Molecular cytogenetic studies of Xq critical regions in premature ovarian failure patients

Premature ovarian insufficiency is associated with global alterations in the regulatory landscape and gene expression in balanced X-autosome translocations

BACKGROUND

Patients with balanced X-autosome translocations and premature ovarian insufficiency (POI) constitute an interesting paradigm to study the effect of chromosome repositioning. Their breakpoints are clustered within cytobands Xq13-Xq21, 80% of them in Xq21, and usually, no gene disruption can be associated with POI phenotype. As deletions within Xq21 do not cause POI, and since different breakpoints and translocations with different autosomes lead to this same gonadal phenotype, a "position effect" is hypothesized as a possible mechanism underlying POI pathogenesis.

OBJECTIVE AND METHODS

To study the effect of the balanced X-autosome translocations that result in POI, we fine-mapped the breakpoints in six patients with POI and balanced X-autosome translocations and addressed gene expression and chromatin accessibility changes in four of them.

RESULTS

We observed differential expression in 85 coding genes, associated with protein regulation, multicellular regulation, integrin signaling, and immune response pathways, and 120 differential peaks for the three interrogated histone marks, most of which were mapped in high-activity chromatin state regions. The integrative analysis between transcriptome and chromatin data pointed to 12 peaks mapped less than 2 Mb from 11 differentially expressed genes in genomic regions not related to the patients' chromosomal rearrangement, suggesting that translocations have broad effects on the chromatin structure.

CONCLUSION

Since a wide impact on gene regulation was observed in patients, our results observed in this study support the hypothesis of position effect as a pathogenic mechanism for premature ovarian insufficiency associated with X-autosome translocations. This work emphasizes the relevance of chromatin changes in structural variation, since it advances our knowledge of the impact of perturbations in the regulatory landscape within interphase nuclei, resulting in the position effect pathogenicity.

Comprehensive analysis of three female patients with different types of X/Y translocations and literature review

BACKGROUND

X/Y translocations are highly heterogeneity in terms of clinical genetic effects, and most patients lack complete pedigree analysis for clinical and genetic characterization.

RESULTS

This study comprehensively analyzed the clinical and genetic characteristics of three new patients with X/Y translocations. Furthermore, cases with X/Y translocations reported in the literature and studies exploring the clinical genetic effects in patients with X/Y translocations were reviewed. All three female patients were carriers of X/Y translocations with different phenotypes. The karyotype for patient 1 was 46,X,der(X)t(X;Y)(p22.33;q12)mat, patient 2 was 46,X,der(X)t(X;Y)(q21.2;q11.2)dn, and patient 3 was 46,X,der(X)t(X;Y)(q28;q11.223)t(Y;Y)(q12;q11.223)mat. C-banding analysis of all three patients revealed a large heterochromatin region in the terminal region of the X chromosome. All patients underwent chromosomal microarray analysis, which revealed the precise copy number loss or gain. Data on 128 patients with X/Y translocations were retrieved from 81 studies; the phenotype of these patients was related to the breakpoint of the chromosome, size of the deleted region, and their sex. We reclassified the X/Y translocations into new types based on the breakpoints of the X and Y chromosomes.

CONCLUSION

X/Y translocations have substantial phenotypic diversity, and the genetic classification standards are not unified. With the development of molecular cytogenetics, it is necessary to combine multiple genetic methods to obtain an accurate and reasonable classification. Thus, clarifying their genetic causes and effects promptly will help in genetic counseling, prenatal diagnosis, preimplantation genetic testing, and improvement in clinical treatment strategies.

Cytogenetic abnormalities in a sample of females with premature ovarian failure

Background

Premature ovarian failure (POF) is a complex heterogeneous disorder characterized by the triad of amenorrhea, hypergonadotropinism, and hypoestrogenism in women before the expected age of menopause. In most POF patients, the etiology is idiopathic. X chromosome abnormalities are known to be responsible for many POF cases but the effect of sex chromosome low level mosaicism on ovarian function still remains unclear. The aim of this study was to investigate the prevalence and type of cytogenetic abnormalities as well as low-level sex chromosome mosaicism in Egyptian females with POF.

Results

The present study recruited thirty women with POF and thirty women with normal reproductive history as a control group. Conventional cytogenetic analysis was carried out on POF patients in order to detect cytogenetic abnormalities. FISH on interphase and metaphase nuclei from patients with normal karyotype as well as from thirty control women with normal reproductive history was performed using X, Y, and 18 centromeric probes to evaluate low-level sex chromosome mosaicism. Conventional cytogenetic analysis of peripheral blood lymphocytes demonstrated chromosomal aberrations in 7 cases. FISH revealed that the rate of X chromosome mosaicism was significantly higher in POF patients than in the control group.

Conclusion

We concluded that X chromosome abnormalities including low level mosaicism may be underlying the pathology of POF as increased mosaicism may lead to accelerated oocyte aging and premature follicular atresia.

