Fragile X Associated Primary Ovarian Insufficiency (FXPOI): Case Report and Literature Review

Unmethylated Mosaic Full Mutation Males without Fragile X Syndrome

Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability (ID) and single gene cause of autism. Although most patients with FXS and the full mutation (FM) have complete methylation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene, some have mosaicism in methylation and/or CGG repeat size, and few have completely unmethylated FM alleles. Those with a complete lack of methylation are rare, with little literature about the cognitive and behavioral phenotypes of these individuals. A review of past literature was conducted regarding individuals with unmethylated and mosaic FMR1 FM. We report three patients with an unmethylated FM FMR1 alleles without any behavioral or cognitive deficits. This is an unusual presentation for men with FM as most patients with an unmethylated FM and no behavioral phenotypes do not receive fragile X DNA testing or a diagnosis of FXS. Our cases showed that mosaic males with unmethylated FMR1 FM alleles may lack behavioral phenotypes due to the presence of smaller alleles producing the FMR1 protein (FMRP). However, these individuals could be at a higher risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS) due to the increased expression of mRNA, similar to those who only have a premutation.

Destabilizing Effect of Organo Ru(II) Salts on the Intermolecular Parallel CGG Repeat DNA Quadruplex Associated with Neurodegenerative/Neuromuscular Diseases

The cationic organo ruthenium(II) salts ([Ru(p-cymene)(ipit)(Cl)](Cl) (RuS), 1-isopropyl-3-(pyridin-2-yl)-imidazol-2-thione (ipit) and [Ru(p-cymene)(ipis)(Cl)](Cl) (RuSe), 1-isopropyl-3-(pyridin-2-yl)-imidazol-2-selenone (ipis)) are isolated, and their binding efficacy with d(CGG)15 quadruplex is investigated. Circular dichroism (CD) wavelength scan titration experiments of RuS and RuSe compounds with the intermolecular parallel quadruplex formed by d(CGG)15 (associated with neurodegenerative/neuromuscular/neuronal intranuclear inclusion disorders like FXTAS, OPMD, OPDM types 1-4, and OPML as well as FXPOI) and with the control d(CGG)15·d(CCG)15 duplex indicate their specificity toward the former. Electrophoretic mobility shift titration experiments also confirm the binding of the ligands with d(CGG)15. CD thermal denaturation experiments indicate that both RuS and RuSe destabilize the quadruplex, specifically at 10 mM concentration of the ligands. This is further confirmed by 1D 1H NMR experiments. Such a destabilizing effect of these ligands on the d(CGG)15 quadruplex indicates that RuS and RuSe chalcogen complexes can act as a template for the design of novel molecules for the diagnostics and/or therapeutics of CGG repeat expansion-associated diseases.

Narrative Review: Update on the Molecular Diagnosis of Fragile X Syndrome

The diagnosis and management of fragile X syndrome (FXS) have significantly improved in the last three decades, although the current diagnostic techniques are not yet able to precisely identify the number of repeats, methylation status, level of mosaicism, and/or the presence of AGG interruptions. A high number of repeats (>200) in the fragile X messenger ribonucleoprotein 1 gene (FMR1) results in hypermethylation of promoter and gene silencing. The actual molecular diagnosis is performed using a Southern blot, TP-PCR (Triplet-Repeat PCR), MS-PCR (Methylation-Specific PCR), and MS-MLPA (Methylation-Specific MLPA) with some limitations, with multiple assays being necessary to completely characterise a patient with FXS. The actual gold standard diagnosis uses Southern blot; however, it cannot accurately characterise all cases. Optical genome mapping is a new technology that has also been developed to approach the diagnosis of fragile X syndrome. Long-range sequencing represented by PacBio and Oxford Nanopore has the potential to replace the actual diagnosis and offers a complete characterization of molecular profiles in a single test. The new technologies have improved the diagnosis of fragile X syndrome and revealed unknown aberrations, but they are a long way from being used routinely in clinical practice.

