The FMR1 gene as regulator of ovarian recruitment and ovarian reserve

Current understanding of the genomic abnormities in premature ovarian failure: chance for early diagnosis and management

Premature ovarian failure (POF) is an insidious cause of female infertility and a devastating condition for women. POF also has a strong familial and heterogeneous genetic background. Management of POF is complicated by the variable etiology and presentation, which are generally characterized by abnormal hormone levels, gene instability and ovarian dysgenesis. To date, abnormal regulation associated with POF has been found in a small number of genes, including autosomal and sex chromosomal genes in folliculogenesis, granulosa cells, and oocytes. Due to the complex genomic contributions, ascertaining the exact causative mechanisms has been challenging in POF, and many pathogenic genomic characteristics have yet to be elucidated. However, emerging research has provided new insights into genomic variation in POF as well as novel etiological factors, pathogenic mechanisms and therapeutic intervention approaches. Meanwhile, scattered studies of transcriptional regulation revealed that ovarian cell function also depends on specific biomarker gene expression, which can influence protein activities, thus causing POF. In this review, we summarized the latest research and issues related to the genomic basis for POF and focused on insights gained from their biological effects and pathogenic mechanisms in POF. The present integrated studies of genomic variants, gene expression and related protein abnormalities were structured to establish the role of etiological genes associated with POF. In addition, we describe the design of some ongoing clinical trials that may suggest safe, feasible and effective approaches to improve the diagnosis and therapy of POF, such as Filgrastim, goserelin, resveratrol, natural plant antitoxin, Kuntai capsule et al. Understanding the candidate genomic characteristics in POF is beneficial for the early diagnosis of POF and provides appropriate methods for prevention and drug treatment. Additional efforts to clarify the POF genetic background are necessary and are beneficial for researchers and clinicians regarding genetic counseling and clinical practice. Taken together, recent genomic explorations have shown great potential to elucidate POF management in women and are stepping from the bench to the bedside.

Evidence for a fragile X messenger ribonucleoprotein 1 (FMR1) mRNA gain-of-function toxicity mechanism contributing to the pathogenesis of fragile X-associated premature ovarian insufficiency

Fragile X-associated premature ovarian insufficiency (FXPOI) is among a family of disorders caused by expansion of a CGG trinucleotide repeat sequence located in the 5' untranslated region (UTR) of the fragile X messenger ribonucleoprotein 1 (FMR1) gene on the X chromosome. Women with FXPOI have a depleted ovarian follicle population, resulting in amenorrhea, hypoestrogenism, and loss of fertility before the age of 40. FXPOI is caused by expansions of the CGG sequence to lengths between 55 and 200 repeats, known as a FMRI premutation, however the mechanism by which the premutation drives disease pathogenesis remains unclear. Two main hypotheses exist, which describe an mRNA toxic gain-of-function mechanism or a protein-based mechanism, where repeat-associated non-AUG (RAN) translation results in the production of an abnormal protein, called FMRpolyG. Here, we have developed an in vitro granulosa cell model of the FMR1 premutation by ectopically expressing CGG-repeat RNA and FMRpolyG protein. We show that expanded CGG-repeat RNA accumulated in intranuclear RNA structures, and these aggregates were able to cause significant granulosa cell death independent of FMRpolyG expression. Using an innovative RNA pulldown, mass spectrometry-based approach we have identified proteins that are specifically sequestered by CGG RNA aggregates in granulosa cells in vitro, and thus may be deregulated as consequence of this interaction. Furthermore, we have demonstrated reduced expression of three proteins identified via our RNA pulldown (FUS, PA2G4 and TRA2β) in ovarian follicles in a FMR1 premutation mouse model. Collectively, these data provide evidence for the contribution of an mRNA gain-of-function mechanism to FXPOI disease biology.