Human adipose-derived stromal cells transplantation prolongs reproductive lifespan on mouse models of mild and severe premature ovarian insufficiency

Background

Although recent studies have investigated the ability of Mesenchymal Stromal Cells (MSCs) to alleviate short-term ovarian damage in animal models of chemotherapy-induced Premature Ovarian Insufficiency (POI), no data are available on reproductive lifespan recovery, especially in a severe POI condition. For this reason, we investigated the potential of MSCs isolated from human adipose tissue (hASCs), since they are easy to harvest and abundant, in ameliorating the length and performance of reproductive life in both mild and severe chemotherapy-induced murine POI models.

Methods

Mild and severe POI models were established by intraperitoneally administering a light (12 mg/kg busulfan + 120 mg/kg cyclophosphamide) or heavy (30 mg/kg busulfan + 120 mg/kg cyclophosphamide) dose of chemotherapy, respectively, in CD1 mice. In both cases, a week later, 1 × 10⁶ hASCs were transplanted systemically through the tail vein. After four additional weeks, some females were sacrificed to collect ovaries for morphological evaluation. H&E staining was performed to assess stroma alteration and to count follicle numbers; immunofluorescence staining for αSMA was used to analyse vascularization. Of the remaining females, some were mated after superovulation to collect 2-cell embryos in order to evaluate their pre-implantation developmental capacity in vitro, while others were naturally mated to monitor litters and reproductive lifespan length. F1 litters’ weight, ovaries and reproductive lifespan were also analysed.

Results

hASC transplantation alleviated ovarian weight loss and size decrease and reduced alterations on ovarian stroma and vasculature, concurrently preventing the progressive follicle stockpile depletion caused by chemotherapy. These effects were associated with the preservation of the oocyte competence to develop into blastocyst in vitro and, more interestingly, with a significant decrease of chemotherapy-induced POI features, like shortness of reproductive lifespan, reduced number of litters and longer time to plug (the latter only presented in the severe POI model).

Conclusion

Human ASC transplantation was able to significantly reduce all the alterations induced by the chemotherapeutic treatment, while improving oocyte quality and prolonging reproductive functions, thus counteracting infertility. These results, strengthened by the use of an outbred model, support the potential applications of hASCs in women with POI, nowadays mainly induced by anticancer therapies.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02590-5.

Adipose-Derived Mesenchymal Stem Cells: A Promising Tool in the Treatment of pre mature ovarian failure

Despite being rare, primary ovarian insufficiency (POI) is a significant cause of infertility and deficiency of ovarian hormone in women. Several health risks are also associated with POI, which include dry eye syndrome, reduced density of bones and enhanced fracture risks, troublesome menopausal symptoms, early development of cardiovascular disease, and psychological effects such as declined cognition, reduced perceived psychological support, anxiety, and depression. Replacing premenopausal levels of ovarian sex steroids through proper hormone replacement therapy could improve the quality of life for POI women and ameliorate related health risks. Herein, POI and its complications, in addition to hormone replacement therapies, which are safe and effective, are discussed. It is proposed that the use of HRT) Hormone replacement therapy (formulations which mimic normal production of ovarian hormones could reduce POI-associated morbidity rates if they are continued by the age 50, which is approximately the natural age of menopause. Particular populations of POI women are also addressed, which include those with enhanced risk of ovarian or breast cancer, those with Turner syndrome, those approaching natural menopause, and those who are breastfeeding. It is generally predicted that stem cell-based therapies would be both safe and effective. In fact, several types of cells have been described as safe, though their effectiveness and therapeutic application are yet to be defined. Several factors exist which could affect the results of treatment, such as cell handling, ex-vivo preparation strategies, variations in tissue of origin, potency, and immunocompatibility. Accordingly, cell types potentially effective in regenerative medicine could be recognized. Notably, products of MSCs from various sources of tissues show different levels of regenerative capabilities. The ultimate focus of the review is on adipose tissue-derive MCSs (ADMSCs), which possess exceptional features such as general availability, great ability to proliferate and differentiate, immunomodulatory capabilities, and low immunogenicity.

Live Birth Rate in Patients With Premature Ovarian Insufficiency During Long-Term Follow-Up Under Hormone Replacement With or Without Ovarian Stimulation

We analyzed data from 466 patients with premature ovarian insufficiency (POI) who wished to have a biological child and were followed up while undergoing hormone replacement (HR) therapy with or without ovarian stimulation (OS) between April 2014 and December 2020. OS was conducted in 6891 cycles in 429 patients (Group OS), whereas only HR (Group HR) was conducted in 1117 cycles in 37 patients. The follicle growth rate was 48.3% (207/429) per patient in Group OS and 5.4% (2/37) in Group HR (p<0.01). There were 51 live births (LBs) in 50 patients during follow-up. In Group OS, the LB rate was 5.8% (47/807) in cycles where in vitro fertilization (IVF) and embryo transfer were attempted (Group IVF), and 1.3% (3/236) in cycles where intrauterine insemination/timed intercourse was attempted (p<0.01). No pregnancies occurred in Group HR. Among the patients in Group IVF, the LB rate was significantly higher in patients aged <35 years at the initiation of follow-up than in patients who started at later ages (p<0.01). Among the cases who achieved an LB, 39 were patients with idiopathic POI (Group IVF-1, n=297) and seven were patients who had undergone surgical treatment for benign ovarian tumors (Group IVF-2, n=50); however, no LBs occurred in patients who had undergone treatment for malignancy (n=17), and only one in patients with chromosomal abnormalities (n=22). The LB rate per case in the patients in Group IVF-1 and those aged <35 years at the start of follow-up (Group IVF-1-a) was 24.1% (26/108), which was higher than those of the other age groups. The LB rate per case in the patients in Group IVF-1-a with <4 years of amenorrhea was 37.3% (19/51), and that in the patients in Group IVF-2 with <4 years of amenorrhea was 21.2% (7/33). These results suggest that infertility treatment is possible in some patients with POI, especially those that can be classified in Group IVF-1-a and Group IVF-2 with <4 years of amenorrhea. Therefore, OS combined with HR therapy should be considered for such patients before attempts at oocyte donation.

