Search Results (263)

Fragile X syndrome (FRAX) is caused by CGG repeat expansion in the FMR1 gene, which triggers aberrant DNA hypermethylation, chromatin condensation, and transcriptional gene silencing. However, the mechanism that underlies this repeat-induced epigenetic defect remains poorly understood. SMCHD1 is a chromatin regulator that promotes de novo DNA methylation and heterochromatin formation at long repetitive elements, including the D4Z4 macrosatellite repeat implicated in facioscapulohumeral muscular dystrophy (FSHD). Given the mechanistic parallels between FSHD and FRAX, we hypothesized that SMCHD1 contributes to repeat-induced FMR1 hypermethylation. To test this, we disrupted SMCHD1 in an XY FRAX human embryonic stem cell (hESC) line carrying a heavily methylated CGG-expanded FMR1 allele. Despite efficient loss of SMCHD1, FMR1 hypermethylation remained unchanged, indicating that SMCHD1 is dispensable for FMR1 gene silencing. We next combined SMCHD1 knockout with CRISPR-mediated CGG repeat contraction to determine whether removal of the pathogenic mutation could restore the aberrant methylation. Nevertheless, FMR1 hypermethylation was preserved in all edited clones. These findings demonstrate that, unlike D4Z4 silencing in FSHD, FMR1 repeat-induced hypermethylation does not depend on SMCHD1 activity. Moreover, correction of the underlying CGG expansion through repeat contraction is insufficient to restore the normal hypomethylated state of the FMR1 locus in pluripotent stem cells. Full article

Background: Fragile X syndrome (FXS) is the most common monogenic cause of inherited intellectual disability and is primarily caused by CGG repeat expansion in the FMR1 gene. Conventional diagnostic methods have limited precision for sizing long repeat sequences and cannot resolve AGG interruptions, which are critical for comprehensive risk assessment. Existing national FXS reference materials are based on conventional methods and provide limited molecular information. Methods: We developed a targeted long-read sequencing assay for comprehensive FMR1 characterization, termed tLRS-FMR1, and applied it to a panel of 22 national FXS reference materials. Results: The tLRS-FMR1 assay demonstrated 100% concordance with standard methods while overcoming key limitations of conventional approaches. It enabled precise quantification of CGG repeat numbers, including full mutations (>200 repeats) that were only qualitatively reported by traditional techniques and provided comprehensive mapping of AGG interruption patterns. The assay showed high reproducibility, with 100% genotyping concordance across intra- and inter-assay replicates and achieved a detection limit of 3 ng/μL. Conclusions: This study successfully developed tLRS-FMR1 and established a new-generation national FXS reference material system with expanded molecular information and improved precision, providing a foundation for advancing the standardization and accuracy of FXS molecular diagnosis. Full article

Fragile X Syndrome (FXS) is an inherited cause of intellectual disability and autism, arising from silencing of the Fmr1 gene and loss of Fragile X Messenger Ribonucleoprotein 1 (FMRP). FMRP is an RNA-binding protein critically involved in neurodevelopmental processes, including neurogenesis. We examined the proliferation and maturation of adult-born dentate granule cells (abDGCs) and glial populations in Fmr1 knockout (KO) and wild-type (WT) mice at 4, 12, and 24 weeks of age under control and early-life stress (ELS) conditions. Based on prior findings, we hypothesized that KO mice would exhibit increased neurogenesis and atypical responses to ELS compared with WT mice. Using immunohistochemistry, we quantified multiple stages of neurogenesis in the dentate gyrus, including proliferating (Ki67+), immature (doublecortin [DCX]+), and apoptotic (cleaved caspase-3 [CC3]+) cells. We also assessed glia using Iba1 (microglia) and GFAP (astrocytes) immunoreactivity. KO mice displayed significantly increased Ki67+ proliferating and reduced CC3+ apoptotic cells across ages, accompanied by increased Iba1+ and GFAP+ glial densities. However, KO mice exhibited fewer DCX+ neuroblasts at later time points. When reared in ELS conditions, KO mice show blunted or no changes in neurogenesis and glial populations relative to WT mice reared in ELS conditions or KO mice in control conditions. These results indicate that FMRP loss disrupts hippocampal neurogenesis by increasing cell proliferation while limiting neuronal maturation and expanding glial populations. Moreover, the absence of neurogenic and glial responses to ELS in KO mice highlights a gene–environment interaction that may influence FXS-related neuropathology by limiting the adaptive capacity of the hippocampal neurogenic niche. Full article

