Fragile X and reproduction

The management of infertility for primary care physicians

To conduct this review of primary care, we looked for related papers in PubMed from the last 15 years. WHO's initial concept of Health defined a condition of physical, mental, and social well-being, nowadays extended to quality of life. Infertility or not being able to form a family fits perfectly into the definition. Primary care is responsible for mandatory discussions about fertility as part of a broader aspect regarding reproductive health issues. Having children is a decision taken by heterosexual couples, same sex couples, or single individuals. Understanding factors associated with infertility help guiding propedeutic. Although woman's age is one of the main factors to influence treatment success rates, multifactorial male factor may contribute to 50 percent. Infertility consultations should include partners, alleviating the accompanying stress and anxiety. Anamnesis must focus on duration of infertility, primary or secondary, sexual activity, and lifestyle habits such as smoking, alcohol consumption, diet, physical activity, use of licit and/or illicit drugs, and occupational risks. Previous treatments should be accessed. Management of infertility by primary care is mandatory, and patients requiring specialized treatments must not have their journey protracted. Strategies and couple-based interventions are essential to continuity of care and close follow-up should follow these patients.

An explanation of the mechanisms underlying fragile X-associated premature ovarian insufficiency

Fragile X and fragile X-associated tremor-ataxia syndrome (FXTAS) are caused by mutations of the FMR1 gene. The mutations causing FXTAS can expand in a generation to a "full mutation" causing fragile X syndrome. The mutations causing FXTAS and the phenotype, fragile X-associated premature ovarian insufficiency (FXPOI), are referred to as the FMR1 premutation (PM). The objective of this paper was to formulate a theory to explain the Mechanism for FXPOI.Recent research on fragile X syndrome and FXTAS has led to sophisticated theories about the mechanisms underlying these diseases. It has been proposed that similar mechanisms underlie FXPOI. Utilizing recent research on FXTAS, but a more detailed application of ovarian physiology, we present a more ovarian specific theory as to the primary mechanism explaining the development of FXPOI.The FXPOI phenotype may best be viewed as derivative of the observation that fragile X PM carriers experience menopause an average of 5 years earlier than non-carriers. Women carrying the PM experience an earlier menopause because of an accelerated activation of their primordial follicle pool. This acceleration of primordial follicle activation occurs, in part, because of diminished AMH production. AMH production is diminished because of accelerated atresia of early antral follicles. This accelerated atresia likely occurs because the fragile X PM leads to a slowing of the rate of granulosa cell mitosis in some follicles.

Preimplantation genetic diagnosis versus prenatal diagnosis-decision-making among pregnant FMR1 premutation carriers

PURPOSE

To detect which factors influence decision-making among pregnant FMR1 premutation carriers regarding the preferred mode of genetic diagnosis: IVF-PGT-M (in vitro fertilization with preimplantation genetic testing for monogenic gene diseases), or CVS (chorionic villus sampling), or AC (amniocentesis) after spontaneous conception.

METHODS

In Israel FMR1 premutation preconception genetic screening is offered, free of charge, to every woman in her reproductive years. FMR1 premutation carriers with ≥ 70 CGG repeats, or a history of FXS offspring, are offered IVF-PGT-M. This is a historical cohort study including all pregnant FMR1 premutation carriers who underwent prenatal diagnosis between the years 2011 and 2016 at a tertiary medical center. Data were collected from electronic charts and through phone interviews.

RESULTS

One hundred seventy-five women with high-risk pregnancies who were offered IVF-PGT-M were evaluated. In 37 pregnancies (21%), the women decided to undergo IVF-PGT-M. Using the generalized estimating equations (GEE) statistical method including seven parameters, we found that previous termination of pregnancy due to FXS and advanced woman's age were significantly associated with making the decision to undergo IVF-PGT-M. Previously failed IVF was the most significant parameter in a woman's decision not to undergo IVF-PGT-M.

CONCLUSION

The most dominant factor affecting the decision of FMR1 premutation carriers to choose spontaneous conception with prenatal diagnosis versus IVF-PGT-M is a previous experience of failed IVF treatments. Women whose IVF treatments failed in the past tended to try to conceive naturally and later, during the course of the pregnancy, perform CVS or AC. Conversely, women who previously experienced a termination of pregnancy (TOP) due to an affected fetus, and older women, preferred to undergo IVF-PGT-M procedures.