Icariin exerts a protective effect against d-galactose induced premature ovarian failure via promoting DNA damage repair

Icariin is one of the most common active ingredients in traditional Chinese medicine, while its function against Premature ovarian failure (POF) has not been explored. POF animal model was induced by d-galactose, and icariin at different doses was administered. Ovarian structure and follicle counting were observed via hematoxylin and eosin staining. The levels of serum hormones were measured by ELISA. Primary ovarian granulosa cells were cultured to compare the protective effects of icariin on cell aging, and DNA damage markers including γH2AX and 53BP1 were assessed by Western Blot. Administration of icariin promoted ovary/body weight, follicles numbers and fertility outcomes. In addition, icariin downregulated the levels of follicle stimulating hormone and luteinizing hormone, and upregulated the levels of estradiol and anti-Müllerian hormone. Icariin protected ovarian granulosa cells from d-galactose induced aging, with increased cell viability and lower endogenous β-galactosidase activity. The alterations of expression level of γH2AX and 53BP1 by icariin indicated that the protection is via promoting DNA damage repair. In this study we tested the biological function of icariin against the d-galactose induced POF. Our results demonstrated that icariin effectively attenuated ovarian injury via promoting DNA damage repair, suggesting that icariin can be developed as a protective agent against POF.

A high-resolution X chromosome copy-number variation map in fertile females and women with primary ovarian insufficiency

PURPOSE

Sex-biased expression of genes on the X chromosome is accomplished by a complex mechanism of dosage regulation that leads to anatomical and physiological differences between males and females. Copy-number variations (CNVs) may impact the human genome by either affecting gene dosage or disturbing a chromosome structural and/or functional integrity.

METHODS

We performed a high-resolution CNV profiling to investigate the X chromosome integrity in cohorts of 269 fertile females and 111 women affected with primary ovarian insufficiency (POI) and assessed CNVs impact into functional and nonfunctional genomic elements.

RESULTS

In POI patients, we observed a 2.5-fold enrichment for rare CNVs comprising ovary-expressed genes, and genes implicated in autoimmune response and apoptotic signaling. Moreover, there was a higher prevalence of deletions encompassing genes that escape X inactivation, noncoding RNAs, and intergenic DNA sequences among POI females, highlighting structural differences between X chromosomes of fertile and POI females. Furthermore, we discovered a ~4% carrier incidence for X-linked disorders among fertile women.

CONCLUSION

We constructed a high-resolution map of female-specific CNVs that provides critical insights into the spectrum of human genetic variation, sex-specific disease risk factors, and reproductive potential. We discovered novel CNVs associated with ovarian dysfunction and support polygenic models for POI.

Current approaches for the treatment of premature ovarian failure with stem cell therapy

One of the common disorders found in women is premature ovarian failure (POF). Recently some studies have explained premature ovarian insufficiency (POI). The causes of it are unknown although various types of study have been done. The most common causes such as genetic and autoimmune conditions can have a role in POF and can lead to infertility. Some characterization of POF are hypo-oestrogenism (estrogen deficiency), increased gonadotropin level and most importantly amenorrhea. The main purpose of this review is to describe the cause and treatment of POF, especially stem cell therapy proposed in previous studies. Stem cells have self-renewal and regeneration potential, hence they can be very effective in the treatment of ovarian failure and consequently infertility. There are several kinds of stem cells such as, mesenchymal stem cells (MSCs), stem cells from extra-embryonic tissues, induced pluripotent stem cells (iPSCs), and ovarian stem cells that are used in POF stem cell therapy as observed in previous studies. This article reviews the latest studies on POF to summarize current understanding and future directions.

Primary ovarian insufficiency associated with autosomal abnormalities: from chromosome to genome-wide and beyond

OBJECTIVE

The pathophysiology of primary ovarian insufficiency (POI) is not well elucidated. Many candidate genetic aberrations are on the X-chromosome; on the contrary, many genetic perturbations are also on the autosomes. The aim of this review is to summarize the knowledge of genetic aberrations on autosomes from chromosomal rearrangement, gene abnormality, genome-wide association studies and epigenetics.

METHODS

Searches of electronic databases were performed. Articles and abstracts relevant to POI and genetic studies associated with autosomes were summarized in this interpretive literature review.

