Outcome measures for clinical trials in fragile X syndrome

Assessing Communication Impairments in a Rare Neurodevelopmental Disorder: The SCN2A Clinical Trials Readiness Study

Background and Objectives

SCN2A-related disorders (SCN2A-RDs) entail severe impairments in multiple domains that could serve as nonseizure outcomes in clinical trials. This study evaluated the fitness for purpose of several clinical instruments with both standardized and alternative scoring and with some measures used out of their intended age range for assessing communication in SCN2A-affected participants.

Methods

Parents of SCN2A-affected children were recruited through FamilieSCN2A Foundation outreach for a combined cross-sectional and longitudinal study. They completed assessments of their children at study entry and 6 and 12 months later. Assessments included the Vineland Adaptive Behavior Scale (VABS-3), Adaptive Behavior Assessment System (ABAS), Communication Matrix, and Communication and Symbolic Behavior Scale (CSBS). Analyses examined floor and ceiling effects, inter-rater and test-retest reliability, discrimination among different levels of functional impairment, and sensitivity to clinical aspects of SCN2A-RDs.

Results

Of 65 participants (28 females, median age 6.4 years, IQR 4.1-10.5), 56 (86%) had epilepsy. Eleven (17%) used speech as their primary communication mode; 84% were considered ineffective communicators. The mean Vineland composite standardized score (SS) was 34 (IQR 26-46). Cross-sectionally, standardized scores decreased with increasing age. There were substantial floor effects for receptive (75%) and expressive (83%) communication. SSs discriminated poorly between verbal vs nonverbal and communicative vs noncommunicative participants and were not sensitive to features reflecting epilepsy severity (e.g., epileptic spasms and number of current medications). By contrast, Vineland growth scale value (GSV) and ABAS, Matrix, and CSBS raw scores had minimal floor effects; most increased with age. These alternative scores distinguished clearly between participants with different levels of communication and were sensitive to aspects of epilepsy severity. Longitudinally, SSs decreased, but other scores remained relatively stable over a year.

Discussion

SCN2A-RD is characterized by severe-to-profound impairment with a SS <4 SDs of the norm-referenced mean. Owing to severe floor effects and their insensitivity to markers of communication function, age-standardized scores (e.g., Vineland SS) are not fit for purpose in clinical trials or other settings for evaluating nonseizure outcomes such as communication. GSVs and alternative scoring and assessments have much better measurement profiles in all these regards and should be considered in future precision medicine trials for SCN2A-RDs and other similar rare diseases.

Sensory Symptoms and Signs of Hyperarousal in Individuals with Fragile X Syndrome: Findings from the FORWARD Registry and Database Multisite Study

This study was designed to increase our understanding about characteristics and the impact of sensory symptoms (SS) and signs of hyperarousal (HA) in individuals with fragile X syndrome (FXS) from childhood through early adulthood and by gender. Data derived from the Fragile X Online Registry With Accessible Research Database (FORWARD), a natural history study of FXS, were analyzed using descriptive statistics and multivariate linear and logistic regression models to examine SS and signs of HA, their impact on behavioral regulation and limitations on the subject/family. The sample (N = 933) consisted of 720 males and 213 females. More males were affected with SS (87% vs. 68%) and signs of HA (92% vs. 79%). Subjects who were endorsed as having a strong sensory response had more comorbidities, including behavioral problems. The predominant SS was difficulty with eye gaze that increased with age in both genders. As individuals age, there was less use of non-medication therapies, such as occupational therapy (OT)/physical therapy (PT), but there was more use of psychopharmacological medications and investigational drugs for behaviors. Multiple regression models suggested that endorsing SS and signs of HA was associated with statistically significantly increased ABC-C-I subscale scores and limited participation in everyday activities. This study improves our understanding of SS and signs of HA as well as their impact in FXS. It supports the need for more research regarding these clinical symptoms, especially to understand how they contribute to well-known behavioral concerns.

