Primary ovarian insufficiency (POI) is characterized by marked heterogeneity, but with a significant genetic contribution. Identifying exact causative genes has been challenging, with many ...discoveries not replicated. It is timely to take stock of the field, outlining the progress made, framing the controversies and anticipating future directions in elucidating the genetics of POI.
A search for original articles published up to May 2015 was performed using PubMed and Google Scholar, identifying studies on the genetic etiology of POI. Studies were included if chromosomal analysis, candidate gene screening and a genome-wide study were conducted. Articles identified were restricted to English language full-text papers.
Chromosomal abnormalities have long been recognized as a frequent cause of POI, with a currently estimated prevalence of 10-13%. Using the traditional karyotype methodology, monosomy X, mosaicism, X chromosome deletions and rearrangements, X-autosome translocations, and isochromosomes have been detected. Based on candidate gene studies, single gene perturbations unequivocally having a deleterious effect in at least one population include Bone morphogenetic protein 15 (BMP15), Progesterone receptor membrane component 1 (PGRMC1), and Fragile X mental retardation 1 (FMR1) premutation on the X chromosome; Growth differentiation factor 9 (GDF9), Folliculogenesis specific bHLH transcription factor (FIGLA), Newborn ovary homeobox gene (NOBOX), Nuclear receptor subfamily 5, group A, member 1 (NR5A1) and Nanos homolog 3 (NANOS3) seem likely as well, but mostly being found in no more than 1-2% of a single population studied. Whole genome approaches have utilized genome-wide association studies (GWAS) to reveal loci not predicted on the basis of a candidate gene, but it remains difficult to locate causative genes and susceptible loci were not always replicated. Cytogenomic methods (array CGH) have identified other regions of interest but studies have not shown consistent results, the resolution of arrays has varied and replication is uncommon. Whole-exome sequencing in non-syndromic POI kindreds has only recently begun, revealing mutations in the Stromal antigen 3 (STAG3), Synaptonemal complex central element 1 (SYCE1), minichromosome maintenance complex component 8 and 9 (MCM8, MCM9) and ATP-dependent DNA helicase homolog (HFM1) genes. Given the slow progress in candidate-gene analysis and relatively small sample sizes available for GWAS, family-based whole exome and whole genome sequencing appear to be the most promising approaches for detecting potential genes responsible for POI.
Taken together, the cytogenetic, cytogenomic (array CGH) and exome sequencing approaches have revealed a genetic causation in ∼20-25% of POI cases. Uncovering the remainder of the causative genes will be facilitated not only by whole genome approaches involving larger cohorts in multiple populations but also incorporating environmental exposures and exploring signaling pathways in intragenic and intergenic regions that point to perturbations in regulatory genes and networks.
The characteristics of polycystic ovary syndrome (PCOS), a common reproductive endocrinal disorder, are high incidence, complicated aetiology and poor therapeutic effects. PCOS patients frequently ...exhibit gut dysbiosis; however, its roles in the regulation of metabolic and endocrinal balances in PCOS pathophysiology are not clear.
In this study, gut dysbiosis was reproduced in dehydroepiandrosterone (DHEA)-induced PCOS-like rats. An antibiotic cocktail was used to eliminate gut microbiota during DHEA treatment; however, depletion of the gut microbiota did not prevent the occurrence of PCOS phenotypes in DHEA-treated rats. DHEA-shaped gut microbiota transplanted to pseudo germ-free recipients trigged disturbances in hepatic glucolipid metabolism and reproductive hormone imbalance. The clinical features of PCOS may be correlated with the relative abundance of gut microbes and the levels of faecal metabolites in faecal microbiota transplantation (FMT) recipient rats.
These findings indicate that androgen-induced gut microbiota dysbiosis may aggravate metabolic and endocrinal malfunction in PCOS. Video Abstract.
Premature ovarian insufficiency (POI) is highly heterogeneous in genetic etiology. Yet identifying causative genes has been challenging with candidate gene approaches. Recent approaches using next ...generation sequencing (NGS), especially whole exome sequencing (WES), in large POI pedigrees have identified new causatives and proposed relevant candidates, mainly enriched in DNA damage repair, homologous recombination, and meiosis. In the near future, NGS or whole genome sequencing will help better define genes involved in intricate regulatory networks. The research into miRNA and age at menopause represents an emerging field that will help unveil the molecular mechanisms underlying pathogenesis of POI. Shedding light on the genetic architecture is important in interpreting pathogenesis of POI, and will facilitate risk prediction for POI.