High normal sized CGG repeat on the FMR1 gene reduces live birth rates after in vitro fertilization in Han Chinese

Substantial evidence now suggests an association between the FMR1 genotype and female fertility. The aim of this study was to determine whether a high normal FMR1 allele (35-54 repeats) affects in vitro fertilization (IVF) outcomes in Chinese women. A total of 120 women with 210 IVF cycles were retrospectively recruited in this study. The patients were divided into two groups based on the FMR1 repeat lengths at allele 2 (normal repeat group: <35 repeats; high repeat group: 35-54 repeats). The observed primary outcomes were the clinical pregnancy rate and live birth rate. No associations were observed between the high normal FMR1 allele and lower clinical pregnancy rate or live birth rate after adjusting for maternal age, education, work status, duration of infertility and number of embryos transferred (aOR 0.633, 95% CI 0.249-1.601, p = 0.337; aOR 0.325, 95% CI 0.094-1.118, p = 0.075; respectively). However, after additionally adjusting for anti-Müllerian hormone (AMH) level, there was a weak but significant association between high normal sized CGG repeats and a lower live birth rate (aOR 0.218, 95% CI 0.057-0.836, p = 0.026). The rate of available embryos showed a decreasing trend in patients with a high normal FMR1 allele, although the difference was not statistically significant after adjusting for maternal age, education, work status, duration of infertility and AMH level (aOR 0.905, 95% CI 0.810-1.011, p = 0.078). Furthermore, the number of CGG repeats in either allele was not associated with the live birth rate after adjusting for all confounding factors (aOR 0.832, 95% CI 0.677-1.023, p = 0.081; aOR 0.865, 95% CI 0.651-1.148, p = 0.315; respectively). In addition, no significant differences were found in the rates of good-quality embryos (p = 0.263), miscarriage (p = 0.861) or cycle cancellation (p = 0.295) between the groups. Taken together, in the Chinese population, individuals with high normal sized CGG repeats on the FMR1 gene have a higher risk of reduced live birth rates in childbearing age. Therefore, we recommend enhanced screening for fragile X syndrome in women of childbearing age in China. This study also suggests that the association between the FMR1 genotype and fertility in Chinese women merits further research.

A study on the role of FMR1 CGG trinucleotide repeats in Jordanian poor ovarian responders

The expansion of trinucleotide CGG repeats in the promoter of fragile X mental retardation 1 (FMR1) gene is associated with fragile X and fragile X associated tremor/ataxia syndromes. While the expansion of CGG repeats has been associated with such neuro/psychiatric diseases, the contraction of CGG repeats has been recently suggested as an indication of ovarian dysfunction. This study aimed to evaluate a possible association of the short CGG repeats with poor ovarian responders (POR) and to test for a possible correlation between the CGG size and different known markers of the ovarian reserve, namely FSH, AMH, and the number of retrieved oocytes from Jordanian females. We found a significant difference between the CGG median allele size between the cases and the controls (p < 0.001), where poor ovarian responders had shorter CGG repeats compared to the healthy controls. Also, females with alleles <26 had twice the odds to be presented in the POR compared to the controls. However, we did not find a significant correlation between CGG sizes and the markers of ovarian reserve. We conclude that although low CGG repeats appear to be linked to POR, the clinical utility of FMR1 for predicting ovarian response needs further investigation.

The association of miR-25T>C, miR-32C>A, miR-125C>T, and miR-222G>T polymorphisms with a risk of primary ovarian insufficiency in Korean women

OBJECTIVE

The purpose of this study was to investigate the association of microRNA polymorphisms (miR-25T>C, miR-32C>A, miR-125C>T, and miR-222G>T) with primary ovarian insufficiency (POI) in Korean women.

METHODS

We conducted a case-control study of Korean women: 142 participants with POI and 266 controls with at least 1 live birth and no history of pregnancy loss.

RESULTS

The haplotype-based multifactor dimensionality reduction analysis revealed that the T-C-T-G (miR-25/-32/-125/-222), T-A-C-G (miR-25/-32/-125/-222), C-T-G (miR-32/-125/-222), A-C-G (miR-32/-125/-222), T-G (miR-122/-222), C-T (miR-32/-125), and C-C (miR-25/-32) inferred haplotypes were significantly less frequent in POI (P < 0.05), which suggested potential protective effects. Participants with POI had significantly increased luteinizing hormone levels (P < 0.05), but hormonal levels, including luteinizing hormone, were not significantly different between POI women and control women with miR-32/-125/-222.

CONCLUSIONS

After considering multiple comparisons, we concluded that miR-25T>C, miR-32C>A, miR-125C>T, and miR-222G>T had no relation with POI.

