysis including data from 7049 premenopausal women of European ancestry, which more than doubles the sample size of the largest previous GWAS. We identified four loci associated with AMH levels at p < 5×10 -8 : the previously reported MCM8 locus and three novel signals in or near AMH, TEX41 , and CDCA7 . The strongest signal was a missense variant in the AMH gene (rs10417628). Most prioritized genes at the other three identified loci were involved in cell cycle regulation. Genetic correlation analyses indicated a strong positive correlation among SNPs for AMH levels and for age at menopause (r g = 0.82, FDR=0.003). Exploratory Mendelian randomization analyses did not support a causal effect of AMH on breast cancer or PCOS risk, but should be interpreted with caution as they may be underpowered and the validity of genetic instruments could not be extensively explored. In conclusion, we identified a variant in the AMH gene and three other loci that may affect circulating AMH levels in women.

Hippo signaling disruption and ovarian follicle activation in infertile patients

The Hippo signaling pathway, which is important in organ size regulation, is present in organisms from the fly to mammals. Disruption of the Hippo signaling pathway leads to increased nuclear translocation of the effector Yes-associated protein (YAP), resulting in the expression of cystein-rich 61, connective tissue growth factor, and nephroblastoma overexpressed (CCN) growth factors and baculoviral inhibitors of apoptosis repeat containing (BIRC) apoptosis inhibitors to increase organ sizes. Furthermore, genome-wide knockdown of genes in insect cells demonstrated that actin polymerization promoted nuclear translocation of YAP. In the mammalian ovary, we demonstrated the expression of Hippo signaling pathway genes and showed that ovarian fragmentation increased actin polymerization, leading to YAP nuclear translocation and increased expression of cystein-rich 61, CCN growth factors and BIRC apoptosis inhibitors, followed by enhanced follicle growth. Here we summarize evidence suggesting the role of mechanical stress on follicle growth in the ovary and describe recent use of ovary-damaging procedures to treat ovarian infertility. Ovarian fragmentation, together with in vitro incubation with Akt-stimulating drugs, formed the basis of an in vitro activation (IVA) therapy to treat patients with premature ovarian insufficiency, whereas ovarian fragmentation alone (drug-free IVA) was successful in treating patients with premature ovarian insufficiency with recent menses cessation. For middle-aged women with poor ovarian responses and diminished ovarian reserve, drug-free IVA was also effective in promoting follicle growth for infertility treatment. In addition, an in vivo follicle activation approach based on laparoscopic ovarian incision showed promise for patients with resistant ovary syndrome. With initial success using mechanical disruption approaches, future investigation could evaluate possibilities to refine mechanical methods and to locally administer actin polymerization-enhancing drugs for ovarian infertility treatment.

Discovery of polypeptide ligand-receptor pairs based on their co-evolution

Sequencing diverse genomes allowed the tracing of orthologous and paralogous genes to understand the co-evolution of polypeptide ligands and receptors. This review documents the discovery of several polypeptide ligands and their cognate receptors mainly expressed in the reproductive tissue using evolutionary genomics. We discussed the sub-functionization of paralogs and co-evolution of ligand-receptor families. Based on the conserved signaling among paralogous receptors and common knock-out phenotypes of ligand-receptor pairs, relationships between relaxin family peptides and leucine-rich repeat-containing, G protein-coupled receptors (LGR) were revealed. We also described the identification of a novel paralogous glycoprotein hormone thyrostimulin and design of a long-acting FSH. Human stresscopin and stresscopin-related peptide, paralogous to CRH, were also identified based on the conserved signaling pathways. Recently, a novel ligand placensin expressed in human placenta was found based on the paralogous relationship with a metabolic hormone asprosin. Placensin likely contributes to stage-dependent increases in insulin resistance during human pregnancy and its elevated secretion was associated with gestational diabetes mellitus. Although many ligands were predicted based on sequence signatures, ligands of shorter sequences have not been identified, together with many "orphan" receptors without known ligands. Future development of tools for predicting ligands and high throughput assays to identify ligand-receptor pairs based on ligand binding and/or signal transduction could advance hormone-based physiology and pathophysiology.

Demographic and evolutionary trends in ovarian function and aging

BACKGROUND

The human female reproductive lifespan is regulated by the dynamics of ovarian function, which in turn is influenced by several factors: from the basic molecular biological mechanisms governing folliculogenesis, to environmental and lifestyle factors affecting the ovarian reserve between conception and menopause. From a broader point of view, global and regional demographic trends play an additional important role in shaping the female reproductive lifespan, and finally, influences on an evolutionary scale have led to the reproductive senescence that precedes somatic senescence in humans.

OBJECTIVE AND RATIONALE

The narrative review covers reproductive medicine, by integrating the molecular mechanisms of ovarian function and aging with short-term demographic and long-term evolutionary trends.

SEARCH METHODS

PubMed and Google Scholar searches were performed with relevant keywords (menopause, folliculogenesis, reproductive aging, reproductive lifespan and life history theory). The reviewed articles and their references were restricted to those written in English.

