Genetics of Primary Ovarian Insufficiency in the Next-Generation Sequencing Era

Dysgerminoma Probably Due to a Novel SOHLH1-pathogenic Variant Causing Familial Ovarian Dysgenesis

Pathogenic variants of the SOHLH1 gene are responsible for an autosomal recessive form of ovarian dysgenesis; this gene encodes a transcription factor expressed early in spermatogonia and oocytes and contributes to folliculogenesis. Previously, four affected women from two unrelated families reported homozygous variants in the SOHLH1 gene, but none had a history of gonadal malignancy or a histologic description. We present two sisters and their paternal great-aunt with a history of primary amenorrhea, pubertal delay, and hypergonadotrophism who came from an inbred Mexican family. The proband was the younger sister who was referred for bilateral dysgerminoma. She had a normal blood karyotype, and whole-exome sequencing analysis revealed a novel homozygous missense variant, c.275C>T, in SOHLH1; several family members were also analyzed. In addition to pure dysgerminoma, histopathological analysis revealed an ovarian cortex with fibrosis and almost total absence of follicles. This work confirms the inheritance of ovarian dysgenesis 5, supports the occurrence of cell loss in mouse models, and suggests that affected women should undergo periodic imaging surveillance due to the likely risk of tumor development.

Screening of premature ovarian insufficiency associated genes in Hungarian patients with next generation sequencing

BACKGROUND

Premature ovarian insuffiency (POI) is one of the main cause behind infertility. The genetic analysis of POI should be part of the clinical diagnostics, as several genes have been implicated in the genetic background of it. The aim of our study was to analyse the genetic background of POI in a Hungarian cohort.

METHODS

The age of onset was between 15 and 39 years. All patients had the 46,XX karyotype and they were prescreened for the most frequent POI associated FMR1 premutation. To identify genetic alterations next-generation sequencing (NGS) of 31 genes which were previously associated to POI were carried out in 48 unrelated patients from Hungary.

RESULTS

Monogenic defect was identified in 16.7% (8 of 48) and a potential genetic risk factor was found in 29.2% (14 of 48) and susceptible oligogenic effect was described in 12.5% (6 of 48) of women with POI using the customized targeted panel sequencing. The genetic analysis identified 8 heterozygous damaging and 4 potentially damaging variants in POI-associated genes. Further 10 potential genetic risk factors were detected in seven genes, from which EIF2B and GALT were the most frequent. These variants were related to 15 genes: AIRE, ATM, DACH2, DAZL, EIF2B2, EIF2B4, FMR1, GALT, GDF9, HS6ST2, LHCGR, NOBOX, POLG, USP9X and XPNPEP2. In six cases, two or three coexisting damaging mutations and risk variants were identified.

CONCLUSIONS

POI is characterized by heterogenous phenotypic features with complex genetic background that contains increasing number of genes. Deleterious variants, which were detected in our cohort, related to gonadal development (oogenesis and folliculogenesis), meiosis and DNA repair, hormonal signaling, immune function, and metabolism which were previously associated with the POI phenotype. This is the first genetic epidemiology study targeting POI associated genes in Hungary. The frequency of variants in different POI associated genes were similar to the literature, except EIF2B and GALT. Both of these genes potential risk factor were detected which could influence the phenotype, although it is unlikely that they can be responsible for the development of the disease by themselves. Advances of sequencing technologies make it possible to aid diagnostics of POI Since individual patients show high phenotypic variance because of the complex network controlling human folliculogenesis. Comprehensive NGS screening by widening the scope to genes which were previously linked to infertility may facilitate more accurate, quicker and cheaper genetic diagnoses for POI. The investigation of patient's genotype could support clinical decision-making process and pave the way for future clinical trials and therapies.

Proteomic analysis reveals that cigarette smoke exposure diminishes ovarian reserve in mice by disrupting the CREB1-mediated ovarian granulosa cell proliferation-apoptosis balance

Exposure to cigarette smoke (CS) adversely affects ovarian health and it is currently unknown how CS exposure causes ovarian injury. This study compared the differences in proteomics between CS exposure and healthy control groups using liquid chromatography-tandem mass spectrometry quantitative proteomics to further understand the molecular mechanism of ovarian cell injury in mice exposed to CS. Furthermore, western blotting and qPCR were carried out to validate the proteomic analysis outcomes. CREB1 was selected from the differentially expressed proteins, and then the down-regulation of CREB1 and phosphorylated CREB1(Ser133) expressions were confirmed in mice ovarian tissue and human ovarian granulosa cells (KGN cells) after CS exposure. In addition, the expressions of apoptosis-related proteins BCL-2 and BCL-XL were downregulated, and BAX expression was up-regulated. Moreover, the results of cellular immunofluorescence, flow cytometry, and transmission electron microscopy (TEM) showed that cigarette smoke extract (CSE) efficiently stimulated the production of reactive oxygen species, apoptosis, G1 phase arrest, mitochondrial membrane potential decreases, and ultrastructural changes in KGN cells. KG-501 (CREB inhibitor) aggravated CSE-induced mitochondrial dysfunction and apoptosis-proliferation imbalance in KGN cells mediated by down-regulated CREB1/BCL-2 axis. In addition, CREB1 over-expression partially restores mitochondrial dysfunction and apoptosis-proliferation imbalance of KGN cells induced by CSE. The results suggested that CSE diminished ovarian reserve in mice by disrupting the CREB1-mediated ovarian granulosa cell (GCs) proliferation-apoptosis balance and provided possible therapeutic targets for the clinical intervention of premature ovarian failure (POI) caused by CS exposure.

Case report: The evolving phenotype of ESCO2 spectrum disorder in a 15-year-old Malaysian child

ESCO2 spectrum disorder is an autosomal recessive developmental disorder characterized by growth retardation, symmetrical mesomelic limb malformation, and distinctive facies with microcephaly, with a wide phenotypic continuum that ranges from Roberts syndrome (MIM #268300) at the severe end to SC phocomelia (MIM #269000) at the milder end. ESCO2 encodes a 601-amino acid protein belonging to the Eco1/Ctf7 family of acetyltransferases that is involved in the establishment of sister chromatid cohesion, which is essential for accurate chromosome segregation and genomic stability and thus belongs to a group of disorders called "cohesinopathies". We describe a 15-year-old Malaysian female who presented with the characteristic triad of ESCO2 spectrum disorder, with an equivocal chromosomal breakage study and normal karyotyping findings. She was initially suspected to have mosaic Fanconi anemia but whole exome sequencing (WES) showed a likely pathogenic homozygous splice variant c.955 + 2_955+5del in the ESCO2 gene. During the 15-year diagnostic odyssey, she developed type 2 diabetes mellitus, primary ovarian insufficiency, increased optic cup-to-disc ratio with tortuous vessels bilaterally, and an evolving but distinct facial and skin hypopigmentation phenotype. Of note, there was an absence of learning disabilities. Our findings provide further evidence for ESCO2 spectrum disorder in an Asian child and contribute to defining the clinical and radiographic spectrum.

Improving diagnostic precision in primary ovarian insufficiency using comprehensive genetic and autoantibody testing

STUDY QUESTION

Is it possible to find the cause of primary ovarian insufficiency (POI) in more women by extensive screening?

SUMMARY ANSWER

Adding next generation sequencing techniques including a POI-associated gene panel, extended whole exome sequencing data, as well as specific autoantibody assays to the recommended diagnostic investigations increased the determination of a potential etiological diagnosis of POI from 11% to 41%.

WHAT IS KNOWN ALREADY

POI affects ∼1% of women. Clinical presentations and pathogenic mechanisms are heterogeneous and include genetic, autoimmune, and environmental factors, but the underlying etiology remains unknown in the majority of cases.