Reduced RNA expression of the FMR1 gene in women with low (CGGn<26) repeats

Low FMR1 variants (CGG_n<26) have been associated with premature ovarian aging, female infertility and poor IVF treatment success. Until now, there is little published information concerning possible molecular mechanisms for this effect. We wished to examine whether relative expression of RNA and the FMR1 gene’s fragile X mental retardation protein (FMRP) RNA isoforms differ in women with various FMR1 sub-genotypes (normal, low CGG_n<26 and/or high CGG_n≥34). This prospective cohort study was conducted between 2014 and 2017 in a clinical research unit of the Center for Human Reproduction in New York City. The study involved a total of 98 study subjects, including 18 young oocyte donors and 80 older infertility patients undergoing routine in vitro fertilization (IVF) cycles. The main outcome measure was RNA expression in human luteinized granulosa cells of 5 groups of FMRP isoforms. The relative expression of FMR1 RNA in human luteinized granulosa cells was measured by real-time PCR and a possible association with CGG_n was explored. All 5 groups of FMRP RNA isoforms examined were found to be differentially expressed in human luteinized granulosa cells. The relative expression of four FMR1 RNA isoforms showed significant differences among 6 FMR1 sub-genotypes. Women with at least one low allele expressed significantly lower levels of all 5 sets of FRMP isoforms in comparison to the non-low group. While it would be of interest to see whether FMRP is also decreased in the low-group we recognize that in recent years it has been increasingly documented that information flow of genetics may be regulated by non-coding RNA, that is, without translation to a protein product. We, thus, conclude that various CGG expansions of FMR1 allele may lead to changes of RNA levels and ratios of distinct FMRP RNA isoforms, which could regulate the translation and/or cellular localization of FMRP, affect the expression of steroidogenic enzymes and hormonal receptors, or act in some other epigenetic process and therefore result in the ovarian dysfunction in infertility.

Reevaluation of FMR1 Hypermethylation Timing in Fragile X Syndrome

Fragile X syndrome (FXS) is one of the most common heritable forms of cognitive impairment. It results from a fragile X mental retardation protein (FMRP) protein deficiency caused by a CGG repeat expansion in the 5'-UTR of the X-linked FMR1 gene. Whereas in most individuals the number of CGGs is steady and ranges between 5 and 44 units, in patients it becomes extensively unstable and expands to a length exceeding 200 repeats (full mutation). Interestingly, this disease is exclusively transmitted by mothers who carry a premutation allele (55-200 CGG repeats). When the CGGs reach the FM range, they trigger the spread of abnormal DNA methylation, which coincides with a switch from active to repressive histone modifications. This results in epigenetic gene silencing of FMR1 presumably by a multi-stage, developmentally regulated process. The timing of FMR1 hypermethylation and transcription silencing is still hotly debated. There is evidence that hypermethylation varies considerably between and within the tissues of patients as well as during fetal development, thus supporting the view that FMR1 silencing is a post-zygotic event that is developmentally structured. On the other hand, it may be established in the female germ line and transmitted to the fetus as an integral part of the mutation. This short review summarizes the data collected to date concerning the timing of FMR1 epigenetic gene silencing and reassess the evidence in favor of the theory that gene inactivation takes place by a developmentally regulated process around the 10th week of gestation.

Epigenetic Aberration of FMR1 Gene in Infertile Women with Diminished Ovarian Reserve

OBJECTIVES

The diminished ovarian reserve (DOR) is a condition characterized by a reduction in the number and/or quality of oocytes. This primary infertility disorder is usually accompanied with an increase in the follicle-stimulating hormone (FSH) levels and regular menses. Although there are many factors contributing to the DOR situation, it is likely that many of idiopathic cases have genetic/epigenetic bases. The association between the FMR1 premutation (50-200 CGG repeats) and the premature ovarian failure (POF) suggests that epigenetic disorders of FMR1 can act as a risk factor for the DOR as well. The aim of this study was to analyze the mRNA expression and epigenetic alteration (histone acetylation/methylation) of the FMR1 gene in blood and granulosa cells of 20 infertile women.

MATERIALS AND METHODS

In this case-control study, these women were referred to the Royan Institute, having been clinically diagnosed as DOR patients. Our control group consisted of 20 women with normal antral follicle numbers and serum FSH level. All these women had normal karyotype and no history of genetic disorders. The number of CGG triplet repeats in the exon 1 of the FMR1 gene was analyzed in all samples.