OUTCOMES

We discuss and summarize the rapidly accumulating information from large-scale population-based and single-reproductive-cell genomic studies, their constraints and advantages in the context of female reproductive aging as well as their possible evolutionary significance on the life history trajectory from foetal-stage folliculogenesis until cessation of ovarian function in menopause. The relevant environmental and lifestyle factors and demographic trends are also discussed in the framework of predominant evolutionary hypotheses explaining the origin and maintenance of menopause.

WIDER IMPLICATIONS

The high speed at which new data are generated has so far raised more questions than it has provided solid answers and has been paralleled by a lack of satisfactory interpretations of the findings in the context of human life history theory. Therefore, the recent flood of data could offer an unprecedented tool for future research to possibly confirm or rewrite human evolutionary reproductive history, at the same time providing novel grounds for patient counselling and family planning strategies.

Genomics of Reproductive Traits and Cardiometabolic Disease Risk in African American Women

BACKGROUND

Age at menarche and age at natural menopause occur significantly earlier in African American women than in other ethnic groups. African American women also have twice the prevalence of cardiometabolic disorders related to the timing of these reproductive traits.

OBJECTIVES

The objectives of this integrative review were to (a) summarize the genome-wide association studies of reproductive traits in African American women, (b) identify genes that overlap with reproductive traits and cardiometabolic risk factors in African American women, and (c) propose biological mechanisms explaining the link between reproductive traits and cardiometabolic risk factors.

METHODS

PubMed was searched for genome-wide association studies of genes associated with reproductive traits in African American women. After extracting and summarizing the primary genes, we examined whether any of the associations with reproductive traits had also been identified with cardiometabolic risk factors in African American women.

RESULTS

Seven studies met the inclusion criteria. Associations with both reproductive and cardiometabolic traits were reported in or near the following genes: FTO, SEC16B, TMEM18, APOE, PHACTR1, KCNQ1, LDLR, PIK3R1, and RORA. Biological pathways implicated include body weight regulation, vascular homeostasis, and lipid metabolism.

DISCUSSION

A better understanding of the genetic basis of reproductive traits in African American women may provide insight into the biological mechanisms linking variation in these traits with increased risk for cardiometabolic disorders in this population.

Genetics of human female infertility†

About 10% of women of reproductive age are unable to conceive or carry a pregnancy to term. Female factors alone account for at least 35% of all infertility cases and comprise a wide range of causes affecting ovarian development, maturation of oocytes, and fertilization competence, as well as the potential of a fertilized egg for preimplantation development, implantation, and fetal growth. Genetic abnormalities leading to infertility in females comprise large chromosome abnormalities, submicroscopic chromosome deletion and duplications, and DNA sequence variations in the genes that control numerous biological processes implicated in oogenesis, maintenance of ovarian reserve, hormonal signaling, and anatomical and functional development of female reproductive organs. Despite the great number of genes implicated in reproductive physiology by the study of animal models, only a subset of these genes is associated with human infertility. In this review, we mainly focus on genetic alterations identified in humans and summarize recent knowledge on the molecular pathways of oocyte development and maturation, the crucial role of maternal-effect factors during embryogenesis, and genetic conditions associated with ovarian dysgenesis, primary ovarian insufficiency, early embryonic lethality, and infertility.

Oncofertility in urologic oncology: Fertility preservation for women undergoing cancer treatment

Thousands of reproductive age women are treated for urologic malignancies each year in the United States. Treatments for advanced bladder and renal cancers have the potential to affect future fertility in female patients. The American Society of Clinical Oncology and the American Society of Reproductive Medicine recognize the importance of fertility preservation, categorizing it as a necessary part of medical care. Iatrogenic infertility has a tremendous impact on quality of life in survivors' of cancer. Fertility preservation counseling and treatment can improve long-term quality of life, therefore access to such counseling and treatment should be expanded.

Links between age at menarche, antral follicle count, and body mass index in African American and European American women

OBJECTIVE

To examine the relationships between age at menarche, antral follicle count (AFC), and body mass index (BMI) in a multi-ethnic population of women.

DESIGN

Community-based, cross-sectional study.

SETTING

Academic setting.

PATIENT(S)

A total of 245 African American women and 273 European American women, aged 25-45 years, with regular menstrual cycles and no reproductive disorders. The ethnicity of these women was self-reported and genetically validated.

INTERVENTION(S)

The AFCs were measured by transvaginal ultrasound during the early follicular phase. Anthropometric measurements were taken, and age at menarche was gathered by questionnaire.

MAIN OUTCOME MEASURE(S)

Determination of the associations between age of menarche and adult AFC and BMI.

RESULT(S)

Earlier age of menarche was associated with both higher BMIs and higher AFCs in adulthood, with control for female age. The antral follicle difference between early (<12 years) vs. late (≥15 years) initiation of menarche in both white and black women was +3.81 and +3.34 follicles, respectively, which is equivalent to an approximately 20% difference in AFC.

