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

Purpose Of The Review: 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.

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.

Using a Combination of Novel Research Tools to Understand Social Interaction in the Model for Fragile X Syndrome.

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 () gene. Individuals with FXS experience various challenges related to social interaction (SI). Animal models, such as the model for FXS where the only ortholog of human () is mutated, have played a crucial role in the understanding of FXS.

Insight and Recommendations for Fragile X-Premutation-Associated Conditions from the Fifth International Conference on Premutation.

The premutation of the fragile X messenger ribonucleoprotein 1 () gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, 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.

as a Model to Study Fragile X-Associated Disorders.

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 () 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.

Latent Class Analysis Identifies Distinctive Behavioral Subtypes in Children with Fragile X Syndrome.

Fragile X syndrome (FXS) is characterized by variable neurobehavioral abnormalities, which leads to difficulties in developing and evaluating treatments and in determining accurate prognosis. We employed a pediatric cross-sectional sample (1,072 males, 338 females) from FORWARD, a clinic-based natural history study, to identify behavioral subtypes by latent class analysis. Input included co-occurring behavioral conditions, sleep and sensory problems, autistic behavior scales (SCQ, SRS-2), and the Aberrant Behavior Checklist revised for FXS (ABC).

Fragile X Mental Retardation Protein and Cerebral Expression of Metabotropic Glutamate Receptor Subtype 5 in Men with Fragile X Syndrome: A Pilot Study.

Multiple lines of evidence suggest that a deficiency of Fragile X Mental Retardation Protein (FMRP) mediates dysfunction of the metabotropic glutamate receptor subtype 5 (mGluR5) in the pathogenesis of fragile X syndrome (FXS), the most commonly known single-gene cause of inherited intellectual disability (ID) and autism spectrum disorder (ASD). Nevertheless, animal and human studies regarding the link between FMRP and mGluR5 expression provide inconsistent or conflicting findings about the nature of those relationships. Since multiple clinical trials of glutamatergic agents in humans with FXS did not demonstrate the amelioration of the behavioral phenotype observed in animal models of FXS, we sought measure if mGluR5 expression is increased in men with FXS to form the basis for improved clinical trials.

Fragile X Syndrome: From Molecular Aspect to Clinical Treatment.

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by the full mutation as well as highly localized methylation of the fragile X mental retardation 1 () gene on the long arm of the X chromosome. Children with FXS are commonly co-diagnosed with Autism Spectrum Disorder, attention and learning problems, anxiety, aggressive behavior and sleep disorder, and early interventions have improved many behavior symptoms associated with FXS. In this review, we performed a literature search of original and review articles data of clinical trials and book chapters using MEDLINE (1990-2021) and ClinicalTrials.

Raising Knowledge and Awareness of Fragile X Syndrome in Serbia, Georgia, and Colombia: A Model for Other Developing Countries?

Fragile X syndrome is the most common monogenetic cause of inherited intellectual disability and syndromic autism spectrum disorder. Fragile X syndrome is caused by an expansion (full mutation ≥200 CGGs repeats, normal 10-45 CGGs) of the fragile X mental retardation 1 () gene, epigenetic silencing of the gene, which leads to reduction or lack of the gene's product: the fragile X mental retardation protein. In this cross-sectional study, we assessed general and pharmacotherapy knowledge (GK and PTK) of fragile X syndrome and satisfaction with education in neurodevelopmental disorders (NDDs) among senior medical students in Serbia (N=348), Georgia (N=112), and Colombia (N=58).

Sleep problems in fragile X syndrome: Cross-sectional analysis of a large clinic-based cohort.

Fragile X syndrome (FXS), the leading cause of inherited intellectual disability and autism spectrum disorder, is associated with multiple neurobehavioral abnormalities including sleep difficulties. Nonetheless, frequency, severity, and consequences of sleep problems are still unclear. The Fragile X Online Registry with Accessible Research Database (FORWARD-version-3), including Clinician Report and Parent Report forms, was analyzed for frequency, severity, relationship with behavioral problems, and impact of sleep difficulties in a mainly pediatric cohort.

Gaboxadol in Fragile X Syndrome: A 12-Week Randomized, Double-Blind, Parallel-Group, Phase 2a Study.

