FMR1 repeat sizes in the gray zone and high end of the normal range are associated with premature ovarian failure

Prevalence of the FMR1 Gene Premutation in Young Women with a Diminished Ovarian Reserve Included in an IVF Program: Implications for Clinical Practice

The relationship between premature ovarian insufficiency (FXPOI) and premutation in the FMR1 gene is well established. In recent years, though, a potential relationship between the latter and a low ovarian reserve has been suggested. To explore it, we conducted a retrospective study in an IVF program at a university tertiary referral center in Barcelona (Spain). Data were obtained retrospectively from a total of 385 women referred for FMR1 gene testing at our institution from January 2018 to December 2021. We compared the prevalence of FMR1 gene premutation between 93 of them, younger than 35 years, with a diminished ovarian reserve (DOR), characterized by levels of anti-Mullerian hormone < 1.1 ng/mL and antral follicle count < 5; and 132 egg donors screened by protocol that served as the controls. We found a higher prevalence of FMR1 premutation in the DOR group (seven patients (7.69%)) than in the control group (one patient (1.32%)), Fisher-exact test p-value = 0.012). We concluded that compared with the general population represented by young egg donors, the prevalence of FMR1 gene premutation is higher in young patients with a diminished ovarian reserve. Although these findings warrant further prospective validation in a larger cohort of patients within DOR, they suggest that, in clinical practice, FMR1 premutation should be determined in infertile young patients with DOR in order to give them adequate genetic counselling.

Cytosine-guanine-guanine repeats of FMR1 gene negatively affect ovarian reserve and response in Chinese women

RESEARCH QUESTION

Do cytosine-guanine-guanine (CGG) repeats of the FMR1 gene affect ovarian function, ovarian response and assisted reproductive technology (ART) outcomes in Chinese women?

DESIGN

A retrospective cohort study of 5869 women who underwent 8932 ART cycles at Women's Hospital, School of Medicine, Zhejiang University between January 2018 and June 2021. Basic hormone level, oocyte yield, embryo quality and the rate of live birth were considered as main outcome measures to evaluate the effects of CGG repeats on ovarian function, ovarian response and ART outcomes.

RESULTS

The CGG repeats were negatively related to serum anti-Müllerian hormone (AMH), oestradiol, antral follicle count (AFC) and oocyte yield. A significant association was found between serum AMH, oestradiol and AFC even after age was controlled for. No statistically significant association, however, was found between CGG repeats and embryo quality or live birth rate. Ovarian function mediated the association between CGG repeats and ovarian response.

CONCLUSION

Increased CGG repeats on the FMR1 gene were associated with diminished ovarian function and poor ovarian response, and ovarian function played an intermediary role in the relationship between CGG repeats and ovarian response.

Stratification of the risk of ovarian dysfunction by studying the complexity of intermediate and premutation alleles of the FMR1 gene

FMR1 premutation female carriers are at risk of developing premature/primary ovarian insufficiency (POI) with an incomplete penetrance. In this study, we determined the CGG repeat size among 1095 women with diminished ovarian reserve (DOR) / POI and characterized the CGG/AGG substructure in 44 women carrying an abnormal FMR1 repeat expansion number, compared to a group of 25 pregnant women carrying an abnormal FMR1 CGG repeat size. Allelic complexity scores of the FMR1 gene were calculated and compared between the two groups. In the DOR/POI cohort, 2.1% of women presented with an intermediate repeat size and 1.9% with a premutation. Our results suggest that the risk of POI is highest in the mid-range of CGG repeats. We observed that the allelic score is significantly higher in POI women compared to the pregnant women group (p-value = 0.02). We suggest that a high allelic score due to more than 2 AGG interspersions in the context of an intermediate number of repetitions could favor POI. Larger studies are still needed to evaluate the relevance of this new tool for the determination of the individual risk of developing POI in women with abnormal number of CGG repeats.

PGT-M for Premature Ovarian Failure Related to CGG Repeat Expansion of the FMR1 Gene

Primary ovarian failure (POF) is caused by follicle exhaustion and is associated with menstrual irregularities and elevated gonadotropin levels, which lead to infertility before the age of 40 years. The etiology of POI is mostly unknown, but a heterogeneous genetic and familial background can be identified in a subset of cases. Abnormalities in the fragile X mental retardation 1 gene (FMR1) are among the most prevalent monogenic causes of POI. These abnormalities are caused by the expansion of an unstable CGG repeat in the 5' untranslated region of FMR1. Expansions over 200 repeats cause fragile X syndrome (FXS), whereas expansions between 55 and 200 CGG repeats, which are defined as a fragile X premutation, have been associated with premature ovarian failure type 1 (POF1) in heterozygous females. Preimplantation genetic testing for monogenic diseases (PGT-M) can be proposed when the female carries a premutation or a full mutation. In this narrative review, we aim to recapitulate the clinical and molecular features of POF1 and their implications in the context of PGT-M.

Mortality in Women across the FMR1 CGG Repeat Range: The Neuroprotective Effect of Higher Education

Higher education has been shown to have neuroprotective effects, reducing the risk of Alzheimer's and Parkinson's diseases, slowing the rate of age-related cognitive decline, and is associated with lower rates of early mortality. In the present study, the association between higher education, fragile X messenger ribonucleoprotein 1 (FMR1) cytosine-guanine-guanine (CGG) repeat number, and mortality before life expectancy was investigated in a population cohort of women born in 1939. The findings revealed a significant interaction between years of higher education and CGG repeat number. Counter to the study's hypothesis, the effects of higher education became more pronounced as the number of CGG repeats increased. There was no effect of years of higher education on early mortality for women who had 25 repeats, while each year of higher education decreased the hazard of early mortality by 8% for women who had 30 repeats. For women with 41 repeats, the hazard was decreased by 14% for each additional year of higher education. The interaction remained significant after controlling for IQ and family socioeconomic status (SES) measured during high school, as well as factors measured during adulthood (family, psychosocial, health, and financial factors). The results are interpreted in the context of differential sensitivity to the environment, a conceptualization that posits that some people are more reactive to both negative and positive environmental conditions. Expansions in CGG repeats have been shown in previous FMR1 research to manifest such a differential sensitivity pattern.

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.

Ovarian Reserve Disorders, Can We Prevent Them? A Review

The ovarian reserve is finite and begins declining from its peak at mid-gestation until only residual follicles remain as women approach menopause. Reduced ovarian reserve, or its extreme form, premature ovarian insufficiency, stems from multiple factors, including developmental, genetic, environmental exposures, autoimmune disease, or medical/surgical treatment. In many cases, the cause remains unknown and resulting infertility is not ultimately addressed by assisted reproductive technologies. Deciphering the mechanisms that underlie disorders of ovarian reserve could improve the outcomes for patients struggling with infertility, but these disorders are diverse and can be categorized in multiple ways. In this review, we will explore the topic from a perspective that emphasizes the prevention or mitigation of ovarian damage. The most desirable mode of fertoprotection is primary prevention (intervening before ablative influence occurs), as identifying toxic influences and deciphering the mechanisms by which they exert their effect can reduce or eliminate exposure and damage. Secondary prevention in the form of screening is not recommended broadly. Nevertheless, in some instances where a known genetic background exists in discrete families, screening is advised. As part of prenatal care, screening panels include some genetic diseases that can lead to infertility or subfertility. In these patients, early diagnosis could enable fertility preservation or changes in family-building plans. Finally, Tertiary Prevention (managing disease post-diagnosis) is critical. Reduced ovarian reserve has a major influence on physiology beyond fertility, including delayed/absent puberty or premature menopause. In these instances, proper diagnosis and medical therapy can reduce adverse effects. Here, we elaborate on these modes of prevention as well as proposed mechanisms that underlie ovarian reserve disorders.