RESULTS

Various genetic aberrations located on the autosomes were found. These abnormalities are from chromosomal rearrangement, which might disrupt the critical region on chromosome loci or disturbance of the meiosis process. Specific gene aberrations are also identified. The genes that have functions in ovarian development, folliculogenesis, and steroidogenesis on autosomes are proposed to be involved from gene association studies. Gene-to-gene interaction or epistasis also might play a role in POI occurrence. Recently, genetic techniques to study the whole genome have emerged. Although no specific conclusion has been made, the studies using genome-wide association to find the specific aberration throughout the genome in POI have been published. Epigenetic mechanisms might also take part in the pathogenesis of POI.

CONCLUSIONS

The considerably complex process of POI is still not well understood. Further research is needed for gene functional validation studies to confirm the contribution of genes in POI, or additional genome-wide association studies using novel clustered regularly interspaced short palindromic repeat/Cas9 technique might make these mechanisms more comprehensible.

A Rare Combination of Functional Disomy Xp, Deletion Xq13.2-q28 Spanning the XIST Gene, and Duplication 3q25.33-q29 in a Female with der(X)t(X;3)(q13.2;q25.33)

We report a 19-year-old female patient with a history of short stature, primary ovarian insufficiency, sensorineural hearing loss, sacral teratoma, neurogenic bladder, and intellectual disability with underlying mosaicism for der(X)t(X;3)(q13.2;q25.33), a ring X chromosome, and monosomy X. Derivative X chromosomes from unbalanced X-autosomal translocations are preferentially silenced by the XIST gene (Xq13.2) located within the X-inactivation center. The unbalanced X-autosomal translocation in our case resulted in loss of the XIST gene thus precluding the inactivation of the derivative X chromosome. As a result, clinical features of functional disomy Xp, Turner's syndrome, and duplication 3q syndrome were observed. Importantly, indications of the derivative X chromosome were revealed by microarray analysis following an initial diagnosis of Turner's syndrome made by conventional cytogenetic studies approximately 18 months earlier. This case demonstrates the importance of utilizing microarray analysis as a first-line test in patients with clinical features beyond the scope of a well-defined genetic syndrome.

Next generation sequencing identifies abnormal Y chromosome and candidate causal variants in premature ovarian failure patients

Premature ovarian failure (POF) is characterized by heterogeneous genetic causes such as chromosomal abnormalities and variants in causal genes. Recently, development of techniques made next generation sequencing (NGS) possible to detect genome wide variants including chromosomal abnormalities. Among 37 Korean POF patients, XY karyotype with distal part deletions of Y chromosome, Yp11.32-31 and Yp12 end part, was observed in two patients through NGS. Six deleterious variants in POF genes were also detected which might explain the pathogenesis of POF with abnormalities in the sex chromosomes. Additionally, the two POF patients had no mutation in SRY but three non-synonymous variants were detected in genes regarding sex reversal. These findings suggest candidate causes of POF and sex reversal and show the propriety of NGS to approach the heterogeneous pathogenesis of POF.

Two girls with a de novo Xq rearrangement of paternal origin: t(X;9)(q24;q12) or rea(X)dup q

OBJECTIVE

We report on two rare Xq rearrangements, namely a t(X;9)(q24;q12) found in a mildly-affected girl (Patient 1) and a rea(X)dup q concomitant with a rob(14;21)mat in a Down syndrome girl (Patient 2).

CASE REPORT

Both rearrangements were characterized by banding techniques [Giemsa (G), constitutive heterochromatin (C), and bromodeoxyuridine (BrdU) pulse], fluorescence in situ hybridization (FISH) assays, human androgen receptor (HUMAR) assays, and microarray analyses. Patient 1 had a t(X;9)(q24;q12)dn. Patient 2 had a de novo rea(X)(qter→q23 or q24::p11.2→qter) concomitant with an unbalanced rob(14;21)mat. X-Inactivation studies in metaphases and DNA revealed a fully skewed inactivation: the normal homolog was silenced in Patient 1 and the rea(X) in Patient 2. Both rearranged X chromosomes were of paternal descent. Microarray analyses revealed no imbalances in Patient 1 whereas loss of Xp (∼52 Mb) and duplication of Xq (∼44 Mb) and 21q were confirmed in Patient 2.

CONCLUSION

Our observations further document the cytogenetic heterogeneity and predominant paternal origin of certain de novo X-chromosome rearrangements.

Analysis of FMR1 gene premutation and X chromosome cytogenetic abnormalities in 100 Tunisian patients presenting premature ovarian failure

OBJECTIVE

To evaluate the prevalence of FMR1 premutations and X chromosome cytogenetic abnormalities in a large cohort of Tunisian women with premature ovarian failure (POF).

PATIENTS AND METHODS

The cohort consisted of 127 Tunisian women with POF referred by endocrinologists and gynecologists for genetic investigation in the context of idiopathic POF and altered hormonal profiles. Clinical information concerning the reproductive function in the family, previous hormonal measurements and/or possible fertility treatment were collected. Karyotype, FISH analyses, FMR1 and FMR2 testing were performed for all patients.