RESULTS

Results clearly demonstrated significantly higher expression of the FMR1 gene in blood and granulosa cells of the DOR patients with the FMR1 premutation compared to the control group. In addition, epigenetic marks of histone 3 lysine 9 acetylation (H3K9ac) and di-metylation (H3K9me2) showed significantly higher incorporations in the regulatory regions of the FMR1 gene, including the promoter and the exon 1, whereas tri-metylation (H3K9me3) mark showed no significant difference between two groups.

CONCLUSIONS

Our data demonstrates, for the first time, the dynamicity of gene expression and histone modification pattern in regulation of FMR1 gene, and implies the key role played by epigenetics in the development of the ovarian function.

Association of skewed X-chromosome inactivation with FMR1 CGG repeat length and anti-Mullerian hormone levels: a cohort study

BACKGROUND

Premutation range CGGn repeats of the FMR1 gene denote risk toward primary ovarian insufficiency (POI), also called premature ovarian failure (POF). This prospective cohort study was undertaken to determine if X-chromosome inactivation skew (sXCI) is associated with variations in FMR1 CGG repeat length and, if so, is also associated with age adjusted antimüllerian hormone (AMH) levels as an indicator of functional ovarian reserve (FOR).

METHODS

DNA samples of 58 women were analyzed for methylation status and confirmation of CGG_n repeat length. Based on previously described FMR1 genotypes, there were 18 women with norm FMR1 (both alleles in range of CGG _n=26-34), and 40 women who had at least one allele at CGG_n<26 or CGG_{>34 (} not-norm FMR1). As part of a routine evaluation of ovarian reserve, patients at our fertility center have their serum AMH assessed at first visit. Regression models were used to test the association of ovarian reserve, as indicated by serum AMH, with sXCI.

RESULTS

sXCI was significantly lower among infertility patients with norm FMR1 (6.5 ± 11.1, median and IQR) compared to those with not-norm FMR1 (12.0 ± 14.6, P = 0.005), though among young oocyte donors the opposite effect was observed. Women age >30 to 38 years old demonstrated greater ovarian reserve in the presence of lower sXCI as evidenced by significantly higher AMH levels (GLM sXCI_10%, f = 11.27; P = 0.004).

CONCLUSIONS

Together these findings suggest that FMR1 CGG repeat length may have a role in determining X-chromosome inactivation which could represent a possible mechanism for previously observed association of low age adjusted ovarian reserve with FMR1 variations in repeat length. Further, larger, investigations will be required to test this hypothesis.

Evidence of an age-related correlation of ovarian reserve and FMR1 repeat number among women with "normal" CGG repeat status

PURPOSE

The objective of this analysis is to examine the relationship between Fragile X Mental Retardation 1 gene (FMR1) cytosine-guanine-guanine (CGG) repeat number and ovarian reserve, with a particular focus exclusively on the range of CGG repeat number below the premutation (PM) range (<55 CGG repeats).

METHODS

Our study included female patients who underwent assessment of FMR1 CGG repeat number and serum anti-Mullerian hormone (AMH) in 2009-2014. To examine the association between FMR1 repeat number and serum AMH, we created three summary measures of CGG repeat number for the two alleles-"Sum," "Max," and "Gap" (absolute difference). Using multivariable regression models, controlling for age, we then analyzed the impact of these summary measures on AMH.

RESULTS

A total of 566 patients were included in our study. Using multivariable regression models, we found that the relationship between CGG repeat number and AMH differed depending on age. Specifically, in younger women, AMH increased by 7-8 % (Sum p < 0.01, Max p = 0.04) for every 1 unit increase in CGG repeat number. In contrast, starting at age 40, there was a 3 to 5 % decline in AMH for every 1 unit increase in CGG repeat number (Sum p < 0.01, Max p = 0.04).

CONCLUSIONS

This is the first study to report a statistically significant correlation of ovarian reserve and CGG repeat number in women with <55 CGG repeats. Although these women are generally considered to have a normal phenotype, our data suggest that increasing CGG repeat number within this normal range is associated with a more rapid decline in ovarian reserve.