Screening for FMR1 CGG Repeat Expansion in Thai Patients with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex disorder with a heterogeneous etiology. Fragile X syndrome (FXS) is recognized as the most common single gene mutation associated with ASD. FXS patients show some autistic behaviors and may be difficult to distinguish at a young age from autistic children. However, there have been no published reports on the prevalence of FXS in ASD patients in Thailand. In this study, we present a pilot study to analyze the CGG repeat sizes of the FMR1 gene in Thai autistic patients. We screened 202 unrelated Thai patients (168 males and 34 females) with nonsyndromic ASD and 212 normal controls using standard FXS molecular diagnosis techniques. The distributions of FMR1 CGG repeat sizes in the ASD and normal control groups were similar, with the two most common alleles having 29 and 30 CGG repeats, followed by an allele with 36 CGG repeats. No FMR1 full mutations or premutations were found in either ASD individuals or the normal controls. Interestingly, three ASD male patients with high normal CGG and intermediate CGG repeats (44, 46, and 53 CGG repeats) were identified, indicating that the prevalence of FMR1 intermediate alleles in Thai ASD patients was approximately 1% while these alleles were absent in the normal male controls. Our study indicates that CGG repeat expansions of the FMR1 gene may not be a common genetic cause of nonsyndromic ASD in Thai patients. However, further studies for mutations other than the CGG expansion in the FMR1 gene are required to get a better information on FXS prevalence in Thai ASD patients.

FMR1 and AKT/mTOR Signaling in Human Granulosa Cells: Functional Interaction and Impact on Ovarian Response

We aimed to determine whether a functional link with impact on female ovarian reserve exists between FMR1 expression and expression ratios of AKT/mTOR signaling genes in human granulosa cells in vivo, as suggested from prior in vitro data. Three hundred and nine women, who were classified as normal (NOR; n = 225) and poor (POR; n = 84) responders based on their ovarian reserve, were recruited during stimulation for assisted reproductive techniques. Expressions of FMR1 and of key genes of the AKT/mTOR and AKT/FOXO1/3 signaling pathways were comparatively analyzed in their granulosa cells. FMR1 expression in granulosa cells of NOR and POR correlated significantly with AKT1, TSC2, mTOR, and S6K expression. No correlation was found between FMR1 and FOXO1 in all, and FOXO3 expression in POR, patients. AKT1 expression was significantly higher and FOXO1 expression lower in POR samples, whereas AKT1 expression was lower and FOXO1 expression was higher in NOR samples. In human native granulosa cells, FMR1 expression significantly correlated with the expression of key genes of the AKT/mTOR signaling pathway, but not with the FOXO1/3 signaling pathway. Our data point to a functional link between FMR1 expression and expression of the AKT/mTOR signaling pathway genes controlling human follicular maturation.

Searching for female reproductive aging and longevity biomarkers

Female reproductive aging is, in a way, a biological phenomenon that develops along canonical molecular pathways; however, it has particular features. Recent studies revealed complexity of the interconnections between reproductive aging and aging of other systems, and even suggested a cause-effect uncertainty between them. It was also shown that reproductive aging can impact aging processes in an organism at the level of cells, tissues, organs, and systems. Women at the end of their reproductive lives are characterized by the accelerated incidence of age-related diseases. Timing of the onset of menarche and menopause and variability in the duration of reproductive life carry a latent social risk: not having enough information about the reproductive potential, women keep on postponing childbirth. Identification and use of the most accurate and sensitive aging biomarkers enable the prediction of menopause timing and quantification of the true biological and reproductive ages of an organism. We discuss current views on reproductive aging and peculiarities of using available biomarkers of aging. We also consider latest advances in the search for potential genetic markers of reproductive aging. Finally, we posit the importance of determining the female biological age and highlight potential research directions in this area.

Refining the risk for fragile X-associated primary ovarian insufficiency (FXPOI) by FMR1 CGG repeat size

Purpose

Approximately 20–30% of women with an FMR1 premutation experience fragile X–associated primary ovarian insufficiency (FXPOI); however, current risk estimates based on repeat size only identify women with the midrange of repeats to be at the highest risk.

Methods

To better understand the risk by repeat size, we collected self-reported reproductive histories on 1,668 women and divided them into high-resolution repeat size bins of ~5 CGG repeats to determine a more accurate risk for FXPOI in relation to CGG repeat length.

Results

As previously reported, women with 70–100 CGG repeats were at the highest risk for FXPOI using various statistical models to compare average age at menopause and risk of FXPOI, with women with 85–89 repeats being at the highest risk. Importantly, women with <65 repeats or >120 repeats did not have a significantly increased risk for FXPOI compared to women with <45 repeats.

Conclusion

Using a large cross-section study on 1,668 women, we have provided more personalized risk assessment for FXPOI using high-resolution repeat size bins. Understanding the variability in risk has important implications for family planning and overall health among women with a premutation.

A Unique Visual Attention Profile Associated With the FMR1 Premutation

Atypical visual attention patterns have been observed among carriers of the fragile X mental retardation gene (FMR1) premutation (PM), with some similarities to visual attention patterns observed in autism spectrum disorder (ASD) and among clinically unaffected relatives of individuals with ASD. Patterns of visual attention could constitute biomarkers that can help to inform the neurocognitive profile of the PM, and that potentially span diagnostic boundaries. This study examined patterns of eye movement across an array of fixation measurements from three distinct eye-tracking tasks in order to investigate potentially overlapping profiles of visual attention among PM carriers, ASD parents, and parent controls. Logistic regression analyses were conducted to examine whether variables constituting a PM-specific looking profile were able to effectively predict group membership. Participants included 65PM female carriers, 188 ASD parents, and 84 parent controls. Analyses of fixations across the eye-tracking tasks, and their corresponding areas of interest, revealed a distinct visual attention pattern in carriers of the FMR1 PM, characterized by increased fixations on the mouth when viewing faces, more intense focus on bodies in socially complex scenes, and decreased fixations on salient characters and faces while narrating a wordless picture book. This set of variables was able to successfully differentiate individuals with the PM from controls (Sensitivity = 0.76, Specificity = 0.85, Accuracy = 0.77) as well as from ASD parents (Sensitivity = 0.70, Specificity = 0.80, Accuracy = 0.72), but did not show a strong distinction between ASD parents and controls (Accuracy = 0.62), indicating that this set of variables comprises a profile that is unique to PM carriers. Regarding predictive power, fixations toward the mouth when viewing faces was able to differentiate PM carriers from both ASD parents and controls, whereas fixations toward other social stimuli did not differentiate PM carriers from ASD parents, highlighting some overlap in visual attention patterns that could point toward shared neurobiological mechanisms. Results demonstrate a profile of visual attention that appears strongly associated with the FMR1 PM in women, and may constitute a meaningful biomarker.

