Fragile X Research Articles

Challenges in diagnosis of fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disease recently described in the literature with a low percentage of detectability in patients due to insufficient awareness of doctors. The clinical picture is characterized by high phenotypic variability and coincidence of symptoms with other, more well-known motor disorders, in connection with which patients are observed for a long time with erroneous diagnoses. The issue of the differential diagnosis fragile X-associated tremor/ataxia syndrome with essential tremor, Parkinson’s disease, multiple system atrophy, spinocerebellar ataxia and progressive supranuclear paralysis is highlighted separately. In order to demonstrate the complexity of the diagnosis of this disease, a description of a case of genetically confirmed case of genetically confirmed fragile X-associated tremor/ataxia syndrome is presented. The described clinical case is represented by a combination of asymmetric disabling postural kinetic tremor of the hands, minor resting tremor, moderate cerebellar ataxia, asymmetric moderate dopa-responsive parkinsonism syndrome, mild cognitive impairment and psychotic symptoms. Not only the clinical picture of the disease is described in detail, but also the hereditary history of the patient: the results of a genetic study of a daughter premutation carriers of the FMR1 gene and a grandson suffering from Martin–Bell syndrome. A special feature of the clinical case is the long-term erroneous observation of a patient diagnosed with Parkinson’s disease, as well as high-dose therapy with levodopa/carbidopa 250 mg + 25 mg (up to 6 tablets per day). When studying the available domestic literature, the previously described cases of fragile X-associated tremor/ataxia syndrome were not found.

Women's healthcare providers' knowledge and practices surrounding fragile-X associated primary ovarian insufficiency (FXPOI).

This study investigates the knowledge gaps about fragile X-associated primary ovarian insufficiency (FXPOI) among women's healthcare providers. Previous research highlighted a lack of awareness regarding FXPOI as a cause of primary ovarian insufficiency (POI) and its diagnosis. The objective of this study was to describe these gaps and explore demographic factors influencing FXPOI knowledge in women's healthcare practitioners. A survey assessed familiarity with primary ovarian insufficiency and FXPOI knowledge among 107 women's healthcare providers and 14 medical students in the USA. Knowledge Scores, ranging from 0 to 16, were assigned, and demographic data, including healthcare provider type, specialty, and genetics exposure in education or training, were collected. Participants scored an average of 6.92 (± 2.19) out of 16 (42%) despite 88% of participants reporting genetics exposure in training. Maternal fetal medicine (MFM) and reproductive endocrinology (REI) providers significantly outperformed general obstetrics and gynecology (OBGYN) practitioners (p = 0.0186 and 0.0125, respectively). Participants with a genetic counselor in their clinic scored 8% higher (p = 0.0083) than those without. Additionally, medical school graduation year was a significant predictor for knowledge score (p = 0.0397). This study underscores limited FXPOI knowledge among women's healthcare providers, aligning with patient reports. Notably, medical specialty and the presence of a genetic counselor impacted knowledge, emphasizing the urgency for broader education in women's healthcare, particularly among OBGYNs, the initial point of contact for patients with POI symptoms.

Drug Treatments for Neurodevelopmental Disorders: Targeting Signaling Pathways and Homeostasis.

Preclinical and clinical evidence support the notion that neurodevelopmental disorders (NDDs) are synaptic disorders, characterized by excitatory-inhibitory imbalance. Despite this, NDD drug development programs targeting glutamate or gamma-aminobutyric acid (GABA) receptors have been largely unsuccessful. Nonetheless, recent drug trials in Rett syndrome (RTT), fragile X syndrome (FXS), and other NDDs targeting other mechanisms have met their endpoints. The purpose of this review is to identify the basis of these successful studies. Despite increasing evidence of disruption in synaptic homeostasis, most genetic variants associated with NDDs implicate proteins involved in cell regulation and not in neurotransmission. Metabolic processes, in particular mitochondrial function, appear to play a role in NDD pathophysiology. NDDs are also characterized by distinctive cell signaling abnormalities, which link cellular and synaptic homeostasis. Recent successful trials in NDDs, including those of trofinetide, the first drug specifically approved for one of these disorders (i.e., RTT), implicate the targeting of downstream processes (i.e., signaling pathways) rather than neurotransmitter receptors. Recent positive drug studies in NDDs and their underlying mechanisms, in conjunction with new knowledge on the pathophysiology of these disorders, support the concept that targeting signaling and cellular and synaptic homeostasis may be a preferred approach for ameliorating synaptic abnormalities in many NDDs.