Background/Objectives: Fragile X Syndrome (FXS) is a neurodevelopmental disorder caused by a triplet repeat expansion in the Fmr1 gene leading to the loss of Fragile X Messenger Ribonucleoprotein (Fmr1 protein). The loss of Fmr1 protein modulates many cell biological processes and leads to the emergence of intellectual disability and autism. FXS is modeled in Fmr1-KO mice that display features consistent with human FXS, including hypersensitivity, cognitive and learning deficits, hyperactivity and audiogenic seizures. Here, we investigated the effect of auditory stimulation during a range of developmental stages on recognition memory and sociability deficits in Fmr1-KO mice. Methods: Fmr1-KO mice were subjected to auditory stimulation for 2 min three times a day at one-hour intervals for 5 days at the nursing, juvenile and adult stages. The animals were tested for social interaction and novel object recognition at 2 to 3 months old. Results: During auditory stimulation, the wild running phenotype was observed in the Fmr1-KO juvenile animals and two animals at the nursing stage experienced status epilepticus and died. Fmr1-KO animals showed social deficits compared to both the control and animals exposed to auditory stimulation at the juvenile stage. In the novel object recognition task, auditory stimulation was more effective at the nursing and juvenile stages. Conclusions: These data show that auditory stimulation may be an effective way to restore cognitive and social deficits in FXS. Full article

Background: Cushing’s syndrome (CS) causes excessive cortisol exposure, leading to significant skeletal complications. However, there is no validated, CS-specific model to predict osteoporosis and fracture risk. This study aimed to identify independent predictors and develop a practical clinical scoring system. Methods: A retrospective study was conducted on 139 patients with CS diagnosed between 2014 and 2025. Demographic, clinical, and biochemical data were analyzed. Osteoporosis was defined using dual-energy X-Ray absorptiometry criteria. Logistic regression analyses identified independent predictors, and the Cushing-Related Osteoporosis Risk Estimation (CORE) Score was constructed from normalized beta coefficients of significant variables. Results: Osteoporosis was present in 35.9% and fragility fractures in 13.4% of patients. Independent predictors included age ≥ 51 years, symptom duration ≥ 13.5 months, diabetes mellitus, late-night salivary cortisol ≥ 0.42 μg/dL, and midnight serum cortisol ≥ 10.25 μg/dL (all p < 0.05). The CORE Score (0–6 points) showed strong diagnostic performance for osteoporosis (AUC 0.827; sensitivity 88%, specificity 72%) and fractures (AUC 0.866; sensitivity 84%, specificity 78%). Each one-point increase in the CORE Score elevates the risk of osteoporotic fracture by 3.13 times (p < 0.001). Conclusions: The CORE Score represents a promising disease-specific tool for early identification of CS patients at increased risk of osteoporosis and fragility fractures, enabling more personalized management and follow-up strategies, such as prioritizing bone-protective interventions and closer skeletal monitoring. Early identification of high-risk individuals may also facilitate timely therapeutic interventions, potentially reducing future fracture risk. Full article