Association analysis of FMR1 genetic variants and primary ovarian insufficiency in South Indian women with a novel approach of CGG repeats classification

Around 20-28% of FMR1gene CGG premutation (PM) carriers are at augmented risk towards an infertility related disorder, Fragile X-associated primary ovarian insufficiency (FXPOI). Except the effect of CGG repeats, reports are not available on the mechanism through which the cis-acting variations, namely, SNPs involved in POI susceptibility. Addressing the hypothesis that the FMR1 gene polymorphisms [CGG repeats, rs25731(T > A) and rs4949(A > G)] might increase their individual and combined impact in disease predisposition, we tested the genetic variants in 200 south Indian DNA samples consists of 100 patients and 100 healthy volunteers. We used gene scan method to score the CGG repeat length, and ARMS and RFLP methods to genotype the SNPs. Only 0.5% of each Gray zone and PM alleles were found among patient group, however, no disease association was noticed with repeat length. The rs25731 showed protection [OR:0.32; (0.13-0.76), p = 0.006] and rs4949 reported a 2.5-fold risk towards the disease predisposition [OR:2.46; (1.06-5.74), p = 0.031] but, both found insignificant after Bonferroni correction was done under different Genetic Models. Novel classification of genotype combinations, 'Normal&Variant Homozygote' [OR:2.89,(1.12-7.9), p < 0.05] and 'Allele2-T-G' haplotype block (6%vs.1%, p = 0.08) were noticed to be at marginal risk for POI. We demonstrated a susceptible role of the combined effect of variant allele-G and Allele-2 (repeat allele outside the normal range) for FXPOI. To support our findings of its first kind, further studies with large samples are warranted in understanding the role of FMR1 genetic variants in FXPOI etio-pathophysiology, the outcome might help in providing better reproductive treatment options for females, who are at risk for FXPOI.

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.

Auricular acupuncture for premature ovarian insufficiency: A protocol for systematic review and meta-analysis

BACKGROUND

A lot of attention has been given to premature ovarian insufficiency (POI) as it poses considerable health risks to women. It is characterized by oligomenorrhea, amenorrhea, infertility, autoimmune disorders, and ischemic heart disease, with increased mortality. Previous research indicates that auricular acupuncture is proven effective in treating POI in clinical practice. However, systematic review has not been carried out. Therefore, this study aims at evaluating the curative effect and safety of auricular acupuncture treatment for POI through systematic review and meta-analysis.

METHODS AND ANALYSIS

The following databases will be searched for relevant information before August 2020: PubMed, Embase, Cochrane Library, Web of Science, and CNKI.

MAJOR RESULTS

levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estrogen (E2). Secondary results: modified Kupperman Index, imaging results including ovarian size, antral follicle count, and blood flow changes in the ovary using color Doppler ultrasound; total effective rate, adverse event and intervention, and hospitalization expenses. Data will be collected independently by 2 researchers, and the risk of bias in meta-analysis will be evaluated according to "Cochrane Handbook for Systematic Reviews of Interventions". All data analysis will be conducted using Review Manager V.5.3. and Stata V.12.0.

RESULTS

The curative effect and safety of auricular acupuncture treatment for POI patients will be evaluated systematically.

CONCLUSION

In the systematic review, the published evidence of auricular acupuncture treatment for POI will be summarized to provide guidance for promotion and application.

ETHICS AND DISSEMINATION

The private information from individuals will not be published. This systematic review also will not involve endangering participant rights. Ethical approval is not required. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.Open Science Framework (OSF) registration number: http://osf.io/tg9mw.

The significance of FMR1 CGG repeats in Chinese women with premature ovarian insufficiency and diminished ovarian reserve

BACKGROUND

Previous studies have shown that there is an association between FMR1 CGG repeats and ovarian dysfunction. The aim of this study is to assess the association between the number of CGG repeats in FMR1 in Chinese patients with premature ovarian insufficiency (POI) and diminished ovarian reserve (DOR).

METHODS

This is a cross-sectional, case-control study, which enrolled 124 patients with POI, 57 patients with DOR and 111 normal menopausal controls. The demographic details along with other clinical data were recorded. The FMR1 CGG repeats were analyzed by polymerase chain reaction and microfluidic capillary electrophoresis.

RESULTS

We could detect two premutation carriers in the POI group (1.6%) and one in the control group (0.9%). No premutation carriers were identified in the DOR group. The frequency of FMR1 premutations was not different between POI or DOR and controls. The most common CGG repeat was 29 and 30, and the repeat length for allele 2 had a secondary peak around 36-39 repeats. The CGG repeats were divided into groups of five consecutive values, and the distribution of allele 1 in the POI group was different from that in the control group (P < 0.001). No statistically significant differences were found for allele 1 between DOR group vs. controls, and for allele 2 between three groups (P > 0.05).

CONCLUSIONS

The study shows that the frequency of FMR1 premutations is relatively low (1.6%) in Chinese women with POI. The distribution of allele 1 CGG repeat in patients with POI showed difference from that in healthy women.

The RNA-binding fragile-X mental retardation protein and its role beyond the brain

It is well-established that variations of a CGG repeat expansion in the gene FMR1, which encodes the fragile-X mental retardation protein (FMRP), cause the neurocognitive disorder, fragile-X syndrome (FXS). However, multiple observations suggest a general and complex regulatory role of FMRP in processes outside the brain: (1) FMRP is ubiquitously expressed in the body, suggesting it functions in multiple organ systems; (2) patients with FXS can exhibit a physical phenotype that is consistent with an underlying abnormality in connective tissue; (3) different CGG repeat expansion lengths in FMR1 result in different clinical outcomes due to different pathogenic mechanisms; (4) the function of FMRP as an RNA-binding protein suggests it has a general regulatory role. This review details the complex nature of FMRP and the different CGG repeat expansion lengths and the evidence supporting the essential role of the protein in a variety of biological and pathological processes.

Chinese women with 29-30 FMR1 CGG repeats have an earlier menopause

Purpose: A strong, well-established non-linear relationship exists between fragile X mental retardation (FMR1) premutation and menopausal age. The aim of this study is to evaluate whether this relationship continues into the normal CGG repeat range.Methods: FMR1 CGG repeats of 111 Chinese postmenopausal women from a prospective cohort and the relationship with age at menopause were analyzed. Associations of FMR1 genotypes with annually measured estradiol and follicle stimulating hormone (FSH) levels were also assessed.Results: One premutation and two intermediate carriers were identified, with a prevalence of 0.90% and 1.80%, respectively. The age at menopause differed with statistical significance (p = 0.007) between women carrying bi-allelic 29-30 repeats (49.66 ± 3.26 years) and those carrying a different number of repeats (51.26 ± 2.74 years). Age at menopause among subgroups (≤28, 29-30, and ≥31 repeats) of alleles 1 and 2 were also different (p = 0.014, p = 0.044). FSH trajectories to final menstrual period differed between women with the bi-allelic 29-30 repeats and others (p = 0.019).Conclusions: Women with 29-30 FMR1 CGG repeats may experience menopause approximately 2 years earlier than those carrying ≤28 or ≥31 CGG repeats, and have a longer FSH fluctuant period.

Does the presence of AGG interruptions within the CGG repeat tract have a protective effect on the fertility phenotype of female FMR1 premutation carriers?

PURPOSE

While FMR1 premutation carriers (CGG 55-200) were shown to have reduced success with IVF treatment (lower oocyte yield), studies reporting on the association between the number of CGG repeats and patients' response to controlled ovarian hyperstimulation (COH) are inconsistent. In the present study, we aim to explore whether the number of CGG repeats in women with premutation in FMR1 gene, undergoing COH for IVF, correlates with COH variables and whether the number of AGG interruptions may function as a "protective factor" by improving the ovarian response to COH.

METHODS

Retrospective study, in an academic IVF-PGD unit. Fifty-seven consecutive FMR1 premutation carriers who underwent 285 IVF treatment cycles were included. The numbers of CGG repeats and AGG interruptions were retrieved and correlated to the demographics and COH variables.