Is trofinetide a future treatment for Rett syndrome? A comprehensive systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Rett syndrome (RTT) is a rare, life-threatening, genetic neurodevelopmental disorder. Treatment in RTT encounters many challenges. Trofinetide, a modified amino-terminal tripeptide of insulin-like growth factor 1, has demonstrated clinically promising results in RTT. In this study, trofinetide efficacy and safety in RTT are systematically reviewed and meta-analyzed.

METHODS

A systematic search of five electronic databases was conducted until January 2024. Review Manager 5.4 software was used for the analysis. The analysis was based on a weighted mean difference and standard error with a confidence interval (CI) of 95%, and a statistically significant P-value was considered if it was < 0.05. The study was registered on PROSPERO with registration number CRD42024499849. Quality of evidence was assessed using GRADE.

RESULTS

Three randomized controlled trials (RCTs) with 276 patients were included in the analysis. Trofinetide improved both caregiver outcomes and clinical scales by improving the Rett Syndrome Behavior Questionnaire (RSBQ) (mean difference (MD): - 3.46 points, 95% CI: - 5.63 to - 1.27, P = 0.0002) and Clinical Global Impression Scale-Improvement (CGI-I) (MD: - 0.35, 95% CI: - 0.51 to - 0.18, P < 0.0001), respectively. However, trofinetide neither improved the Caregiver Top 3 Concerns Visual Analog Scale nor the Rett Motor Behavioral Assessment. Regarding safety, trofinetide was significantly associated with vomiting compared to placebo (odds ratio (OR): 3.17, 95% CI: 1.57 to 6.43, P = 0.001). After solving heterogeneity, results showed a statistically significant incidence of diarrhea in the trofinetide (200 mg) group compared to placebo (OR: 18.51, 95% CI: 9.30 to 36.84, P ≤ 0.00001).

CONCLUSIONS

Trofinetide demonstrated statistically significant improvements in CGI-I and RSBQ in pediatrics and adult patients with Rett. Side effects are limited to vomiting and diarrhea. Although diarrhea yielded an insignificant result in our analysis, it emerged as a cause for treatment discontinuation in the participating trials, and a statistically significant risk for diarrhea emerged when excluding the study using a lower dose of the drug, hence causing heterogeneity, in the meta-analysis. Given the diverse genetic landscape of RTT, future RCTs investigating correlations between RTT genotype and phenotypic improvements by trofinetide will be beneficial. RCTs encompassing male patients with larger and longer cohorts are recommended.

Adult Inception of Ketogenic Diet Therapy Increases Sleep during the Dark Cycle in C57BL/6J Wild Type and Fragile X Mice

Sleep problems are a significant phenotype in children with fragile X syndrome. Our prior work assessed sleep-wake cycles in Fmr1KO male mice and wild type (WT) littermate controls in response to ketogenic diet therapy where mice were treated from weaning (postnatal day 18) through study completion (5-6 months of age). A potentially confounding issue with commencing treatment during an active period of growth is the significant reduction in weight gain in response to the ketogenic diet. The aim here was to employ sleep electroencephalography (EEG) to assess sleep-wake cycles in mice in response to the Fmr1 genotype and a ketogenic diet, with treatment starting at postnatal day 95. EEG results were compared with prior sleep outcomes to determine if the later intervention was efficacious, as well as with published rest-activity patterns to determine if actigraphy is a viable surrogate for sleep EEG. The data replicated findings that Fmr1KO mice exhibit sleep-wake patterns similar to wild type littermates during the dark cycle when maintained on a control purified-ingredient diet but revealed a genotype-specific difference during hours 4-6 of the light cycle of the increased wake (decreased sleep and NREM) state in Fmr1KO mice. Treatment with a high-fat, low-carbohydrate ketogenic diet increased the percentage of NREM sleep in both wild type and Fmr1KO mice during the dark cycle. Differences in sleep microstructure (length of wake bouts) supported the altered sleep states in response to ketogenic diet. Commencing ketogenic diet treatment in adulthood resulted in a 15% (WT) and 8.6% (Fmr1KO) decrease in body weight after 28 days of treatment, but not the severe reduction in body weight associated with starting treatment at weaning. We conclude that the lack of evidence for improved sleep during the light cycle (mouse sleep time) in Fmr1KO mice in response to ketogenic diet therapy in two studies suggests that ketogenic diet may not be beneficial in treating sleep problems associated with fragile X and that actigraphy is not a reliable surrogate for sleep EEG in mice.