Challenging behaviors, including noncompliance, aggression, hyperactivity, and impulsivity, are common among individuals with Fragile X Syndrome (FXS) and Down Syndrome (DS). To identify treatment needs specific to these populations, we conducted focus groups with caregivers and educators and used their input to adapt an evidence-based caregiver training program originally designed for caregivers of autistic children (i.e., The Research Units in Behavioral Intervention; RUBI). We then completed a feasibility trial in which five families of children with FXS and four families of children with DS completed a nine-session caregiver training program targeting behavioral principles, syndrome-specific information, and visual supports tailored to the unique needs of FXS or DS (adapted version of RUBI for non-autism developmental disabilities; RUBI-DD). The program demonstrated strong acceptability, with high caregiver satisfaction, 100% retention, and 100% session attendance. Across the combined sample, caregiver reports indicated significant improvements in irritability/aggression (F_(2,15.14) = 4.42, p = 0.03), lethargy/social withdrawal (F_(2,14.47) = 3.97, p = 0.04), stereotypies (F_(2,15.29) = 4.45, p = 0.03), hyperactivity (F_(2,15.14) = 6.51, p = 0.009), social inflexibility (F_(2,15.43) = 6.33, p = 0.01), demand-based noncompliance (F_(2,15.41) = 4.95, p = 0.02), and the impact of behavior on the family (F_(2,15.07) = 4.23, p = 0.04) following participation in RUBI-DD. Caregivers of children with FXS reported significant reductions in lethargy/social withdrawal (F_(2,8.000) = 6.256, p = 0.023) and hyperactivity (F_(2,8.000) = 12.497, p = 0.003) immediately post-treatment and upon 12-week follow-up (g = 1.153, p = 0.044, and g = 1.178, p = 0.003, respectively). Among families of children with DS, caregivers reported reductions in irritability and aggression (F_(2,5.047) = 14.073, p = 0.009) and improvements in the impact on the family (F_(2,6.000) = 5.489, p = 0.044) immediately post-treatment and at follow-up (g = 1.643, p = 0.016, and g = 0.448, p = 0.045, respectively). These findings support the feasibility, acceptability, and preliminary efficacy of RUBI-DD for children with FXS or DS. Full article

Background/Objectives: Cannabinoids are increasingly recognised for their therapeutic potential beyond well-established indications such as chronic pain, multiple sclerosis, and specific epileptic syndromes. Recent advances have highlighted their possible role in less-common or orphan diseases, opening new avenues for pharmaceutical research and clinical application. Methods: This review provides a critical synthesis of the most recent evidence (2020–2025), available in PubMed and Scopus, regarding the use of cannabinoids in conditions including refractory epilepsies beyond Dravet and Lennox–Gastaut syndromes, movement disorders such as dystonia and Tourette syndrome, rare dermatological diseases like epidermolysis bullosa, and emerging data in Crohn’s disease. Results: Negative outcomes, such as those reported in Fragile X syndrome trials, are also discussed as instructive examples of methodological and pharmacological challenges. Particular attention is given to the optimisation of pharmaceutical formulations and advanced separation technologies, including oromucosal sprays, transdermal gels, and novel nanocarrier systems, which aim to overcome issues of bioavailability and variability in patient response. Finally, safety concerns, regulatory aspects, and the need for robust clinical trials are addressed. Conclusions: Overall, cannabinoids represent a promising yet underexplored therapeutic option in rare and complex disorders, warranting further investigation supported by innovative pharmaceutical approaches. Full article

Background: Fragile X Syndrome (FXS) is an X-linked neurodevelopmental disorder characterised by intellectual disability, developmental delays, anxiety, and social and behavioural challenges. Currently, no effective treatments exist to address the root cause of FXS. Mouse models are the most widely used for studying molecular pathogenesis and conducting preclinical treatment testing. However, therapeutic interventions that show promise in rodent models have yet to succeed in clinical trials. After evaluating the current models, we have developed an ovine model to address this clinical translation gap. We expect this model to more accurately reflect the human condition in brain size, structure, and neurodevelopmental trajectory. We aim to establish this model as a valuable preclinical platform for testing therapies for FXS. Methods: To generate the sheep model, we used CRISPR-Cas9 dual-guide editing to knock out the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene in ovine embryos. Results: Two founder animals were created, one ram (male) and one ewe (female), both of which carried FMR1 gene knockouts. The ewe carries inactivating mutations on both alleles, with the edits in both animals resulting in no detectable Fragile X Messenger Ribonucleoprotein (FMRP) as expected. Both founders have undergone molecular characterisation and basic health checks, with the female founder showing increased joint flexibility, a characteristic of FXS. The ram has been used for breeding, with the successful transmission of the edited allele to his offspring. Importantly, specific lamb cohorts for postnatal treatment testing can be produced efficiently utilising accelerated breeding methods and preimplantation selection. Full article