RESULTS

There were no significant association between the numbers of CGG or the AGG interruptions and the number of oocyte retrieved or the peak estradiol levels. The lack of association was also observed when including all the IVF treatment cycles or only the first or last IVF treatment cycle. Moreover, no associations were found between the number of CGG repeats or AGG interruptions and other COH variables, i.e., duration of stimulation, the total dose of gonadotropin used, or the number of top-quality embryos.

CONCLUSIONS

No associations were observed between the number of CGG repeats or AGG interruptions and any of the COH variables. Further studies are required to identify early biomarkers of POI to empower FMR1 premutation carriers with risk assessment tools to consider procedures such as fertility preservation.

FMR1 Low Zone CGG Repeats: Phenotypic Associations in the Context of Parenting Stress

The FMR1 gene on the X chromosome has varying numbers of CGG repeats. The modal number is 30, and expansion to >200 results in fragile X syndrome, but the copy number extends down to 6. Past research suggests that individuals whose CGGs are in the "low zone" (LZ; defined here as ≤ 25 CGGs) may be more environmentally-reactive than those with normal range repeats (26-40 CGGs)-a gene x environment interaction. Using a population-based DNA biobank, in our primary analysis we compared 96 mothers with LZ CGG repeats on both alleles to 280 mothers who had CGG repeats in the normal range. Secondarily, we conducted parallel analyses on fathers. We investigated how parents in these two CGG repeat categories differentially responded to stress, defined as parenting a child with disabilities. Significant gene x environment interactions indicated that LZ mothers who had children with disabilities had greater limitations (in executive functioning, depression, anxiety, daily health symptoms, and balance) than LZ mothers whose children did not have disabilities. In contrast, mothers with normal-range CGG repeats did not differ based on stress exposure. For fathers, a similar pattern was evident for one phenotype only (hand tremors). Although on average LZ CGGs are not associated with compromised functioning, the average masks differential response to the environment.

Association between the FMR1 CGG repeat lengths and the severity of idiopathic primary ovarian insufficiency: a meta analysis

Aim: Reports on the association of the CGG repeat length in the FMR1 gene with the severity of idiopathic POI are inconclusive. Therefore, a meta analysis was performed to investigate the relationship between the expansion of repeat CGG and idiopathic POI risk. Methods: Up to January 2019, 18 case-control or cohort studies involving 3394 idiopathic POI patients and 8461 controls were included for meta analysis. Results: Thirteen studies, including 2047 cases and 6912 controls, met our criteria for the assessment of the premutation and intermediate repeat length in patients with overt POI. Compared with controls, FMR1 gene premutation is significantly associated with overt POI (OR = 8.13; 95% CI: 4.35-15.19; p < .00001), whereas there was no significant correlation between intermediate repeat length and overt POI (OR = 0.86; 95% CI: 0.62-1.18; p = .34). Seven studies, representing 1347 patients and 1948 controls, were eligible for evaluation of the premutation and intermediate repeat length in occult POI. The association between premutation and occult POI was significant (p < .00001), with a pooled fixed effects OR of 11.32 (4.45-28.80), and no significant correlation of intermediate size to occult POI was found in the case-control comparison (OR = 1.00; 95% CI: 0.68-1.47; p = .98). Conclusion: There is a close association between premutation of the FMR1 gene and increased susceptibility to idiopathic POI of each stage and no correlation between intermediate repeat length of the FMR1 gene and the severity of idiopathic POI.

Defining the role of FMR1 gene in unexplained recurrent spontaneous abortion

INTRODUCTION

Recurrent spontaneous abortion is a multifactorial disorder and till date, various factors have been attributed in its pathogenesis. Still, approximately 50% of RSA cases remain unexplained. Premutation (PM) expanded allele of fragile-X mental retardation 1 (FMR1) gene is known to contribute to ovarian dysfunction in 20% of the cases. Recently, the link between expanded FMR1 allele and recurrent miscarriages has been reported.

METHOD

In the present prospective case-control study, we have investigated the status of CGG repeat size at 5'UTR of the FMR1 gene in women with unexplained RSA in comparison to age-matched healthy control women (n = 100 each). The genomic DNA from these samples was subjected to molecular analysis for characterization of CGG repeat size and composition at FMR1 gene RESULTS: As compared to the control women, the RSA women cohort had a higher frequency of carriers with alleles in gray zone (GZ) and expanded PM range, i.e., 2% (2/100) versus 5% (5/100), respectively. Also, the RSA cohort had a significantly higher number of normal alleles with ≥ 35 CGG repeats (24 out of 200 alleles) as compared to control cohort (8 out of 200 alleles). The number of larger FMR1 alleles with pure CGG repeat tract was found to be significantly higher (P = 0.0063) in the RSA cohort (15 out of 200 alleles) as compared to that in control cohort (3 out of 200 alleles).

CONCLUSION

Henceforth, the CGG expanded uninterrupted FMR1 allele might be associated with recurrent abortions and may help to explain many of these unexplained cases.

Long Noncoding RNA Can Be a Probable Mechanism and a Novel Target for Diagnosis and Therapy in Fragile X Syndrome

Fragile X syndrome (FXS) is the most common congenital hereditary disease of low intelligence after Down syndrome. Its main pathogenic gene is fragile X mental retardation 1 (FMR1) gene associated with intellectual disability, autism, and fragile X-related primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS). FMR1 gene transcription leads to the absence of fragile X mental retardation protein (FMRP). How to relieve or cure disorders associated with FXS has also become a clinically disturbing problem. Previous studies have recently shown that long noncoding RNAs (lncRNAs) contribute to the pathogenesis. And it has been identified that several lncRNAs including FMR4, FMR5, and FMR6 contribute to developing FXPOI/FXTAS, originating from the FMR1 gene locus. FMR4 is a product of RNA polymerase II and can regulate the expression of relevant genes during differentiation of human neural precursor cells. FMR5 is a sense-oriented transcript while FMR6 is an antisense lncRNA produced by the 3' UTR of FMR1. FMR6 is likely to contribute to developing FXPOI, and it overlaps exons 15-17 of FMR1 as well as two microRNA binding sites. Additionally, BC1 can bind FMRP to form an inhibitory complex and lncRNA TUG1 also can control axonal development by directly interacting with FMRP through modulating SnoN-Ccd1 pathway. Therefore, these lncRNAs provide pharmaceutical targets and novel biomarkers. This review will: (1) describe the clinical manifestations and traditional pathogenesis of FXS and FXTAS/FXPOI; (2) summarize what is known about the role of lncRNAs in the pathogenesis of FXS and FXTAS/FXPOI; and (3) provide an outlook of potential effects and future directions of lncRNAs in FXS and FXTAS/FXPOI researches.

The Contribution of Pluripotent Stem Cell (PSC)-Based Models to the Study of Fragile X Syndrome (FXS)

Fragile X syndrome (FXS) is the most common heritable form of cognitive impairment. It results from a deficiency in the fragile X mental retardation protein (FMRP) due to a CGG repeat expansion in the 5′-UTR of the X-linked FMR1 gene. When CGGs expand beyond 200 copies, they lead to epigenetic gene silencing of the gene. In addition, the greater the allele size, the more likely it will become unstable and exhibit mosaicism for expansion size between and within tissues in affected individuals. The timing and mechanisms of FMR1 epigenetic gene silencing and repeat instability are far from being understood given the lack of appropriate cellular and animal models that can fully recapitulate the molecular features characteristic of the disease pathogenesis in humans. This review summarizes the data collected to date from mutant human embryonic stem cells, induced pluripotent stem cells, and hybrid fusions, and discusses their contribution to the investigation of FXS, their key limitations, and future prospects.

