Introduction:Carriers of the FMR1 gene premutation (PM) are at increased risk for Fragile X-associated PM Conditions (FXPAC). Some clinically significant symptoms can be further classified as Fragile X-associated Neuropsychiatric Disorders (FXAND). Many FXAND-related cases may go underrated and untreated. This study aimed to investigate the rates of FXAND-related symptoms among female PM carriers. Methods:The study was conducted at the Belgrade Fragile X Clinic on a clinical sample of 35 women with the PM and 35 controls using an adapted version of the Symptom Impact Questionnaire and the Fatigue Assessment Scale. The survey was designed to collect data on FXAND symptoms, including chronic pain, fatigue, anxiety, and depressive symptoms. Each symptom was self-rated by participants on a scale from 0 to 10. Data were analyzed using appropriate statistical methods. Results:Women with the PM (mean age: 44.51 ± 12.90 y.; 90.51 ± 22.04 CGG repeats) had statistically significant higher frequency and severity of chronic pain (p = 0.03; p = 0.02) and fatigue (p = 0.001 for both) in contrast to age-matched controls. Although the prevalence of anxiety symptoms was not significantly different between groups, the severity of anxiety symptoms were significantly higher in the PM group (p < 0.001), and was positively correlated with chronic fatigue (p = 0.003 vs. p = 0.27 in controls). Depressive symptom frequency and severity did not differ between groups (p = 0.47; p = 0.55), but there were a significant positive correlation between anxiety and depressive symptoms in the PM group (p = 0.003). Depressive symptoms were also positively correlated with chronic fatigue in the PM group (p = 0.02), but not in controls (p = 0.58). Compared to controls, PM carriers reported more frequently lower energy, poorer sleep, greater memory issues, cognitive difficulties, balance problems, and increased sensory sensitivity (p ≤ 0.001, all). Conclusion:Female PM carriers experience significantly higher frequency and severity of FXAND-related symptoms. Our findings of an association between fatigue, anxiety, and depressive symptoms highlight the need for comprehensive screening and underscore the importance of recognizing and treating individuals with FXAND.

The full mutation and epigenetic silencing of the FMR1 gene lead to a deficiency of its protein, FMRP , resulting in Fragile X Syndrome (FXS). Although significant advances have been made in understanding the molecular mechanisms underlying FXS, no cure or targeted pharmacological treatments have yet been approved for this neurodevelopmental disorder. Current clinical management primarily relies on symptomatic therapies, which often offer limited benefits and do not address the core molecular causes of the condition, especially given the multifaceted roles of the FMRP. This review highlights the crucial role of molecular insights in guiding the development of drugs for FXS. It provides an overview of existing pharmacotherapies, discusses their benefits and limitations, and emphasizes the unmet need for interventions that target the specific pathways disrupted by FMR1 dysfunction. Recent and ongoing clinical trials were examined, focusing on how a deeper understanding of FXS molecular biology can inform the design of more effective and precise therapeutic strategies. In summary, key molecular pathways relevant to FXS are presented, and the potential synergy between clinical pharmacology and molecular medicine is discussed as a means to promote the advancement of tailored therapeutic approaches.

Muscarinic acetylcholine receptors (mAChRs) are a subfamily of G protein-coupled receptors that have been identified as promising targets for drug development. Five different mAChR subtypes regulate various fundamental functions. In the central nervous system (CNS), they play a crucial role in regulating numerous cognitive, behavioral, and autonomic functions. Outside the CNS, they facilitate the effects of acetylcholine in organs and tissues innervated by parasympathetic nerves, participating in various vegetative functions such as regulating heart rate, smooth muscle contraction, and glandular secretion. The disruption in cholinergic signalling contributes to several pathophysiological conditions and diseases. Thus, muscarinic agonists and antagonists have a wide therapeutic potential in the treatment of neuropsychiatric disorders, such as Alzheimer's disease, schizophrenia or pain, and also in diseases like COPD and incontinence. Activation of different mAChR with selective ligands could be beneficial for treating the above-mentioned diseases while avoiding side effects. Clinical trials targeting mAChRs have shown promising results, with several compounds demonstrating efficacy and better tolerability profiles. However, developing drugs targeting mAChR still presents challenges, primarily due to the high homology in the structure of the orthosteric binding site. The recent insights into the physiology, pharmacology, and structure of mAChRs have provided opportunities for the development of novel drugs targeting these receptors, including allosteric modulators. Allosteric modulators offer the advantage of selective binding mAChR, potentially enhancing therapeutic efficacy while minimizing off-target effects. In conclusion, mAChRs represent promising targets for drug development. Further research and clinical trials are needed to develop effective therapies targeting muscarinic receptors for various diseases.