RESULTS

Fifteen patients (11.81%) presented structural or numerical X chromosomal abnormalities. Moreover, we detected in 12 patients (10.71%) a high level of X mosaicism. Analysis of FMR1 gene in the 100 patients without X chromosomal abnormalities showed that five percent of the patients carried a FMR1 premutation allele. On the other hand, the FMR2 screening did not reveal any deletion.

CONCLUSION

Our study confirms the major role of X chromosome abnormalities in POF and highlights the importance of karyotype analyses and FMR1 screening. These investigations provide valuable information for diagnosis and genetic counseling for these women who still have a 5% chance of spontaneous conception.

Genetics of primary ovarian insufficiency: new developments and opportunities

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Genetic mechanisms leading to primary amenorrhea in balanced X-autosome translocations

OBJECTIVE

To map the X-chromosome and autosome breakpoints in women with balanced X-autosome translocations and primary amenorrhea, searching candidate genomic loci for female infertility.

DESIGN

Retrospective and case-control study.

SETTING

University-based research laboratory.

PATIENT(S)

Three women with balanced X-autosome translocation and primary amenorrhea.

INTERVENTION(S)

Conventional cytogenetic methods, genomic array, array painting, fluorescence in situ hybridization, and quantitative reverse transcription-polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

Karyotype, copy number variation, breakpoint mapping, and gene expression levels.

RESULT(S)

All patients presented with breakpoints in the Xq13q21 region. In two patients, the X-chromosome breakpoint disrupted coding sequences (KIAA2022 and ZDHHC15 genes). Although both gene disruptions caused absence of transcription in peripheral blood, there is no evidence that supports the involvement of these genes with ovarian function. The ZDHHC15 gene belongs to a conserved syntenic region that encompasses the FGF16 gene, which plays a role in female germ line development. The break in the FGF16 syntenic block may have disrupted the interaction between the FGF16 promoter and its cis-regulatory element. In the third patient, although both breakpoints are intergenic, a gene that plays a role in the DAX1 pathway (FHL2 gene) flanks distally the autosome breakpoint. The FHL2 gene may be subject to position effect due to the attachment of an autosome segment in Xq21 region.

CONCLUSION(S)

The etiology of primary amenorrhea in balanced X-autosome translocation patients may underlie more complex mechanisms than interruption of specific X-linked candidate genes, such as position effect. The fine mapping of the rearrangement breakpoints may be a tool for identifying genetic pathogenic mechanisms for primary amenorrhea.

Differentiation of primordial germ cells from induced pluripotent stem cells of primary ovarian insufficiency

STUDY QUESTION

Can the induced pluripotent stem cells (iPSCs) derived from women with primary ovarian insufficiency (POI) differentiate into germ cells for potential disease modeling in vitro?

SUMMARY ANSWER

The iPSC lines derived from POI patients with 46, X, del(X)(q26) or 46, X, del(X)(q26)9qh+ could differentiate into germ cells and expressed lower levels of genes in the deletion region of the X chromosome.

WHAT IS KNOWN ALREADY

iPSC technology has been envisioned as an approach for generating patient-specific stem cells for disease modeling and for developing novel therapies. It has also been confirmed that iPSCs differentiate into germ cells.

STUDY DESIGN, SIZE, DURATION

We compared the differentiation ability of germ cells and the gene expression level of germ cell-related genes in the X chromosome deletion region of iPSC lines derived from POI patients (n = 2) with an iPSC line derived from normal fibroblasts (n = 1).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We established three iPSC lines from two patients with partial Xq deletion-induced POI and normal fibroblasts by overexpressing four factors: octamer-binding transcription factor 4 (OCT4), sex-determining region Y-box 2 (SOX2), Nanog homeobox (NANOG), and lin-28 homolog (LIN28), using lentiviral vectors. We then generated stable-transfected fluorescent reporter cell lines under the control of the Asp-Glu-Ala-Asp box polypeptide 4 (DDX4, also called VASA) promoter, and selected clonal derived sublines. We induced subline differentiation into germ cells by adding Wnt3a (30 ng/ml) and bone morphogenetic protein 4 (100 ng/ml). After 12 days of differentiation, green fluorescent protein (GFP)-positive and GFP-negative cells were isolated via fluorescence-activated cell sorting and analyzed for endogenous VASA protein (immunostaining) and for germ cell markers and genes expressed in the deleted region of the X chromosome (quantitative RT-PCR).