Safety and efficacy of trofinetide in Rett syndrome: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Rett syndrome is a rare genetic neurodevelopmental disorder that predominantly impacts females. It presents with loss of acquired skills, impaired communication, and stereotypic hand movements. Given the limited treatment options for Rett syndrome, there is a dire need for effective interventions.

OBJECTIVE

To evaluate the safety and efficacy of trofinetide in Randomized Controlled Trials (RCTs) that report on Rett syndrome patients.

METHODS

We identified 109 articles from four databases (Scopus, PubMed, Web of Science, and Cochrane CENTRAL). After removing the duplicates, we narrowed them down to 59 articles for further assessment. We included RCTs that evaluated the efficacy and safety of trofinetide in patients with Rett syndrome. Three studies were eligible for inclusion. Two independent reviewers evaluated the identified studies' titles, abstracts, and full texts, extracting pertinent data. We assessed the quality of the studies using the Cochrane Risk of Bias (RoB) 2.0 tool. We then conducted a meta-analysis using the fixed effects model in the case of insignificant heterogeneity; otherwise, we used the random effects model. Based on the nature of the outcome, we analyzed the mean difference or the odds ratio. Analysis was conducted using RevMan version 5.3.

RESULTS

Among the analyzed outcomes in 181 patients in the trofinetide group and 134 patients in the placebo group, significant improvement in Rett Syndrome Behavior Questionnaire (RSBQ) scores was observed at 200 mg dosage (overall mean difference: -3.53, p = 0.001). Clinical Global Impression-Improvement (CGI-I) scores improved considerably at 200 mg dosage (overall mean difference: -0.34, p < 0.0001). No substantial changes were observed in Motor Behavioral Assessment (MBA) or Top 3 Caregiver Concerns. We evaluated Treatment Emergent Adverse Events (TEAEs) across the various dosages and noted significant associations with diarrhea (200 mg), vomiting (200 mg), and irritability (200 mg). However, we did not find a significant association between any of the dosages and the incidence of decreased appetite.

CONCLUSION

Trofinetide demonstrated potential in improving RSBQ and CGI-I scores at 200 mg dosage. Although no substantial changes were found in MBA and top 3 caregiver concerns. Adverse events were linked to specific dosages.

Psychometric Assessment of the Rett Syndrome Caregiver Assessment of Symptom Severity (RCASS)

Rett syndrome is a severe neurodevelopmental disorder that affects about 1 in 10,000 females. Clinical trials of disease modifying therapies are on the rise, but there are few psychometrically sound caregiver-reported outcome measures available to assess treatment benefit. We report on a new caregiver-reported outcome measure, the Rett Caregiver Assessment of Symptom Severity (RCASS). Using data from the Rett Natural History Study (n = 649), we examined the factor structure, using both exploratory and confirmatory factor analysis, and the reliability and validity of the RCASS. The four-factor model had the best overall fit, which covered movement, communication, behavior, and Rett-specific symptoms. The RCASS had moderate internal consistency. Strong face validity was found with age and mutation type, and convergent validity was established with other similar measures, including the Revised Motor-Behavior Assessment Scale, Clinical Severity Scale, Clinical Global Impression Scale, and the Child Health Questionnaire. These data provide initial evidence that the RCASS is a viable caregiver-outcome measure for use in clinical trials in Rett syndrome. Future work to assess sensitivity to change and other measures of reliability, such as test-retest and inter-rater agreement, are needed.