CONCLUSION(S)

This study provides the first evidence that timing of menarche may influence AFC. Because of limited studies on African American women, this work provides additional needed data and may enhance our ability to prospectively screen and better treat various diseases associated with the female reproductive lifespan.

Minichromosome maintenance complex component 8 and 9 gene expression in the menstrual cycle and unexplained primary ovarian insufficiency

PURPOSE

DNA repair genes Minichromosome maintenance complex component (MCM) 8 and 9 have been linked with gonadal development, primary ovarian insufficiency (POI), and age at menopause. Our objective was to characterize MCM 8 and 9 gene expression in the menstrual cycle, and to compare MCM 8/9 expression in POI vs normo-ovulatory women.

METHODS

Normo-ovulatory controls (n = 11) and unexplained POI subjects (n = 6) were recruited. Controls provided three blood samples within one menstrual cycle: (1) early follicular phase, (2) ovulation, and (3) mid-luteal phase. Six of 11 controls only provided a follicular phase sample. Amenorrheic POI subjects provided a single, random blood sample. MCM8/9 expression in peripheral blood was assessed with qRTPCR. Analyses were performed using delta-Ct measurements; group differences were transformed to a fold change (FC) and confidence interval (CI). Differences across menstrual cycle phases were compared using random effects ANOVA. Two-sample t tests were used to compare two groups.

RESULTS

MCM8 expression was significantly lower at ovulation and during the luteal phase, when compared to the follicular phase [FC = 0.69 in the luteal vs follicular phase (p = 0.012, CI = 0.53, 0.90); and 0.65 in the ovulatory vs follicular phase (p = 0.0057, CI = 0.50, 0.85)]. No change in MCM9 expression was noted throughout the menstrual cycle. No significant difference was seen in MCM8/9 expression when comparing POI to control subjects.

CONCLUSIONS

Our study showed greater MCM8 expression in the follicular phase of the menstrual cycle, compared to the ovulatory and luteal phases. No cyclic changes were seen with MCM9. Significant differences in MCM8/9 expression were not detected between POI and controls; however, we recommend further investigation with a larger sample population.

Genetic Architecture and Candidate Genes Identified for Follicle Number in Chicken

Follicular development has a major impact on reproductive performance. Most previous researchers focused on molecular mechanisms of follicular development. The genetic architecture underlying the number of follicle, however, has yet not to be thoroughly defined in chicken. Here we report a genome-wide association study for the genetic architecture determining the numbers of follicles in a large F₂ resource population. The results showed heritability were low to moderate (0.05-0.28) for number of pre-ovulatory follicles (POF), small yellow follicles (SYF) and atresia follicles (AF). The highly significant SNPs associated with SYF were mainly located on GGA17 and GGA28. Only four significant SNPs were identified for POF on GGA1. The variance partitioned across chromosomes and chromosome lengths had a linear relationship for SYF (R² = 0.58). The enriched genes created by the closest correspondent significant SNPs were found to be involved in biological pathways related to cell proliferation, cell cycle and cell survival. Two promising candidate genes, AMH and RGS3, were suggested to be prognostic biomarkers for SYF. In conclusion, this study offers the first evidence of genetic variance and positional candidate genes which influence the number of SYF in chicken. These identified informative SNPs may facilitate selection for an improved reproductive performance of laying hens.

Decreased live births among women of Middle Eastern/North African ethnicity compared to Caucasian women

PURPOSE

The objective of this study is to determine if IVF outcome disparities exist among MENA women in the USA in comparison to a control group of Caucasian women.

METHODS

A retrospective cohort study comparing MENA (N = 190) and Caucasian (N = 200) women undergoing their first IVF cycle between 5/2006 and 5/2014 was carried out at an academically affiliated fertility practice. All MENA cycles during that time period undergoing IVF/ICSI using autologous embryos and blastocyst transfers were compared to a control group of Caucasian women.

RESULTS

MENA women were significantly younger (32.9 vs 34.5, P < 0.005) and had a lower BMI (25.2 vs 27.1, P < 0.001). Male factor infertility was higher among partners of MENA women (62 vs 50%, P < 0.05). MENA women experienced decreased live birth rates per blastocyst transfer compared to Caucasian women after controlling for age and BMI (OR 0.55, 95% CI 0.35-0.85 P = 0.007). The odds of a miscarriage were also significantly higher among MENA women (OR 2.55, 95% CI 1.04-6.27 P = 0.036).

CONCLUSION

Middle Eastern/North African women have worse IVF outcomes with decreased live birth rates per blastocyst transfer and increased miscarriage rates compared to Caucasian women.

Age at natural menopause genetic risk score in relation to age at natural menopause and primary open-angle glaucoma in a US-based sample

OBJECTIVE

Several attributes of female reproductive history, including age at natural menopause (ANM), have been related to primary open-angle glaucoma (POAG). We assembled 18 previously reported common genetic variants that predict ANM to determine their association with ANM or POAG.