Selected Genetic Factors Associated with Primary Ovarian Insufficiency

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

The International Fragile X Premutation Registry: building a resource for research and clinical trial readiness

FMR1 premutation cytosine-guanine-guanine repeat expansion alleles are relatively common mutations in the general population that are associated with a neurodegenerative disease (fragile X-associated tremor/ataxia syndrome), reproductive health problems and potentially a wide range of additional mental and general health conditions that are not yet well-characterised. The International Fragile X Premutation Registry (IFXPR) was developed to facilitate and encourage research to better understand the FMR1 premutation and its impact on human health, to facilitate clinical trial readiness by identifying and characterising diverse cohorts of individuals interested in study participation, and to build community and collaboration among carriers, family members, researchers and clinicians around the world. Here, we describe the development and content of the IFXPR, characterise its first 747 registrants from 32 countries and invite investigators to apply for recruitment support for their project(s). With larger numbers, increased diversity and potentially the future clinical characterisation of registrants, the IFXPR will contribute to a more comprehensive and accurate understanding of the fragile X premutation in human health and support treatment studies.

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

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

TAF4b transcription networks regulating early oocyte differentiation

Establishment of a healthy ovarian reserve is contingent upon numerous regulatory pathways during embryogenesis. Previously, mice lacking TBP-associated factor 4b (Taf4b) were shown to exhibit a diminished ovarian reserve. However, potential oocyte-intrinsic functions of TAF4b have not been examined. Here, we use a combination of gene expression profiling and chromatin mapping to characterize TAF4b-dependent gene regulatory networks in mouse oocytes. We find that Taf4b-deficient oocytes display inappropriate expression of meiotic, chromatin modification/organization, and X-linked genes. Furthermore, dysregulated genes in Taf4b-deficient oocytes exhibit an unexpected amount of overlap with dysregulated genes in oocytes from XO female mice, a mouse model of Turner Syndrome. Using Cleavage Under Targets and Release Using Nuclease (CUT&RUN), we observed TAF4b enrichment at genes involved in chromatin remodeling and DNA repair, some of which are differentially expressed in Taf4b-deficient oocytes. Interestingly, TAF4b target genes were enriched for Sp/Klf family and NFY target motifs rather than TATA-box motifs, suggesting an alternative mode of promoter interaction. Together, our data connect several gene regulatory nodes that contribute to the precise development of the mammalian ovarian reserve.

Fragile X Premutation: Medications, Therapy and Lifestyle Advice

The fragile X premutation is characterized by 55–200 CGG repeats in the 5ʹ untranslated region of FMR1, whereas full fragile X mutation has greater than 200 repeats and full methylation, which manifests as fragile X syndrome (FXS). The premutation spectrum of clinical involvement includes fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND). In addition, premutation carriers also suffer from various other health problems such as endocrine abnormalities and autoimmune problems. In this paper, we have discussed different health issues faced by the carriers and interventions including medications, therapy and lifestyle changes that could improve their health.

Incomplete Penetrance and Variable Expressivity: From Clinical Studies to Population Cohorts

The same genetic variant found in different individuals can cause a range of diverse phenotypes, from no discernible clinical phenotype to severe disease, even among related individuals. Such variants can be said to display incomplete penetrance, a binary phenomenon where the genotype either causes the expected clinical phenotype or it does not, or they can be said to display variable expressivity, in which the same genotype can cause a wide range of clinical symptoms across a spectrum. Both incomplete penetrance and variable expressivity are thought to be caused by a range of factors, including common variants, variants in regulatory regions, epigenetics, environmental factors, and lifestyle. Many thousands of genetic variants have been identified as the cause of monogenic disorders, mostly determined through small clinical studies, and thus, the penetrance and expressivity of these variants may be overestimated when compared to their effect on the general population. With the wealth of population cohort data currently available, the penetrance and expressivity of such genetic variants can be investigated across a much wider contingent, potentially helping to reclassify variants that were previously thought to be completely penetrant. Research into the penetrance and expressivity of such genetic variants is important for clinical classification, both for determining causative mechanisms of disease in the affected population and for providing accurate risk information through genetic counseling. A genotype-based definition of the causes of rare diseases incorporating information from population cohorts and clinical studies is critical for our understanding of incomplete penetrance and variable expressivity. This review examines our current knowledge of the penetrance and expressivity of genetic variants in rare disease and across populations, as well as looking into the potential causes of the variation seen, including genetic modifiers, mosaicism, and polygenic factors, among others. We also considered the challenges that come with investigating penetrance and expressivity.