Developing a Measure of Key Adult Outcomes in Adults with Developmental Disabilities: Conceptual Model and Item Generation of the REALS (Relationships, Employment, Autonomy, and Life Satisfaction)

Employment, social relationships, and autonomy are priorities to people with intellectual and developmental disabilities (IDDs). However, few validated measures exist to systematically assess these key adult outcomes in this population. This research includes first steps to develop self- and proxy report measures of life outcomes for adults with IDDs-the Relationships, Employment, Autonomy, and Life Satisfaction (REALS). A literature search identified existing adult outcome measures, and comparison of their domains informed initial conceptual model development. External consultants revised the model, and items were generated. Autistic adults (n = 15), adults with other IDDs (n = 7), caregivers of autistic adults (n = 13), and caregivers of adults with other IDDs (n = 10) completed in-depth cognitive interviews to assess comprehension of items and response categories, factors influencing how participants respond to items, and the inclusiveness of the item pool. A final conceptual model was generated with three subdomains (social relationships, employment, and autonomy), including assessment of life satisfaction within each domain. Cognitive interviews revealed that response set restructuring and item-level revisions were needed to capture the complexity of adult life and make the measure more accessible across a range of abilities. This study developed a conceptual model of relationships, work, and autonomy specific to adults with IDDs. Future work will involve collecting data from 800 + self-reporters with IDDs and 800 + caregivers of adults with IDDs to conduct psychometric analyses. Improving measurement in this area is critical to better understanding the needs of adults with IDDs and improving services available to them.

Cannabidiol (Epidyolex®) for severe behavioral manifestations in patients with tuberous sclerosis complex, mucopolysaccharidosis type III and fragile X syndrome: protocol for a series of randomized, placebo-controlled N-of-1 trials

BACKGROUND

Many rare genetic neurodevelopmental disorders (RGNDs) are characterized by intellectual disability (ID), severe cognitive and behavioral impairments, potentially diagnosed as a comorbid autism spectrum disorder or attention-deficit hyperactivity disorder. Quality of life is often impaired due to irritability, aggression and self-injurious behavior, generally refractory to standard therapies. There are indications from previous (case) studies and patient reporting that cannabidiol (CBD) may be an effective treatment for severe behavioral manifestations in RGNDs. However, clear evidence is lacking and interventional research is challenging due to the rarity as well as the heterogeneity within and between disease groups and interindividual differences in treatment response. Our objective is to examine the effectiveness of CBD on severe behavioral manifestations in three RGNDs, including Tuberous Sclerosis Complex (TSC), mucopolysaccharidosis type III (MPS III), and Fragile X syndrome (FXS), using an innovative trial design.

METHODS

We aim to conduct placebo-controlled, double-blind, block-randomized, multiple crossover N-of-1 studies with oral CBD (twice daily) in 30 patients (aged ≥ 6 years) with confirmed TSC, MPS III or FXS and severe behavioral manifestations. The treatment is oral CBD up to a maximum of 25 mg/kg/day, twice daily. The primary outcome measure is the subscale irritability of the Aberrant Behavior Checklist. Secondary outcome measures include (personalized) patient-reported outcome measures with regard to behavioral and psychiatric outcomes, disease-specific outcome measures, parental stress, seizure frequency, and adverse effects of CBD. Questionnaires will be completed and study medication will be taken at the participants' natural setting. Individual treatment effects will be determined based on summary statistics. A mixed model analysis will be applied for analyzing the effectiveness of the intervention per disorder and across disorders combining data from the individual N-of-1 trials.

DISCUSSION

These N-of-1 trials address an unmet medical need and will provide information on the effectiveness of CBD for severe behavioral manifestations in RGNDs, potentially generating generalizable knowledge at an individual-, disorder- and RGND population level.

TRIAL REGISTRATION

EudraCT: 2021-003250-23, registered 25 August 2022, https://www.clinicaltrialsregister.eu/ctr-search/trial/2021-003250-23/NL .