METHODS

Using data from the Nurses' Health Study (7,143 women), we validated the ANM weighted genetic risk score in relation to self-reported ANM. Subsequently, to assess the relation with POAG, we used data from 2,160 female POAG cases and 29,110 controls in the National Eye Institute Glaucoma Human Genetics Collaboration Heritable Overall Operational Database (NEIGHBORHOOD), which consists of 8 datasets with imputed genotypes to 5.6+ million markers. Associations with POAG were assessed in each dataset, and site-specific results were meta-analyzed using the inverse weighted variance method.

RESULTS

The genetic risk score was associated with self-reported ANM (P = 2.2 × 10) and predicted 4.8% of the variance in ANM. The ANM genetic risk score was not associated with POAG (Odds Ratio (OR) = 1.002; 95% Confidence Interval (CI): 0.998, 1.007; P = 0.28). No single genetic variant in the panel achieved nominal association with POAG (P ≥0.20). Compared to the middle 80 percent, there was also no association with the lowest 10 percentile or highest 90 percentile of genetic risk score with POAG (OR = 0.75; 95% CI: 0.47, 1.21; P = 0.23 and OR = 1.10; 95% CI: 0.72, 1.69; P = 0.65, respectively).

CONCLUSIONS

A genetic risk score predicting 4.8% of ANM variation was not related to POAG; thus, genetic determinants of ANM are unlikely to explain the previously reported association between the two phenotypes.

Reproductive outcome in European and Middle Eastern/North African patients

The aim of this retrospective cohort study was to assess differences in infertility-related baseline characteristics and IVF outcome between European and Middle Eastern/North African (MENA) patients. Of 2703 patients undergoing their first IVF cycle, 2485 were Caucasian of European descent and 218 originated from the MENA region. MENA patients were significantly younger (30.6 versus 34.0 years, P < 0.001), less likely smokers, with higher body mass indexes. Infertility duration was longer in MENA patients (P < 0.001), their male partners were younger (P < 0.001) and smoked more often than European male patients (P = 0.005). Male factor infertility (P = 0.017) and polycystic ovary syndrome (PCOS; P = 0.032) was more prevalent in MENA patients, showed significantly higher basal FSH concentrations (P = 0.012) and significantly fewer oocytes retrieved (RR 0.83, 95% CI 0.74-0.93, P = 0.001). Clinical pregnancy rates were comparable (22.4% [European] versus 22.9% [MENA]). Fewer MENA patients had surplus embryos cryopreserved (OR 0.41, 95% CI 0.22-0.76, P = 0.004). Despite younger age and higher prevalence of PCOS, MENA patients had significantly lower oocyte yields than their European counterparts (P = 0.001). These findings suggest a more rapid decline in ovarian function in women of MENA descent.

Are anti-Müllerian hormone and its receptor polymorphism associated with the hormonal condition of undescended testes?

PURPOSE

Numerous genetic and endocrine factors are involved in the process of testicular descent, but only a few genetic causes have been reported in human. The aim of this study was to investigate the density and distribution of single nucleotide polymorphisms (SNPs) anti-Müllerian hormone (AMH) and AMHRII receptors in cryptorchid patients and determine potential hormone imbalance connected with undescended testes by assessing the levels of AMH, Insulin-like factor 3 (INSL3) and inhibin B.

MATERIALS AND METHODS

The serum hormone levels (AMH, INSL3 and inhibin B) were compared in the two groups - cryptorchidism (n=105) and control group (n=58). The frequency of AMHRII -482 A>G, AMHRII IVS 10+77 A>G, AMHRII IVS 5-6 C>T, and AMH Ile49Ser polymorphisms among cryptorchid boys were compared with the control group.

RESULTS

None of the hormones levels were different between the cryptorchid and the control groups. All cases of IVS 5-6 C>T homozygote and heterozygote mutation were accompanied by an IVS 10+77 A>G and 482 A>G homozygote and heterozygote mutation. Interestingly, in most cases of all four polymorphisms, homozygote recessive genotype was associated with cases of cryptorchidism. However, the groups of patients were too small to draw definite conclusions.

CONCLUSION

The AMHRII -482 A>G, AMHRII IVS 10+77 A>G, AMHRII IVS 5-6 C>T and AMH Ile49Ser genotypes should be determined in a much larger group of boys with cryptorchidism.

Molecular cytogenetic characterization of two Turner syndrome patients with mosaic ring X chromosome

PURPOSE

In the present study, we reported two cases of TS with mosaic ring X chromosome showing common clinical characteristics of TS like growth retardation and ovarian dysfunction. The purpose of the present study was to cytogenetically characterize both cases.

METHODS

Whole blood culture and G-banding were performed for karyotyping the cases following standard protocol. Origin of the ring chromosome and degree of mosaicism were further determined by fluorescence in situ hybridization (FISH). Breakpoints and loss of genetic material in formation of different ring X chromosomes r (X) in cases were determined with the help of cytogenetic microarray.