The FMR1 Premutation Phenotype and Mother-Youth Synchrony in Fragile X Syndrome

A subset of mothers who carry the FMR1 premutation may express a unique phenotype. The relationship between the FMR1 phenotype and mother-child interaction in families with fragile X-associated disorders has not been well characterized, despite the importance of high-quality mother-child interaction for child development. This study examined the association between the FMR1 phenotype and the quality of interactions between mothers and their adolescent/young adult sons with fragile X syndrome. Mother-youth synchrony was coded from a dyadic interaction. Maternal anxiety and depression symptoms, executive function deficits, and pragmatic language difficulties were evaluated. Results indicated that pragmatic language was associated with mother-youth synchrony. These findings highlight the importance of family-centered intervention practices for families with fragile X-associated disorders.

Not just carriers: experiences of X-linked female heterozygotes

PURPOSE

To better understand the needs and experiences of the X-linked carrier community to improve future recognition, diagnosis, and treatment by bringing X-linked carrier voices together.

METHODS

An anonymous survey link was distributed to members of Remember the Girls, a non-profit organization for female (XX) carriers of X-linked conditions, through its website, Facebook group, Instagram, and Twitter. The survey was developed to gather data on XX carriers of numerous X-linked conditions.

RESULTS

One hundred and fifty individuals participated in the study. The majority (81/150) of individuals learned about their carrier status by giving birth to a son diagnosed with an X-linked condition. However, over 80% (120/145) believed that they should learn this information before the age of 18. Over 80% of participants (124/148) felt that they either have or may have symptoms attributable to their X-linked condition. Yet, only 10.1% (15/148) felt that they had sufficient access to knowledgeable healthcare providers and/or medical information. Additionally, 46.7% (70/150) of participants reported that healthcare providers did not discuss reproductive options with them. Improving carrier access to medical information, research studies, new treatments, and reproductive methods was found to be the top priority.

CONCLUSION

Limited information exists on X-linked carriers' risk for symptoms and there is a lack of available treatments. This study demonstrates the need for more knowledgeable healthcare providers and medical information within the X-linked carrier community.

Molecular Pathogenesis and Peripheral Monitoring of Adult Fragile X-Associated Syndromes

Abnormal trinucleotide expansions cause rare disorders that compromise quality of life and, in some cases, lifespan. In particular, the expansions of the CGG-repeats stretch at the 5’-UTR of the Fragile X Mental Retardation 1 (FMR1) gene have pleiotropic effects that lead to a variety of Fragile X-associated syndromes: the neurodevelopmental Fragile X syndrome (FXS) in children, the late-onset neurodegenerative disorder Fragile X-associated tremor-ataxia syndrome (FXTAS) that mainly affects adult men, the Fragile X-associated primary ovarian insufficiency (FXPOI) in adult women, and a variety of psychiatric and affective disorders that are under the term of Fragile X-associated neuropsychiatric disorders (FXAND). In this review, we will describe the pathological mechanisms of the adult “gain-of-function” syndromes that are mainly caused by the toxic actions of CGG RNA and FMRpolyG peptide. There have been intensive attempts to identify reliable peripheral biomarkers to assess disease progression and onset of specific pathological traits. Mitochondrial dysfunction, altered miRNA expression, endocrine system failure, and impairment of the GABAergic transmission are some of the affectations that are susceptible to be tracked using peripheral blood for monitoring of the motor, cognitive, psychiatric and reproductive impairment of the CGG-expansion carriers. We provided some illustrative examples from our own cohort. Understanding the association between molecular pathogenesis and biomarkers dynamics will improve effective prognosis and clinical management of CGG-expansion carriers.