Ketogenic Diet Affects Sleep Architecture in C57BL/6J Wild Type and Fragile X Mice

Nearly half of children with fragile X syndrome experience sleep problems including trouble falling asleep and frequent nighttime awakenings. The goals here were to assess sleep-wake cycles in mice in response to Fmr1 genotype and a dietary intervention that reduces hyperactivity. Electroencephalography (EEG) results were compared with published rest-activity patterns to determine if actigraphy is a viable surrogate for sleep EEG. Specifically, sleep-wake patterns in adult wild type and Fmr1KO littermate mice were recorded after EEG electrode implantation and the recordings manually scored for vigilance states. The data indicated that Fmr1KO mice exhibited sleep-wake patterns similar to wild type littermates when maintained on a control purified ingredient diet. Treatment with a high-fat, low-carbohydrate ketogenic diet increased the percentage of non-rapid eye movement (NREM) sleep in both wild type and Fmr1KO mice during the dark cycle, which corresponded to decreased activity levels. Treatment with a ketogenic diet flattened diurnal sleep periodicity in both wild type and Fmr1KO mice. Differences in several sleep microstructure outcomes (number and length of sleep and wake bouts) supported the altered sleep states in response to a ketogenic diet and were correlated with altered rest-activity cycles. While actigraphy may be a less expensive, reduced labor surrogate for sleep EEG during the dark cycle, daytime resting in mice did not correlate with EEG sleep states.

Toward Equity in Research on Intellectual and Developmental Disabilities

Lack of diversity in IDD research is typically conceptualized only in terms of (1) recruitment of samples that do not appropriately represent the sociodemographics of the population, or (2) the limited number of researchers from historically marginalized backgrounds. Critically, the field also suffers from over-reliance on perspectives and social systems of dominant culture-both in how disability is regarded and in relation to other dimensions of identity and culture. These lenses lead to research findings that reinforce, rather than reduce, social inequities. We propose a framework that minimizes reliance on diagnostic categories, shifts from deficit- to person-centered models, acknowledges people's multiple identities, and includes self-advocates and diverse communities as partners in the research enterprise. The systems change necessary to support this framework is described.

Antisense oligonucleotide rescue of CGG expansion-dependent FMR1 mis-splicing in fragile X syndrome restores FMRP

Aberrant alternative splicing of mRNAs results in dysregulated gene expression in multiple neurological disorders. Here, we show that hundreds of mRNAs are incorrectly expressed and spliced in white blood cells and brain tissues of individuals with fragile X syndrome (FXS). Surprisingly, the FMR1 (Fragile X Messenger Ribonucleoprotein 1) gene is transcribed in >70% of the FXS tissues. In all FMR1-expressing FXS tissues, FMR1 RNA itself is mis-spliced in a CGG expansion-dependent manner to generate the little-known FMR1-217 RNA isoform, which is comprised of FMR1 exon 1 and a pseudo-exon in intron 1. FMR1-217 is also expressed in FXS premutation carrier-derived skin fibroblasts and brain tissues. We show that in cells aberrantly expressing mis-spliced FMR1, antisense oligonucleotide (ASO) treatment reduces FMR1-217, rescues full-length FMR1 RNA, and restores FMRP (Fragile X Messenger RibonucleoProtein) to normal levels. Notably, FMR1 gene reactivation in transcriptionally silent FXS cells using 5-aza-2'-deoxycytidine (5-AzadC), which prevents DNA methylation, increases FMR1-217 RNA levels but not FMRP. ASO treatment of cells prior to 5-AzadC application rescues full-length FMR1 expression and restores FMRP. These findings indicate that misregulated RNA-processing events in blood could serve as potent biomarkers for FXS and that in those individuals expressing FMR1-217, ASO treatment may offer a therapeutic approach to mitigate the disorder.

Expressive language sampling and outcome measures for treatment trials in fragile X and down syndromes: composite scores and psychometric properties

The lack of psychometrically sound outcome measures has been a barrier to evaluating the efficacy of treatments proposed for core symptoms of intellectual disability (ID). Research on Expressive Language Sampling (ELS) procedures suggest it is a promising approach to measuring treatment efficacy. ELS entails collecting samples of a participant's talk in interactions with an examiner that are naturalistic but sufficiently structured to ensure consistency and limit examiner effects on the language produced. In this study, we extended previous research on ELS by analyzing an existing dataset to determine whether psychometrically adequate composite scores reflecting multiple dimensions of language can be derived from ELS procedures administered to 6- to 23-year-olds with fragile X syndrome (n = 80) or Down syndrome (n = 78). Data came from ELS conversation and narration procedures administered twice in a 4-week test-retest interval. We found that several composites emerged from variables indexing syntax, vocabulary, planning processes, speech articulation, and talkativeness, although there were some differences in the composites for the two syndromes. Evidence of strong test-retest reliability and construct validity of two of three composites were obtained for each syndrome. Situations in which the composite scores would be useful in evaluating treatment efficacy are outlined.