Premature recruitment of oocyte pool and increased mTOR activity in Fmr1 knockout mice and reversal of phenotype with rapamycin

While mutations in the fragile X mental retardation-1 (FMR1) gene are associated with varying reproductive outcomes in females, the effects of a complete lack of FMR1 expression are not known. Here, we studied the ovarian and reproductive phenotypes in an Fmr1 knockout (KO) mouse model and the role of mammalian target of rapamycin (mTOR) signaling. Breeding, histologic and mTOR signaling data were obtained at multiple time points in KO and wild type (WT) mice fed a control or rapamycin (mTOR inhibitor) diet. KO mice showed an earlier decline in ovarian reserve than WT mice with an increased proportion of activated follicles. mTOR and phosphorylated S6 kinase (p-S6K) levels, a measure of downstream mTOR signaling, were elevated in the KO ovaries. Rapamycin blocked these effects in KO mice, and increased the primordial follicle pool and age of last litter in WT mice. Our data demonstrates an early decline in reproductive capacity in Fmr1 KO mice and proposes that premature recruitment of the primordial pool via altered mTOR signaling may be the mechanism. Reversal of phenotypes and protein levels in rapamycin-treated KO mice, as well as increased reproductive lifespan of rapamycin-fed WT mice, suggest the mTOR pathway as a potential therapeutic target.

Expanded alleles of the FMR1 gene are related to unexplained recurrent miscarriages

Up to 50% of recurrent miscarriage cases in women occur without an underlying etiology. In the current prospective case-control study, we determined the impact of CGG trinucleotide expansions of the fragile-X mental retardation 1 (FMR1) gene in 49 women with unexplained recurrent miscarriages. Case group consisted of women with two or more unexplained consecutive miscarriages. Blood samples were obtained and checked for the presence of expanded alleles of the FMR1 gene using PCR. Patients harboring the expanded allele, with a threshold set to 40 repeats, were further evaluated by sequencing. The number of abortions each woman had, was not associated with her respective CGG repeat number (P=0.255). The repeat sizes of CGG expansion in the FMR1 gene were significantly different in the two population groups (P=0.027). All the positive cases involved intermediate zone carriers. Hence, the CGG expanded allele of the FMR1 gene might be associated with unexplained multiple miscarriages; whether such an association is coincidental or causal can be confirmed by future studies using a larger patient cohort.

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.

Loss of FMRP Impaired Hippocampal Long-Term Plasticity and Spatial Learning in Rats

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by mutations in the FMR1 gene that inactivate expression of the gene product, the fragile X mental retardation 1 protein (FMRP). In this study, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology to generate Fmr1 knockout (KO) rats by disruption of the fourth exon of the Fmr1 gene. Western blotting analysis confirmed that the FMRP was absent from the brains of the Fmr1 KO rats (Fmr1^exon4-KO ). Electrophysiological analysis revealed that the theta-burst stimulation (TBS)-induced long-term potentiation (LTP) and the low-frequency stimulus (LFS)-induced long-term depression (LTD) were decreased in the hippocampal Schaffer collateral pathway of the Fmr1^exon4-KO rats. Short-term plasticity, measured as the paired-pulse ratio, remained normal in the KO rats. The synaptic strength mediated by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) was also impaired. Consistent with previous reports, the Fmr1^exon4-KO rats demonstrated an enhanced 3,5-dihydroxyphenylglycine (DHPG)-induced LTD in the present study, and this enhancement is insensitive to protein translation. In addition, the Fmr1^exon4-KO rats showed deficits in the probe trial in the Morris water maze test. These results demonstrate that deletion of the Fmr1 gene in rats specifically impairs long-term synaptic plasticity and hippocampus-dependent learning in a manner resembling the key symptoms of FXS. Furthermore, the Fmr1^exon4-KO rats displayed impaired social interaction and macroorchidism, the results consistent with those observed in patients with FXS. Thus, Fmr1^exon4-KO rats constitute a novel rat model of FXS that complements existing mouse models.