Short stature and primary ovarian insufficiency possibly due to chromosomal position effect in a balanced X;1 translocation

BACKGROUND

Primary ovarian insufficiency (POI) is defined as a primary ovarian defect characterized by absent menarche (primary amenorrhea), a decrease in the initial primordial follicle number, high follicle-stimulating hormone (FSH) levels and hypoestrogenism. Although the etiology of a majority of POI cases is not yet identified, several data suggest that POI has a strong genetic component. Conventional cytogenetic and molecular analyses have identified regions of the X chromosome that are associated with ovarian function, as well as POI candidate genes, such as FMR1 and DIAPH2. Here we describe a 10.5-year-old girl presenting with high FSH and luteinizing hormone (LH) levels, pathologic GH stimulation arginine and clonidine tests, short stature, pterygium, ovarian dysgenesis, hirsutism and POI.

RESULTS

Cytogenetic analysis demonstrated a balanced reciprocal translocation between the q arms of chromosomes X and 1, with breakpoints falling in Xq21 and 1q41 bands. Molecular studies did not unravel any chromosome microdeletion/microduplication, and no XIST-mediated inactivation was found on the derivative chromosome 1. Interestingly, through immunofluorescence assays, we found that part of the Xq21q22 trait, translocated to chromosome 1q41, was late replicating and therefore possibly inactivated in 30 % metaphases both in lymphocytes and skin fibroblasts, in addition to a skewed 100 % inactivation of the normal X chromosome. These findings suggest that a dysregulation of gene expression might occur in this region. Two genes mapping to the Xq translocated region, namely DIAPH2 and FMR1, were found overexpressed if compared with controls.

CONCLUSIONS

We report a case in which gonadal dysgenesis and POI are associated with over-expression of DIAPH2 gene and of FMR1 gene in wild type form. We hypothesize that this over-expression is possibly due to a phenomenon known as "chromosomal position effect", which accounts for gene expression variations depending on their localization within the nucleus. For the same effect a double mosaic inactivation of genes mapping to the Xq21-q22 region, demonstrated by immunofluorescence assays, may be the cause of a functional Xq partial monosomy leading to most Turner traits of the proband's phenotype.

Live birth following serial vitrification of embryos and PGD for fragile X syndrome in a patient with the premutation and decreased ovarian reserve

PURPOSE

To present a live birth resulting from serial vitrification of embryos and pre-implantation genetic diagnosis (PGD).

METHODS

A 31-year-old with primary infertility, fragile-X premutation, and decreased ovarian reserve (DOR) (baseline FSH level 33 IU/L), presented after failing to stimulate to follicle diameters >10 mm with three cycles of invitro fertilization (IVF). After counseling, the couple opted for serial in-vitro maturation (IVM), embryo vitrification, and genetic testing using array comparative genomic hybridization (aCGH) and PGD. Embryos were vitrified 2 days after intra-cytoplasmic sperm injection (ICSI). Thawed embryos were biopsied on day-three and transferred on day-five.

RESULTS

The couple underwent 20 cycles of assisted reproductive technology. A total of 23 in-vivo mature and five immature oocytes were retrieved, of which one matured in-vitro. Of 24 embryos, 17/24 (71 %) developed to day two and 11/24 (46 %) survived to blastocyst stage with a biopsy result available. Four blastocysts had normal PGD and aCGH results. Both single embryo transfers resulted in a successful implantation, one a blighted ovum and the other in a live birth.

CONCLUSIONS

Young patients with DOR have potential for live birth as long as oocytes can be obtained and embryos created. Serial vitrification may be the mechanism of choice in these patients when PGD is needed.

The relationship between the number of CGG repeats and serum level of anti-Müllerian hormone in women without FMR1 premutation

OBJECTIVE

To investigate the relationship between the number of CGG repeats in the fragile X mental retardation 1 (FMR1) gene and serum levels of anti-Müllerian hormone (AMH) in Korean infertility patients without premutation.

STUDY DESIGN

A retrospective study of 228 infertile women who received fertility treatment in a single private in vitro fertilization (IVF) clinic from May 2010 to August 2012 was performed. Serum FSH and AMH were measured on menstrual day 3 and the number of CGG repeats was evaluated.