Optimizing Fertility in Primary Ovarian Insufficiency: Case Report and Literature Review

Primary ovarian insufficiency (POI) is a clinical spectrum of ovarian dysfunction. Overt POI presents with oligo/amenorrhea and hypergonadotropic hypogonadism before age 40 years. Overt POI involves chronic health problems to include increased morbidity and mortality related to estradiol deficiency and the associated osteoporosis and cardiovascular disease as well as psychological and psychiatric disorders related to the loss of reproductive hormones and infertility. Presently, with standard clinical testing, a mechanism for Overt POI can only be identified in about 10% of cases. Now discovery of new mechanisms permits an etiology to be identified in a research setting in 25-30% of overt cases. The most common genetic cause of Overt POI is premutation in FMR1. The associated infertility is life altering. Oocyte donation is effective, although many women prefer to conceive with their own ova. Surprisingly, the majority who have Overt POI still have detectable ovarian follicles (70%). The major mechanism of follicle dysfunction in Overt POI has been histologically defined by a prospective NIH study: inappropriate follicle luteinization due to the tonically elevated serum LH levels. A trial of physiologic hormone replacement therapy, clinically proven to suppress the elevated LH levels in these women, may improve follicle function and increase the chance of ovulation. Here, we report the case of a woman with Overt POI diagnosed at age 35 years. To attempt pregnancy, she elected a trial of intrauterine insemination (IUI) in conjunction with follicle monitoring and physiologic hormone replacement therapy. She conceived on the eighth cycle of treatment and delivered a healthy baby. Our report calls for a concerted effort to define the best methods by which to optimize fertility for women who have POI.

FMR1 locus isoforms: potential biomarker candidates in fragile X-associated tremor/ataxia syndrome (FXTAS)

Fragile X associated tremor/ataxia syndrome (FXTAS) is a late adult-onset neurodegenerative disorder that affects movement and cognition in male and female carriers of a premutation allele of 55–200 CGG repeats in the Fragile X mental retardation (FMR1) gene. It is currently unknown if and when an individual carrier of a premutation allele will develop FXTAS, as clinical assessment fails to identify carriers at risk before significant neurological symptoms are evident. The primary objective of this study was to investigate the alternative splicing landscape at the FMR1 locus in conjunction with brain measures in male individuals with a premutation allele enrolled in a very first longitudinal study, compared to age-matched healthy male controls, with the purpose of identifying biomarkers for early diagnosis, disease prediction and, a progression of FXTAS. Our findings indicate that increased expression of FMR1 mRNA isoforms, including Iso4/4b, Iso10/10b, as well as of the ASFMR1 mRNAs Iso131bp, are present in premutation carriers as compared to non-carrier healthy controls. More specifically, we observed a higher expression of Iso4/4b and Iso10/10b, which encode for truncated proteins, only in those premutation carriers who developed symptoms of FXTAS over time as compared to non-carrier healthy controls, suggesting a potential role in the development of the disorder. In addition, we found a significant association of these molecular changes with various measurements of brain morphology, including the middle cerebellar peduncle (MCP), superior cerebellar peduncle (SCP), pons, and midbrain, indicating their potential contribution to the pathogenesis of FXTAS. Interestingly, the high expression levels of Iso4/4b observed both at visit 1 and visit 2 and found to be associated with a decrease in mean MCP width only in those individuals who developed FXTAS over time, suggests their role as potential biomarkers for early diagnosis of FXTAS.

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.

Successful Spontaneous Pregnancy and Live Birth in a Woman With Premature Ovarian Insufficiency and 10 Years of Amenorrhea: A Case Report

Background: Primary ovarian insufficiency (POI) is a devastating diagnosis for reproductive-aged women due to the associated infertility and other serious health consequences. Spontaneous pregnancy without hormone replacement therapy (HRT) and/or assisted reproductive technology (ART) rarely occurs in POI patients, particularly in those patients with long-term amenorrhea.