Hereditary ataxias are a heterogeneous group of disorders with overlapping clinical presentations but diverse genetic and molecular etiologies. Biomarkers are increasingly essential to improve diagnosis, refine prognosis, and accelerate the development of targeted therapies. Following PRISMA-ScR guidelines, we conducted a scoping review of PubMed and complementary sources (2010–2025) to map and describe the current landscape of genetic, imaging, fluid, electrophysiological, and digital biomarkers across the most prevalent hereditary ataxias, including SCA1, SCA2, SCA3, SCA6, SCA7, SCA17, SCA27B, dentatorubral–pallidoluysian atrophy (DRPLA), Friedreich’s ataxia (FRDA), RFC1-related ataxia (CANVAS), SPG7, and fragile X-associated tremor/ataxia syndrome (FXTAS). Eligible evidence encompassed observational cohorts, clinical trials, case series, and case reports providing primary biomarker data, with the objective of characterizing evidence breadth and identifying knowledge gaps rather than assessing comparative effectiveness. Across modalities, converging evidence highlights subtype-specific biomarker signatures. MRI volumetry, DTI, and FDG-PET map characteristic neurodegeneration patterns. Fluid biomarkers such as neurofilament light chain are informative across several SCAs and FRDA, while frataxin levels constitute robust endpoints in FRDA trials. Pathology-specific biomarkers such as ataxin-3 are advancing as tools for target engagement and may generalize to future gene-lowering strategies. Electrophysiological and oculographic measures show sensitivity for early disease detection, and wearable technologies are emerging as scalable tools for longitudinal monitoring. This scoping review synthesizes the heterogeneous evidence on hereditary ataxia biomarkers, highlighting multimodal frameworks that link molecular mechanisms with clinical endpoints. Mapping current approaches also reveals substantial variability and gaps across diseases and modalities, underscoring the need for harmonized validation in international multicenter cohorts and systematic integration into future clinical trials to advance precision medicine in hereditary ataxias. Full article

Background/Objectives: Fragile X-associated tremor/ataxia syndrome (FXTAS) is characterized by tremor, gait ataxia, and cerebellar white matter degeneration, along with possible cognitive and cerebral changes. Although diagnostic criteria were originally developed in males, emerging evidence suggests that FXTAS may present differently in females. The present study examined sensorimotor and memory features of aging in female premutation carriers with (FXTAS+) and without FXTAS (FXTAS−). Methods: We studied 51 female premutation carriers (FXTAS+ = 16, FXTAS− = 35) and 24 age-matched female controls. Participants ranged in age from 47–80 years. All participants completed genetic testing, clinical evaluations, T2-weighted MRIs, and quantitative assessments of sensorimotor (precision grip force task) and memory (reading span; visual paired associates task) functions. Results: During precision grip testing, FXTAS+ carriers showed higher sustained force regularity than FXTAS− carriers (p = 0.03, d = 1.0) and controls (p = 0.004, d = 1.1) at low gain levels only. FXTAS+ participants were slower than controls on motor reaction time (p = 0.009, d = 0.82). Initial force output was higher in FXTAS+ than FXTAS− carriers (p = 0.03, d = 1.0) and controls (p = 0.03, d = 1.0) but at low gain only. FXTAS+ carriers exhibited poorer working memory than FXTAS− carriers (p = 0.03, d = 0.91) and controls (p = 0.02, d = 1.0). During a long-term memory task, FXTAS+ participants were less accurate than FXTAS− carriers (p = 0.04, d = 0.86) and controls (p = 0.004, d = 1.1) and showed increased reaction times relative to FXTAS− carriers (p = 0.03, d = −0.82) and controls (p = 0.01, d = −1.2). Conclusions: Together, these findings indicate that FXTAS+ females exhibit distinct motor and cognitive impairments, underscoring the value of quantitative behavioral measures for detecting and tracking neurodegenerative progression in female premutation carriers. Full article