RESULTS

The mean age of the study population was 33.3±3.8 years. No significant correlation was observed between CGG repeat count in both alleles and the serum FSH, AMH or multiples of median (MoM) of AMH in whole study subjects. In women with age ≥35 years, however, there was an increasing tendency in the MoM of AMH with increasing number of CGG repeats in allele 2 (R(2)=0.075, p=0.008). This correlation was not observed in patients aged less than 35 years.

CONCLUSION

We observed a positive correlation between MoM of AMH and number of CGG repeats in allele 2 in women aged over 35 years. Our findings are discordant with other reports, and therefore further studies are needed to determine whether this discrepancy is due to ethnic differences.

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

OBJECTIVE

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

PATIENTS

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

RESULTS

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

CONCLUSIONS

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

Clinical characteristics and genetic analysis in women with premature ovarian insufficiency

OBJECTIVE

Premature ovarian insufficiency (POI) is defined as a primary ovarian defect characterized by absent menarche (primary amenorrhea) or premature depletion of ovarian follicles before the age of 40 (secondary amenorrhea) with hypergonadotropism and hypoestrogenism.

METHODS

We studied the clinical, biological, and genetic data related to 50 POI patients with a mean age of menopause of 29 years (94% with secondary amenorrhea, 6% with primary amenorrhea and 15% with a family history of POI). Seventeen patients were affected by endocrine autoimmune diseases, antral follicles were observed in 31 patients by ultrasonography.

RESULTS

Karyotype analysis did not show any abnormality of the X chromosome. No mutation in FSH receptor and GDF-9 genes was reported, while in one patient a variant of BMP-15 gene (A180T) was found. Four patients had fragile X mental retardation 1 gene (FMR1) premutation and one an intermediate sized CGG repeats of the same gene. Two patients with FMR1 premutation were sister and developed secondary amenorrhea at the age of 34 and 37 years. The other two patients presented with oligoamenorrhea at the age of 39 and 34 years. The patient harboured the intermediate sized CGG repeats developed secondary amenorrhea at the age of 33 years.

CONCLUSIONS

The genetic analysis performed on a cohort of patients with POI revealed that 8% had FMR1 premutation and only one patient a previously known variant of BMP-15 gene. No alteration of the karyotype and FSH receptor and GDF-9 genes was evidenced.

Caprin controls follicle stem cell fate in the Drosophila ovary

Adult stem cells must balance self-renewal and differentiation for tissue homeostasis. The Drosophila ovary has provided a wealth of information about the extrinsic niche signals and intrinsic molecular processes required to ensure appropriate germline stem cell renewal and differentiation. The factors controlling behavior of the more recently identified follicle stem cells of the ovary are less well-understood but equally important for fertility. Here we report that translational regulators play a critical role in controlling these cells. Specifically, the translational regulator Caprin (Capr) is required in the follicle stem cell lineage to ensure maintenance of this stem cell population and proper encapsulation of developing germ cells by follicle stem cell progeny. In addition, reduction of one copy of the gene fmr1, encoding the translational regulator Fragile X Mental Retardation Protein, exacerbates the Capr encapsulation phenotype, suggesting Capr and fmr1 are regulating a common process. Caprin was previously characterized in vertebrates as Cytoplasmic Activation/Proliferation-Associated Protein. Significantly, we find that loss of Caprin alters the dynamics of the cell cycle, and we present evidence that misregulation of CycB contributes to the disruption in behavior of follicle stem cell progeny. Our findings support the idea that translational regulators may provide a conserved mechanism for oversight of developmentally critical cell cycles such as those in stem cell populations.

Diminished ovarian reserve and infertility

Over the past several decades, social and demographic trends have led to an increased tendency for women to delay childbearing. Owing primarily to abnormalities in the oocyte and resulting embryonic aneuploidy, implantation, clinical pregnancy, and live birth rates decline sharply by the end of the fourth decade. As a result, the incidence of age-related infertility has increased. Improved awareness of the effects of aging on fertility combined with ovarian reserve assessment, patient education, and early infertility evaluation and intervention are important elements in appropriate family planning and prevention of age-related infertility.