Trofinetide for the treatment of Rett syndrome: a randomized phase 3 study

Rett syndrome is a rare, genetic neurodevelopmental disorder. Trofinetide is a synthetic analog of glycine-proline-glutamate, the N-terminal tripeptide of the insulin-like growth factor 1 protein, and has demonstrated clinical benefit in phase 2 studies in Rett syndrome. In this phase 3 study ( https://clinicaltrials.gov identifier NCT04181723 ), females with Rett syndrome received twice-daily oral trofinetide (n = 93) or placebo (n = 94) for 12 weeks. For the coprimary efficacy endpoints, least squares mean (LSM) change from baseline to week 12 in the Rett Syndrome Behaviour Questionnaire for trofinetide versus placebo was -4.9 versus -1.7 (P = 0.0175; Cohen's d effect size, 0.37), and LSM Clinical Global Impression-Improvement at week 12 was 3.5 versus 3.8 (P = 0.0030; effect size, 0.47). For the key secondary efficacy endpoint, LSM change from baseline to week 12 in the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist Social Composite score was -0.1 versus -1.1 (P = 0.0064; effect size, 0.43). Common treatment-emergent adverse events included diarrhea (80.6% for trofinetide versus 19.1% for placebo), which was mostly mild to moderate in severity. Significant improvement for trofinetide compared with placebo was observed for the coprimary efficacy endpoints, suggesting that trofinetide provides benefit in treating the core symptoms of Rett syndrome.

Brief intensive social gaze training reorganizes functional brain connectivity in boys with fragile X syndrome

Boys with fragile X syndrome (FXS), the leading known genetic cause of autism spectrum disorder (ASD), demonstrate significant impairments in social gaze and associated weaknesses in communication, social interaction, and other areas of adaptive functioning. Little is known, however, concerning the impact of behavioral treatments for these behaviors on functional brain connectivity in this population. As part of a larger study, boys with FXS (mean age 13.23 ± 2.31 years) and comparison boys with ASD (mean age 12.15 ± 2.76 years) received resting-state functional magnetic resonance imaging scans prior to and following social gaze training administered by a trained behavior therapist in our laboratory. Network-agnostic connectome-based predictive modeling of pretreatment resting-state functional connectivity data revealed a set of positive (FXS > ASD) and negative (FXS < ASD) edges that differentiated the groups significantly and consistently across all folds of cross-validation. Following administration of the brief training, the FXS and ASD groups demonstrated reorganization of connectivity differences. The divergence in the spatial pattern of reorganization response, based on functional connectivity differences pretreatment, suggests a unique pattern of response to treatment in the FXS and ASD groups. These results provide further support for implementing targeted behavioral treatments to ameliorate syndrome-specific behavioral features in FXS.

Patient Centricity: Design and Conduct of Clinical Trials in Orphan Diseases: Third of Three Sets of Expanded Proceedings from the 2020 ISCTM Autumn Conference on Pediatric Drug Development