RESULTS

Cases 1 and 2 with ring chromosome were cytogenetically characterized as 45, X [114]/46Xr (X) (p22.11q21.32) [116] and 45, X [170]/46, Xr (X) (p22.2q21.33) [92], respectively. Sizes of these ring X chromosomes were found to be ~75 and ~95 Mb in cases 1 and 2, respectively, using visual estimation as part of cytogenetic observation. In both cases, we observed breakpoints on Xq chromosome were within relatively narrow region between Xq21.33 and Xq22.1 compared to regions in previously reported cases associated with ovarian dysgenesis.

CONCLUSIONS

Our observation agrees with the fact that despite of large heterogeneity, severity of the cases with intact X-inactive specific transcript (XIST) is dependent on degree of mosaicism and extent of Xq deletion having crucial genes involved directly or indirectly in various physiological involving ovarian cyclicity.

Age-associated events in bovine oocytes and possible countermeasures

Maternal aging profoundly affects oocyte quality. This has become common knowledge in industrialized countries and extensive studies addressing the causes and possible countermeasures against age-associated deterioration of oocytes suggest that mitochondrial dysfunction is a causal factor in infertility. However, almost all studies addressing age-associated events in oocytes have used mice as an animal model, and the reproductive life of mice is very short, making it difficult to study the gradual decline in fertility observed in humans. In the present review, age-associated changes in the quality and quantity of bovine oocytes and possible countermeasures related to mitochondrial quality control are introduced.

Ovarian Physiology and GWAS: Biobanks, Biology, and Beyond

Ovarian function is central to female fertility, and several genome-wide association studies (GWAS) have been carried out to elucidate the genetic background of traits and disorders that reflect and affect ovarian physiology. While GWAS have been successful in reporting numerous genetic associations and highlighting involved pathways relevant to reproductive aging, for ovarian disorders, such as premature ovarian insufficiency and polycystic ovary syndrome, research has lagged behind due to insufficient study sample size. Novel approaches to study design and analysis methods that help to fit GWAS findings into biological context will improve our knowledge about genetics governing ovarian function in fertility and disease, and provide input for clinical tools and better patient management.

An Update on Ovarian Aging and Ovarian Reserve Tests

Ovaries are the female organs that age more quickly than other tissues such as the uterus, the pituitary gland or pancreas. Different from males, an interesting question is why and how the females lose fertility so rapidly. During the aging process, both the number and quality of the oocytes in the ovaries decrease and reach to a point beyond that no more viable offspring may be produced and the associated cyclic endocrinological activities cease, entering the menopause in females at an average age of 50 years. Females who delayed childbearing with or without their willing until their 30 years or 40 years constitute the largest portion of the total infertility population. Ovarian reserve tests (ORTs) provide an indirect estimate of a female’s diminishing ovarian reserve or remaining follicular pool. This article briefly reviews recent progresses in relation to ovarian aging and ORTs.

Ethnicity or environment: effects of migration on ovarian reserve among Bangladeshi women in the United Kingdom

OBJECTIVE

To assess whether the quality of early childhood environments among different groups of Bangladeshi women, including migrants to the United Kingdom (UK), contributes to variation in ovarian reserve and the rate of reproductive aging in later life.

DESIGN

Cross-sectional study.

SETTING

Not applicable.

PATIENT(S)

A total of 179 healthy women volunteers aged 35-59 years were divided into four groups: [1] 36 Bangladeshis living in Sylhet, Bangladesh; [2] 53 Bangladeshis who migrated to the UK as adults; [3] 40 Bangladeshis who migrated to the UK as children aged 0-16 years; and [4] a reference group of 50 women of European origin living in London.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Levels of serum antimüllerian hormone, inhibin B, FSH, and E2, and anthropometrics derived from biomarkers; reproductive, demographic, and health variables from structured questionnaires.

RESULT(S)

Bangladeshi migrants who moved to the UK as children and European women had a highly significantly larger, age-related ovarian reserve compared with migrant Bangladeshis who had moved to the UK as adults or Bangladeshi women still living in Bangladesh. There were no other significant covariates in the model aside from age and menopausal status.

CONCLUSION(S)

The study points to the importance of childhood development in considering variation in ovarian reserve across different ethnic groups. Clinical studies and research in assisted reproductive technology have emphasized the role of genes or race in determining inter-population variation in ovarian reserve. Early life developmental factors should be given due consideration when evaluating inter-group differences in response to assisted reproductive technology.

Genetics of the ovarian reserve

Primordial follicles or non-growing follicles (NGFs) are the functional unit of reproduction, each comprising a single germ cell surrounded by supporting somatic cells. NGFs constitute the ovarian reserve (OR), prerequisite for germ cell ovulation and the continuation of the species. The dynamics of the reserve is determined by the number of NGFs formed and their complex subsequent fates. During the reproductive lifespan, the OR progressively diminishes due to follicle atresia as well as recruitment, maturation, and ovulation. The depletion of the OR is the major determining driver of menopause, which ensues when the number of primordial follicles falls below a threshold of ∼1,000. Therefore, genes and processes involved in follicle dynamics are particularly important to understand the process of menopause, both in the typical reproductive lifespan and in conditions like primary ovarian insufficiency, defined as menopause before age 40. Genes and their variants that affect the timing of menopause thereby provide candidates for diagnosis of and intervention in problems of reproductive lifespan. We review the current knowledge of processes and genes involved in the development of the OR and in the dynamics of ovarian follicles.