The gut microbiome (GM) is increasingly recognized as a key modulator of neurodevelopment via the microbiome-gut-brain axis. Fragile X syndrome (FXS), the most common inherited monogenic cause of intellectual disability, shares behavioural and molecular features with other neurodevelopmental disorders (NDDs), yet the role of the GM in FXS remains largely unexplored. In this open-label, single-arm trial, 15 children with genetically confirmed FXS received a daily probiotic formulation containing Lactobacillus casei, Lactobacillus salivarius, and Bifidobacterium breve for 12 weeks. Behavioural analysis and metagenomic sequencing with network and pathway analyses were performed before and after probiotic supplementation. Significant improvements were observed in irritability (-3.9, SD: ± 5.2; p = 0.027), communication (+ 1.7, SD: ± 2.5; p = 0.022), socialization (+ 1.4, SD: ± 2.1; p = 0.033), and adaptive behaviour (+ 1.3, SD: ± 1.4; p = 0.004). While overall microbial diversity remained stable, SparCC network analysis revealed increases in connectivity measures such as edge count and clustering coefficient, indicating denser microbial interactions and greater community coordination after probiotic supplementation. Functional profiling showed trends toward increased microbial activity in fatty acid biosynthesis, NAD salvage, and starch degradation pathways. This pilot study provides initial evidence that probiotics may modulate structural and functional properties of the GM, with potential links to improved behavioural outcomes in children with FXS. Larger, controlled trials are needed to validate the therapeutic potential of GM-targeted interventions in FXS and related NDDs.

Neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and other cognitive and behavioral impairments, are increasing globally, placing significant burdens on individuals and healthcare systems. Traditional therapeutic strategies, primarily pharmacologic and behavioral, offer limited efficacy and often fail to address the multifactorial etiology of these conditions. Recent advances in microbiome research highlight the gut microbiota as a potential modulator of brain function via the microbiota-gut-brain axis (MGBA). This bidirectional network influences neurodevelopment through neural, immune, endocrine, and metabolic pathways. Dysbiosis, or microbial imbalance, has been consistently reported in individuals with NDDs, particularly in ASD and ADHD, correlating with symptom severity and gastrointestinal comorbidities. Emerging interventions aimed at restoring microbial balance, such as probiotics, prebiotics, synbiotics, faecal microbiota transplantation (FMT), and dietary modifications – demonstrate potential in modulating behaviour and cognition. However, the current evidence is limited by small sample sizes, heterogeneous methodologies, and a lack of long-term follow-up. This mini-review synthesizes current findings on the role of gut microbiome modulation in NDDs, evaluates the therapeutic efficacy of microbiome-based interventions, and discusses future directions, including personalized microbiome-targeted strategies and the need for robust randomized controlled trials.

The control of parasitic nematode infections relies mostly on anthelmintics. The potential pharmacotherapeutic application of phytochemicals, in order to overcome parasite resistance and enhance the effect of existing drugs, is becoming increasingly important. The antinematodal effects of carveol was tested on the free-living nematode Caenorhabditis elegans and the neuromuscular preparation of the parasitic nematode Ascaris suum. Carveol caused spastic paralysis in C. elegans. In A. suum carveol potentiated contractions induced by acetylcholine (ACh) and this effect was confirmed with two-electrode voltage-clamp electrophysiology on the A. suum nicotinic ACh receptor expressed in Xenopus oocytes. However, potentiating effect of carveol on ACh-induced contractions was partially sensitive to atropine, indicates a dominant nicotine effect but also the involvement of some muscarinic structures. The effects of carveol on the neuromuscular system of mammals are also specific. In micromolar concentrations, carveol acts as a non-competitive ACh antagonist on ileum contractions. Unlike atropine, it does not change the EC50 of ACh, but reduces the amplitude of contractions. Carveol caused an increase in Electrical Field Stimulation-evoked contractions of the isolated rat diaphragm, but at higher concentrations it caused an inhibition. Also, carveol neutralized the mecamylamine-induced tetanic fade, indicating a possibly different pre- and post-synaptic action at the neuromuscular junction.