STUDY DESIGN, SIZE, DURATION

Prospective cross-sectional study of 100 women with newly diagnosed POI of unknown cause consecutively referred to Haukeland University Hospital, Bergen, Norway, January 2019 to December 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In addition to standard recommended diagnostic investigations including screening for chromosomal anomalies and premutations in the fragile X mental retardation 1 gene (FMR1) we used whole exome sequencing, including targeted analysis of 103 ovarian-related genes, and assays of autoantibodies against steroid cell antigens.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified chromosomal aberrations in 8%, FMR1 premutations in 3%, genetic variants related to POI in 16%, and autoimmune POI in 3%. Furthermore in 11% we identified POI associated genetic Variants of unknown signifcance (VUS). A homozygous pathogenic variant in the ZSWIM7 gene (NM_001042697.2) was found in two women, corroborating this as a novel cause of monogenic POI. No associations between phenotypes and genotypes were found.

LIMITATIONS, REASONS FOR CAUTION

Use of candidate genetic and autoimmune markers limit the possibility to discover new markers. To further investigate the genetic variants, family studies would have been useful. We found a relatively high proportion of genetic variants in women from Africa and lack of genetic diversity in the genomic databases can impact diagnostic accuracy.

WIDER IMPLICATIONS OF THE FINDINGS

Since no specific clinical or biochemical markers predicted the underlying cause of POI discussion of which tests should be part of diagnostic screening in clinical practice remains open. New technology has altered the availability and effectiveness of genetic testing, and cost-effectiveness analyses are required to aid sustainable diagnostics.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by grants and fellowships from Stiftelsen Kristian Gerhard Jebsen, the Novonordisk Foundation, the Norwegian Research Council, University of Bergen, and the Regional Health Authorities of Western Norway. The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

NCT04082169.

DNA double-strand break genetic variants in patients with premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a clinically heterogeneous disease that may seriously affect the physical and mental health of women of reproductive age. POI primarily manifests as ovarian function decline and endocrine disorders in women prior to age 40 and is an established cause of female infertility. It is crucial to elucidate the causative factors of POI, not only to expand the understanding of ovarian physiology, but also to provide genetic counselling and fertility guidance to affected patients. Factors leading to POI are multifaceted with genetic factors accounting for 7% to 30%. In recent years, an increasing number of DNA damage-repair-related genes have been linked with the occurrence of POI. Among them, DNA double-strand breaks (DSBs), one of the most damaging to DNA, and its main repair methods including homologous recombination (HR) and non-homologous end joining (NHEJ) are of particular interest. Numerous genes are known to be involved in the regulation of programmed DSB formation and damage repair. The abnormal expression of several genes have been shown to trigger defects in the overall repair pathway and induce POI and other diseases. This review summarises the DSB-related genes that may contribute to the development of POI and their potential regulatory mechanisms, which will help to further establish role of DSB in the pathogenesis of POI and provide theoretical guidance for the study of the pathogenesis and clinical treatment of this disease.

Penetrance of pathogenic genetic variants associated with premature ovarian insufficiency

Premature ovarian insufficiency (POI) affects 1% of women and is a leading cause of infertility. It is often considered to be a monogenic disorder, with pathogenic variants in ~100 genes described in the literature. We sought to systematically evaluate the penetrance of variants in these genes using exome sequence data in 104,733 women from the UK Biobank, 2,231 (1.14%) of whom reported at natural menopause under the age of 40 years. We found limited evidence to support any previously reported autosomal dominant effect. For nearly all heterozygous effects on previously reported POI genes, we ruled out even modest penetrance, with 99.9% (13,699 out of 13,708) of all protein-truncating variants found in reproductively healthy women. We found evidence of haploinsufficiency effects in several genes, including TWNK (1.54 years earlier menopause, P = 1.59 × 10-6) and SOHLH2 (3.48 years earlier menopause, P = 1.03 × 10-4). Collectively, our results suggest that, for the vast majority of women, POI is not caused by autosomal dominant variants either in genes previously reported or currently evaluated in clinical diagnostic panels. Our findings, plus previous studies, suggest that most POI cases are likely oligogenic or polygenic in nature, which has important implications for future clinical genetic studies, and genetic counseling for families affected by POI.

A systematic review and evidence assessment of monogenic gene-disease relationships in human female infertility and differences in sex development

BACKGROUND

As in other domains of medicine, high-throughput sequencing methods have led to the identification of an ever-increasing number of gene variants in the fields of both male and female infertility. The increasing number of recently identified genes allows an accurate diagnosis for previously idiopathic cases of female infertility and more appropriate patient care. However, robust evidence of the gene-disease relationships (GDR) allowing the proper translation to clinical application is still missing in many cases.

OBJECTIVE AND RATIONALE

An evidence-based curation of currently identified genes involved in female infertility and differences in sex development (DSD) would significantly improve both diagnostic performance and genetic research. We therefore performed a systematic review to summarize current knowledge and assess the available GDR.

SEARCH METHODS

PRISMA guidelines were applied to curate all available information from PubMed and Web of Science on genetics of human female infertility and DSD leading to infertility, from 1 January 1988 to 1 November 2021. The reviewed pathologies include non-syndromic as well as syndromic female infertility, and endocrine and reproductive system disorders. The evidence that an identified phenotype is caused by pathogenic variants in a specific gene was assessed according to a standardized scoring system. A final score (no evidence, limited, moderate, strong, or definitive) was assigned to every GDR.

OUTCOMES

A total of 45 271 publications were identified and screened for inclusion of which 1078 were selected for gene and variant extraction. We have identified 395 genes and validated 466 GDRs covering all reported monogenic causes of female infertility and DSD. Furthermore, we present a genetic diagnostic flowchart including 105 genes with at least moderate evidence for female infertility and suggest recommendations for future research. The study did not take into account associated genetic risk factor(s) or oligogenic/polygenic causes of female infertility.

WIDER IMPLICATIONS

We have comprehensively reviewed the existing research on the genetics of female infertility and DSD, which will enable the development of diagnostic panels using validated genes. Whole genome analysis is shifting from predominantly research to clinical application, increasing its diagnostic potential. These new diagnostic possibilities will not only decrease the number of idiopathic cases but will also render genetic counselling more effective for infertile patients and their families.

Selected Genetic Factors Associated with Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) is a heterogeneous disease resulting from non-functional ovaries in women before the age of 40. It is characterized by primary amenorrhea or secondary amenorrhea. As regards its etiology, although many POI cases are idiopathic, menopausal age is a heritable trait and genetic factors play an important role in all POI cases with known causes, accounting for approximately 20% to 25% of cases. This paper reviews the selected genetic causes implicated in POI and examines their pathogenic mechanisms to show the crucial role of genetic effects on POI. The genetic factors that can be found in POI cases include chromosomal abnormalities (e.g., X chromosomal aneuploidies, structural X chromosomal abnormalities, X-autosome translocations, and autosomal variations), single gene mutations (e.g., newborn ovary homeobox gene (NOBOX), folliculogenesis specific bHLH transcription factor (FIGLA), follicle-stimulating hormone receptor (FSHR), forkhead box L2 (FOXL2), bone morphogenetic protein 15 (BMP15), etc., as well as defects in mitochondrial functions and non-coding RNAs (small ncRNAs and long ncRNAs). These findings are beneficial for doctors to diagnose idiopathic POI cases and predict the risk of POI in women.