The traditional candidate gene approaches, although critical in establishing the field of POI genetics, have been proceeding slowly.
Recent advances of NGS, especially WES in large POI pedigrees, have revealed new causative genes, with a preponderance for DNA damage repair and homologous recombination.
The insights from GWAS on age of menopause and miRNA research will facilitate identification of new causative genes or signaling pathways for POI.
Targeted panels of causative genes, or WES/whole genome sequencing in the future are promising in risk prediction for POI; however, the causative role of identified variants should be elucidated.
Abstract
Context:
Premature ovarian insufficiency (POI) is highly heterogeneous, both in phenotype and etiology. They are not yet clearly stated and correlated.
Objective:
To characterize clinical ...presentations of a large, well-phenotyped cohort of women with POI, and correlate phenotypes with etiologies to draw a comprehensive clinical picture of POI.
Design, Patients, Interventions, and Main Outcome Measures:
In this retrospective study, a total of 955 Chinese women with overt POI between 2006 and 2015 were systemically evaluated and analyzed. The phenotypic features, including menstrual characteristics, hormone profiles, ovarian ultrasonography/biopsy, pregnancy/family history, and genetic/autoimmune/iatrogenic etiologies were assessed and further compared within different subgroups.
Results:
Among 955 women with POI, 85.97% presented with secondary amenorrhea (SA) and 14.03% with primary amenorrhea (PA). PA represented the most severe ovarian dysfunction and more chromosomal aberrations than SA. The decline of ovarian function in patients with SA progressed quickly. They had shortened reproductive periods (approximately 10 years) and developed amenorrhea within 1 to 2 years after menstrual irregularity. The ovaries were invisible or small, and the presence of follicles (28.43%) was correlated with other good reproductive indicators. Familial patients (12.25%) manifested better ovarian status and fewer chromosomal aberrations than sporadic patients. The etiologies consisted of genetic (13.15%), autoimmune (12.04%), and iatrogenic (7.29%), approximately 68% remaining idiopathic. There were significant differences among different etiologies, with the genetic group representing the most severe phenotype.
Conclusion:
Our results regarding distinct phenotypic characteristics and association with different etiologies further confirmed the high heterogeneity of POI. Additional longitudinal clinical studies and pathogenesis research are warranted.
There is high heterogeneity of phenotype and etiology in women with overt POI. Phenotypic variabilities exist among patients, even when stratified by different etiological diagnosis.
Embryo selection with preimplantation genetic testing for aneuploidy (PGT-A) may improve pregnancy outcomes after initial embryo transfer. However, it remains uncertain whether PGT-A improves the ...cumulative live-birth rate as compared with conventional in vitro fertilization (IVF).
In this multicenter, randomized, controlled trial, we randomly assigned subfertile women with three or more good-quality blastocysts to undergo either PGT-A or conventional IVF; all the women were between 20 and 37 years of age. Three blastocysts were screened by next-generation sequencing in the PGT-A group or were chosen by morphologic criteria in the conventional-IVF group and then were successively transferred one by one. The primary outcome was the cumulative live-birth rate after up to three embryo-transfer procedures within 1 year after randomization. We hypothesized that the use of PGT-A would result in a cumulative live-birth rate that was no more than 7 percentage points higher than the rate after conventional IVF, which would constitute the noninferiority margin for conventional IVF as compared with PGT-A.
A total of 1212 patients underwent randomization, and 606 were assigned to each trial group. Live births occurred in 468 women (77.2%) in the PGT-A group and in 496 (81.8%) in the conventional-IVF group (absolute difference, -4.6 percentage points; 95% confidence interval CI, -9.2 to -0.0; P<0.001). The cumulative frequency of clinical pregnancy loss was 8.7% and 12.6%, respectively (absolute difference, -3.9 percentage points; 95% CI, -7.5 to -0.2). The incidences of obstetrical or neonatal complications and other adverse events were similar in the two groups.
Among women with three or more good-quality blastocysts, conventional IVF resulted in a cumulative live-birth rate that was noninferior to the rate with PGT-A. (Funded by the National Natural Science Foundation of China and others; ClinicalTrials.gov number, NCT03118141.).
To the best of our knowledge, no study has investigated the potential joint effect of large for gestational age (LGA) and assisted reproductive technology (ART) on the long-term health of children.