Endocrinology of the Menopause

In women, age-related changes in ovarian function begin in the mid-30s with decreased fertility and compensatory hormonal changes in the hypothalamus-pituitary-gonadal axis that maintain follicle development and estrogen secretion in the face of a waning pool of ovarian follicles. The menopause transition is characterized by marked variability in follicle development, ovulation, bleeding patterns, and symptoms of hyper- and hypoestrogenism. The menopause, which is clinically defined by the last menstrual period, is followed by the consistent absence of ovarian secretion of estradiol.

Assessment of anti-Müllerian hormone levels in premenopausal patients with systemic lupus erythematosus

OBJECTIVE

The ovarian reserve of patients with systemic lupus erythematosus (SLE) may be affected by disease activity and medication use. Studies have found that patients with SLE have similar fertility rates as healthy women of the same age. The goal of the present study was to investigate the ovarian reserve of patients with SLE by measuring anti-Müllerian hormone (AMH) levels, and compare it to that of healthy controls.

METHOD

This was a case-control study performed on 80 premenopausal women, of whom 40 fulfilled the 1997 American College of Rheumatology (ACR) criteria for SLE and 40 healthy controls paired by oral contraceptive use. Serum concentrations of AMH in peripheral venous blood were measured using a human AMH ELISA kit (CUSABIO, Wuhan, China).

RESULTS

AMH serum levels did not differ between patients with SLE and controls (22.79 ± 17.32 ng/ml versus 21.41 ± 16.22 ng/ml, respectively, p = 0.7), even after adjusting for age (21.03 ± 2.074 ng/ml versus 23.97 ± 2.71 ng/ml; p = 0.5). AHM levels were not significantly correlated with disease duration (r = 0.2; p = 0.3), body mass index (r = 0.2; p = 0.2) and disease activity (SLEDAI (r = 0.1; p = 0.7)) and damage indices (SLICC (r = 0.1; p = 0.7)). No associations were found between AMH and ethnicity, current smoking, as well as current or prior use of cyclophosphamide and other immunosuppressants.

CONCLUSION

In this cross-sectional study, women with SLE demonstrated similar AMH levels as healthy controls, suggesting preserved ovarian reserve in this population.

Neighborhood socioeconomic status during childhood versus puberty in relation to endogenous sex hormone levels in adult women

BACKGROUND

Socioeconomic adversity in early life is related to cardiovascular risk in adulthood; however, no studies have examined whether such adversity may be related to endogenous sex hormones, which are themselves associated with cardiovascular outcomes, or whether the timing of adversity exposures (childhood vs. puberty) matters.

OBJECTIVE

The goal of the current study was to separately examine neighborhood socioeconomic status (SES) during periods of childhood and puberty in relation to adulthood levels of endogenous sex hormones (estradiol [E2], testosterone), sex hormone binding globulin (SHBG), and a derived index of bioavailable testosterone (free androgen index).

METHODS

In a sample of 143 premenopausal women (mean age = 36.8 [SD = 5.5]; 51.7% White, 32.2% African American, 5.6% Latina, 7.0% Chinese, and 3.5% Filipina), retrospective reports of residential address information in designated periods of childhood and puberty were used to derive U.S. census-based neighborhood SES composite scores characterizing the socioeconomic environments of women during these periods.

RESULTS

In covariate-adjusted analyses, higher neighborhood SES in puberty predicted higher levels of SHBG in adulthood, but neighborhood SES during childhood did not (standardized regression coefficient = .24, p = .01 vs. standardized regression coefficient = .04, p = .75, respectively). Neighborhood SES was not predictive of other hormones (E2, testosterone, and free androgen index).

DISCUSSION

The current findings suggest that puberty may be a time of particular vulnerability to the effects of neighborhood SES on SHBG levels, which have been linked to cardiovascular risk factor profiles and atherosclerotic disease progression.

Intraovarian control of early folliculogenesis

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

MCM9 mutations are associated with ovarian failure, short stature, and chromosomal instability

Premature ovarian failure (POF) is genetically heterogeneous and manifests as hypergonadotropic hypogonadism either as part of a syndrome or in isolation. We studied two unrelated consanguineous families with daughters exhibiting primary amenorrhea, short stature, and a 46,XX karyotype. A combination of SNP arrays, comparative genomic hybridization arrays, and whole-exome sequencing analyses identified homozygous pathogenic variants in MCM9, a gene implicated in homologous recombination and repair of double-stranded DNA breaks. In one family, the MCM9 c.1732+2T>C variant alters a splice donor site, resulting in abnormal alternative splicing and truncated forms of MCM9 that are unable to be recruited to sites of DNA damage. In the second family, MCM9 c.394C>T (p.Arg132(∗)) results in a predicted loss of functional MCM9. Repair of chromosome breaks was impaired in lymphocytes from affected, but not unaffected, females in both families, consistent with MCM9 function in homologous recombination. Autosomal-recessive variants in MCM9 cause a genomic-instability syndrome associated with hypergonadotropic hypogonadism and short stature. Preferential sensitivity of germline meiosis to MCM9 functional deficiency and compromised DNA repair in the somatic component most likely account for the ovarian failure and short stature.