Fragile X syndrome (FXS) is caused by the full mutation in the FMR1 gene on the Xq27.3 chromosome region. It is the most common monogenic cause of autism spectrum disorder (ASD) and inherited intellectual disability (ID). Besides ASD and ID and other symptoms, individuals with FXS may exhibit sleep problems and impairment of circadian rhythm (CR). The Drosophila melanogaster models of FXS, such as dFMR1B55, represent excellent models for research in the FXS field. During this study, sleep patterns and CR in dFMR1B55 mutants were analyzed, using a new platform based on continuous high-resolution videography integrated with a highly-customized version of an open-source software. This methodology provides more sensitive results, which could be crucial for all further research in this model of fruit flies. The study revealed that dFMR1B55 male mutants sleep more and can be considered weak rhythmic flies rather than totally arrhythmic and present a good alternative animal model of genetic disorder, which includes impairment of CR and sleep behavior. The combination of affordable videography and software used in the current study is a significant improvement over previous methods and will enable broader adaptation of such high-resolution behavior monitoring methods.

Background: Fragile X syndrome, with an approximate incidence rate of 1 in 4000 males to 1 in 8000 females, is the most prevalent genetic cause of heritable intellectual disability and the most common monogenic cause of autism spectrum disorder. The full mutation of the Fragile X Messenger Ribonucleoprotein-1 gene, characterized by an expansion of CGG trinucleotide repeats (>200 CGG repeats), leads to fragile X syndrome. Currently, there are no targeted treatments available for fragile X syndrome. In a recent large multi-site trial, FXLEARN, the effects of the mGluR5 negative allosteric modulator, AFQ056 (mavoglurant), were investigated, but did not show a significant impact of AFQ056 on language development in children with fragile X syndrome aged 3–6 years. Objectives: The current analyses from biospecimens collected in the FXLEARN study aimed to determine whether AFQ056 affects the level of potential biomarkers associated with Akt/mTOR and matrix metalloproteinase 9 signaling in young individuals with fragile X syndrome. Previous research has indicated that these biomarkers play crucial roles in the pathophysiology of fragile X syndrome. Design: A double-blind placebo-controlled parallel-group flexible-dose forced titration design. Methods: Blood samples for biomarkers were collected during the FXLEARN at baseline and subsequent visits (1- and 8-month visits). Biomarker analyses included fragile X messenger ribonucleoprotein-1 genotyping by Southern blot and PCR approaches, fragile X messenger ribonucleoprotein-1 mRNA levels determined by PCR, matrix metalloproteinase 9 levels’ detection using a magnetic bead panel, and targets of the Akt/mTOR signaling pathway with their phosphorylation levels detected. Results: This research revealed that administering AFQ056 does not affect the expression levels of the investigated blood biomarkers in young children with fragile X syndrome. Conclusion: Our findings of the lack of association between clinical improvement and biomarkers’ levels in the treatment group are in line with the lack of benefit observed in the FXLEARN study. These findings indicate that AFQ056 does not provide benefits as assessed by primary or secondary endpoints. Registration: ClincalTrials.gov NCT02920892.

Fragile X syndrome (FXS) is a genetic condition caused by the inheritance of alleles with >200 CGG repeats in the 5′ UTR of the fragile X messenger ribonucleoprotein 1 (FMR1) gene. These full mutation (FM) alleles are associated with DNA methylation and gene silencing, which result in intellectual disabilities, developmental delays, and social and behavioral issues. Mosaicism for both the size of the CGG repeat tract and the extent of its methylation is commonly observed in individuals with the FM. Mosaicism has also been reported in carriers of premutation (PM) alleles, which have 55–200 CGG repeats. PM alleles confer risk for the fragile X premutation-associated conditions (FXPAC), including FXTAS, FXPOI, and FXAND, conditions thought to be due to the toxic consequences of transcripts containing large CGG-tracts. Unmethylated FM (UFM) alleles are transcriptionally and translationally active. Thus, they produce transcripts with toxic effects. These transcripts do produce some FMRP, the encoded product of the FMR1 gene, albeit with reduced translational efficiency. As a result, mosaicism can result in a complex clinical presentation. Here, we review the concept of mosaicism in both FXS and in PM carriers, including its potential clinical significance.