Next-generation sequencing of 500 POI patients identified novel responsible monogenic and oligogenic variants

BACKGROUND

Premature ovarian insufficiency refers to the loss of ovarian function before 40 years of age. The etiology is heterogeneous, and genetic factors account for 20-25% of cases. However, how to transform genetic findings to clinical molecular diagnose remains a challenge. To identify potential causative variations for POI, a next generation sequencing panel with 28 known causative genes of POI was designed, and a large cohort of 500 Chinese Han patients was screened directly. Pathogenic evaluation of the identified variants and the phenotype analysis were performed according to monogenic or oligogenic variants.

RESULTS

A total of 14.4% (72/500) of the patients carried 61 pathogenic or likely pathogenic variants in 19 of the genes in the panel. Interestingly, 58 variants (95.1%, 58/61) were firstly identified in patients with POI. FOXL2 harbored the highest occurrence frequency (3.2%, 16/500), among whom presented with isolated ovarian insufficiency instead of blepharophimosis-ptosis-epicanthus inversus syndrome. Moreover, luciferase reporter assay confirmed variant p.R349G, which account for 2.6% of POI cases, impaired the transcriptional repressive effect of FOXL2 on CYP17A1. The novel compound heterozygous variants in NOBOX and MSH4 were confirmed by pedigree haplotype analysis, and digenic heterozygous variants in MSH4 and MSH5 were firstly identified. Furthermore, nine patients (1.8%, 9/500) with digenic or multigenic pathogenic variants presented with delayed menarche, early onset of POI and high prevalence of primary amenorrhea compared with those with monogenic variation(s).

CONCLUSIONS

The genetic architecture of POI has been enriched through the targeted gene panel in a large cohort of patients with POI. Specific variants in pleiotropic genes may result in isolated POI rather than syndromic POI, whereas oligogenic defects might have cumulative deleterious effects on the severity of POI phenotype.

Stem cell-derived extracellular vesicles: A novel and potential remedy for primary ovarian insufficiency

Primary ovarian insufficiency (POI) is an essential cause of young female fertility loss. At present, there are many treatments for primary ovarian insufficiency, but due to the complexity of the pathogenesis of primary ovarian insufficiency, the efficacy still could not be satisfactory. Stem cell transplantation is a feasible intervention protocol for primary ovarian insufficiency. However, its wide application in the clinic is limited by some defects such as tumorigenic and controversial ethical issues. Stem cell-derived extracellular vesicles (EVs) represent an important mode of intercellular communication attracting increasing interest. It is well documented that stem cell-derived extracellular vesicles for primary ovarian insufficiency with exciting therapeutic effects. Studies have found that stem cell-derived extracellular vesicles could improve ovarian reserve, increase the growth of follicles, reduce follicle atresia, and restore hormone levels of FSH and E2. Its mechanisms include inhibiting ovarian granulosa cells (GCs) apoptosis, reactive oxygen species, and inflammatory response and promoting granulosa cells proliferation and angiogenesis. Thus, stem cell-derived extracellular vesicles are a promising and potential method for primary ovarian insufficiency patients. However, stem cell-derived extracellular vesicles are still a long way from clinical translation. This review will provide an overview of the role and the mechanisms of stem cell-derived extracellular vesicles in primary ovarian insufficiency, and further elaborate on the current challenges. It may suggest new directions for future research.

Primary ovarian insufficiency has strong familiality: results of a multigenerational genealogical study

OBJECTIVE

To determine the familiality of primary ovarian insufficiency (POI) at population level through examination of multigenerational genealogical information linked to electronic medical records.

DESIGN

Case-control study.

SETTING

Not applicable.

PATIENT(S)

Women with POI were identified using International Classification of Disease 9 and 10 codes in electronic medical records (1995-2021) from 2 major health care systems in Utah and reviewed for accuracy. Cases were linked to genealogy information in the Utah Population Database (UPDB). All included POI cases (n = 396) were required to have genealogy information available for at least 3 generations of ancestors. The risk of POI in relatives was compared with population rates for POI matched by age, sex, and birthplace.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Relative risk of POI in first-, second-, and third-degree relatives.

RESULT(S)

We identified 396 validated cases of POI with an associated 2,132 first-degree relatives, 5,245 second-degree relatives, and 10,853 third-degree relatives. We found an increased risk of POI among the extended relatives of cases. Specifically, first-degree relatives demonstrated an 18-fold increased risk of POI compared with controls relative risk ([RR],18.52 95% confidence interval [CI], 10.12-31.07), second-degree relatives demonstrated a 4-fold increase (RR, 4.21; CI, 1.15-10.79), and third-degree relatives demonstrated a 2.7-fold increase (RR, 2.65; CI, 1.14-5.21]).

CONCLUSION(S)

This is the first population-based study to assess the familial clustering of POI. The data demonstrate excess familiality, familial clustering of POI in excess compared with matched population rates of disease, among first-, second-, and third-degree relatives. These findings support a genetic contribution to POI.

A truncating variant of RAD51B associated with primary ovarian insufficiency provides insights into its meiotic and somatic functions

Primary ovarian insufficiency (POI) causes female infertility by abolishing normal ovarian function. Although its genetic etiology has been extensively investigated, most POI cases remain unexplained. Using whole-exome sequencing, we identified a homozygous variant in RAD51B -(c.92delT) in two sisters with POI. In vitro studies revealed that this variant leads to translation reinitiation at methionine 64. Here, we show that this is a pathogenic hypomorphic variant in a mouse model. Rad51bc.92delT/c.92delT mice exhibited meiotic DNA repair defects due to RAD51 and HSF2BP/BMRE1 accumulation in the chromosome axes leading to a reduction in the number of crossovers. Interestingly, the interaction of RAD51B-c.92delT with RAD51C and with its newly identified interactors RAD51 and HELQ was abrogated or diminished. Repair of mitomycin-C-induced chromosomal aberrations was impaired in RAD51B/Rad51b-c.92delT human and mouse somatic cells in vitro and in explanted mouse bone marrow cells. Accordingly, Rad51b-c.92delT variant reduced replication fork progression of patient-derived lymphoblastoid cell lines and pluripotent reprogramming efficiency of primary mouse embryonic fibroblasts. Finally, Rad51bc.92delT/c.92delT mice displayed increased incidence of pituitary gland hyperplasia. These results provide new mechanistic insights into the role of RAD51B not only in meiosis but in the maintenance of somatic genome stability.

Health-related quality of life in women with primary ovarian insufficiency: a scoping review of the literature and implications for targeted interventions

STUDY QUESTION

What is known about health-related quality of life (HR-QoL) in women with idiopathic primary ovarian insufficiency (POI)?

SUMMARY ANSWER

Women with POI have a range of unmet psychosocial needs relating to three interrelated themes: 'diagnostic odyssey', 'isolation and stigma' and impaired 'ego integrity'.

WHAT IS KNOWN ALREADY

Prior studies have reported increased depressive symptoms, diminished sexual function and altered body image/self-concept in women with POI.

STUDY DESIGN, SIZE, DURATION

A systematic scoping review (11 databases) on HR-QoL in POI including published quantitative, qualitative and mixed-methods studies as well as unpublished gray literature (i.e. unpublished dissertations) through June, 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After removing duplicates, 1244 articles underwent title and abstract review by independent reviewers. The remaining 72 relevant articles underwent dual full text review to determine inclusion criteria yielding 24 articles (100% concordance) for data extraction. Findings were summarized in tables by methodology and recurrent HR-QoL themes/sub-themes were mapped to define key aspects of HR-QoL in POI. Promoters of active coping were charted at the individual, interpersonal and healthcare system levels. Targets for tailored interventions supporting active coping and improved HR-QoL were mapped to the Theory of Planned Behavior (TPB).