Fragile X Premutation Carrier Epidemiology and Symptomatology in Israel-Results from a Tertiary Child Developmental Center

Fragile X syndrome (FXS) is the most prevalent known genetically inherited cause for autism and intellectual disability. Premutation state can cause several clinical disorders as well. We aimed to perform a nesting approach to acquire data with regard to first degree relatives of index fragile X cases at the largest child development center in Israel in order to map characteristics of Israeli FXS permutation women carriers. Seventy-nine women were referred due to a related fragile X syndrome patient, mainly an offspring or sibling. General information regarding demographics, ethnicity, and associated medical conditions were collected using interviews and structured questionnaires. Thirteen (17 %) of the women who were referred as "carrier" were proven to be actually full mutation. The mean years of education were 14 (±1.51, range 12-17). Twenty-one women (27 %) originated from Tunisia (mainly from the island of Djerba). Ten women (13 %) reported delivery of their affected offspring beyond 41 gestational weeks. Twenty-two percent of women with premutation reported symptoms consistent with learning difficulties, mainly dyscalculia, and 14 % reported ADHD symptoms. Awareness about clinical disorders of the carriers was existent only in 25 % of the patients. Increased awareness and knowledge dissemination concerning premutation symptomatology and associated medical conditions are warranted. We suggest a national registry to be installed in different countries in order to identify fragile X premutation carriers at increased risk for various medical complications.

Genetic aspects of premature ovarian failure: a literature review

BACKGROUND

The diagnosis of premature ovarian failure (POF) is based on the finding of amenorrhea before the age of 40 years associated with follicle-stimulating hormone levels in the menopausal range. It is a heterogeneous disorder affecting approximately 1% of women <40 years, 1:10,000 women by age 20 years and 1:1,000 women by age 30 years. POF is generally characterized by low levels of gonadal hormones (estrogens and inhibins) and high levels of gonadotropins (LH and FSH) (hypergonadotropic amenorrhea).

METHODS

Review of significant articles regarding genetic causes that are associated with POF.

RESULTS

Heterogeneity of POF is reflected by a variety of possible causes, including autoimmunity, toxics, drugs, as well as genetic defects. Changes at a single autosomal locus and many X-linked loci have been implicated in women with POF. X chromosome abnormalities (e.g., Turner syndrome) represent the major cause of primary amenorrhea associated with ovarian dysgenesis. Many genes have been involved in POF development, among them BMP15, FMR1, FMR2, LHR, FSHR, INHA, FOXL2, FOXO3, ERα, SF1, ERβ and CYP19A1 genes.

CONCLUSION

Despite the description of several candidate genes, the cause of POF remains undetermined in the vast majority of cases.

PGD for fragile X syndrome: ovarian function is the main determinant of success

BACKGROUND

PGD for fragile X syndrome (FRAX) is inefficient, probably owing to fewer oocytes, poor embryo quality and difficulties in genetic analysis. We investigated IVF-PGD in FRAX mutation carriers compared with controls, looking at the effects of oocyte and embryo number/quality on live birth outcome.

METHODS

We performed IVF-PGD in 27 patients with the FRAX mutation and 33 controls with other genetic diseases. Genetic testing was by multiplex PCR.

RESULTS

Seventy-nine and 108 IVF-PGD cycles were started in FRAX mutation carriers and controls, respectively. Twenty-two patients had a premutation (CGG repeat number 60-200) and five had a full mutation (300-2000 CGG repeats). FRAX patients required higher doses of gonadotrophins (6788 ± 2379 versus 4360 ± 2330, P< 0.001) but had lower peak serum estradiol levels (8166 ± 5880 versus 10 211 ± 4673, P = 0.03) and fewer oocytes retrieved (9.8 ± 6 versus 14 ± 8, P = 0.01). The cancellation rate (unsatisfactory ovarian response) was higher in the FRAX group than in the control group (13 versus 1%, P < 0.001). When embryos were transferred, ongoing pregnancy/live birth rates per transfer were similar (29 versus 36%, P = 0.54).

CONCLUSIONS

Ovarian dysfunction in FRAX carriers is more prevalent and profound than previously appreciated, with a high cancelation rate and reduced efficiency of PGD. The main determinant for successful PGD for FRAX is ovarian dysfunction. When embryo transfer is possible, the results are comparable to PGD for other monogenic diseases.

Premature ovarian failure from current perspective

Premature ovarian failure (POF) is a syndrome characterised by amenorrhoea, hypoestrogenism and hypergonadotropinism before the age of 40. It is a disorder affecting approximately 1% of women <40 years, 1/1,000 women by the age of 30 and 1/10,000 women by the age of 20. POF is not merely an early menopause. Up to 50% of the patients with POF will have intermittent and unpredictable ovarian function which may persist for some years. Heterogeneity of POF is also reflected by the variety of possible causes, including autoimmunity, toxics, drugs, radiation, infectious as well as genetic defects. HRT remains the cornerstone of treatment and the only proven method of achieving pregnancy in these patients is by ovum donation.