Fragile X syndrome (FXS), the most common single-gene cause of intellectual disability and autism spectrum disorder (ASD), is caused by a >200-trinucleotide repeat expansion in the 5' untranslated region of the fragile X mental retardation 1 () gene. Individuals with FXS can present with a range of neurobehavioral impairments including, but not limited to: cognitive, language, and adaptive deficits; ASD; anxiety; social withdrawal and avoidance; and aggression. Decreased expression of the γ-aminobutyric acid type A (GABA) receptor subunit and deficient GABAergic tonic inhibition could be associated with symptoms of FXS.

Reduced Expression of Cerebral Metabotropic Glutamate Receptor Subtype 5 in Men with Fragile X Syndrome.

Glutamatergic receptor expression is mostly unknown in adults with fragile X syndrome (FXS). Favorable behavioral effects of negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGluR) in knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR expression in humans with FXS exposed to NAMs might help in that effort.

A Genotype-Phenotype Study of High-Resolution Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments.

Fragile X syndrome (FXS) is caused by silencing of the gene, which encodes a protein with a critical role in synaptic plasticity. The molecular abnormality underlying silencing, CGG repeat expansion, is well characterized; however, delineation of the pathway from DNA to RNA to protein using biosamples from well characterized patients with FXS is limited. Since FXS is a common and prototypical genetic disorder associated with intellectual disability (ID) and autism spectrum disorder (ASD), a comprehensive assessment of the DNA-RNA-protein pathway and its correlations with the neurobehavioral phenotype is a priority.

Response to Placebo in Fragile X Syndrome Clinical Trials: An Initial Analysis.

Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability and autism spectrum disorder. Individuals with FXS often present with a wide range of cognitive deficits and problem behaviors. Educational, behavioral and pharmacological interventions are used to manage these and other complex issues affecting individuals with FXS.

Best Practices in Fragile X Syndrome Treatment Development.

Preclinical studies using animal models of fragile X syndrome have yielded several agents that rescue a wide variety of phenotypes. However, translation of these treatments to humans with the disorder has not yet been successful, shedding light on a variety of limitations with both animal models and human trial design. As members of the Clinical Trials Committee of the National Fragile X Foundation, we have discussed a variety of recommendations at the level of preclinical development, transition from preclinical to human projects, family involvement, and multi-site trial planning.

Autism Spectrum Disorder in Fragile X Syndrome: Cooccurring Conditions and Current Treatment.

Background And Objective: Individuals with fragile X syndrome (FXS) are frequently codiagnosed with autism spectrum disorder (ASD). Most of our current knowledge about ASD in FXS comes from family surveys and small studies. The objective of this study was to examine the impact of the ASD diagnosis in a large clinic-based FXS population to better inform the care of people with FXS.

Updated report on tools to measure outcomes of clinical trials in fragile X syndrome.

Objective: Fragile X syndrome (FXS) has been the neurodevelopmental disorder with the most active translation of preclinical breakthroughs into clinical trials. This process has led to a critical assessment of outcome measures, which resulted in a comprehensive review published in 2013. Nevertheless, the disappointing outcome of several recent phase III drug trials in FXS, and parallel efforts at evaluating behavioral endpoints for trials in autism spectrum disorder (ASD), has emphasized the need for re-assessing outcome measures and revising recommendations for FXS.

Fragile X Syndrome: Lessons Learned from the Most Translated Neurodevelopmental Disorder in Clinical Trials.

Fragile X syndrome (FXS) is the leading genetic cause of autism spectrum disorder (ASD) and inherited intellectual disability (ID) worldwide. Preclinical successes in understanding the biology of FXS have led to numerous translational attempts in human clinical trials of therapeutics that target the excitatory/inhibitory neural signaling imbalances thought to underlie FXS. Despite the preclinical success story, the negative results of the human clinical trials have been deemed to be at least in part disappointing by the field.

Paliperidone and aripiprazole differentially affect the strength of calcium-secretion coupling in female pituitary lactotrophs.

Hyperprolactinemia is a common adverse in vivo effect of antipsychotic medications that are used in the treatment of patients with schizophrenia. Here, we compared the effects of two atypical antipsychotics, paliperidone and aripiprazole, on cAMP/calcium signaling and prolactin release in female rat pituitary lactotrophs in vitro. Dopamine inhibited spontaneous cAMP/calcium signaling and prolactin release.