Curvilinear Association Between Language Disfluency and FMR1 CGG Repeat Size Across the Normal, Intermediate, and Premutation Range

Historically, investigations of FMR1 have focused almost exclusively on the clinical effects of CGG expansion within the categories of the premutation (55-200 CGG repeats) and fragile X syndrome (>200 CGG repeats). However, emerging evidence suggests that CGG-dependent phenotypes may occur across allele sizes traditionally considered within the "normal" range. This study adopted an individual-differences approach to determine the association between language production ability and CGG repeat length across the full range of normal, intermediate, and premutation alleles. Participants included 61 adult women with CGG repeats within the premutation (n = 37), intermediate (i.e., 41-54 repeats; n = 2), or normal (i.e., 6-40 repeats; n = 22) ranges. All participants were the biological mothers of a child with a developmental disorder, to control for the potential effects of parenting stress. Language samples were collected and the frequency of language disfluencies (i.e., interruptions in the flow of speech) served as an index of language production skills. Verbal inhibition skills, measured with the Hayling Sentence Completion Test, were also measured and examined as a correlate of language disfluency, consistent with theoretical work linking language disfluency with inhibitory deficits (i.e., the Inhibition Deficit Hypothesis). Blood samples were collected to determine FMR1 CGG repeat size. A general linear model tested CGG repeat size of the larger allele (allele-2) as the primary predictor of language disfluency, covarying for education level, IQ, age, and CGG repeats on the other allele. A robust curvilinear association between CGG length and language disfluency was detected, where low-normal (∼ <25 repeats) and mid-premutation alleles (∼90-110 repeats) were linked with higher rates of disfluency. Disfluency was not associated with inhibition deficits, which challenges prior theoretical work and suggests that a primary language deficit could account for elevated language disfluency in FMR1-associated conditions. Findings suggest CGG-dependent variation in language production ability, which was evident across individuals with and without CGG expansions on FMR1.

Recommendations regarding the genetic and immunological study of reproductive dysfunction

In this article several members of diverse scientific associations and reproduction experts from Spain have updated different genetic and immunological procedure recommendations in couples affected by reproductive dysfunction with the goal of providing a set of useful guidelines for the clinic. The laboratory test has been considered as highly recommendable for making clinical decisions when the result of the diagnostic test is relevant, moderately recommendable when the results are of limited evidence because they are inconsistent, and low when the benefit of the test is uncertain. It is expected that these recommendations will provide some useful guidelines for the diagnosis, prognosis and treatment of couples presenting reproductive dysfunction.

Use of human-derived stem cells to create a novel, in vitro model designed to explore FMR1 CGG repeat instability amongst female premutation carriers

OBJECTIVE

Create a model, using reprogrammed cells, to provide a platform to identify the mechanisms of CGG repeat instability amongst female fragile X mental retardation 1 gene (FMR1) premutation (PM) carriers.

METHODS

Female PM carriers (with and without POI) and healthy controls were enrolled from June 2013 to April 2014. Patient-derived fibroblasts (FB) were reprogrammed to induced pluripotent stem cells (iPSC) using viral vectors, encoding KLF4, OCT4, SOX2, and MYC. FMR1 CGG repeat-primed PCR was used to assess the triplet repeat structure of the FMR1 gene. FMR1 promoter methylation (%) was determined using FMR1 methylation PCR (mPCR). Quantification of FMR1 transcripts by RT-qPCR was used to evaluate the effect of reprogramming on gene transcription, as well as to correlate patient phenotype with FMR1 expression. Production of FMR1 protein (FMRP) was determined using a liquid bead array-based immunoassay.

RESULTS

Upon induction to pluripotency, all control clones exhibited maintenance of progenitor cell CGG repeat number, whereas 10 of 12 clones derived from PM carriers maintained their input CGG repeat number, one of which expanded and one contracted. As compared to parent FB, iPSC clones exhibited a skewed methylation pattern; however, downstream transcription and translation appeared unaffected. Further, the PM carriers, regardless of phenotype, exhibited similar FMR1 transcription and translation to the controls.

CONCLUSIONS

This is the first study to establish a stem cell model aimed to understand FMR1 CGG repeat instability amongst female PM carriers. Our preliminary data indicate that CGG repeat number, transcription, and translation are conserved upon induction to pluripotency.

Clinical implication of FMR1 intermediate alleles in a Spanish population

FMR1 premutation carriers (55-200 CGGs) are at risk of developing Fragile X-associated primary ovarian insufficiency as well as Fragile X-associated tremor/ataxia syndrome. FMR1 premutation alleles are also associated with a variety of disorders, including psychiatric, developmental, and neurological problems. However, there is a major concern regarding clinical implications of smaller CGG expansions known as intermediate alleles (IA) or gray zone alleles (45-54 CGG). Although several studies have hypothesized that IA may be involved in the etiology of FMR1 premutation associated phenotypes, this association still remains unclear. The aim of this study was to provide new data on the clinical implications of IA. We reviewed a total of 17 011 individuals: 1142 with primary ovarian insufficiency, 478 with movement disorders, 14 006 with neurodevelopmental disorders and 1385 controls. Similar IA frequencies were detected in all the cases and controls (cases 1.20% vs controls 1.39%, P = .427). When comparing the allelic frequencies of IA ≥ 50CGGs, a greater, albeit not statistically significant, number of alleles were detected in all the cohorts of patients. Therefore, IA below 50 CGGs should not be considered as risk factors for FMR1 premutation-associated phenotypes, at least in our population. However, the clinical implication of IA ≥ 50CGGs remains to be further elucidated.

Molecular Characterization of FMR1 Gene by TP-PCR in Women of Reproductive Age and Women with Premature Ovarian Insufficiency

BACKGROUND

Fragile X syndrome is caused by CGG repeat expansion mutation in the FMR1 gene. Normal alleles have 5-44 CGG repeats with AGG interruptions. The expanded gray zone (GZ) (45-54 repeats) and premutation (PM) (55-200 repeats) alleles are often uninterrupted and are unstably inherited in subsequent generations. The prevalence of PM and GZ carriers is high in the female population, at 1/66 and 1/113, respectively, and PM is associated with fertility problems in 20% of cases.

OBJECTIVE

Our objective was to molecularly characterize CGG repeats and AGG interruption sequences in the FMR1 gene in women of reproductive age and in women with premature ovarian insufficiency (POI).

MATERIALS AND METHODS

We conducted molecular analysis of the FMR1 gene from 300 women of reproductive age and 140 women with POI using triplet primed-polymerase chain reaction. This enabled us to identify carriers and to document CGG repeat size and the AGG interruption pattern.

RESULTS

In women of reproductive age, 1.7% were GZ carriers and 0.3% were PM carriers; in women with POI, 3.6% were GZ carriers and 2.14% were PM carriers. The frequency of GZ and PM carriers did not significantly differ between the cohorts (Fisher's exact test: p < 2.23 for GZ vs. control and p < 0.101 for PM vs. control). Carriers received genetic counselling; family screening identified an additional seven carriers.

CONCLUSION

We documented preliminary data on the prevalence of GZ and PM carriers among the studied cohorts. The identification of PM carriers among women with POI serves a dual purpose of recognizing a cause for ovarian dysfunction and enabling genetic counselling, which will help carriers when making reproductive decisions.