Brain volumes in genetic syndromes associated with mTOR dysregulation: a systematic review and meta-analysis.

Dysregulation of molecular pathways associated with mechanistic target of rapamycin (mTOR) and elevated rates of neurodevelopmental disorders are implicated in the genetic syndromes neurofibromatosis type 1 (NF1), tuberous sclerosis complex (TSC), fragile X syndrome (FXS), and Noonan syndrome (NS). Given shared molecular and clinical features, understanding convergent and divergent implications of these syndromes on brain development may offer unique insights into disease mechanisms. While an increasing number of studies have examined brain volumes in these syndromes, the effects of each syndrome on global and subcortical brain volumes are unclear. Therefore, the aim of the current study was to conduct a systematic review and meta-analysis to synthesize existing literature on volumetric brain changes across TSC, FXS, NF1, and NS. Study outcomes were the effect sizes of the genetic syndromes on whole brain, gray and white matter, and subcortical volumes compared to typically developing controls. We performed a series of meta-analyses synthesizing data from 23 studies in NF1, TSC, FXS, and NS (pooled N = 1556) reporting whole brain volume, gray and white matter volumes, and volumes of subcortical structures compared to controls. Meta-analyses revealed significantly larger whole brain volume, gray and white matter volumes, and subcortical volumes in NF1 compared to controls. FXS was associated with increased whole brain, and gray and white matter volumes relative to controls, but effect sizes were smaller than those seen in NF1. In contrast, studies in NS indicated smaller whole brain and gray matter volumes, and reduced subcortical volumes compared to controls. For individuals with TSC, there were no significant differences in whole brain, gray matter, and white volumes compared to controls. Volumetric effect sizes were not moderated by age, sex, or full-scale IQ. This meta-analysis revealed that dysregulation of mTOR signaling across pre- and post-natal periods of development can result in convergent and divergent consequences for brain volume among genetic syndromes. Further research employing advanced disease modeling techniques with human pluripotent stem cell-derived in vitro models is needed to further refine our understanding of between and within syndrome variability on early brain development and identify shared molecular mechanisms for the development of pharmaceutical interventions.

Bilobalide Activates Autophagy and Enhances the Efficacy of Bone Marrow Mesenchymal Stem Cells on Spinal Cord Injury Via Upregulating FMRP to Promote WNK1 mRNA Decay.

Transplantation of bone marrow mesenchymal stem cells (BMSCs) represents an encouraging strategy for the repair of spinal cord injury (SCI), however, its effectiveness on treating SCI remains controversial. Bilobalide isolated from Ginkgo biloba leaves shows significant neuroprotective effects. We examined the role and underlying mechanism of bilobalide in the efficacy of BMSC transplantation on SCI. Primary BMSCs were isolated from neonatal rats, and cell viability was assessed by MTT assay. Neuronal markers (MAP-2, NeuN, NSE and Tuj1), autophagy markers (LC3 and Beclin1), and Fragile X mental retardation protein (FMRP)/With-no-lysine kinase-1 (WNK1) signaling were measured using RT-qPCR and western blotting. The relationship of FMRP and WNK1 was estimated by RNA immunoprecipitation, while WNK1 mRNA stability was assessed with actinomycin D assay. In a SCI rat model, tissue injury was examined using HE and Nissl staining. Bilobalide treatment facilitated neural differentiation of BMSCs, as well as enhanced autophagy and inhibited WNK1 signaling. The promotive effect of bilobalide on BMSC differentiation was antagonized when overexpressing WNK1 or inhibiting autophagy. Bilobalide upregulated FMRP to promote WNK1 mRNA decay, thus reducing WNK1 expression. FMRP knockdown reversed the promoted functions of bilobalide on autophagy and neuronal differentiation in BMSCs. Additionally, compared to either monotherapy, simultaneous treatments with bilobalide and BMSCs further facilitated autophagy and neuronal differentiation, thereby enhancing the repair of SCI in rats. Bilobalide enhances autophagy activity to promote BMSC neuronal differentiation via FMRP/WNK1 axis, thus improving functional recovery following SCI, which indicates a promising therapeutic approach for SCI.