MAIN RESULTS AND THE ROLE OF CHANCE

The POI- and normal fibroblast-derived iPSCs had typical self-renewal and pluripotency characteristics. After stable transfection with the VASA-GFP construct, the sublines POI1-iPS-V.1, POI2-iPS-V.1 and hEF-iPS-V.1 produced green fluorescent cells in the differentiated cultures, and the percentage of GFP-positive cells increased over the 12 days of differentiation to a maximum of 6.9 ± 0.33%, 5.3 ± 0.57% and 8.5 ± 0.29%, respectively, of the total cell population. Immunohistochemical analysis confirmed that endogenous VASA was enriched in the GFP-positive cells. Quantitative reverse transcription-PCR revealed significantly higher expression of germ cell markers [PR domain containing 1, with ZNF domain (PRDM1, BLIMP1), developmental pluripotency-associated 3 (DPPA3, STELLA), deleted in azoospermia-like (DAZL), and VASA (DDX4)] in GFP-positive cells than in GFP-negative cells. Moreover, the GFP-positive cells from POI-iPSCs had reduced expression of the family with sequence similarity 122C (FAM122C), inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase gamma (IKBKG), and RNA binding motif protein, X-linked (RBMX), genes located in the deleted region of the X chromosome and that are highly expressed in differentiated germ cells, compared with cells from normal iPSCs.

LIMITATIONS, REASONS FOR CAUTION

Gene expression profiling indicated that the germ cells differentiated from POI-iPSCs were pre-meiotic. Therefore, how the differentiated primordial germ cells could progress further to meiosis and form follicles remains to be determined in the study of POI.

WIDER IMPLICATIONS OF THE FINDINGS

Our results might provide an in vitro model for studying germ cell development in patients with POI.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by grants from the Major State Basic Research Development Program of China (No. 2012CB944901), the National Science Foundation of China (No. 81222007 and 81471432), the Program for New Century Excellent Talents in University and the Fundamental Research Funds for Central Universities (No. 721500003). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Cytogenetic abnormalities in Tunisian women with premature ovarian failure

To identify the distribution of chromosome abnormalities among Tunisian women with premature ovarian failure (POF) referred to the department of Cytogenetic at the Pasteur Institute of Tunis (Tunisia), standard cytogenetic analysis was carried out in a total of 100 women younger than 40 affected with premature ovarian failure. We identified 18 chromosomal abnormalities, including seven X-numerical anomalies in mosaic and non-mosaic state (45,X; 47,XXX), four sex reversal, three X-structural abnormalities (terminal deletion and isochromosomes), one autosomal translocation and one supernumerary marker. The overall prevalence of chromosomal abnormalities was 18% in our cohort. X chromosome aneuploidy was the most frequent aberration. This finding confirms the essential role of X chromosome in ovarian function and underlies the importance of cytogenetic investigations in the routine management of POF.

X-autosome translocations in amenorrhoea: a report of a three way translocation from Indian population

Chromosomal translocations have been reported in a number of women undergoing cytogenetic studies for amenorrhoea and gonadal dysgenesis. This study was taken up to emphasize the role of X chromosome and to know the frequency of X-autosomal translocations in women with amenorrhoea in Indian population. Cytogenetic analysis was carried out in 1567 subjects referred for amenorrhoea during the period 2002-2012. GTG-banding was performed from peripheral blood lymphocyte cultures to detect the chromosome abnormalities in all the cases. The karyotype results revealed 43.6% cases with chromosomal abnormalities (n = 683 of 1567 cases). The X-autosomal translocations was found in 2.64% (n = 18 of 683 cases). The common chromosomes involved with X were chromosomes 2, 4, 14 and 20. The translocations involved both p and q arms of the X chromosome.The break point "q26" of X was observed in the majority of the cases. Two interesting cases are discussed: one with three way translocation and another with two translocations. A high number of primary amenorrhoea (PA) and secondary amenorrhoea (SA) cases were involved in X-auto translocation which clearly reveals that chromosomal analysis plays an important role in the evaluation of amenorrhoea.

[Premature ovarian failures]

Premature ovarian failure (POF) is clinically suspected by amenorrhea and confirmed by an elevated FSH serum level above 40 mUI/L (even 20 mUI/L) twice, in a woman before the age of 40. Prevalence of POF is between 1 to 2% in women. In 90% of cases, no aetiology is identified. Obvious causes are chemotherapy, pelvic radiotherapy, ovarian surgery and diethylstilbestrol exposure in utero. A karyotype should be performed as Turner Syndrome is the most frequent genetic cause of POF. Some X abnormalities such as X deletion or X autosome translocation can be found. FMR1 pre-mutation (fragile X syndrome) should be searched for, even though no cases of mental retardation are known, in the family. Other genetic abnormalities can be suggested by associated symptoms (i.e.: FOXL2, SF1 mutations). Auto-immune aetiology can be suspected if other auto-immune features are present, however, there are no reliable auto-antibodies to confirm auto-immunity in POF. Treatment of POF is based on hormonal replacement therapy in order to avoid estrogen deficiency, suppress vasomotor symptoms and avoid bone loss as well as cardiovascular risk. Estrogens should be associated with progesterone or a progestin, at least up to the age of 51. Patients with POF should be informed that spontaneous pregnancies may occur (in 5% of cases). In case of desire of pregnancy, the patient should be oriented to a specialized unit for in vitro fertilization with oocyte donation. Psychological support is essential and should be part of the treatment. POF is associated with an increased risk of emotional distress and depression. No preventive treatment of POF is available so far.

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.