This article expands on a session, titled "Patient Centricity: Design and Conduct of Clinical Trials in Orphan Diseases," that was presented as part of a two-day meeting on Pediatric Drug Development at the International Society for Central Nervous System (CNS) Clinical Trials and Methodology (ISCTM) Autumn Conference in Boston, Massachusetts, in October 2020. Speakers from various areas of pediatric drug development addressed a variety of implications of including children in drug development programs, including implications for rare/orphan diseases. The speakers have written summaries of their talks. The session's lead Chair was Dr. Joan Busner, who wrote introductory and closing comments. Dr. Simon Day, regulatory consultant, outlined some of the past mistakes that have plagued trials that did not consult with patient groups in the early design phase. Dr. Atul Mahableshwarkar provided an industry perspective of a recent trial that benefited from the inclusion of patient input. Drs. Lucas Kempf and Maria Sheean provided regulatory input from the perspectives of the United States (US) Food and Drug Administration (FDA) and European Medicines Agency (EMA), respectively. Dr. Judith Dunn outlined a novel approach for assessing and rank ordering patient and clinician clinical meaningfulness and the disconnect that may occur. Dr. Busner provided closing comments, tied together the presented issues, and provided a synopsis of the lively discussion that followed the session. In addition to the speakers above, the discussion included two representatives from patient advocacy groups, as well as an additional speaker who described the challenges of conducting a pediatric trial in the US and European Union (EU), given the often competing regulatory requirements. This article should serve as an expert-informed reference to those interested and involved in CNS drug development programs that are aimed at children and rare diseases and seek to ensure a patient-centric approach.

Communication in fragile X syndrome: Patterns and implications for assessment and intervention

Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and is associated with a high rate of autism diagnosis. Language delays have been noted in the areas of overall communication and the specific areas of receptive, expressive, and pragmatic language, as well as in development of speech sounds and literacy. It has been widely noted that those individuals with a diagnosis of both FXS and autism tend to have more significant intellectual disability and language disorder. In this study, the research exploring the FXS language phenotype is presented, and the roles of cognition, autistic symptomatology, and gender are highlighted as possible. Implications for assessment and intervention approaches based on the strengths and weaknesses of the FXS language phenotype are provided.

The feasibility and utility of hair follicle sampling to measure FMRP and FMR1 mRNA in children with or without fragile X syndrome: a pilot study

BACKGROUND

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability in males and the most common single gene cause of autism. This X-linked disorder is caused by an expansion of a trinucleotide CGG repeat (> 200 base pairs) on the promotor region of the fragile X messenger ribonucleoprotein 1 gene (FMR1). This leads to the deficiency or absence of the encoded protein, fragile X messenger ribonucleoprotein 1 (FMRP). FMRP has a central role in the translation of mRNAs involved in synaptic connections and plasticity. Recent studies have demonstrated the benefit of therapeutics focused on reactivation of the FMR1 locus towards improving key clinical phenotypes via restoration of FMRP and ultimately disease modification. A key step in future studies directed towards this effort is the establishment of proof of concept (POC) for FMRP reactivation in individuals with FXS. For this, it is key to determine the feasibility of repeated collection of tissues or fluids to measure FMR1 mRNA and FMRP.

METHODS

Individuals, ages 3 to 22 years of age, with FXS and those who were typically developing participated in this single-site pilot clinical biomarker study. The repeated collection of hair follicles was compared with the collection of blood and buccal swabs for detection of FMR1 mRNA and FMRP and related molecules.

RESULTS

There were n = 15 participants, of whom 10 had a diagnosis of FXS (7.0 ± 3.56 years) and 5 were typically developing (8.2 ± 2.77 years). Absolute levels of FMRP and FMR1 mRNA were substantially higher in healthy participants compared to full mutation and mosaic FXS participants and lowest in the FXS boys. Measurement of FMR1 mRNA and FMRP levels by any method did not show any notable variation by collection location at home versus office across the various sample collection methodologies of hair follicle, blood sample, and buccal swab.

CONCLUSION

Findings demonstrated that repeated sampling of hair follicles in individuals with FXS, in both, home, and office settings, is feasible, repeatable, and can be used for measurement of FMR1 mRNA and FMRP in longitudinal studies.

Anxiety, Depression, and Social Skills in Girls with Fragile X Syndrome: Understanding the Cycle to Improve Outcomes

OBJECTIVE

Female patients with fragile X syndrome (FXS), a genetic condition associated with a mutation in the FMR1 gene, are at significantly elevated risk for developing anxiety and depression. This study is designed to better understand these symptoms in school-age girls, particularly as they relate to age, social skills, and functional outcomes.