Dysregulation of the mTOR-FMRP pathway and synapticplasticity in an environmental model of ASD.

Autism Spectrum Disorder (ASD) is caused by genetic, epigenetic, and environmental factors. Mutations in the human FMR1 gene, encoding the Fragile X Messenger Ribonucleoprotein 1 (FMRP), cause the most common monogenic form of ASD, the Fragile X Syndrome (FXS). This study explored the interaction between the FMR1 gene and a viral-like infection as an environmental insult, focusing on the impact on core autistic-like behaviors and the mGluR1/5-mTOR pathway. Pregnant heterozygous Fmr1 mouse females were exposed to maternal immune activation (MIA), by injecting the immunostimulant Poly (I:C) at the embryonic stage 12.5, simulating viral infections. Subsequently, ASD-like behaviors were analyzed in the adult offspring, at 8-10 weeks of age. MIA exposure in wild-type mice led to ASD-like behaviors in the adult offspring. These effects were specifically confined tothe intrauterine infection, as immune activation at later stages, namely puberty (Pubertal Immune Activation, PIA) at post-natal day 35 or adulthood (Adult Immune Activation, AIA) at post-natal day 56, did not alter adult behavior. Importantly, combining the Fmr1 mutation with MIA exposure did not intensify core autistic-like behaviors, suggesting an occlusion effect. Mechanistically, MIA provided a strong activation of the mGluR1/5-mTOR pathway, leading to increased LTP and downregulation of FMRP specifically in the hippocampus. Finally, FMRP modulates mTOR activity via TSC2. These findings further strengthen the key role of the mGluR1/5-mTOR pathway in causing ASD-like core symptoms.

The Breastfeeding Experiences of Mother-Infant Dyads and the Effects of an FMR1 Mutation.

This study examined the early breastfeeding experiences of mothers with an FMR1 premutation (FXPM) and their infants with and without fragile X syndrome (FXS) to identify early feeding needs and potential opportunities for intervention. Data collection occurred through a retrospective national survey that captured data on breastfeeding experiences and co-occurring conditions of mother and child. Participants were 246 mothers with an FXPM. Of their 384 infants, 287 had FXS and 97 were unaffected (i.e., they did not have FXS or an FXPM). Unaffected infants had a longer breastfeeding duration relative to infants with FXS, and infants of mothers who had postpartum depression (PPD). Additionally, infants who were reported to display aggressiveness towards others later in childhood had a shorter breastfeeding duration than those who did not go on to display aggression. Approximately 42% percent of mothers reported difficulties with breastfeeding infants with FXS compared to only 17% of unaffected infants. The most common reason for breastfeeding cessation for mothers of children with FXS was perceived difficulties in breastfeeding for the child (37%), whereas the most common reason for mothers of unaffected infants was a personal choice to stop (37%). This study provides preliminary evidence that infants with FXS show early phenotypes that make breastfeeding more difficult. Future research should investigate whether interventions for infants with FXS could improve breastfeeding outcomes.

De novo genetic variant in epileptic encephalopathy: Importance of specific diagnosis

Introduction: Early infantile epileptic encephalopathies (EIEE) are rare syndromes that affect neurological development. The etiology has been uncertain for a long time, but advances in genetics have identified numerous associated genes. Variants in the CYFIP2 gene have been linked to EIEE. Clinical case: An 11-year-old female born at term without complications, with microcephaly, synophrys, and short neck. No relevant family history. At one month, she developed generalized seizures and delayed neurodevelopment, progressing to severe spastic quadriparesis, requiring gastrostomy and tracheostomy, with paroxysmal discharges on electroencephalogram. She received multiple anticonvulsant medications and ketogenic therapy. Complete individual exome sequencing and analysis of deletions and duplications were requested. Individual complete exome + deletions and duplications analysis (CNV) identified a probably pathogenic heterozygous variant in the CYFIP2 gene variant c.259C>T (p.Arg87Cys) missense type, allelic ratio (VAF) 0.45. The results of this molecular study support the diagnosis of developmental and epileptic encephalopathy de novo. Discussion: Developmental and epileptic encephalopathy (EED) disorders are severe conditions that begin in childhood, characterized by epileptic seizures, abnormalities in the electroencephalogram, and deterioration of neurodevelopment. Genetic EEDs are associated with variants in various genes related to cellular and neuronal functions. The CYFIP2 gene, on chromosome 5q33.3, encodes protein 2 that interacts with FMRP (fragile X mental retardation protein), playing a crucial role in neurological development. De novo variants, such as nonsense mutations and truncation in CYFIP2, are associated with intellectual disability, seizures, and muscle hypotonia. Advancements in genomics are improving the understanding of epilepsy, impacting targeted treatment, prognosis, and patient counseling. Childhood epilepsy has a heterogeneous genetic basis, and some patients without previous diagnosis can now receive one, crucial for the implementation of precision medicine.