Cytogenetic analysis of 179 Iranian women with premature ovarian failure

The importance of chromosomal abnormalities in etiology of premature ovarian failure (POF) is well known but in many cases, POF still remains idiopathic. We investigated the frequency and type of chromosomal aberrations in Iranian women diagnosed with idiopathic POF. Standard cytogenetic analysis was carried out in a total of 179 patients. Karyotype analysis of these patients revealed that 161 (89.95%) patients had normal female karyotype and 18 (10.05%) patients had abnormal karyotypes. The abnormal karyotypes included sex reverse sex determining region Y (SRY) negative (five Cases), X chromosome mosaicism (five cases), abnormal X chromosomes (three cases), abnormal autosomes (three cases) and X-autosome translocation (two cases). The overall prevalence of chromosomal abnormalities was 10.05% in this first large-scale report of chromosomal aberrations in Iranian women with POF. The results confirm previous observations and emphasis on the critical role of X chromosome abnormalities as one of the possible etiologies for POF.

Translocation t(X;11)(q22;q25) in a woman with premature ovarian failure

Genetic, autoimmune, environmental, iatrogenic, and idiopathic factors are known to cause premature ovarian failure (POF). This report describes an X;11 translocation, t(X;11)(q22;q25), in a woman diagnosed with POF. The FSH level was found to be elevated. Menstrual cycle was regular initially, and she had a spontaneous abortion at the 5th month of gestation at 16 years of age. Her mother was karyotypically normal while her father was not investigated. Male carriers of X;autosome translocations are mostly infertile, and hence the translocation is presumed to be of de novo origin. Fluorescence in situ hybridization using whole chromosome paint probes confirmed the rearrangement.

Investigating the role of X chromosome breakpoints in premature ovarian failure

The importance of the genetic factor in the aetiology of premature ovarian failure (POF) is emphasized by the high percentage of familial cases and X chromosome abnormalities account for 10% of chromosomal aberrations. In this study, we report the detailed analysis of 4 chromosomal abnormalities involving the X chromosome and associated with POF that were detected during a screening of 269 affected women. Conventional and molecular cytogenetics were valuable tools for locating the breakpoint regions and thus the following karyotypes were defined: 46,X,der(X)t(X;19)(p21.1;q13.42)mat, 46,X,t(X;2)(q21.33;q14.3)dn, 46,X,der(X)t(X;Y)(q26.2;q11.223)mat and 46,X,t(X;13)(q13.3;q31)dn. A bioinformatic analysis of the breakpoint regions identified putative candidate genes for ovarian failure near the breakpoint regions on the X chromosome or on autosomes that were involved in the translocation event. HS6ST1, HS6ST2 and MATER genes were identified and their functions and a literature review revealed an interesting connection to the POF phenotype. Moreover, the 19q13.32 locus is associated with the age of onset of the natural menopause. These results support the position effect of the breakpoint on flanking genes, and cytogenetic techniques, in combination with bioinformatic analysis, may help to improve what is known about this puzzling disorder and its diagnostic potential.

Algorithmic approach for methyl-CpG binding protein 2 (MECP2) gene testing in patients with neurodevelopmental disabilities

Methyl-CpG binding protein 2 gene (MECP2) testing is indicated for patients with numerous clinical presentations, including Rett syndrome (classic and atypical), unexplained neonatal encephalopathy, Angelman syndrome, nonspecific mental retardation, autism (females), and an X-linked family history of developmental delay. Because of this complexity, a gender-specific approach for comprehensive MECP2 gene testing is described. Briefly, sequencing of exons 1 to 4 of MECP2 is recommended for patients with a Rett syndrome phenotype, unexplained neonatal encephalopathy, an Angelman syndrome phenotype (with negative 15q11-13 analysis), nonspecific mental retardation, or autism (females). Additional testing for large-scale MECP2 deletions is recommended for patients with Rett syndrome or Angelman syndrome phenotypes (with negative 15q11-13 analysis) following negative sequencing. Alternatively, testing for large-scale MECP2 duplications is recommended for males presenting with mental retardation, an X-linked family history of developmental delay, and a significant proportion of previously described clinical features (particularly a history of recurrent respiratory infections).

[Atypical presentation of a premature ovarian failure with deletion of X chromosome]

In order to illustrate a particular clinical presentation of premature ovarian failure, we report the case of a 16-year-old girl, who presented with primary amenorrhea. Physical examination discovered central obesity and an extent acanthosis nigricans in the neck and in the axillae. Pubertal stage was quoted S3P3 and external genitalia were normal. Oral glucose test revealed glucose intolerance and hormonal investigation discovered hyperinsulinemia and elevated level of FSH. Pelvic echography found infantile internal genitalia and genetic analysis discovered a deletion in the long arm of one of X chromosomes.

Cytogenetics of premature ovarian failure: an investigation on 269 affected women

The importance of X chromosome in the aetiology of premature ovarian failure (POF) is well-known but in many cases POF still remains idiopathic. Chromosome aneuploidy increase is a physiological phenomenon related to aging, but the role of low-level sex chromosome mosaicism in ovarian function is still undiscovered. Standard cytogenetic analysis was carried out in a total of 269 patients affected by POF: 27 chromosomal abnormalities were identified, including X chromosome and autosomal structural and numerical abnormalities. In 47 patients with 46,XX karyotype we performed interphase FISH using X alpha-satellite probe in order to identify X chromosome mosaicism rate. Aneuploidy rate in the patient group was significantly higher than the general population group. These findings underline the importance of X chromosome in the aetiology of POF and highlight the potential role of low-level sex chromosome mosaicism in ovarian aging that may lead to a premature onset of menopause.