Case: On March 4, 2019, a 31-year-old Chinese POI patient visited our hospital for a spontaneous pregnancy after 10 years of amenorrhea and discontinuation of HRT 4 years prior. The patient had menarche at the age of 13, with 3 years of regular menstruation followed by amenorrhea occurring at the age of 20. POI was diagnosed by several hospitals; chromosome examination revealed a normal 46, XX karyotype. Treatment with estradiol valerate and progesterone did lead to resumed menstruation, while amenorrhea resumed after withdrawal of HRT. The patient married at the age of 23 and tried to conceive by HRT until the age of 25; her beta-human chorionic gonadotropin (HCG), estrogen (E2), and progesterone levels were 32987.7~119151.4 mIU/ml, 671.0~>1,000 pg/mL, and 6.6~27.9 ng/ml, respectively. On March 22, 2019, ultrasonography showed an intrauterine pregnancy with a normally developed gestational sac sized 45 × 42 × 32 mm with a 17 mm crown-rump length. On October 29, a 3,400 g healthy girl baby was delivered; the patient had a spontaneous delivery with natural labor.

Conclusion: Spontaneous pregnancy is possible in women with POI and 10 years of amenorrhea.

Disruption of Spermatogenesis and Infertility in Ataxia with Oculomotor Apraxia Type 2 (AOA2)

Ataxia with oculomotor apraxia type 2 (AOA2) is a rare autosomal recessive cerebellar ataxia characterized by onset between 10 and 20 years of age and a range of neurological features that include progressive cerebellar atrophy, axonal sensorimotor neuropathy, oculomotor apraxia in a majority of patients, and elevated serum alpha-fetoprotein (AFP). AOA2 is caused by mutation of the SETX gene which encodes senataxin, a DNA/RNA helicase involved in transcription regulation, RNA processing, and DNA maintenance. Disruption of senataxin in rodents led to defective spermatogenesis and sterility in males uncovering a key role for senataxin in male germ cell survival. Here, we report the first clinical and cellular evidence of impaired spermatogenesis in AOA2 patients. We assessed sperm production in three AOA2 patients and testicular pathology in one patient and compared the findings to those of Setx-knockout mice. Sperm production was impaired in all patients assessed (3/3, 100%). Analyses of testicular biopsies from an AOA2 patient recapitulate features of the histology seen in Setx-knockout mice, strongly suggesting an underlying mechanism centering on DNA-damage-mediated germ cell apoptosis. These findings support a role for senataxin in human reproductive function and highlight a novel clinical feature of AOA2 that extends the extra-neurological roles of senataxin. This raises an important reproductive counseling issue for clinicians, and fertility specialists should be aware of SETX mutations as a possible diagnosis in young male patients presenting with oligospermia or azoospermia since infertility may presage the later onset of neurological manifestations in some individuals.

The role of AGG interruptions in the FMR1 gene stability: A survey in ethnic groups with low and high rate of consanguinity

Background

The prevalence and the role of AGG interruptions within the FMR1 gene in the normal population is unknown. In this study, we investigated the frequent of AGG loss, in one or two alleles within the normal population. The role of AGG in the FMR1 stability has been assessed by correlating AGG loss to the prevalence of premutation/full mutation in two ethnic groups differing in their consanguinity rate: high versus low consanguinity rate (HCR vs. LCR).

Methods

The CGG repeat allele size and AGG presence were measured in 6,865 and 6,204 females belonging to the LCR (5%) and HCR (>45%) groups, respectively, by Tripled‐Primed‐PCR technique.

Results

A lower prevalence of the premutation was observed in the HCR (1:158) as compared to the LCR group (1:128). No full mutation was found in the HCR females while in the LCR group the prevalence found was 1:1,149. Homozygosity rate was higher in the HCR population compared to the LCR group.The overall AGG loss was higher in the HCR population than in the LCR and increased with increased CGG repeat number in both ethnic groups.

Conclusions

Although we observed a significantly higher rate of homozygosity and AGG loss in the HCR group, this did not affect the prevalence of the premutation and full mutation in this population. Their prevalence was significantly lower than in the LCR population. Finally, we discuss whether the loss of AGG could be also a polymorphic event but not only a stabilizing factor.

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.