Fragile X-Associated Diminished Ovarian Reserve and Primary Ovarian Insufficiency from Molecular Mechanisms to Clinical Manifestations

Fragile X syndrome (FXS), is caused by a loss-of-function mutation in the FMR1 gene located on the X-chromosome, which leads to the most common cause of inherited intellectual disability in males and the leading single-gene defect associated with autism. A full mutation (FM) is represented by more than 200 CGG repeats within the FMR1 gene, resulting in FXS. A FM is inherited from women carrying a FM or a premutation (PM; 55–200 CGG repeats) allele. PM is associated with phenotypes distinct from those associated with FM. Some manifestations of the PM are unique; fragile-X-associated tremor/ataxia syndrome (FXTAS), and fragile-X-associated primary ovarian insufficiency (FXPOI), while others tend to be non-specific such as intellectual disability. In addition, women carrying a PM may suffer from subfertility or infertility. There is a need to elucidate whether the impairment of ovarian function found in PM carriers arises during the primordial germ cell (PGC) development stage, or due to a rapidly diminishing oocyte pool throughout life or even both. Due to the possibility of expansion into a FM in the next generation, and other ramifications, carrying a PM can have an enormous impact on one’s life; therefore, preconception counseling for couples carrying the PM is of paramount importance. In this review, we will elaborate on the clinical manifestations in female PM carriers and propose the definition of fragile-X-associated diminished ovarian reserve (FXDOR), then we will review recent scientific findings regarding possible mechanisms leading to FXDOR and FXPOI. Lastly, we will discuss counseling, preventative measures and interventions available for women carrying a PM regarding different aspects of their reproductive life, fertility treatment, pregnancy, prenatal testing, contraception and fertility preservation options.

Distribution of FMR1 and FMR2 Repeats in Argentinean Patients with Primary Ovarian Insufficiency

The premutation state of FMR1 (Fragile X Mental Retardation 1) has been associated with primary ovarian insufficiency (POI), and is the most common known genetic cause for 46,XX patients. Nevertheless, very few studies have analyzed its frequency in Latin American populations. Additionally, a relationship between alleles carrying a cryptic microdeletion in the 5’UTR of FMR2 and the onset of POI has only been studied in one population. Our aim was to analyze the incidence of FMR1 premutations and putative microdeletions in exon 1 of FMR2 in a cohort of Argentinean women with POI. We studied 133 patients and 84 controls. Fluorescent PCR was performed, and the FMR2 exon 1 was further sequenced in samples presenting less than 11 repeats. We found the frequency of FMR1 premutations to be 6.7% and 2.9% for familial and sporadic patients, respectively. Among controls, 1/84 women presented a premutation. In addition, although we did not find microdeletions in FMR2, we observed a change (T >C) adjacent to the repeats in two sisters with POI. Given the repetitive nature of the sequence involved, we could not ascertain whether this represents a single nucleotide polymorphism (SNP) or a deletion. Therefore, a relationship between FMR2 and POI could not be established for our population.

FMR1 genotype interacts with parenting stress to shape health and functional abilities in older age

This study investigated the association of genotype (CGG repeats in FMR1) and the health and well-being of 5,628 aging adults (mean age = 71) in a population-based study. Two groups were contrasted: aging parents who had adult children with developmental or mental health disabilities (n = 785; the high-stress parenting group) and aging parents of healthy children who did not have disabilities (n = 4843; the low-stress parenting group). There were significant curvilinear interaction effects between parenting stress group and CGG repeats for body mass index and indicators of health and functional limitations, and the results were suggestive of interactions for limitations in cognitive functioning. Parents who had adult children with disabilities and whose genotype was two standard deviations above or below the mean numbers of CGGs had poorer health and functional outcomes at age 71 than parents with average numbers of CGGs. In contrast, parents who had healthy adult children and who had similarly high or low numbers of CGG repeats had better health and functional outcomes than parents with average numbers of CGGs. This pattern of gene by environment interactions was consistent with differential susceptibility or the flip-flop phenomenon. This study illustrates how research that begins with a rare genetic condition (such as fragile X syndrome) can lead to insights about the general population and contributes to understanding of how genetic differences shape the way people respond to environments. © 2017 Wiley Periodicals, Inc.

Pathological Effects of the FMR1 CGG-Repeat Polymorphism (5-55 Repeat Numbers): Systematic Review and Meta-Analysis

The fragile X mental retardation 1 (FMR1) gene contains a highly polymorphic trinucleotide (CGG) repeat and consists of various allelic forms. Traditionally, 55-200 repeats and over 200 CGG repeats have been highlighted to be associated with ovarian dysfunction and neuro-psychiatric risks. However, previous studies had paid little attention to the allelic forms of 5-55 CGG repeats. Herein, we sought to evaluate the pathological features of FMR1 allelic category with a range of 5-55 CGG repeats. We further classified the spectrum of CGG sizes (5-55 repeats) into three sub-groups as low numbers of CGG repeat (< 26 repeats), normal CGG count (26-34 repeats), and small CGG expansion (35-54 repeats). Our systematic review documented that low numbers of CGG repeat (< 26 repeats) revealed a close relationship with premature ovarian failure. Correspondingly, the meta-analysis showed that small CGG expansion, involving allelic sizes with 35-54 (n = 8, OR = 1.22, 95% CI: 0.75-2.00, P > 0.05) and 41-54 (n = 7, OR = 1.62, 95% CI: 1.14-2.30, P < 0.05), was both linked to the risk of ovarian dysfunction. Additionally, small CGG expansion exerts significant influence on male Parkinsonism cohorts (OR = 2.17, 95% CI: 1.50-3.14, P < 0.05), mental retardation, and repeat instability. Our data provide evidence that the CGG-repeat numbers below 26 or above 34 of FMR1 gene are also associated with disease risks and thus should be regarded as pathological genotypes for a routine test.

Study of the Genetic Etiology of Primary Ovarian Insufficiency: FMR1 Gene

Menopause is a period of women’s life characterized by the cessation of menses in a definitive way. The mean age for menopause is approximately 51 years. Primary ovarian insufficiency (POI) refers to ovarian dysfunction defined as irregular menses and elevated gonadotrophin levels before or at the age of 40 years. The etiology of POI is unknown but several genes have been reported as being of significance. The fragile X mental retardation 1 gene (FMR1) is one of the most important genes associated with POI. The FMR1 gene contains a highly polymorphic CGG repeat in the 5′ untranslated region of exon 1. Four allelic forms have been defined with respect to CGG repeat length and instability during transmission. Normal (5–44 CGG) alleles are usually transmitted from parent to offspring in a stable manner. The full mutation form consists of over 200 repeats, which induces hypermethylation of the FMR1 gene promoter and the subsequent silencing of the gene, associated with Fragile X Syndrome (FXS). Finally, FMR1 intermediate (45–54 CGG) and premutation (55–200 CGG) alleles have been principally associated with two phenotypes, fragile X tremor ataxia syndrome (FXTAS) and fragile X primary ovarian insufficiency (FXPOI).