MAIN RESULTS AND THE ROLE OF CHANCE

Three interrelated themes affecting HR-QoL in POI emerged from the data synthesis. First, the theme 'diagnostic odyssey' comprised sub-themes of uncertainty, lack of control, knowledge gaps, discontinuous care and negative clinical interactions. The second theme 'isolation and stigma' included sub-themes of guilt, shame, concealment, feeling labeled as infertile, lack of social support and unsympathetic clinicians. The third theme, impaired 'ego integrity' captured sub-themes of decreased sexual function, altered body image, psychological vulnerability and catastrophizing. Targets promoting active coping at the individual (n = 2), interpersonal (n = 1) and healthcare system (n = 1) levels were mapped to the TPB to inform development of tailored interventions supporting active coping and improved HR-QoL in POI (i.e. narrative intervention, co-creating patient-facing materials, peer-to-peer support and provider resources).

LIMITATIONS, REASONS FOR CAUTION

No studies using a POI-specific HR-QoL instrument were identified. No interventional studies aimed at improving HR-QoL in POI were identified. Only articles published in English were included in the study.

WIDER IMPLICATIONS OF THE FINDINGS

Women with POI frequently have impaired HR-QoL related to the life-altering infertility diagnosis. The range of unmet psychosocial needs may be relevant for informing interventions for other populations with infertility.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development 'Massachusetts General Hospital-Harvard Center for Reproductive Medicine' (1 P50 HD104224-01 NICHD). The authors have no conflicts to declare.

REGISTRATION NUMBER

N/A.

Genetics of Oocyte Maturation Defects and Early Embryo Development Arrest

Various pathogenic factors can lead to oogenesis failure and seriously affect both female reproductive health and fertility. Genetic factors play an important role in folliculogenesis and oocyte maturation but still need to be clarified. Oocyte maturation is a well-organized complex process, regulated by a large number of genes. Pathogenic variants in these genes as well as aneuploidy, defects in mitochondrial genome, and other genetic and epigenetic factors can result in unexplained infertility, early pregnancy loss, and recurrent failures of IVF/ICSI programs due to poor ovarian response to stimulation, oocyte maturation arrest, poor gamete quality, fertilization failure, or early embryonic developmental arrest. In this paper, we review the main genes, as well as provide a description of the defects in the mitochondrial genome, associated with female infertility.

Artificial Oocyte: Development and Potential Application

Millions of people around the world suffer from infertility, with the number of infertile couples and individuals increasing every year. Assisted reproductive technologies (ART) have been widely developed in recent years; however, some patients are unable to benefit from these technologies due to their lack of functional germ cells. Therefore, the development of alternative methods seems necessary. One of these methods is to create artificial oocytes. Oocytes can be generated in vitro from the ovary, fetal gonad, germline stem cells (GSCs), ovarian stem cells, or pluripotent stem cells (PSCs). This approach has raised new hopes in both basic research and medical applications. In this article, we looked at the principle of oocyte development, the landmark studies that enhanced our understanding of the cellular and molecular mechanisms that govern oogenesis in vivo, as well as the mechanisms underlying in vitro generation of functional oocytes from different sources of mouse and human stem cells. In addition, we introduced next-generation ART using somatic cells with artificial oocytes. Finally, we provided an overview of the reproductive application of in vitro oogenesis and its use in human fertility.

Whole-exome sequencing reveals new potential genes and variants in patients with premature ovarian insufficiency

PURPOSE

Premature ovarian insufficiency (POI) is a heterogeneous disorder characterized by the cessation of menstrual cycles before the age of 40 years due to the depletion or dysfunction of the ovarian follicles. POI is a highly heterogeneous disease in terms of etiology. The aim of this study is to reveal the genetic etiology in POI patients.

METHODS

A total of 35 patients (mean age: 27.2 years) from 28 different families diagnosed with POI were included in the study. Karyotype, FMR1 premutation analysis, single nucleotide polymorphism (SNP) array, and whole-exome sequencing (WES) were conducted to determine the genetic etiology of patients.

RESULTS

A total of 35 patients with POI were first evaluated by karyotype analysis, and chromosomal anomaly was detected in three (8.5%) and FMR1 premutation was detected in six patients (17%) from two different families. A total of 29 patients without FMR1 premutation were included in the SNP array analysis, and one patient had a 337-kb deletion in the chromosome 6q26 region including PARK2 gene, which was thought to be associated with POI. Twenty-nine cases included in SNP array analysis were evaluated simultaneously with WES analysis, and genetic variant was detected in 55.1% (16/29).

CONCLUSION

In the present study, rare novel variants were identified in genes known to be associated with POI, which contribute to the mutation spectrum. The effects of detected novel genes and variations on different pathways such as gonadal development, meiosis and DNA repair, or metabolism need to be investigated by experimental studies. Molecular etiology allows accurate genetic counseling to the patient and family as well as fertility planning.

Pathogenic Variations of Homologous Recombination Gene HSF2BP Identified in Sporadic Patients With Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is defined as depletion of ovarian function before 40 years of age, which affects 3.7% of women in reproductive age. The etiology of POI is heterogeneous. Recently, with the widespread use of whole-exome sequencing (WES), the DNA repair genes, especially for those involved in meiosis progress, were enriched in the causative gene spectrum of POI. In this study, through the largest in-house WES database of 1,030 patients with sporadic POI, we identified two novel homozygous variations in HSF2BP (c.382T>C, p.C128R; c.557T>C, p.L186P). An in vitro functional study revealed that both variations impaired the nuclear location of HSF2BP and affected its DNA repair capacity. Our studies highlighted the essential role of meiotic homologous recombination genes in the pathogenesis of sporadic POI.

Overexpression of Lin28a induces a primary ovarian insufficiency phenotype via facilitation of primordial follicle activation in mice

Lin28a is an RNA binding protein and increasing evidence has indicated its role in regulating female fertility. Lin28a has been reported to be involved in ovarian follicle activation. However, its role and mechanisms in regulating primordial follicle activation have not yet been explored. To test whether overexpression of Lin28a activates ovarian primordial follicles, studies were conducted in wild type (WT) and Lin28a Tg mice. Female Lin28a Tg mice at 4-month old exhibited significantly smaller litter size and fewer ovulated oocytes when compared with the WT mice. By 6-month of age, these parameters in Lin28a Tg mice were less than 20% of the WT mice. At postnatal day (PD) 14, the number of primordial follicles was significantly decreased but the number of primary follicles was significantly increased in the transgenic mice. The number of primordial follicles, secondary and antral follicles in these mice were drastically reduced at PD21. In the ovary of Lin28a Tg mice, there were activation of Wnt/β-catenin signaling and its downstream mTOR pathway. Interestingly, overexpression of Lin28a, which can also act as transcriptional activator, activated Wnt signaling through enhancing the transcription of Wnt co-receptor LRP5. In conclusion, overexpression of Lin28a induced a primary ovarian insufficiency phenotype in long term via facilitating Wnt/β-catenin signaling leading to activation of primordial follicles.