...This was a prospective cohort study that recruited children whose parents had received ART treatment in the Center for Reproductive Medicine, Shandong Provincial Hospital, affiliated to Shandong University, between January 2006 and December 2017. Linear mixed model was used to compare the main outcomes. The mediation model was used to evaluate the intermediary effect of body mass index (BMI).
4138 (29.5%) children born LGA and 9910 (70.5%) children born appropriate for gestational age (AGA) were included in the present study. The offspring ranged from 0.4 to 9.9 years. LGAs conceived through ART were shown to have higher BMI, blood pressure, fasting blood glucose, fasting insulin, and homeostatic model assessment of insulin resistance values, even after controlling for all covariates. The odds of overweight and insulin resistance are also higher in LGA subjects. After adjusting for all covariates, LGAs conceived through ART had BMI and BMI z-scores that were 0.48 kg/m
and 0.34 units greater than those of AGAs, respectively. The effect of LGA on BMI was identified as early as infancy and remained consistently significant throughout pre-puberty.
Compared to AGA, LGA children conceived from ART were associated with increased cardiovascular-metabolic events, which appeared as early as infancy and with no recovery by pre-puberty.
Elective single embryo transfer (eSET) has been increasingly advocated, but concerns about the lower pregnancy rate after reducing the number of embryos transferred have encouraged transfer of ...multiple embryos. Extended embryo culture combined with electively freezing all embryos and undertaking a deferred frozen embryo transfer might increase pregnancy rate after eSET. We aimed to establish whether elective frozen single blastocyst transfer improved singleton livebirth rate compared with fresh single blastocyst transfer.
This multicentre, non-blinded, randomised controlled trial was undertaken in 21 academic fertility centres in China. 1650 women with regular menstrual cycles undergoing their first cycle of in-vitro fertilisation were enrolled from Aug 1, 2016, to June 3, 2017. Eligible women were randomly assigned to either fresh or frozen single blastocyst transfer. The randomisation sequence was computer generated, with block sizes of two, four, or six, stratified by study site. For those assigned to frozen blastocyst transfer, all blastocysts were cryopreserved and a delayed frozen-thawed single blastocyst transfer was done. The primary outcome was singleton livebirth rate. Analysis was by intention to treat. This trial is registered at the Chinese Clinical Trial Registry, number ChiCTR-IOR-14005405.
825 women were assigned to each group and included in analyses. Frozen single blastocyst transfer resulted in higher rates of singleton livebirth than did fresh single blastocyst transfer (416 50% vs 329 40%; relative risk RR 1·26, 95% CI 1·14–1·41, p<0·0001). The risks of moderate or severe ovarian hyperstimulation syndrome (four of 825 0·5% in frozen single blastocyst transfer vs nine of 825 1·1% in fresh single blastocyst transfer; p=0·16), pregnancy loss (134 of 583 23·0% vs 124 of 481 25·8%; p=0·29), other obstetric complications, and neonatal morbidity were similar between the two groups. Frozen single blastocyst transfer was associated with a higher risk of pre-eclampsia (16 of 512 3·1% vs four of 401 1·0%; RR 3·13, 95% CI 1·06–9·30, p=0·029).
Frozen single blastocyst transfer resulted in a higher singleton livebirth rate than did fresh single blastocyst transfer in ovulatory women with good prognosis. The increased risk of pre-eclampsia after frozen blastocyst transfer warrants further studies.
The National Key Research and Development Program of China.
Abstract
Background
The PRDM9-dependent histone methylation H3K4me3 and H3K36me3 function in assuring accurate homologous recombination at recombination hotspots in mammals. Beyond histone ...methylation, H3 lysine 9 acetylation (H3K9ac) is also greatly enriched at recombination hotspots. Previous work has indicated the potential cross-talk between H3K4me3 and H3K9ac at recombination hotspots, but it is still unknown what molecular mechanisms mediate the cross-talk between the two histone modifications at hotspots or how the cross-talk regulates homologous recombination in meiosis.
Results
Here, we find that the histone methylation reader ZCWPW1 is essential for maintaining H3K9ac by antagonizing HDAC proteins’ deacetylation activity and further promotes chromatin openness at recombination hotspots thus preparing the way for homologous recombination during meiotic double-strand break repair. Interestingly, ectopic expression of the germ-cell-specific protein ZCWPW1 in human somatic cells enhances double-strand break repair via homologous recombination.
Conclusions
Taken together, our findings provide new insights into how histone modifications and their associated regulatory proteins collectively regulate meiotic homologous recombination.
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