Background: Fragile X syndrome (FXS) is a rare disease with prevalence 1/4000 males and 1/7000 females. It is a neurodevelopmental disorder caused by a full mutation in the FMR1 gene. FXS is the leading cause of inherited intellectual disabilities and the most commonly known genetic cause of autism spectrum disorder. Children with FXS experience behavioural and sleep problems, anxiety, inattention, learning difficulties, and speech and language delays. There are no approved medications for FXS; however, there are several interventions and treatments aimed at managing the symptoms and improving the quality of life of individuals with FXS. Methods and Objectives: This presentation aims to summarize all healthcare and scientific activities in the field of fragile X over the past decade in the Republic of Serbia. The study utilizes a comprehensive review of presented results. Results: The results will include following: (i) Research studies have been conducted to understand the genetic and molecular basis of FXS. Collaborative research with international institutions has helped advance the understanding of FXS in Serbia; (ii) Healthcare initiatives: Development and implementation of specialized healthcare programs for individuals with Fragile X. Introduction of programs for early detection and diagnosis of FXS; (iii) Enhanced training for healthcare professionals to improve diagnosis, management, and care for patients with FXS; (iv) Support and advocacy: Establishment of support group and networks for families affected by fragile X; (v) International collaboration: Participation in international consortia and research projects to align with global standards and practices in fragile X research and care in Serbia. Conclusions: Over the past decade, Serbia has emerged as a regional leader in the field of Fragile X. Through pioneering research and comprehensive healthcare initiatives, supported by international and local institutions, Serbia serves as a model for best practices and innovative approaches to managing and understanding FXS worldwide.

Fragile X syndrome (FXS), the most common monogenic cause of inherited intellectual disability and autism spectrum disorder, is caused by a full mutation (>200 CGG repeats) in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene. Individuals with FXS experience various challenges related to social interaction (SI). Animal models, such as the Drosophila melanogaster model for FXS where the only ortholog of human FMR1 (dFMR1) is mutated, have played a crucial role in the understanding of FXS. The aim of this study was to investigate SI in the dFMR1B55 mutants (the groups of flies of both sexes simultaneously) using the novel Drosophila Shallow Chamber and a Python data processing pipeline based on social network analysis (SNA). In comparison with wild-type flies (w1118), SNA analysis in dFMR1B55 mutants revealed hypoactivity, fewer connections in their networks, longer interaction duration, a lower ability to transmit information efficiently, fewer alternative pathways for information transmission, a higher variability in the number of interactions they achieved, and flies tended to stay near the boundaries of the testing chamber. These observed alterations indicate the presence of characteristic strain-dependent social networks in dFMR1B55 flies, commonly referred to as the group phenotype. Finally, combining novel research tools is a valuable method for SI research in fruit flies.

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by a full mutation (> 200 CGG repeats) in the FMR1 gene. FXS is the leading cause of inherited intellectual disabilities and the most commonly known genetic cause of autism spectrum disorder. Children with FXS experience behavioral and sleep problems, anxiety, inattention, learning difficulties, and speech and language delays. There are no approved medications for FXS; however, there are several interventions and treatments aimed at managing the symptoms and improving the quality of life of individuals with FXS. A combination of non-pharmacological therapies and pharmacotherapy is currently the most effective treatment for FXS. Currently, several targeted treatments, such as metformin, sertraline, and cannabidiol, can be used by clinicians to treat FXS. Gene therapy is rapidly developing and holds potential as a prospective treatment option. Soon its efficacy and safety in patients with FXS will be demonstrated. WHAT THIS PAPER ADDS: Targeted treatment of fragile X syndrome (FXS) is the best current therapeutic approach. Gene therapy holds potential as a prospective treatment for FXS in the future.

Introduction: Fragile X syndrome (FXS) is the most common monogenetic cause of intellectual disability (ID) and autism spectrum disorder (ASD) in humans. The Drosophila melanogaster model of FXS (dFMR1 mutants) is an excellent model for research in the field of FXS. The aim of this study was a comprehensive investigation of climbing abilities, as a measurement of locomotion, in the dFMR1B55 line as a Drosophila model of FXS. Methods: In this study, control w1118 and dFMR1B55 lines of fruit flies were used. The climbing performance of flies was examined using a climbing performance assay for groups of flies as well as for individual flies. Parameters that represent climbing ability, speed and endurance were determined. Females and males were analyzed separately. Results: This study revealed the following: (i) worse climbing performance of dFMR1B55 males in comparison to w1118 males; (ii) worse climbing success of dFMR1B55 females in comparison to w1118 females; (iii) better climbing performance of top performer males in comparison to top performer females in the group climbing test in both dFMR1B55 and w1118 groups; (iv) better, but not statistically significant, climbing performance (based on the time needed for 50% of flies to complete the task), and a higher success rate in dFMR1B55 females in comparison to dFMR1B55 males. Conclusion: According to the results of the current study, climbing impairment was proved only in dFMR1B55 males, while dFMR1B55 females had climbing abilities similar to control w1118 females.