Genetics of ovarian insufficiency and defects of folliculogenesis

Primary ovarian insufficiency (POI) is determined by exhaustion of follicles in the ovaries, which leads to infertility before the age of 40 years. It is characterized by a strong familial and heterogeneous genetic background. Therefore, we will mainly discuss the genetic basis of POI in this review. We identified 107 genes related to POI etiology in mammals described by several independent groups. Thirty-four of these genes (AARS2, AIRE, ANTXR1, ATM, BMPR1B, CLPP, CYP17A1, CYP19A1, DCAF17, EIF2B, ERAL1, FANCA, FANCC, FMR1, FOXL2, GALT, GNAS, HARS2, HSD17B4, LARS2, LMNA, MGME1, NBN, PMM2, POLG, PREPL, RCBTB1, RECQL2/3/4, STAR, TWNK, and XRCC4/9) have been linked to syndromic POI and are mainly implicated in metabolism function and meiosis/DNA repair. In addition, the majority of genes associated with nonsyndromic POI, widely expanded by high-throughput techniques over the last decade, have been implicated in ovarian development and meiosis/DNA repair pathways (ATG7, ATG9, ANKRD31, BMP8B, BMP15, BMPR1A, BMPR1B, BMPR2, BNC1, BRCA2, CPEB1, C14ORF39, DAZL, DIAPH2, DMC1, ERCC6, FANCL, FANCM, FIGLA, FSHR, GATA4, GDF9, GJA4, HELQ, HSF2BP, HFM1, INSL3, LHCGR, LHX8, MCM8, MCM9, MEIOB, MSH4, MSH5, NANOS3, NOBOX, NOTCH2, NR5A1, NUP107, PGRMC1, POLR3H, PRDM1, PRDM9, PSMC3IP, SOHLH1, SOHLH2, SPIDR, STAG3, SYCE1, TP63, UBR2, WDR62, and XRCC2), whereas a few are related to metabolic functions (EIF4ENIF1, KHDRBS1, MRPS22, POLR2C). Some genes, such as STRA8, FOXO3A, KIT, KITL, WNT4, and FANCE, have been shown to cause ovarian insufficiency in rodents, but mutations in these genes have yet to be elucidated in women affected by POI. Lastly, some genes have been rarely implicated in its etiology (AMH, AMHR2, ERRC2, ESR1, INHA, LMN4, POF1B, POU5F1, REC8, SMC1B). Considering the heterogeneous genetic and familial background of this disorder, we hope that an overview of literature data would reinforce that genetic screening of those patients is worthwhile and helpful for better genetic counseling and patient management.

Diagnosis and management of premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a complex clinical syndrome with life-changing physiological and psychological consequence in young women of reproductive age. However, the understanding of the etiology, diagnosis and optimal intervention strategies for this condition remains poorly understood. In recent years advances in epidemiologic and genetic research has improved our knowledge and awareness of POI. Further prospective randomised trials are required to improve the psychological and sexual health, fertility treatment options and long-term management of the impact on bone, cardiovascular and cognitive impact in women with POI. In this paper we aim to provide an overview on the diagnosis and management of POI, discuss the current understanding of the condition and future directions.

A Long Contiguous Stretch of Homozygosity Disclosed a Novel STAG3 Biallelic Pathogenic Variant Causing Primary Ovarian Insufficiency: A Case Report and Review of the Literature

Primary ovarian insufficiency (POI) refers to an etiologically heterogeneous disorder characterized by hypergonadotropic hypogonadism that represents a major cause of infertility in women under 40 years of age. Most cases are apparently sporadic, but about 10–15% have an affected first-degree relative, indicating a genetic etiology. Pathogenic variations in genes involved in development, meiosis and hormonal signaling have been detected in the hereditary form of the disorder. However, most cases of POI remain unsolved even after exhaustive investigation. A 19-year-old Senegalese female affected by non-syndromic POI presented with primary amenorrhoea and answered well to the hormonal induction of puberty. In order to investigate the presence of a genetic defect, aCGH-SNP analysis was performed. A 13.5 Mb long contiguous stretch of homozygosity (LCSH) was identified on chromosome 7q21.13-q22.1 where the exome sequencing revealed a novel homozygous 4-bp deletion (c.3381_3384delAGAA) in STAG3. Pathogenic variants in this gene, encoding for a meiosis-specific protein, have been previously reported as the cause of POI in only eight families and recently as the cause of infertility in a male. The here-identified mutation leads to the truncation of the last 55 amino acids, confirming the important role in meiosis of the STAG3 C-terminal domain.

Targeted whole exome sequencing and Drosophila modelling to unveil the molecular basis of primary ovarian insufficiency

STUDY QUESTION

Can a targeted whole exome sequencing (WES) on a cohort of women showing a primary ovarian insufficiency (POI) phenotype at a young age, combined with a study of copy number variations, identify variants in candidate genes confirming their deleterious effect on ovarian function?

SUMMARY ANSWER

This integrated approach has proved effective in identifying novel candidate genes unveiling mechanisms involved in POI pathogenesis.

WHAT IS KNOWN ALREADY

POI, a condition occurring in 1% of women under 40 years of age, affects women’s fertility leading to a premature loss of ovarian reserve. The genetic causes of POI are highly heterogeneous and several determinants contributing to its prominent oligogenic inheritance pattern still need to be elucidated.

STUDY DESIGN, SIZE, DURATION

WES screening for pathogenic variants of 41 Italian women with non-syndromic primary and early secondary amenorrhoea occurring before age 25 was replicated on another 60 POI patients, including 35 French and 25 American women, to reveal statistically significant shared variants.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The Italian POI patients’ DNA were processed by targeted WES including 542 RefSeq genes expressed or functioning during distinct reproductive or ovarian processes (e.g. DNA repair, meiosis, oocyte maturation, folliculogenesis and menopause). Extremely rare variants were filtered and selected by means of a Fisher Exact test using several publicly available datasets. A case-control Burden test was applied to highlight the most significant genes using two ad-hoc control female cohorts. To support the obtained data, the identified genes were screened on a novel cohort of 60 Caucasian POI patients and the same case-control analysis was carried out. Comparative analysis of the human identified genes was performed on mouse and Drosophila melanogaster by analysing the orthologous genes in their ovarian phenotype, and two of the selected genes were fruit fly modelled to explore their role in fertility.

MAIN RESULTS AND THE ROLE OF CHANCE

The filtering steps applied to search for extremely rare pathogenic variants in the Italian cohort revealed 64 validated single-nucleotide variants/Indels in 59 genes in 30 out of 41 screened women. Burden test analysis highlighted 13 ovarian genes as being the most enriched and significant. To validate these findings, filtering steps and Burden analysis on the second cohort of Caucasian patients yielded 11 significantly enriched genes. Among them, AFP, DMRT3, MOV10, FYN and MYC were significant in both patient cohorts and hence were considered strong candidates for POI. Mouse and Drosophila comparative analysis evaluated a conserved role through the evolution of several candidates, and functional studies using a Drosophila model, when applicable, supported the conserved role of the MOV10 armitage and DMRT3 dmrt93B orthologues in female fertility.

LARGE SCALE DATA

The datasets for the Italian cohort generated during the current study are publicly available at ClinVar database (http://www.ncbi.nlm.nih.gov/clinvar/): accession numbers SCV001364312 to SCV001364375.

LIMITATIONS, REASONS FOR CAUTION

This is a targeted WES analysis hunting variants in candidate genes previously identified by different genomic approaches. For most of the investigated sporadic cases, we could not track the parental inheritance, due to unavailability of the parents’ DNA samples; in addition, we might have overlooked additional rare variants in novel candidate POI genes extracted from the exome data. On the contrary, we might have considered some inherited variants whose clinical significance is uncertain and might not be causative for the patients’ phenotype. Additionally, as regards the Drosophila model, it will be extremely important in the future to have more mutants or RNAi strains available for each candidate gene in order to validate their role in POI pathogenesis.

WIDER IMPLICATIONS OF THE FINDINGS

The genomic, statistical, comparative and functional approaches integrated in our study convincingly support the extremely heterogeneous oligogenic nature of POI, and confirm the maintenance across the evolution of some key genes safeguarding fertility and successful reproduction. Two principal classes of genes were identified: (i) genes primarily involved in meiosis, namely in synaptonemal complex formation, asymmetric division and oocyte maturation and (ii) genes safeguarding cell maintenance (piRNA and DNA repair pathways).