Understanding pathophysiology in fragile X syndrome: a comprehensive review.

Fragile X syndrome (FXS) is the leading hereditary cause of intellectual disability and the most commonly associated genetic cause of autism. Historically, research into its pathophysiology has focused predominantly on neurons; however, emerging evidence suggests involvement of additional cell types and systems. The objective of this study was to review and synthesize current evidence regarding the pathophysiology of Fragile X syndrome. A comprehensive literature review was conducted using databases such as PubMed and Google Scholar, employing MeSH terms including "Fragile X Syndrome," "FMR1 gene," and "FMRP." Studies on both human and animal models, from inception to 2022, published in recognized journals were included. The evidence supports those neurons, glial cells, stem cells, the immune system, and lipid metabolism pathways contribute to the pathophysiology of Fragile X syndrome. Further research is necessary to explore these fields independently and to elucidate their interactions.

Parent-Reported Outcome Measures for Individuals with Fragile X Syndrome: Clinically Meaningful Change Thresholds.

Estimating meaningful change thresholds (MCT) on clinical outcome assessments is an important consideration when evaluating treatments. In fragile X syndrome (FXS) research, there has been no consensus on how to define MCT's on several commonly used outcome measures. The purpose of the current study was to determine clinically relevant MCT's of caregiver-rated assessments using data from a phase 3 clinical trials of arbaclofen (Berry-Kravis et al., 2017). Data were collected as a part of previous phase 3, double-blind, placebo-controlled studies of arbaclofen in individuals with FXS (Berry-Kravis et al., 2017). The two studies enrolled age groups of 5-11-years (n = 159) and 12-50-years (n = 119). The current study examines meaningful within-patient change thresholds from baseline to treatment week 8 across several measures: ABC-CFXS; PSI; Vineland-II; and a Visual Analog Scale (VAS) of Anxiety and Disruptive Behaviors. MCT's were established by using anchor-based methods, using the CGI-S and CGI-I as anchors. Examining the results of the anchor-based analyses and visual CDF plots, MCT's were observed for the pediatric study for the ABC-CFXS subscales (with a range depending on use of CGI-S or CGI-I as anchor): Irritability: 11.1-14.8 points; Hyperactivity: 6.7-8.9 points; and Socially Unresponsive/Lethargic: 6.6-8.1 points; as well both VAS subscales: Anxiety: 28.3-36.2mm; and Disruptive Behavior: 22.4-27.4mm. Such thresholds were not observed for the Vineland-II and PSI subscales. Our analysis of MCT's helps set the stage for interpreting clinical trial results in FXS. This may include use of relevant subscales of the ABC-CFXS and VAS as primary outcomes using the MCT's for response definition. This work may help define future study inclusion criteria and enable future interpretation of treatment outcome results in the field.

Adaptive and Maladaptive Behaviour in Adults with Fragile X Syndrome and Down Syndrome

ABSTRACT This study assesses adaptive and maladaptive behaviour in a sample of 68 adults. The Spanish version of the Adaptive Behaviour Scale: Residence and Community (ABS-RC:2) was applied to 30 subjects with Fragile X Syndrome (FXS) and 38 subjects with Down Syndrome (DS) aged between 25 and 57. The results show that adults with FXS score higher than do those with DS in some adaptive behaviours, such as physical development and economic activities while scoring less than adults with DS in self-direction. Adults with FXS show more stereotyped behaviours, hyperactivity, and social isolation, but less trustworthiness and disturbing interpersonal behaviours than do those with DS. A relation was found between both behaviours in DS: the higher the scores in maladaptive behaviour, the lower those in adaptive behaviour. However, no such relation was found in individuals with FXS.