Genetics of primary ovarian insufficiency

Primary ovarian insufficiency (POI) is characterized by a loss of ovarian function before the age of 40 and account for one major cause of female infertility. POI relevance is continuously growing because of the increasing number of women desiring conception beyond 30 years of age, when POI prevalence is >1%. POI is highly heterogeneous and can present with ovarian dysgenesis and primary amenorrhea, or with secondary amenorrhea, and it can be associated with other congenital or acquired abnormalities. In most cases POI remains classified as idiopathic. However, the age of menopause is an inheritable trait and POI has a strong genetic component. This is confirmed by the existence of several candidate genes, experimental and natural models. The variable expressivity of POI defect may indicate that, this disease may frequently be considered as a multifactorial or oligogenic defect. The most common genetic contributors to POI are the X chromosome-linked defects. Here, we review the principal X-linked and autosomal genes involved in syndromic and non-syndromic forms of POI with the expectation that this list will soon be upgraded, thus allowing the possibility to predict the risk of an early age at menopause in families with POI.

Prognostic dilemmas and genetic counseling for prenatally detected fragile X gene expansions

With widespread adoption of fragile X carrier screening in pregnant women, the number of expectant couples receiving news of an unanticipated Fragile X Mental Retardation 1 (FMR1) gene expansion has increased. The most common abnormal result from maternal FMR1 testing involves an intermediate allele, also known as a gray zone result, which requires genetic counseling but poses minimal risk for an adverse developmental outcome. By contrast, the finding of a maternal FMR1 premutation or full mutation during pregnancy has important implications for the woman herself, her unborn child, and her extended family. These multiple levels of impact, in addition to the complex inheritance pattern and variable expressivity of fragile X-associated disorders, cause significant stress for newly identified expectant couples and pose unique challenges for genetic counselors in the prenatal setting. © 2016 John Wiley & Sons, Ltd.

FMR1 premutation: not only important in premature ovarian failure but also in diminished ovarian reserve

It is recognized that FMR1 premutation expansions are associated with premature ovarian failure (POF), but their role in diminished ovarian reserve (DOR) is not clearly established. Moreover, the impact of smaller repeats at the boundary of premutation and normal is less clear. Therefore, we have compared the frequency of these intermediate (45-54 repeats) and premutation (>55) sized FMR1 CGG repeats among a patients group including 188 DOR and 173 POF women and 200 controls. FSH and LH concentrations were also compared between intermediate and premutation ranges in patients. The 5' UTR of FMR1 gene was amplified using PCR. The numbers of trinucleotide repeats were confirmed by the Sanger sequencing method. The frequency of premutation was higher in POF and DOR patients in comparison with controls, but the difference in the incidence of intermediate alleles was not statistically significant among these groups. The mean level of serum FSH was higher in patients with premutation than patients with intermediate alleles. Based on the current evidence, we concluded that intermediate-sized FMR1 CGG repeat alleles should not be considered as a high-risk factor for POF and DOR.

Distribution of the FMR1 gene in females by race/ethnicity: women with diminished ovarian reserve versus women with normal fertility (SWAN study)

OBJECTIVE

To study whether reported, but inconsistent, associations between the FMR1 CGG repeat lengths in the intermediate, high normal, or low normal range differentiate women diagnosed with diminished ovarian reserve (DOR) from population controls and whether associations vary by race/ethnic group.

DESIGN

Case-control study.

SETTING

Academic and private fertility clinics.

PATIENT(S)

DOR cases (n = 129; 95 Whites, 22 Asian, 12 other) from five U.S. fertility clinics were clinically diagnosed, with regular menses and no fragile X syndrome family history. Normal fertility controls (n = 803; 386 Whites, 219 African-Americans, 102 Japanese, 96 Chinese) from the United States-based SWAN Study had one or more menstrual period in the 3 months pre-enrollment, one or more pregnancy, no history of infertility or hormone therapy, and menopause ≥46 years. Previously, the SWAN Chinese and Japanese groups had similar FMR1 CGG repeat lengths, thus they were combined.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

FMR1 CGG repeat lengths.

RESULT(S)

Median CGG repeats were nearly identical by case/control group. DOR cases had fewer CGG repeats in the shorter FMR1 allele than controls among Whites, but this was not significant among Asians. White cases had fewer CGG repeats in the shorter allele than Asian cases. No significant differences were found in the high normal/intermediate range between cases and controls or by race/ethnic group within cases in the longer allele.

CONCLUSION(S)

This study refutes prior reports of an association between DOR and high normal/intermediate repeats and confirms an association between DOR and low normal repeats in Whites.

Molecular Correlates and Recent Advancements in the Diagnosis and Screening of FMR1-Related Disorders

Fragile X syndrome (FXS) is the most common monogenic cause of intellectual disability and autism. Molecular diagnostic testing of FXS and related disorders (fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS)) relies on a combination of polymerase chain reaction (PCR) and Southern blot (SB) for the fragile X mental retardation 1 (FMR1) CGG-repeat expansion and methylation analyses. Recent advancements in PCR-based technologies have enabled the characterization of the complete spectrum of CGG-repeat mutation, with or without methylation assessment, and, as a result, have reduced our reliance on the labor- and time-intensive SB, which is the gold standard FXS diagnostic test. The newer and more robust triplet-primed PCR or TP-PCR assays allow the mapping of AGG interruptions and enable the predictive analysis of the risks of unstable CGG expansion during mother-to-child transmission. In this review, we have summarized the correlation between several molecular elements, including CGG-repeat size, methylation, mosaicism and skewed X-chromosome inactivation, and the extent of clinical involvement in patients with FMR1-related disorders, and reviewed key developments in PCR-based methodologies for the molecular diagnosis of FXS, FXTAS and FXPOI, and large-scale (CGG)_n expansion screening in newborns, women of reproductive age and high-risk populations.

Length of FMR1 repeat alleles within the normal range does not substantially affect the risk of early menopause

STUDY QUESTION

Is the length of FMR1 repeat alleles within the normal range associated with the risk of early menopause?

SUMMARY ANSWER

The length of repeat alleles within the normal range does not substantially affect risk of early menopause.

WHAT IS KNOWN ALREADY

There is a strong, well-established relationship between length of premutation FMR1 alleles and age at menopause, suggesting that this relationship could continue into the normal range. Within the normal range, there is conflicting evidence; differences in ovarian reserve have been identified with FMR1 repeat allele length, but a recent population-based study did not find any association with age at menopause as a quantitative trait.

STUDY DESIGN, SIZE, DURATION

We analysed cross-sectional baseline survey data collected at recruitment from 2004 to 2010 from a population-based, prospective epidemiological cohort study of >110 000 women to investigate whether repeat allele length was associated with early menopause.

PARTICIPANTS/MATERIALS, SETTING, METHOD

We included 4333 women from the Breakthrough Generations Study (BGS), of whom 2118 were early menopause cases (menopause under 46 years) and 2215 were controls. We analysed the relationship between length of FMR1 alleles and early menopause using logistic regression with allele length as continuous and categorical variables. We also conducted analyses with the outcome age at menopause as a quantitative trait as well as appropriate sensitivity and exploratory analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no association of the shorter or longer FMR1 allele or their combined genotype with the clinically relevant end point of early menopause in our main analysis. Likewise, there were no associations with age at menopause as a quantitative trait in our secondary analysis.

LIMITATIONS, REASONS FOR CAUTION

Women with homozygous alleles in the normal range may have undetected FMR1 premutation alleles, although there was no evidence to suggest this. We estimate minor dilution of risk of early menopause from the likely inclusion of some women with menopause at over 45 years in the early menopause cases due to age-rounding bias in self-reports.

WIDER IMPLICATIONS OF THE FINDINGS

There is no robust evidence in this large study that variation within the normal range of FMR1 repeat alleles influences timing of menopause in the general population, which contradicts findings from some earlier, mainly smaller studies. The FMR1 CGG repeat polymorphism in the normal range is unlikely to contribute to genetic susceptibility to early menopause.