Fragile X syndrome (FXS, OMIM#300624) is the most common inherited cause of X-linked intellectual disability and behavior difficulties. In 99% of cases, it is caused by the pathological expansion (>200 repeats, full mutation -FM) of the CGG trinucleotide located at the 5′ UTR of the FMR1 (Fragile X Messenger Ribonucleoprotein 1) gene, leading to the lack of production of the FMRP. Clinical manifestations are well known in boys but are sometimes overlooked in girls, who may remain underdiagnosed. Premutation (PM) populations (55–200 repeats) may present other medical issues, such as FXPOI or FXTAS. Mosaic conditions, such as a combination of PM and FM lines in the same patient, may lead to milder phenotypes. With the improvement of genetic testing, information regarding the exact number of CGG triplet repeats and methylation status could help explain milder phenotypes in patients who may produce some FMRP. Chromosome X preferential inactivation (XCI) in FXS women can also play a role in clinical severity. We present four non-related families who were followed up in our FXS clinic. Some of their members showed FM on Southern blot, but had milder symptoms than expected. To rule out size mosaicism, a RT-PCR was performed, giving a different and more consistent molecular diagnosis. When mosaicism was not present, methylation status was performed, excluding full methylation. For females, XCI showed preferential inactivation in one case. Revisiting old molecular diagnoses should be considered in clinical practice, especially for patients with a milder phenotype than expected from their molecular reports. This personalized follow up may change their former diagnosis, prognosis, and expectations. Full article

Background: Fragile X Syndrome (FXS) is the most common monogenic cause of autism spectrum disorders, and is characterized by the excessive immature excitatory synapses in cortical neurons, leading to excitatory/inhibitory imbalance and core autistic behaviors. This synaptic pathology has been attributed to dysregulated levels of synaptic proteins, including CYFIP2: a key regulator of synaptic structure and plasticity. However, the mechanism underlying the increased CYFIP2 protein level in FXS neurons remains unclear. Neurons abundantly secrete extracellular vesicles (EVs) enriched with bioactive cargos (proteins and miRNAs). Objectives: the goal of this research is to identify whether EV-dependent secretion plays important roles in regulating the intracellular CYFIP2 protein level in WT and FXS neurons. Methods and Results: our proteomic analysis reveals that CYFIP2 protein is packaged in EVs released by mouse cortical neurons. Pharmacological and genetic blockades of neuronal EV release significantly elevated intracellular CYFIP2 levels by 78 ± 14% and 168 ± 39%, respectively. Glutamate-evoked EV release significantly reduced the CYFIP2 level by 24 ± 2%. Neurons from Fmr1 KO mice, an FXS model, secreted significantly less EVs (46 ± 5%) than the wild type, and showed significantly elevated CYFIP2 (by 155 ± 31%). Evoking EV release in FXS neurons significantly lowered the intracellular CYFIP2 (by 53 ± 6%). Conclusions: these findings identify an EV-secretion-dependent mechanism that controls neuronal CYFIP2 level, implicating EV-mediated export in the regulation of synaptic protein homeostasis, synaptic remodeling, and FXS-associated synaptic deficits. Full article

Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are neurodevelopmental disorders marked by deficits in communication and social interaction, often accompanied by anxiety, seizures, and intellectual disability. FXS, the most common monogenic cause of ASD, results from silencing of the FMR1 gene and consequent loss of FMRP, a regulator of synaptic protein synthesis. Disruptions in cyclic nucleotide (cAMP and cGMP) signaling underlie both ASD and FXS contributing to impaired neurodevelopment, synaptic plasticity, learning, and memory. Notably, reduced cAMP levels have been observed in platelets, lymphoblastoid cell lines and neural cells from FXS patients as well as Fmr1 KO and dfmr1 Drosophila models, linking FMRP deficiency to impaired cAMP regulation. Phosphodiesterase (PDE) inhibitors, which prevent the breakdown of cAMP and cGMP, have emerged as promising therapeutic candidates due to their ability to modulate neuronal signaling. Several PDE isoforms—including PDE2A, PDE4D, and PDE10A—have been implicated in ASD, and FXS, as they regulate pathways involved in synaptic plasticity, cognition, and social behavior. Preclinical and clinical studies show that PDE inhibition modulates neuroplasticity, neurogenesis, and neuroinflammation, thereby ameliorating autism-related behaviors. BPN14770 (a PDE4 inhibitor) has shown promising efficacy in FXS patients while cilostazol, pentoxifylline, resveratrol, and luteolin have showed improvements in children with ASD. However, challenges such as isoform-specific targeting, optimal therapeutic window, and timing of intervention remain. Collectively, these findings highlight PDE inhibition as a novel therapeutic avenue with the potential to restore cognitive and socio-behavioral functions in ASD and FXS, for which effective targeted treatments remain unavailable. Full article

The gut microbiota plays an essential role in human health, influencing gut–brain communication. Imbalances in this microbial ecosystem, termed dysbiosis, have been associated with increased gut permeability and gastrointestinal symptoms commonly reported in autism spectrum disorder (ASD), without implying a direct causal role in ASD itself. This study aimed to determine whether alterations in gut microbiota exist in individuals with Fragile X Syndrome (FXS), with or without ASD, compared to ASD patients and neurotypical controls, and to identify microbiota biomarkers associated with these disorders. Stool samples from Caucasian individuals aged 3–18 years belonging to four groups (ASD, FXS, FXS + ASD, and controls) were analysed by amplifying the V3–V4 region of the bacterial 16S rRNA gene to characterize microbiota composition. Significant differences were found among patient groups compared to neurotypical controls, with notable similarities between the ASD and FXS + ASD groups. Additionally, specific microbiota biomarkers were identified for each patient group. These findings suggest that distinct microbiota alterations are associated with FXS and ASD, which may contribute to a more accurate characterization of symptoms in these disorders and could serve as potential biomarkers for assessing neurodevelopmental risk. Full article

Fragile X syndrome (FXS) is the most common form of X-linked intellectual disability (ID). This study aimed to share 30 years of experience in diagnosing FXS and determine its frequency in Thailand. We retrospectively reviewed 1480 unrelated patients (1390 males and 90 females) with ID, developmental delay, or autism spectrum disorder, or individuals referred for FXS DNA testing at Songklanagarind Hospital, Thailand, over a 30-year period. The samples were analyzed using cytogenetic methods, PCR-based techniques, and/or Southern blot analysis. Full mutations (>200 CGG repeats) were identified in 100 males (7.2%) and three females (3.3%). An intermediate allele was detected in one male, while no premutation was found in the index cases. Two males were suspected to have FMR1 gene deletions. Twelve families underwent prenatal testing during this study. Most families undergoing prenatal FXS diagnosis involved mothers who were premutation carriers and had given birth to children affected by FXS. This study represents the largest series of molecular genetic FXS testing cases reported in Thailand. The frequency of FXS identified in different cohorts of Thai patients across various periods was approximately 7%. This study enhances public awareness of at-risk populations and highlights the importance of prenatal testing and genetic counseling for vulnerable families. Full article