ErbB inhibition rescues nigral dopamine neuron hyperactivity and repetitive behaviors in a mouse model of fragile X syndrome.

Repetitive stereotyped behaviors are core symptoms of autism spectrum disorders (ASD) and fragile X syndrome (FXS), the prevalent genetic cause of intellectual disability and autism. The nigrostriatal dopamine (DA) circuit rules movement and creation of habits and sequential behaviors; therefore, its dysregulation could promote autistic repetitive behaviors. Nevertheless, inspection of substantia nigra pars compacta (SNpc) DA neurons in ASD models has been overlooked and specific evidence of their altered activity in ASD and FXS is absent. Here, we show that hyperactivity of SNpc DA neurons is an early feature of FXS. The underlying mechanism relies on an interplay between metabotropic glutamate receptor 1 (mGluR1) and ErbB tyrosine kinases, receptors for the neurotrophic and differentiation factors known as neuregulins. Up-regulation of ErbB4 and ErbB2 in nigral DA neurons drives neuronal hyperactivity and repetitive behaviors of the FXS mouse, concurrently rescued by ErbB inhibition. In conclusion, beyond providing the first evidence that nigral DA neuron hyperactivity is a signature of FXS and nigral mGluR1 and ErbB4/2 play a relevant role in FXS etiology, we demonstrate that inhibiting ErbB is a valuable pharmacological approach to attenuate stereotyped repetitive behaviors, thus opening an avenue toward innovative therapies for ASD and FXS treatment.

Methylation epigenetic analysis of a pedigree affected with Fragile X syndrome based on Nanopore long-read sequencing

To explore the genetic basis for a Chinese pedigree affected with Fragile X syndrome (FXS) through Nanopore long-read sequencing. A FXS pedigree who had undergone genetic counseling at the First Affiliated Hospital of Zhengzhou University in April 2023 was selected as the study subject. Nanopore long-read sequencing, triplet-repeat primed PCR (TP-PCR), methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and trinucleotide polymorphism genotyping of androgen receptor (AR) gene were used to analyze the FMR1 CGG repeat number, methylation, and X chromosome inactivation of the pedigree members. This study has been approved by the Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (No. KS-2018-KY-36). Full mutation and CpG island hypermethylation were detected in the proband. The elder sister of the proband had full mutation of the FMR1 gene on one X chromosome and hypermethylation of CpG island, while the FMR1 gene on the other X chromosome was normal. FMR1 premutation was detected in the proband's mother. Nanopore long-read sequencing can simultaneously detect the dynamic mutation and methylation status of the FMR1 gene on the two X chromosomes of females, which has important value for the diagnosis of FXS in different genders.

Deep functional measurements of Fragile X syndrome human neurons reveal multiparametric electrophysiological disease phenotype

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by hypermethylation of expanded CGG repeats (>200) in the FMR1 gene leading to gene silencing and loss of Fragile X Messenger Ribonucleoprotein (FMRP) expression. FMRP plays important roles in neuronal function, and loss of FMRP in mouse and human FXS cell models leads to aberrant synaptic signaling and hyperexcitability. Multiple drug candidates have advanced into clinical trials for FXS, but no efficacious treatment has been identified to date, possibly as a consequence of poor translation from pre-clinical animal models to human. Here, we use a high resolution all-optical electrophysiology platform applied to multiple FXS patient-derived and CRISPR/Cas9-generated isogenic neuronal cell lines to develop a multi-parametric FXS disease phenotype. This neurophysiological phenotype was optimized and validated into a high throughput assay based on the amount of FMRP re-expression and the number of healthy neurons in a mosaic network necessary for functional rescue. The resulting highly sensitive and multiparameter functional assay can now be applied as a discovery platform to explore new therapeutic approaches for the treatment of FXS.