Exome sequencing reveals MCM8 mutation underlies ovarian failure and chromosomal instability

Premature ovarian failure (POF) is a genetically and phenotypically heterogeneous disorder that includes individuals with manifestations ranging from primary amenorrhea to loss of menstrual function prior to age 40. POF presents as hypergonadotropic hypogonadism and can be part of a syndrome or occur in isolation. Here, we studied 3 sisters with primary amenorrhea, hypothyroidism, and hypergonadotropic hypogonadism. The sisters were born to parents who are first cousins. SNP analysis and whole-exome sequencing revealed the presence of a pathogenic variant of the minichromosome maintenance 8 gene (MCM8, c.446C>G; p.P149R) located within a region of homozygosity that was present in the affected daughters but not in their unaffected sisters. Because MCM8 participates in homologous recombination and dsDNA break repair, we tested fibroblasts from the affected sisters for hypersensitivity to chromosomal breaks. Compared with fibroblasts from unaffected daughters, chromosomal break repair was deficient in fibroblasts from the affected individuals, likely due to inhibited recruitment of MCM8 p.P149R to sites of DNA damage. Our study identifies an autosomal recessive disorder caused by an MCM8 mutation that manifests with endocrine dysfunction and genomic instability.

Serum anti-Mullerian hormone levels across different ethnic groups: a cross-sectional study

OBJECTIVE

To assess whether ethnic differences in serum anti-Mullerian hormone (AMH) exist in a population of subfertile women presenting to a fertility clinic.

DESIGN

Observational cross-sectional study.

SETTING

Homerton University Hospital Fertility Centre, London, UK.

POPULATION

A total of 865 women attending the fertility clinic for their first consultation appointment between September 2012 and September 2013.

METHODS

Serum AMH was compared amongst women from five different ethnic groups.

MAIN OUTCOME MEASURES

Serum AMH and ethnicity were the primary outcome variables.

RESULTS

Although initial comparison showed South Asian women to have a higher serum AMH, compared with white European and Afro-Caribbean women (F = 3.817; P < 0.005), South Asian women attending the clinic were significantly younger and less likely to be smokers than women from other ethnic groups. The prevalence of polycystic ovary syndrome (PCOS) was significantly higher in South Asian and South East Asian women than in other ethnic groups. Differences in serum AMH were no longer significant after controlling for confounding factors: age, body mass index (BMI), and smoking status with (P = 0.869) and without (P = 0.215) controlling for PCOS.

CONCLUSION

The results from our study show that there was no independent association of ethnicity and serum AMH levels in an unselected population of women attending the fertility clinic.

Meta-analysis of loci associated with age at natural menopause in African-American women

Age at menopause marks the end of a woman's reproductive life and its timing associates with risks for cancer, cardiovascular and bone disorders. GWAS and candidate gene studies conducted in women of European ancestry have identified 27 loci associated with age at menopause. The relevance of these loci to women of African ancestry has not been previously studied. We therefore sought to uncover additional menopause loci and investigate the relevance of European menopause loci by performing a GWAS meta-analysis in 6510 women with African ancestry derived from 11 studies across the USA. We did not identify any additional loci significantly associated with age at menopause in African Americans. We replicated the associations between six loci and age at menopause (P-value < 0.05): AMHR2, RHBLD2, PRIM1, HK3/UMC1, BRSK1/TMEM150B and MCM8. In addition, associations of 14 loci are directionally consistent with previous reports. We provide evidence that genetic variants influencing reproductive traits identified in European populations are also important in women of African ancestry residing in USA.

Ethnicity as a determinant of ovarian reserve: differences in ovarian aging between Spanish and Indian women

OBJECTIVE

To investigate differences in ovarian reserve markers (antimüllerian hormone [AMH] and antral follicle count [AFC]) in Indian and Spanish women.

DESIGN

Cross-sectional study.

SETTING

In vitro fertilization (IVF) clinics.

PATIENT(S)

Infertile Spanish (n=229) and Indian (n=236) women who underwent controlled ovarian stimulation for IVF from January to October 2012.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Data on ovarian reserve markers and results after ovarian stimulation were collected.

RESULT(S)

The mean age of women undergoing their first or second IVF cycle was significantly higher in Spanish than in Indian women (37.5±3.3 years vs. 31.5±3.8 years). Despite this 6-year age gap, AFCs were similar (9.5±4.7 vs. 9.9±4.6), as were day 3 FSH levels (7.5±4.5 IU/L vs. 6.9±2.3 IU/L). AMH levels were slightly lower in Spanish women (1.6±1.7 ng/mL vs. 2.5±1.6 ng/mL). Multivariate regression analysis showed that being Indian decreased AFC by 2.3, such that AFC in Indian women was similar to that in Spanish women 6.3 years older (95% confidence interval 3.39-1.10).