STUDY FUNDING/COMPETING INTERESTS

We thank Breast Cancer Now and The Institute of Cancer Research for funding the BGS. The Institute of Cancer Research acknowledges NHS funding to the NIHR Biomedical Research Centre. The study was funded by the Wellcome Trust (grant number 085943). There are no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

The impact of FMR1 gene mutations on human reproduction and development: a systematic review

PURPOSE

This is a comprehensive review of the literature in this field attempting to put the FMR1 gene and its evaluation into context, both in general and for the reproductive health audience.

METHODS

Online database search of publications with systematic review of all papers relevant to ovarian reserve and assisted reproduction was done.

RESULTS

Relevant papers were identified and assessed, and an attempt was made to understand, rationalize and explain the divergent views in this field of study. Seminal and original illustrations were employed.

CONCLUSIONS

FMR1 is a highly conserved gene whose interpretation and effect on outcomes remains controversial in the reproductive health setting. Recent re-evaluations of the commonly accepted normal range have yielded interesting tools for possibly explaining unexpected outcomes in assisted reproduction. Fragile X investigations should perhaps become more routinely assessed in the reproductive health setting, particularly following a failed treatment cycle where oocyte quality is thought to be a contributing factor, or in the presence of a surprise finding of diminished ovarian reserve in a young patient.

Neuropsychiatry of fragile X-premutation carriers with and without fragile X-associated tremor-ataxia syndrome: implications for neuropsychology

OBJECTIVES

Clinical neuropsychologists benefit from clinical currency in recently ascertained neuropsychiatric illness, such as fragile X premutation (FXPM) disorders. The author reviewed the clinical literature through 2016 for neuropsychiatric phenotypes in FXPM disorders, including patients with fragile X-associated tremor/ataxia syndrome (FXTAS).

METHODS

A PubMed search using the search terms 'Fragile X,' 'Premutation,' 'Carriers,' 'Psychiatric,' 'Dementia,' 'Mood,' and 'Anxiety' for citations in the clinical literature through 2016 was reviewed for studies specifically examining the neuropsychiatric phenotype in FXPM patients. The relevant articles were classified according to specific neuropsychiatric syndromes, including child onset, adult onset with and without FXTAS, as well as common systemic comorbidities in FXPM patients.

RESULTS

Eighty-six articles were reviewed for the neuropsychiatric and other phenotypes in FXPM patients. The neuropsychiatric phenotype in FXPM patients is distinct from that of full mutation (Fragile X Syndrome) patients. FXTAS is associated with a specific cortical-subcortical major or mild neurocognitive disorder (NCD).

CONCLUSIONS

FXPM patients are at risk for neuropsychiatric illness. In addition, FXPM patients are at risk for other systemic conditions that should raise suspicion for FXPM-associated illnesses. Clinicians should consider a diagnosis of FXPM-associated neuropsychiatric illness when patients with specific clinical scenarios are encountered; especially in patient pedigrees consistent with a typical (often multigenerational) presentation of fragile X-associated conditions, confirmatory genetic testing should be considered. Clinical management should take into account the psychological challenges of a multigenerational genetic neuropsychiatric illness with a variable CNS and systemic clinical phenotype.

Is FMR1 CGG repeat length a predictor of in vitro fertilization stimulation response or outcome?

OBJECTIVE

To study a broad range of FMR1 CGG repeat lengths and assisted reproduction technology (ART) outcomes.

DESIGN

Retrospective cohort study.

SETTING

Private ART practice.

PATIENT(S)

Fresh autologous ART stimulation cycles.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Oocyte yield, live birth.

RESULT(S)

We screened 14,088 fresh autologous ART cycles from 2012 to 2015, of which 4,690 cycles in 3,290 patients met the inclusion criteria. The FMR1 repeat length was statistically significantly but weakly associated with oocyte yield and other markers of ovarian response. The receiver operating characteristic curve analysis suggested extremely limited predictive ability. Moreover, the FMR1 repeat length was not statistically significantly associated with outcomes in multivariable models, including other markers of ovarian reserve. The FMR1 repeat length was not associated with embryo quality or live birth. Only patient age had a strong ability to predict live birth.

CONCLUSION(S)

The FMR1 repeat length is associated with ART response, but only weakly. It provides no incremental predictive ability beyond the conventionally used predictors, including patient age, antimüllerian hormone concentration, antral follicle count, and follicle-stimulating hormone level. These data suggest a possible role of the FMR1 repeat length within the normal range in ovarian response but demonstrate no clinically relevant indication for testing FMR1 as a predictor of ART outcomes.

FMR1 CGG Repeats: Reference Levels and Race-Ethnic Variation in Women With Normal Fertility (Study of Women's Health Across the Nation)

FMR1 premutation carriers (55-199 CGG repeats), and potentially women with high normal (35-44) or low normal (<28) CGG repeats, are at risk of premature ovarian aging. The scarcity of population data on CGG repeats <45 CGG, and variation in race-ethnicity, makes it difficult to determine true associations. DNA was analyzed for FMR1 CGG repeat lengths from 803 women (386 caucasians, 219 African Americans, 102 Japanese, and 96 Chinese) from the US-based Study of Women's Health Across the Nation (SWAN). Participants had ≥1 menses in the 3 months before enrollment, ≥1 pregnancy, no history of infertility or hormonal therapy, and menopause ≥46 years. Statistical analyses used Fisher exact tests. Among these women with normal reproductive histories, significant FMR1 repeat length differences were found across race-ethnicity for both the longer (P = .0002) and the shorter (P < .0001) alleles. The trinucleotide length variance was greater for non-Asian than Asian women (P < .0001), despite identical median values. Our data indicate that short allele lengths <25 CGG on one or both alleles are more common in non-Asian than Asian women. We confirm the minor allele in the 35 to 39 CGG range among Asians as reported previously. Only 2 (0.3%) premutation carriers were identified. These data demonstrate that FMR1 distributions do vary by race-ethnicity, even within the "normal" range. This study indicates the need to control for race-ethnicity in FMR1 ovarian aging research and provides race-ethnic population data for females separated by allele.

FMR6 may play a role in the pathogenesis of fragile X-associated premature ovarian insufficiency

The aim of this study was to evaluate whether long noncoding RNA accumulation play a role in the pathophysiology of fragile X-associated premature ovarian insufficiency (FXPOI). The study population consisted of 22 consecutive fragile X mental retardation 1 (FMR1) premutation carriers (CGGn 55-199 repeats) undergoing in vitro fertilization and pre-implantation genetic diagnosis (IVF-PGD) treatment. The control group consists of 11 patients, with <55 CGG repeats, undergoing IVF-ICSI for male factor infertility, matched by age, treated in the same period. After oocyte retrieval, granulosa cells from follicular fluid were washed and stored at -80 °C. RNA was transcribed to generate cDNA and the RNA levels were measured using RT-PCR. Transcripts levels in granulosa cells of long noncoding RNA's FMR4 and FMR6 were measured. In FMR1 premutation carriers there was a significant nonlinear association between the number of CGG repeats and the levels of FMR6 (p = 0.03), but not FMR4. The highest level of FMR6 was seen in women with mid-size CGG repeats (80-120). In addition, a significant negative linear correlation was observed between the number of oocytes retrieved and the RNA levels in granulosa cells of FMR6 (r = -0.53, p = 0.01) but not FMR4. Our study supports previous findings suggesting RNA toxic gain-of-function as one of the possible pathophysiologic mechanisms underlying FXPOI.