The effect of anxiety and autism symptom severity on restricted and repetitive behaviors over time in children with fragile X syndrome

BackgroundRestricted and repetitive behaviors (RRBs) are highly prevalent and reduce function in individuals with fragile X syndrome (FXS). As transdiagnostic features of intellectual disability, elevated rates of RRBs in FXS could represent various underlying known co-occurring conditions in FXS such as anxiety or autism spectrum disorder (ASD), yet this distinction has not been investigated. Further, delineating whether RRBs are more indicative of anxiety or ASD in FXS may clarify phenotypic profiles within FXS and improve differential assessment.MethodsWe longitudinally examined the potentially independent or multiplicative effect of ASD and anxiety symptom severity on RRBs in 60 children with FXS. Anxiety was measured using the Child Behavior Checklist (CBCL), ASD severity was measured using the Childhood Autism Rating Scale (CARS), and RRBs were measured using the Repetitive Behavior Scale – Revised (RBS-R). We estimated a series of moderated regression models with anxiety and ASD symptoms at the initial assessment (Time 1) as predictors of RRBs at the outcome assessment two years later (Time 2), along with an anxiety-by-ASD interaction term to determine the potential multiplicative effect of these co-occurring conditions on RRBs.ResultsResults identified a significant interaction between ASD and anxiety symptom severity at the initial assessment that predicted elevated sensory-motor RRBs two years later. Increased sensory-motor RRBs were predicted by elevated ASD symptoms only when anxiety symptom severity was low. Likewise, increased sensory-motor RRBs were predicted by elevated anxiety symptoms only when ASD symptom severity was low. Interestingly, this relationship was isolated to Sensory-Motor RRBs, with evidence that it could also apply to total RRBs.ConclusionsFindings suggest that ASD and anxiety exert independent and differential effects on Sensory-Motor RRBs when at high severity levels and a multiplicative effect when at moderate levels, which has important implications for early and targeted interventions.

Dampened α7 nAChR activity contributes to audiogenic seizures and hyperactivity in a mouse model of Fragile X Syndrome.

Fragile X Syndrome (FXS) is the most common form of inherited intellectual disability and often accompanied with debilitating pathologies including seizures and hyperactivity. FXS arises from a trinucleotide repeat expansion in the 5' UTR of the FMR1 gene that silences expression of the RNA-binding protein FMRP. Despite progress in understanding FMRP functions, the identification of effective therapeutic targets has lagged and at present there are no viable treatment options. Here we identify the α7 nicotinic acetylcholine receptor (nAChR) as candidate target for intervention in FXS. In the early postnatal hippocampus of Fmr1 knockout (KO) mice, an established pre-clinical model of FXS, the α7 nAChR accessory protein Ly6H is abnormally enriched at the neuronal surface and mislocalized in dendrites. Ly6H, a GPI-anchored protein, binds α7 nAChRs with high affinity and can limit α7 nAChR surface expression and signaling. We find that α7 nAChR-evoked Ca2+ responses are dampened in immature glutamatergic and GABAergic Fmr1 KO neurons compared to wild type. Knockdown of endogenous Ly6H in Fmr1 KO neurons is sufficient to rescue dampened α7 nAChR Ca2+ responses in vitro, providing evidence of a cell-autonomous role for Ly6H aberrant expression in α7 nAChR hypofunction. In line with intrinsic deficits in α7 nAChR activity in Fmr1 KO neurons, in vivo administration of the α7 nAChR-selective positive allosteric modulator PNU-120596 reduced hyperactivity and seizure severity in adolescent Fmr1 KO mice. Our mechanistic studies together with evidence of the in vivo efficacy of α7 nAChR augmentation implicate α7 nAChR hypofunction in FXS pathology.

Auditory N1 event-related potential amplitude is predictive of serum concentration of BPN14770 in fragile X syndrome