CONCLUSION(S)

Similar ovarian reserve markers and ovarian response were observed in women with a 6-year age difference in favor of the Spanish, suggesting ethnic differences in ovarian aging. Further research is needed to understand whether these differences are genetically induced or are caused by other variables, such as nutrition. Our results may help clinicians to counsel infertile women when discussing assisted reproductive technology outcomes according to age and ethnic background.

Genomic markers of ovarian reserve

Ovarian reserve and its utilization, over a reproductive life span, are determined by genetic, epigenetic, and environmental factors. The establishment of the primordial follicle pool and the rate of primordial follicle activation have been under intense study to determine genetic factors that affect reproductive lifespan. Much has been learned from transgenic animal models about the developmental origins of the primordial follicle pool and mechanisms that lead to primordial follicle activation, folliculogenesis, and the maturation of a single oocyte with each menstrual cycle. Recent genome-wide association studies on the age of human menopause have identified approximately 20 loci, and shown the importance of factors involved in double-strand break repair and immunology. Studies to date from animal models and humans show that many genes determine ovarian aging, and that there is no single dominant allele yet responsible for depletion of the ovarian reserve. Personalized genomic approaches will need to take into account the high degree of genetic heterogeneity, family pedigree, and functional data of the genes critical at various stages of ovarian development to predict women's reproductive life span.

The egg. The inside story of a cell

The egg, a fantastic little laboratory of molecular biology, has played a crucial role in redefining modern biology by moving it from the description of living things to the synthesis of living things (synthetic biology). Over the centuries, many hypotheses have been advanced concerning the egg's role in reproduction-from the preformation theory until von Baer's discovery to the present, with the 2012 Nobel Prize for Physiology or Medicine celebrating the egg as a totipotent stem cell able to reprogram fully differentiated somatic nuclei. The molecular dissection of its cytoplasmic components makes the egg an ideal bioreactor for several biotechnological applications, including pharmacological and food production sciences. In addition to its ubiquitous contribution to the worldwide diet, the egg, a powerful symbol, pervades philosophy, art, religion, and idiomatic expressions.

Association of BRCA1/2 mutations with FMR1 genotypes: effects on menarcheal and menopausal age

OBJECTIVE

Female BRCA (breast cancer gene)-1 and BRCA-2 mutations are significantly associated with risk of developing breast and ovarian cancers, in turn, associated with female infertility. BRCA-1 mutations have also been associated with occult primary ovarian insufficiency (OPOI), as have different mutations of the FMR1 gene. We, therefore, hypothesized that FMR1 genotypes may be associated with menarcheal and menopausal ages of BRCA mutation carriers.

PATIENTS

We compared the FMR1 genotype and sub-genotype distribution in 99 BRCA1/2 positive women and in 182 healthy women without a known history of familial breast and ovarian cancer and searched for associations with age at menarche and menopause. T-test was used to assess differences in menarcheal and menopause ages, with times of menarche and menopause as continuous variables.

RESULTS

Women with BRCA1/2 mutations showed significantly different FMR1 genotype and sub-genotype distributions when compared with the control group (p<0.001). This result remained stable in a sub-group analysis of Caucasian BRCA1/2 carriers and healthy controls (p<0.001). In addition, BRCA1/2 carriers indicated a trend toward shorter reproductive lifespan (p=0.18).

CONCLUSIONS

Our data confirm the previously reported highly skewed distribution of FMR1 genotypes and sub-genotypes toward a high preponderance of low FMR1 alleles in BRCA1/2 carriers. We could demonstrate that BRCA-1 mutations are associated with an earlier onset of menopause compared to BRCA-2 carriers, although the distribution of the het-norm/low genotype is similar in both groups. Our findings suggest that there may be other factors beside the genotype that has an influence on menarche and especially menopause age in BRCA mutation carriers.

Potential mechanisms for racial and ethnic differences in antimüllerian hormone and ovarian reserve

Accumulating evidence suggests that reproductive potential and function may be different across racial and ethnic groups. Racial differences have been demonstrated in pubertal timing, infertility, outcomes after assisted reproductive technology (ART) treatment, and reproductive aging. Recently, racial differences have also been described in serum antimüllerian hormone (AMH), a sensitive biomarker of ovarian reserve, supporting the notion that ovarian reserve differs between racial/ethnic groups. The existence of such racial/ethnic differences in ovarian reserve, as reflected by AMH, may have important clinical implications for reproductive endocrinologists. However, the mechanisms which may underlie such racial differences in ovarian reserve are unclear. Various genetic factors and environmental factors such as obesity, smoking, and vitamin D deficiency which have been shown to correlate with serum AMH levels and also display significant racial/ethnic variations are discussed in this review. Improving our understanding of racial differences in ovarian reserve and their underlying causes may be essential for infertility treatment in minority women and lead to better reproductive planning, improved treatment outcomes, and timely interventions which may prolong reproductive lifespan in these women.