X-chromosome terminal deletion in a female with premature ovarian failure: Haploinsufficiency of X-linked genes as a possible explanation

Background

Premature ovarian failure (POF) has repeatedly been associated to X-chromosome deletions. FMR1 gene premutation allele's carrier women have an increased risk for POF. We intent to determine the cause of POF in a 29 year old female, evaluating both of these situations.

Methods

Concomitant analysis of FMR1 gene CGG repeat number and karyotype revealed an X-chromosome terminal deletion. Fluorescence in situ further characterized the breakpoint. A methylation assay for FMR1 gene allowed to determine its methylation status, and hence, the methylation status of the normal X-chromosome.

Results

We report a POF patient with a 46,X,del(X)(q26) karyotype and with skewed X-chromosome inactivation of the structural abnormal X-chromosome.

Conclusions

Despite the hemizygosity of FMR1 gene, the patient does not present Fragile X syndrome features, since the normal X-chromosome is not subject to methylation. The described deletion supports the hypothesis that haploinsufficiency of X-linked genes can be on the basis of POF, and special attention should be paid to X-linked genes in region Xq28 since they escape inactivation and might have a role in this disorder. A full clinical and cytogenetic characterization of all POF cases is important to highlight a pattern and help to understand which genes are crucial for normal ovarian development.

Premature ovarian failure

Premature ovarian failure is the term usually used to describe women aged younger than 40 years who present with amenorrhea, hypergonadotropinism, and hypoestrogenism. Such women may ovulate and even conceive after the diagnosis is made, so it may be more appropriate to refer to these patients as having "primary ovarian insufficiency," or alternatively, as having "hypergonadotropic hypogonadism" or "primary hypogonadism." The clinical presentation is diverse, and several different disorders can lead to premature ovarian failure. Affected women should be investigated for premutations of the FMR1 gene (causing fragile X syndrome in its fullest form) and for adrenal antibodies. Thyroiditis is the most frequent autoimmune disorder associated with premature ovarian failure and should be ruled out as well. Osteopenia is increased in women with premature ovarian failure, and measures to prevent accelerated bone loss are warranted. Hormone therapy (HT) should be provided to eliminate symptoms of estrogen deficiency and help prevent osteopenia, but will not necessarily (and inexplicably) prevent pregnancy in the 5-10% of women who conceive spontaneously after the diagnosis is made. There are no data indicating that these young women are at increased risk of side effects from HT. If pregnancy is desired, use of donor oocytes with in vitro fertilization is most likely to result in pregnancy.

Underlying karyotype abnormalities in IVF/ICSI patients

Cytogenetic investigations are performed in couples asking for IVF or intracytoplasmic sperm injection (ICSI) treatment. These serve a diagnostic purpose because male or female infertility might have a chromosomal origin. Chromosomal aberrations found in these patients include numerical abnormalities, such as Klinefelter syndrome, XYY karyotype or Turner syndrome and its variants; sex reversions, such as XX males or XY females; and also structural abnormalities, such as Robertsonian or reciprocal translocations and inversions. Finding the chromosomal origin of infertility in a patient also has a prognostic value because it aids the management of pregnancies obtained after IVF or ICSI and may lead to a proposal of prenatal or preimplantation genetic diagnosis.

Genetic investigation of four meiotic genes in women with premature ovarian failure

OBJECTIVE

The goal of this study was to determine whether mutations of meiotic genes, such as disrupted meiotic cDNA (DMC1), MutS homolog (MSH4), MSH5, and S. cerevisiae homolog (SPO11), were associated with premature ovarian failure (POF).

DESIGN

Case-control study.

METHODS

Blood sampling, karyotype, hormonal dosage, ultrasound, and ovarian biopsy were carried out on most patients. However, the main outcome measure was the sequencing of genomic DNA from peripheral blood samples of 41 women with POF and 36 fertile women (controls).

RESULTS

A single heterozygous missense mutation, substitution of a cytosine residue with thymidine in exon 2 of MSH5, was found in two Caucasian women in whom POF developed at 18 and 36 years of age. This mutation resulted in replacement of a non-polar amino acid (proline) with a polar amino acid (serine) at position 29 (P29S). Neither 36 control women nor 39 other patients with POF possessed this genetic perturbation. Another POF patient of African origin showed a homozygous nucleotide change in the tenth of DMC1 gene that led to an alteration of the amino acid composition of the protein (M200V).

CONCLUSIONS

The symptoms of infertility observed in the DMC1 homozygote mutation carrier and in both patients with a heterozygous substitution in exon 2 of the MSH5 gene provide indirect evidence of the role of genes involved in meiotic recombination in the regulation of ovarian function. MSH5 and DMC1 mutations may be one explanation for POF, albeit uncommon.