Predictors and risk model development for menopausal age in fragile X premutation carriers

PURPOSE

Women who carry a fragile X mental retardation 1 premutation are at risk for fragile X-associated primary ovarian insufficiency and should be counseled for a potentially reduced fertility. Multiple factors can affect the age of onset and severity of fragile X-associated primary ovarian insufficiency. In this study, we assessed the predictive power of several factors with menopausal age, a surrogate measure of onset of fragile X-associated primary ovarian insufficiency.

METHODS

Genetic, environmental, and reproductive factors were analyzed by Cox proportional hazard models in 1068 women, 385 of fragile X families ascertained through the Nijmegen study and 683 of fragile X families or general population families ascertained through the Atlanta study.

RESULTS

The highest association with menopausal age among fragile X mental retardation 1 premutation carriers was found for risk index by CGG repeat size (hazard ratio, 1.43) and smoking (hazard ratio, 1.34). Women from the Nijmegen cohort showed an overall lower age at menopause onset, for which a correction was made. A prediction model based on these two parameters, mean menopausal age of first-degree relatives with the same mutation status and the correction for ascertainment site, estimated the probability of becoming postmenopausal for premutation carriers, with a margin of 7-10%.

CONCLUSION

We conclude that this model serves as a first step toward clinical application of fragile X-associated primary ovarian insufficiency prediction.

Number of CGG repeats in the FMR1 gene of Japanese patients with primary ovarian insufficiency

OBJECTIVE

To define the number of CGG repeats in the FMR1 gene of Japanese patients with primary ovarian insufficiency (POI) and normal controls.

DESIGN

Retrospective, controlled cohort study.

SETTING

Outpatient department of an academic tertiary center.

PATIENT(S)

One hundred twenty-eight consecutive Japanese patients with sporadic, nonsyndromic POI and 98 controls with normal menstruation.

INTERVENTION(S)

Deoxyribonucleic acid was obtained from the plasma of each subject.

MAIN OUTCOME MEASURE(S)

Differences in the distribution of CGG repeat numbers between patients with POI and controls.

RESULT(S)

Six alleles in the intermediate range and two in the premutation range were found in five and two patients with POI, respectively, but none were identified in normal controls. The prevalence of FMR1 premutation among Japanese POI patients was 1.56% (2 of 128). The prevalence of having >36 CGG repeats in the FMR1 gene was significantly higher in patients with POI than in controls, and age at the onset of amenorrhea was significantly lower in patients with >38 repeats.

CONCLUSION(S)

More than 36 CGG repeats in the FMR1 might intensify the etiology of POI, at least up to the premutation range.

Genetic and molecular analysis of a new unbalanced X;18 rearrangement: localization of the diminished ovarian reserve disease locus in the distal Xq POF1 region

BACKGROUND

Diminished ovarian reserve (DOR) is a heterogeneous disorder causing infertility, characterized by a decreased number of oocytes, the genetic cause of which is still unknown.

METHODS AND RESULTS

We describe a family with a new unbalanced X;18 translocation der(X) associated with either fully attenuated or DOR phenotype in the same family. Cytogenetics and array comparative genomic hybridization (aCGH) studies have revealed the same partial Xq monosomy and partial 18q trisomy in both the 32-year-old female with DOR and the unaffected mother. The genetic analysis has defined a subtelomeric deletion spanning 13.3 Mb from Xq27.3 to -Xqter, which covers the premature ovarian failure locus 1 (POF1); and a duplication spanning 13.4 Mb, from 18q22.1 to 18qter. From a parental-origin study, we have inferred that the rearranged X chromosome is maternally derived. The Xq27 and 18q22 breakpoint regions fall in a region extremely rich in long interspersed nuclear element, a class of retrotransposons able to trigger mispairing and unusual crossovers. X-inactivation studies reveal a skewing of der(X) both in the mother and the proband. Therefore, the phenotypic expression of der(X) is fully attenuated in the fertile mother and partially attenuated in the DOR daughter.

CONCLUSIONS

We report on an unbalanced maternally derived translocation (X;18)(q27;q22) with different intra-familial reproductive performances, ranging from fertility to DOR. Skewed X-inactivation seems to restore the unbalanced genetic make-up, fully silencing the 18q22 trisomy and at least in part the Xq27 monosomy. The chromosomal abnormality observed in this family supports the presence of a DOR susceptibility locus in the distal Xq region and targets the POF1 region for further investigation.