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Italian Ministry of Health grants ‘Ricerca Corrente’ (08C621_2016 and 08C924_2019) provided to IRCCS Istituto Auxologico Italiano, and by ‘Piano Sostegno alla Ricerca’ (PSR2020_FINELLI_LINEA_B) provided by the University of Milan; M.P.B. was supported by Telethon-Italy (grant number GG14181). There are no conflicts of interest.

Genomic Consideration in Chemotherapy-Induced Ovarian Damage and Fertility Preservation

Chemotherapy-induced ovarian damage and fertility preservation in young patients with cancer are emerging disciplines. The mechanism of treatment-related gonadal damage provides important information for targeting prevention methods. The genomic aspects of ovarian damage after chemotherapy are not fully understood. Several studies have demonstrated that gene alterations related to follicular apoptosis or accelerated follicle activation are related to ovarian insufficiency and susceptibility to ovarian damage following chemotherapy. This may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions after chemotherapy. This review highlights the importance of genomic considerations in chemotherapy-induced ovarian damage and multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

A pathogenic DMC1 frameshift mutation causes nonobstructive azoospermia but not primary ovarian insufficiency in humans

Nonobstructive azoospermia (NOA) and diminished ovarian reserve (DOR) are two disorders that can lead to infertility in males and females. Genetic factors have been identified to contribute to NOA and DOR. However, the same genetic factor that can cause both NOA and DOR remains largely unknown. To explore the candidate pathogenic gene that causes both NOA and DOR, we conducted whole-exome sequencing (WES) in a non-consanguineous family with two daughters with DOR and a son with NOA. We detected one pathogenic frameshift variant (NM_007068:c.28delG, p. Glu10Asnfs*31) following a recessive inheritance mode in a meiosis gene DMC1 (DNA meiotic recombinase 1). Clinical analysis showed reduced antral follicle number in both daughters with DOR, but metaphase II oocytes could be retrieved from one of them. For the son with NOA, no spermatozoa were found after microsurgical testicular sperm extraction. A further homozygous Dmc1 knockout mice study demonstrated total failure of follicle development and spermatogenesis. These results revealed a discrepancy of DMC1 action between mice and humans. In humans, DMC1 is required for spermatogenesis but is dispensable for oogenesis, although the loss of function of this gene may lead to DOR. To our knowledge, this is the first report on the homozygous frameshift mutation as causative for both NOA and DOR and demonstrating that DMC1 is dispensable in human oogenesis.

46,XX DSD: Developmental, Clinical and Genetic Aspects

Differences in sex development (DSD) in patients with 46,XX karyotype occur by foetal or postnatal exposure to an increased amount of androgens. These disorders are usually diagnosed at birth, in newborns with abnormal genitalia, or later, due to postnatal virilization, usually at puberty. Proper diagnosis and therapy are mostly based on the knowledge of normal development and molecular etiopathogenesis of the gonadal and adrenal structures. This review aims to describe the most relevant data that are correlated with the normal and abnormal development of adrenal and gonadal structures in direct correlation with their utility in clinical practice, mainly in patients with 46,XX karyotype. We described the prenatal development of structures together with the main molecules and pathways that are involved in sex development. The second part of the review described the physical, imaging, hormonal and genetic evaluation in a patient with a disorder of sex development, insisting more on patients with 46,XX karyotype. Further, 95% of the etiology in 46,XX patients with disorders of sex development is due to congenital adrenal hyperplasia, by enzyme deficiencies that are involved in the hormonal synthesis pathway. The other cases are explained by genetic abnormalities that are involved in the development of the genital system. The phenotypic variability is very important in 46,XX disorders of sex development and the knowledge of each sign, even the most discreet, which could reveal such disorders, mainly in the neonatal period, could influence the evolution, prognosis and life quality long term.

Single-cell RNA-Seq reveals a highly coordinated transcriptional program in mouse germ cells during primordial follicle formation

The assembly of primordial follicles in mammals represents one of the most critical processes in ovarian biology. It directly affects the number of oocytes available to a female throughout her reproductive life. Premature depletion of primordial follicles contributes to the ovarian pathology primary ovarian insufficiency (POI). To delineate the developmental trajectory and regulatory mechanisms of oocytes during the process, we performed RNA‐seq on single germ cells from newborn (P0.5) ovaries. Three cell clusters were classified which corresponded to three cell states (germ cell cyst, cyst breakdown, and follicle) in the newborn ovary. By Monocle analysis, a uniform trajectory of oocyte development was built with a series of genes showed dynamic changes along the pseudo‐timeline. Gene Ontology term enrichment revealed a significant decrease in meiosis‐related genes and a dramatic increase in oocyte‐specific genes which marked the transition from a germ cell to a functional oocyte. We then established a network of regulons by using single‐cell regulatory network inference and clustering (SCENIC) algorithm and identified possible candidate transcription factors that may maintain transcription programs during follicle formation. Following functional studies further revealed the differential regulation of the identified regulon Id2 and its family member Id1, on the establishment of primordial follicle pool by using siRNA knockdown and genetic modified mouse models. In summary, our study systematically reconstructed molecular cascades in oocytes and identified a series of genes and molecular pathways in follicle formation and development.

Onco-fertility and personalized testing for potential for loss of ovarian reserve in patients undergoing chemotherapy: proposed next steps for development of genetic testing to predict changes in ovarian reserve

Women of reproductive age undergoing chemotherapy face the risk of irreversible ovarian insufficiency. Current methods of ovarian reserve testing do not accurately predict future reproductive potential for patients undergoing chemotherapy. Genetic markers that more accurately predict the reproductive potential of each patient undergoing chemotherapy would be critical tools that would be useful for evidence-based fertility preservation counselling. To assess the possible approaches to take to develop personalized genetic testing for these patients, we review current literature regarding mechanisms of ovarian damage due to chemotherapy and genetic variants associated with both the damage mechanisms and primary ovarian insufficiency. The medical literature point to a number of genetic variants associated with mechanisms of ovarian damage and primary ovarian insufficiency. Those variants that appear at a higher frequency, with known pathways, may be considered as potential genetic markers for predictive ovarian reserve testing. We propose developing personalized testing of the potential for loss of ovarian function for patients with cancer, prior to chemotherapy treatment. There are advantages of using genetic markers complementary to the current ovarian reserve markers of AMH, antral follicle count and day 3 FSH as predictors of preservation of fertility after chemotherapy. Genetic markers will help identify upstream pathways leading to high risk of ovarian failure not detected by present clinical markers. Their predictive value is mechanism-based and will encourage research towards understanding the multiple pathways contributing to ovarian failure after chemotherapy.