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

Background

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

Methods

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

Results

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

Conclusions

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

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Preimplantation genetic diagnosis for fragile X syndrome: is there increased transmission of abnormal FMR1 alleles among female heterozygotes?

BACKGROUND

Fragile X syndrome is caused by a CGG triplet-repeat expansion mutation in the FMR1 gene. Previous studies have shown increased transmission of abnormal alleles in the 51-60 repeat range. This study was undertaken to evaluate the performance of preimplantation genetic diagnosis (PGD) for fragile X, and to assess the transmission rate of the abnormal FMR1 alleles in this setting.

METHOD

The study included 18 fragile X carriers who applied for PGD. FMR1 CGG repeats ranged from 70 to 300. PGD was performed using multiplex-nested PCR, with simultaneous amplification of the CGG repeat region and several polymorphic markers, and sex chromosome markers.

RESULTS

Four patients had a poor ovarian response, and could not undergo PGD. The remaining 14 patients underwent 47 PGD cycles. A total of 565 oocytes were aspirated. Of the 386 embryos that were successfully biopsied, 18 (6.4%) could not be analyzed due to amplification failure, and 12 (4.3%) had sex chromosomal abnormalities. Of the remaining 250 embryos, the abnormal allele was transmitted to 124 embryos (49.6%) compared to 126 (50.4%) for the normal allele. This difference was not statistically significant. Only embryos carrying the normal allele were transferred, resulting in 7 clinical pregnancies (18% per embryo transfer).

CONCLUSIONS

Our results demonstrate that PGD for fragile X is feasible, and that carriers transmit the abnormal allele at the same frequency as the normal allele.

Abnormal uterine bleeding: a focus on polycystic ovary syndrome

Abnormal uterine bleeding imposes major medical, social and financial problems for women, their families and the health services. Abnormal uterine bleeding refers to the regularity, frequency, duration and volume of bleeding. Irregular menstrual bleeding is most common at the extremes of reproductive life, in the initial 12-18 months after menarche and 5-6 years before the menopause begins. In Australia, the estimated cost of investigating and managing heavy menstrual bleeding alone is approximately AUS $6 million per annum. This article addresses the common causes of irregular bleeding in pre- and peri-menopausal women and presents an investigational approach.

Childhood developmental disorders: an academic and clinical convergence point for psychiatry, neurology, psychology and pediatrics

BACKGROUND

Significant advances in understanding brain development and behavior have not been accompanied by revisions of traditional academic structure. Disciplinary isolation and a lack of meaningful interdisciplinary opportunities are persistent barriers in academic medicine. To enhance clinical practice, research, and training for the next generation, academic centers will need to take bold steps that challenge traditional departmental boundaries. Such change is not only desirable but, in fact, necessary to bring about a truly innovative and more effective approach to treating disorders of the developing brain.

METHODS

I focus on developmental disorders as a convergence point for transcending traditional academic boundaries. First, the current taxonomy of developmental disorders is described with emphasis on how current diagnostic systems inadvertently hinder research progress. Second, I describe the clinical features of autism, a phenomenologically defined condition, and Rett and fragile X syndromes, neurogenetic diseases that are risk factors for autism. Finally, I describe how the fields of psychiatry, psychology, neurology, and pediatrics now have an unprecedented opportunity to promote an interdisciplinary approach to training, research, and clinical practice and, thus, advance a deeper understanding of developmental disorders.

RESULTS

Research focused on autism is increasingly demonstrating the heterogeneity of individuals diagnosed by DSM criteria. This heterogeneity hinders the ability of investigators to replicate research results as well as progress towards more effective, etiology-specific interventions. In contrast, fragile X and Rett syndromes are 'real' diseases for which advances in research are rapidly accelerating towards more disease-specific human treatment trials.

CONCLUSIONS

A major paradigm shift is required to improve our ability to diagnose and treat individuals with developmental disorders. This paradigm shift must take place at all levels - training, research and clinical activity. As clinicians and scientists who are currently constrained by disciplinary-specific history and training, we must move towards redefining ourselves as clinical neuroscientists with shared interests and expertise that permit a more cohesive and effective approach to improving the lives of patients.