Carriers of the FMR1 premutation (PM) allele are at risk of one or more clinical conditions referred to as FX premutation-associated conditions (FXPAC). Since the FMR1 gene is on the X chromosome, the activation ratio (AR) may impact the risk, age of onset, progression, and severity of these conditions. The aim of this study was to evaluate the reliability of AR measured using different approaches and to investigate potential correlations with clinical outcomes. Molecular and clinical assessments were obtained for 30 PM female participants, and AR was assessed using both Southern blot analysis (AR-Sb) and methylation PCR (AR-mPCR). Higher ARs were associated with lower FMR1 transcript levels for any given repeat length. The higher AR-Sb was significantly associated with performance, verbal, and full-scale IQ scores, confirming previous reports. However, the AR-mPCR was not significantly associated (p > 0.05) with these measures. Similarly, the odds of depression and the number of medical conditions were correlated with higher AR-Sb but not correlated with a higher AR-mPCR. This study suggests that AR-Sb may be a more reliable measure of the AR in female carriers of PM alleles. However, further studies are warranted in a larger sample size to fully evaluate the methylation status in these participants and how it may affect the clinical phenotype.

Fragile X syndrome (FXS) is a global neurodevelopmental disorder caused by the expansion of CGG trinucleotide repeats (≥200) in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene. FXS is the hallmark of Fragile X-associated disorders (FXD) and the most common monogenic cause of inherited intellectual disability and autism spectrum disorder. There are several animal models used to study FXS. In the FXS model of Drosophila, the only ortholog of FMR1, dfmr1, is mutated so that its protein is missing. This model has several relevant phenotypes, including defects in the circadian output pathway, sleep problems, memory deficits in the conditioned courtship and olfactory conditioning paradigms, deficits in social interaction, and deficits in neuronal development. In addition to FXS, a model of another FXD, Fragile X-associated tremor/ataxia syndrome (FXTAS), has also been established in Drosophila. This review summarizes many years of research on FXD in Drosophila models.

The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.

The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region, and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X premutation-associated conditions (FXPAC) include co-transcriptional R loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci, and sequestration of various CGG re-peat-binding proteins, and repeat-associated non-AUG (RAN) initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation, can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.

Background: The fragile X premutation carrier state (PM) (55–200 CGG repeats in the fragile X messenger ribonucleoprotein 1, FMR1 gene) is associated with several conditions, including fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor ataxia (FXTAS), with current literature largely primarily investigating older PM individuals. The aim of this study was to identify the prevalence of fragile X-associated neurodevelopmental disorders (FXAND) in a sample of young PM individuals. Methods: This was a retrospective study conducted through a medical record review of PM individuals who were seen either for clinical concerns (probands, 45.9%) or identified through the cascade testing (non-probands, 54.1%) of an affected sibling with fragile X syndrome. Information on the presence of autism spectrum disorder, attention deficit hyperactivity disorder, anxiety, depression, long-term psychiatric medication intake, and cognitive function, based on standardized assessments, was obtained. Molecular data, including CGG repeat number and FMR1 mRNA levels, were also available for a subset of participants. Analysis included descriptive statistics and a test of comparison to describe the clinical profile of PM individuals pertinent to FXAND. Results: Participants included 61 individuals (52 males and 9 females) aged 7.8 to 20.0 years (mean 12.6 ± 3.4) with a mean full-scale IQ of 90.9 ± 22.7. The majority (N = 52; 85.2%) had at least one mental health disorder, with anxiety being the most common (82.0% of subjects), followed by ADHD (66.5%), and ASD (32.8%). Twenty-seven (87.1%) of non-probands also had at least one mental health condition, with probands having lower cognitive and adaptive skills than non-probands. ASD was present in 20 participants (17/52 males and 3/9 females; 15 probands) with significantly lower FSIQ in those with ASD (mean 73.5 vs. 98.0, p < 0.001). Participants with ASD had a higher number of long-term medications compared to those without (2.32 vs. 1.3, p = 0.002). Conclusions: Our findings indicate a high rate of FXAND diagnoses within a cohort of young PM individuals, including those identified via cascade testing, although this was not a population sample. An awareness of the entity of FXAND and the early recognition of the symptoms of associated conditions may facilitate timely and appropriate care for PM individuals.