Primary ovarian insufficiency in a female with phosphomannomutase-2 gene (PMM2) mutations for congenital disorder of glycosylation

Primary ovarian insufficiency (POI) is a highly heterogeneous condition, and its underlying causes remain to be clarified in a large fraction of patients. Congenital disorders of glycosylation (CDG) are multisystem diseases caused by mutations of a number of genes involved in N-glycosylation or O-glycosylation, and the most frequent form is PMM2-CDG (alias, CDG-Ia) resulting from biallelic mutations in PMM2 encoding phosphomannomutase-2 involved in N-glycosylation. Here, we examined a 46,XX Japanese female with syndromic POI accompanied by an undetectable level of serum anti-Müllerian hormone (AMH). Whole exome sequencing identified biallelic pathogenic mutations of PMM2 (a novel c.34G>C:p.(Asp12His) of maternal origin and a recurrent c.310C>G:p.(Leu104Val) of paternal origin) (NM_000303.3), and N-glycosylation studies detected asialotransferrin and disialotransferrin characteristic of PMM2-CDG, in addition to normally glycosylated tetrasialotransferrin. Clinical assessment showed cerebellar hypotrophy, which is a fairly characteristic and highly prevalent feature in PMM2-CDG, together with multiple non-specific features reported in PMM2-CDG such as characteristic face, intellectual disability, skeletal abnormalities, and low blood antithrombin III value. These results including the undetectable level of serum AMH, in conjunction with previously reported findings suggestive of the critical role of glycosylation in oocyte development and function, imply that PMM2-CDG almost invariably leads to POI primarily because of the defective oogenesis and/or oocyte-dependent early folliculogenesis rather than the compromised bioactivity of FSH/LH with defective glycosylation. Thus, it is recommended to examine PMM2 in patients with syndromic POI, especially in those with cerebellar ataxia/hypotrophy.

Pathophysiological Significance of WDR62 and JNK Signaling in Human Diseases

The c-Jun N-terminal kinase (JNK) is highly evolutionarily conserved and plays important roles in a broad range of physiological and pathological processes. The WD40-repeat protein 62 (WDR62) is a scaffold protein that recruits different components of the JNK signaling pathway to regulate several human diseases including neurological disorders, infertility, and tumorigenesis. Recent studies revealed that WDR62 regulates the process of neural stem cell mitosis and germ cell meiosis through JNK signaling. In this review we summarize the roles of WDR62 and JNK signaling in neuronal and non-neuronal contexts and discuss how JNK-dependent signaling regulates both processes. WDR62 is involved in various human disorders via JNK signaling regulation, and may represent a promising therapeutic strategy for the treatment of related diseases.

Meiotic Recombination Defects and Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is the depletion of ovarian function before 40 years of age due to insufficient oocyte formation or accelerated follicle atresia. Approximately 1–5% of women below 40 years old are affected by POI. The etiology of POI is heterogeneous, including genetic disorders, autoimmune diseases, infection, iatrogenic factors, and environmental toxins. Genetic factors account for 20–25% of patients. However, more than half of the patients were idiopathic. With the widespread application of next-generation sequencing (NGS), the genetic spectrum of POI has been expanded, especially the latest identification in meiosis and DNA repair-related genes. During meiotic prophase I, the key processes include DNA double-strand break (DSB) formation and subsequent homologous recombination (HR), which are essential for chromosome segregation at the first meiotic division and genome diversity of oocytes. Many animal models with defective meiotic recombination present with meiotic arrest, DSB accumulation, and oocyte apoptosis, which are similar to human POI phenotype. In the article, based on different stages of meiotic recombination, including DSB formation, DSB end processing, single-strand invasion, intermediate processing, recombination, and resolution and essential proteins involved in synaptonemal complex (SC), cohesion complex, and fanconi anemia (FA) pathway, we reviewed the individual gene mutations identified in POI patients and the potential candidate genes for POI pathogenesis, which will shed new light on the genetic architecture of POI and facilitate risk prediction, ovarian protection, and early intervention for POI women.

Genetics of Menopause and Primary Ovarian Insufficiency: Time for a Paradigm Shift?

This review summarizes the existing information concerning the genetic background of menopause and primary ovarian insufficiency (POI). There is overwhelming evidence that majority of genes are involved in double-strand break repair, mismatch repair, and base excision repair. The remaining loci were involved in cell energy metabolism and immune response. Gradual (or in case of rapid POI) accumulation of unrepaired DNA damage causes (premature) cell death and cellular senescence. This in turn leads to exhaustion of cell renewal capacity and cellular dysfunction in affected organs and eventually to aging of the entire soma. Similar erosion of the genome occurs within the germ cell line and the ovaries. Subsequently, the systemic "survival" response intentionally suppresses the sex-steroid hormonal output, which in turn may contribute to the onset of menopause. The latter occurs in particular when age-dependent DNA damage accumulation does not cease. Both effects are expected to synergize to promote (premature) ovarian silencing and install (early) menopause. Consequently, aging of the soma seems to be a primary driver for the loss of ovarian function in women. This challenges the current dogma which implies that loss of ovarian function initiates aging of the soma. It is time for a paradigm shift!

Pharmacogenomic Biomarkers of Follicle-Stimulating Hormone Receptor Malfunction in Females with Impaired Ovarian Response-A Genetic Survey

Follicle-stimulating hormone receptor (FSHR) plays an essential role as one of the most important molecules in response to some of infertility related medications. Impaired ovarian reserve and poor response to such treatments are partially dependent on the FSHR molecule itself. However, the function and drug sensitivity for this receptor may change due to various allele and polymorphisms in the FSHR gene. Studies indicated some of the FSHR-mediated treatments utilized in clinical centers display different outcomes in specific populations, which may arise from FSHR altered genotypes in certain patients. To support the increased demands for reaching the personalized drug and hormone therapy in clinics, focusing on actionable variants through Pharmacogenomic analysis of this receptor may be necessary. The current study tries to display a perspective view on genetic assessments for Pharmacogenomic profiling of the FSHR gene via providing a systematic and critical overview on the genetics of FSHR and its diverse responses to ligands for infertility treatment in females with impaired ovarian responses and show the potential effects of the patient genetic make-up on related binding substances efficacy. All identified functional drug-related alleles were selected through a comprehensive literature search and analyzed. Advanced technologies for the genetic evaluation of them are also discussed properly.

Abnormal Expression of Mitochondrial Ribosomal Proteins and Their Encoding Genes with Cell Apoptosis and Diseases

Mammalian mitochondrial ribosomes translate 13 proteins encoded by mitochondrial genes, all of which play roles in the mitochondrial respiratory chain. After a long period of reconstruction, mitochondrial ribosomes are the most protein-rich ribosomes. Mitochondrial ribosomal proteins (MRPs) are encoded by nuclear genes, synthesized in the cytoplasm and then, transported to the mitochondria to be assembled into mitochondrial ribosomes. MRPs not only play a role in mitochondrial oxidative phosphorylation (OXPHOS). Moreover, they participate in the regulation of cell state as apoptosis inducing factors. Abnormal expressions of MRPs will lead to mitochondrial metabolism disorder, cell dysfunction, etc. Many researches have demonstrated the abnormal expression of MRPs in various tumors. This paper reviews the basic structure of mitochondrial ribosome, focuses on the structure and function of MRPs, and their relationships with cell apoptosis and diseases. It provides a reference for the study of the function of MRPs and the disease diagnosis and treatment.

Preconception genome medicine: current state and future perspectives to improve infertility diagnosis and reproductive and health outcomes based on individual genomic data

BACKGROUND

Our genetic code is now readable, writable and hackable. The recent escalation of genome-wide sequencing (GS) applications in population diagnostics will not only enable the assessment of risks of transmitting well-defined monogenic disorders at preconceptional stages (i.e. carrier screening), but also facilitate identification of multifactorial genetic predispositions to sub-lethal pathologies, including those affecting reproductive fitness. Through GS, the acquisition and curation of reproductive-related findings will warrant the expansion of genetic assessment to new areas of genomic prediction of reproductive phenotypes, pharmacogenomics and molecular embryology, further boosting our knowledge and therapeutic tools for treating infertility and improving women's health.