Cutting edge assessment of the impact of autoimmunity on female reproductive success

There, likely, is no more controversial issue in reproductive medicine than the effects of autoimmunity on female reproductive success. Published studies are, therefore, often biased. We performed PubMed, Google Scholar and Medline searches for the years 2000-2010 under various key words and phrases, referring to effects of autoimmunity/autoimmune diseases on pregnancy/pregnancy outcomes/pregnancy rates/reproduction/reproductive outcomes/fertility/infertility/fertility treatments/infertility treatments, and a number of similar terms. Reference lists of selected manuscripts were evaluated for additional, potential references. All selected manuscripts were reviewed by at least one author (N.G.). Opinions were reached based on preferential review of only selected studies, which offered data, primarily developed in pursuit of unrelated scientific questions. Data from various medical fields point, surprisingly effectively, toward significant impacts of autoimmunity on female reproductive success. Autoimmunity not only increases miscarriage risks but also reduces female fecundity and infertility treatment success. A, likely, reason why differences of opinion have persisted is that effects are primarily observed in genetically predisposed women, with specific fragile X mental retardation 1 (FMR1) genotypes. This discovery coincides with recently increasing appreciation of the importance of the long arm of the X chromosome (Xq) in control of functional ovarian reserve (reflective of female fertility) and autoimmunity, with FMR1at Xq27.3, located at cross roads of both. Autoimmune effects on female reproductive success deserve recognition. Further investigations must not ignore patient stratification, based on ovarian FMR1 genotypes. Genetic definition of high-risk patients should lead to development of successful therapeutic interventions.

Intra-individual stability over time of standardized anti-Mullerian hormone in FMR1 premutation carriers

BACKGROUND

Carriers of a premutation (CGG repeat length 55-200) in the fragile X mental retardation (FMR1) gene are at risk for primary ovarian insufficiency (FXPOI). The anti-Müllerian hormone (AMH) level acts as a useful marker of ovarian follicle reserve and, thus, may serve to predict when this ovarian reserve becomes too low to sustain ovarian function. We investigated the intra-individual variation of AMH levels over time for premutation carriers compared with non-carriers.

METHODS

We determined AMH levels in blood samples from 240 women ascertained through fragile X families, of which 127 were premutation carriers and 113 were non-carriers. Linear mixed models were used to assess the effect of age and premutation status on AMH levels and to determine a modeled AMH value. The stability over time of the deviation of observed AMH levels from modeled levels, referred to as standardized AMH values, was assessed through correlation coefficients of 41 longitudinal samples.

RESULTS

At all ages, premutation carriers exhibited lower AMH levels. For all women, AMH was found to decrease by 10% per year. The added effect of having a premutation decreased AMH levels by 54%. The deviation of an individual's AMH level from the modeled value showed a reasonable intra-individual correlation. The Pearson correlation coefficient of two samples taken at different ages was 0.36 (P = 0.05) for non-carriers and 0.69 (P = 0.01) for carriers.

CONCLUSIONS

We developed a unique standardized AMH value, taking FMR1 premutation status and the subject's age into account, which appears to be stable over time and may serve as a predictor for FXPOI after further longitudinal assessment.

Defining ovarian reserve to better understand ovarian aging

Though a widely utilized term and clinical concept, ovarian reserve (OR) has been only inadequately defined. Based on Medline and PubMed searches we here define OR in its various components, review genetic control of OR, with special emphasis on the FMR1 gene, and discuss whether diminished OR (DOR) is treatable. What is generally referred to as OR reflects only a small portion of total OR (TOR), a pool of growing (recruited) follicles (GFs) at different stages of maturation. Functional OR (FOR) depends on size of the follicle pool at menarche and the follicle recruitment rate. Both vary between individuals and, at least partially, are under genetic control. The FMR1 gene plays a role in defining FOR at all ages. Infertility treatments have in the past almost exclusively only centered on the last two weeks of folliculogenesis, the gonadotropin-sensitive phase. Expansions of treatments into earlier stages of maturation will offer opportunity to significantly improve ovarian stimulation protocols, especially in women with DOR. Dehydroepiandrosterone (DHEA) may represent a first such intervention. Data generated in DHEA-supplemented women, indeed, suggest a new ovarian aging concept, based on aging of ovarian environments and not, as currently is believed, aging oocytes.