Fragile X syndrome (FXS) is a rare neurodevelopmental disorder caused by a CGG repeat expansion ≥ 200 repeats in 5’ untranslated region of the FMR1 gene, leading to intellectual disability and cognitive difficulties, including in the domain of communication. A recent phase 2a clinical trial testing BPN14770, a phosphodiesterase 4D inhibitor, showed improved cognition in 30 adult males with FXS on drug relative to placebo. The initial study found significant improvements in clinical measures assessing cognition, language, and daily functioning in addition to marginal improvements in electroencephalography (EEG) results for the amplitude of the N1 event-related potential (ERP) component. These EEG results suggest BPN14770 improved neural hyperexcitability in FXS. The current study investigated the relationship between BPN14770 pharmacokinetics and the amplitude of the N1 ERP component from the initial data. Consistent with the original group-level finding post-period 1 of the study, participants who received BPN14770 in period 1 showed a significant correlation between N1 amplitude and serum concentration of BPN14770 measured at the end of period 1. These findings strengthen the validity of the original result, indicating that BPN14770 improves cognitive performance by modulating neural hyperexcitability. This study represents the first report of a significant correlation between a reliably abnormal EEG marker and serum concentration of a novel pharmaceutical in FXS.

P2X7 expression patterns in the developing Fmr1-knockout mouse hippocampus.

Fragile-X Syndrome (FXS)is the leading monogenetic cause of intellectual disability among children but remains without a cure. Using the Fmr1 KO mouse model of FXS, much work has been done to understand FXS hippocampus dysfunction. Purinergic signaling, where ATP and its metabolites are used as signaling molecules, participates in hippocampus development, but it is unknown if purinergic signaling is affected in the developing Fmr1 KO hippocampus. In our study, we characterized the purinergic receptor P2X7. We first found that P2X7 was reduced in Fmr1 KO whole hippocampus tissue at P14 and P21, corresponding to the periods of neurite outgrowth and synaptic refinement in the hippocampus. We then evaluated the cell-specific expression of P2X7 with immunofluorescenceand found differences between WT and Fmr1 KO mice in P2X7 colocalization with hippocampal microglia and neurons. P2X7 colocalized more with microglia at P14 and P21, but there was a sex-specific reduction in P2X7 colocalization with neurons. In contrast, male mice at P14 and P21 showed reduced neuronal P2X7 colocalization compared to females, but only females showed reduced absolute neuronal P2X7 expression across the dorsal hippocampal formation. Together, our results suggest that P2X7 expression is altered during Fmr1-KO hippocampal development, potentially influencing several developmental processes in the Fmr1-KO hippocampus formation.

Prevalence and implications of fragile X premutation screening in Thailand

The fragile X premutation is a public health concern worldwide. Implementing a comprehensive screening program for FMR1 premutation alleles could empower individuals and families with information, supporting informed health decisions and potentially reducing the incidence of fragile X syndrome (FXS). This study aimed to determine the prevalence of FMR1 premutations in the Thai population. We screened 369 female blood donors and 449 males with tremor and/or ataxia who tested negative for spinocerebellar ataxia (SCA) types 1, 2, and 3 for FMR1 CGG repeat expansions. Among the female blood donors, 0.27% (1/369) had a premutation allele, and 1.08% (4/369) had intermediate alleles. One female with a premutation carrier had 89 CGG repeats with one AGG interruption. In the male cohort, no premutations or full mutations were found; however, intermediate alleles were identified in 0.67% (3/449) of the males. This study provides the evidence of fragile X premutation screening in the Thai population. These findings contribute to the understanding of FMR1 premutation prevalence in Thailand and should encourage wider discussions on the feasibility for a national fragile X carrier screening program in Thailand to reduce the burden of fragile X-associated disorders.

Utility of Optical Genome Mapping in Repeat Disorders.

Genomic repeat sequences are patterns of nucleic acids that exist in multiple copies throughout the genome. More than 60 Mendelian disorders are caused by the expansion or contraction of these repeats. Various specific methods for determining tandem repeat variations have been developed. However, these methods are highly specific to the genomic region being studied and sometimes require specialized tools. In this study, we have investigated the use of Optical Genome Mapping (OGM) as a diagnostic tool for detecting repeat disorders. We evaluated 19 patients with a prediagnosis of repeat disorders and explained the molecular etiology of 9 of them with OGM (5 patients with Facioscapulohumeral Muscular Dystrophy (FSHD), 2 patients with Friedreich's Ataxia (FA), 1 patient with Fragile X Syndrome (FXS), and 1 patient with Progressive Myoclonic Epilepsy 1A (EPM1A)). We confirmed OGM results with more widely used fragment analysis techniques. This study highlights the utility of OGM as a diagnostic tool for repeat expansion and contraction diseases such as FA, FXS, EPM1A, and FSHD.