OBJECTIVE AND RATIONALE

In this article, we review current knowledge and potential development of preconception genome analysis aimed at detecting reproductive and individual health risks (recessive genetic disease and medically actionable secondary findings) as well as anticipating specific reproductive outcomes, particularly in the context of IVF. The extension of reproductive genetic risk assessment to the general population and IVF couples will lead to the identification of couples who carry recessive mutations, as well as sub-lethal conditions prior to conception. This approach will provide increased reproductive autonomy to couples, particularly in those cases where preimplantation genetic testing is an available option to avoid the transmission of undesirable conditions. In addition, GS on prospective infertility patients will enable genome-wide association studies specific for infertility phenotypes such as predisposition to premature ovarian failure, increased risk of aneuploidies, complete oocyte immaturity or blastocyst development failure, thus empowering the development of true reproductive precision medicine.

SEARCH METHODS

Searches of the literature on PubMed Central included combinations of the following MeSH terms: human, genetics, genomics, variants, male, female, fertility, next generation sequencing, genome exome sequencing, expanded carrier screening, secondary findings, pharmacogenomics, controlled ovarian stimulation, preconception, genetics, genome-wide association studies, GWAS.

OUTCOMES

Through PubMed Central queries, we identified a total of 1409 articles. The full list of articles was assessed for date of publication, limiting the search to studies published within the last 15 years (2004 onwards due to escalating research output of next-generation sequencing studies from that date). The remaining articles' titles were assessed for pertinence to the topic, leaving a total of 644 articles. The use of preconception GS has the potential to identify inheritable genetic conditions concealed in the genome of around 4% of couples looking to conceive. Genomic information during reproductive age will also be useful to anticipate late-onset medically actionable conditions with strong genetic background in around 2-4% of all individuals. Genetic variants correlated with differential response to pharmaceutical treatment in IVF, and clear genotype-phenotype associations are found for aberrant sperm types, oocyte maturation, fertilization or pre- and post-implantation embryonic development. All currently known capabilities of GS at the preconception stage are reviewed along with persisting and forthcoming barriers for the implementation of precise reproductive medicine.

WIDER IMPLICATIONS

The expansion of sequencing analysis to additional monogenic and polygenic traits may enable the development of cost-effective preconception tests capable of identifying underlying genetic causes of infertility, which have been defined as 'unexplained' until now, thus leading to the development of a true personalized genomic medicine framework in reproductive health.

Screening of targeted panel genes in Brazilian patients with primary ovarian insufficiency

Primary ovarian insufficiency (POI) is a heterogeneous disorder associated with several genes. The majority of cases are still unsolved. Our aim was to identify the molecular diagnosis of a Brazilian cohort with POI. Genetic analysis was performed using a customized panel of targeted massively parallel sequencing (TMPS) and the candidate variants were confirmed by Sanger sequencing. Additional copy number variation (CNV) analysis of TMPS samples was performed by CONTRA. Fifty women with POI (29 primary amenorrhea and 21 secondary amenorrhea) of unknown molecular diagnosis were included in this study, which was conducted in a tertiary referral center of clinical endocrinology. A genetic defect was obtained in 70% women with POI using the customized TMPS panel. Twenty-four pathogenic variants and two CNVs were found in 48% of POI women. Of these variants, 16 genes were identified as BMP8B, CPEB1, INSL3, MCM9, GDF9, UBR2, ATM, STAG3, BMP15, BMPR2, DAZL, PRDM1, FSHR, EIF4ENIF1, NOBOX, and GATA4. Moreover, a microdeletion and microduplication in the CPEB1 and SYCE1 genes, respectively, were also identified in two distinct patients. The genetic analysis of eleven patients was classified as variants of uncertain clinical significance whereas this group of patients harbored at least two variants in different genes. Thirteen patients had benign or no rare variants, and therefore the genetic etiology remained unclear. In conclusion, next-generation sequencing (NGS) is a highly effective approach to identify the genetic diagnoses of heterogenous disorders, such as POI. A molecular etiology allowed us to improve the disease knowledge, guide decisions about prevention or treatment, and allow familial counseling avoiding future comorbidities.

Genetics of Primary Ovarian Insufficiency

The diagnosis of primary ovarian insufficiency (POI) has untold effects on women and a better understanding alongside potential treatments are paramount to improve quality of life of these women. Various causes have been linked to the development of POI with genetics playing a key role. A better understanding of the genetics of POI could lead to earlier diagnosis and broaden fertility options. This chapter discusses previously known and more recently discovered genes that have been implicated in the development of POI. It explores the varying phenotypic expressions of some genes in different populations and areas for further research in the genetics of POI.

Whole-exome sequencing in patients with premature ovarian insufficiency: early detection and early intervention

Background

The loss of ovarian function in women, referred to as premature ovarian insufficiency (POI), is associated with a series of concomitant diseases. POI is genetically heterogeneous, and in most cases, the etiology is unknown.

Methods

Whole-exome sequencing (WES) was performed on DNA samples obtained from patients with POI, and Sanger sequencing was used to validate the detected potentially pathogenic variants. An in silico analysis was carried out to predict the pathogenicity of the variants.

Results

We recruited 24 patients with POI and identified variants in POI-related genes in 14 patients, including bi-allelic mutations in DNAH6, HFM1, EIF2B2, BNC, and LRPPRC and heterozygous variants in BNC1, EIF2B4, FOXL2, MCM9, FANCA, ATM, EIF2B3, and GHR. No variants in the above genes were detected in the WES data obtained from 29 women in a control group without POI. Determining a clear genetic etiology could significantly increase patient compliance with appropriate intervention strategies.

Conclusions

Our study confirmed that POI is a genetically heterogeneous condition and that whole-exome sequencing is a powerful tool for determining its genetic etiology. The results of this study will aid researchers and clinicians in genetic counseling and suggests the potential of WES for the detection of POI and thus early interventions for patients with POI.

Recent advances in understanding primary ovarian insufficiency

Primary ovarian insufficiency (POI) is an uncommon yet devastating occurrence that results from a premature depletion of the ovarian pool of primordial follicles. Our understanding of both putative and plausible mechanisms underlying POI, previously considered to be largely "idiopathic", has been furthered over the past several years, largely due to advances in the field of genetics and through expansion of translational models for experimental research. In this review, our goal is to familiarize the multidisciplinary readers of the F1000 platform with the strides made in the field of reproductive medicine that hold both preventative and therapeutic implications for those women who are at risk for or who have POI.

Novel variants in women with premature ovarian function decline identified via whole-exome sequencing

PURPOSE

To investigate the potential etiologies of premature ovarian insufficiency (POI) and diminished ovarian reserve (DOR).

METHODS

Fourteen women with sporadic POI and 6 women with DOR were enrolled. We used whole-exome sequencing (WES) and bioinformatics analysis to identify variants in a subset of 599 selected POI candidate genes. The identified genes were subjected to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and protein-protein interaction (PPI) network analyses to uncover key genes and pathways.

RESULTS

Among the 20 patients, 79 heterozygous variants were detected in 49 genes, which were classified as "likely pathogenic" or "variants of uncertain significance" according to the guidelines of the American College of Medical Genetics and Genomics. Most patients (17/20) carried two or more variants. Monoacylglycerol O-acyltransferase 1 mutations were found in six patients, and cytochrome P450 family 26 subfamily B member 1 and Bardet-Biedl syndrome 9 mutations were each found in four patients. Some variants were shared between DOR and POI. Enrichment analyses showed that the identified genes participate in key ovarian processes, such as follicular development, gonadal development, meiosis, Fanconi anemia, homologous recombination, and transforming growth factor β signaling. A PPI network revealed interactions between these proteins.

CONCLUSION

Premature ovarian function decline may be polygenic, and overlap exists between the genetic backgrounds of DOR and POI. WES and in silico analyses may be a useful clinical tool for etiological diagnosis and risk prediction for high-risk women in the future.