METHODS

We compared 58 girls aged 6 to 16 years with FXS with 46 age-matched, sex-matched, and developmentally matched peers without FXS on measures of anxiety, depression, social skills, adaptive behavior, and quality of life.

RESULTS

Girls with FXS 10.5 years and older demonstrated significantly higher levels of depression, withdrawal, and social avoidance than girls younger than 10.5 years with FXS ( p -values < 0.01). Girls in the comparison group did not show any age-related differences on these measures. The older FXS cohort also showed associations between social communication and interaction skills, adaptive behavior, and measures of anxiety and depression ( p -values < 0.05) not seen in the comparison group, regardless of age.

CONCLUSION

We found that age seems to play an important role in the development of mood symptoms and that such symptoms are uniquely correlated with social communication and reciprocal social interaction behaviors and adaptive functioning in girls with FXS after puberty. These data suggest a critical window of intervention for girls with FXS in the improvement of social interaction skills and the prevention of social avoidance and symptoms of anxiety and depression, with the ultimate goal of improving quality of life and promoting greater independence.

Agreement between parents' and clinical researchers' ratings of behavioral problems in children with fragile X syndrome and chromosome 15 imprinting disorders

BACKGROUND

Despite the increasing number of clinical trials involving children with neurodevelopmental disorders, appropriate and objective outcome measures for behavioral symptoms are still required.

AIM

This study assessed the agreement between parents' and clinical researchers' ratings of behavioral problem severity in children with fragile X syndrome (FXS) and chromosome 15 imprinting disorders.

METHODS AND PROCEDURES

The cohort comprised 123 children (64% males), aged 3-17 years, with FXS (n = 79), Prader-Willi (PWS; n = 19), Angelman (AS; n = 15), and Chromosome 15q duplication (n = 10) syndromes. Specific items from the Autism Diagnostic Observation Schedule-Second Edition and Aberrant Behavior Checklist-Community Edition mapping to corresponding behavioral domains were selected ad-hoc, to assess behavioral problems.

OUTCOMES AND RESULTS

Inter-rater agreement for the cohort was slight for self-injury (Intraclass Correlation Coefficient (ICC) = 0.12), fair for tantrums/aggression (0.24) and mannerisms/stereotypies (0.25), and moderate for hyperactivity (0.48). When stratified by diagnosis, ICC ranged from poor (0; self-injury, AS and PWS) to substantial (0.48; hyperactivity, females with FXS).

CONCLUSIONS AND IMPLICATIONS

The high level of inter-rater disagreement across most domains suggests that parents' and researchers' assessments led to discrepant appraisal of behavioral problem severity. These findings have implications for treatment targets and outcome measure selection in clinical trials, supporting a multi-informant approach.

The association between expressive language skills and adaptive behavior in individuals with Down syndrome

The primary goal of this study was to determine whether expressive language skills contribute to adaptive behavior (e.g., socialization and daily living skills) in children, adolescents, and young adults with Down syndrome (DS) whilst controlling for age and nonverbal cognitive ability. Expressive language was assessed using the psychometrically validated Expressive Language Sampling (ELS) conversation and narration procedures. The language produced was transcribed and analyzed to yield measures of expressive vocabulary, syntax, and intelligibility. Socialization and daily living skills of participants with DS were measured with the Vineland Adaptive Behavior Scales, 2nd edition (VABS-2) parent/caregiver rating form. Our results show that the three ELS measures were significantly correlated with multiple measures from the VABS-2 when controlling for age. Several correlations remained significant even when nonverbal cognitive ability was included as a control variable. Our results suggest that expressive language skills contribute to adaptive behavior in children, adolescents, and young adults with DS regardless of age and some of these associations are not explained solely by overall cognitive delays. Further studies including longitudinal data are needed to extend our results.

Disease-Targeted Treatment Translation in Fragile X Syndrome as a Model for Neurodevelopmental Disorders

Fragile X syndrome (FXS), the most common monogenic cause of intellectual disability and autism spectrum disorder, has been one of the first neurodevelopmental disorders in which molecular and neuronal mechanisms of disease were identified, leading to the concept of targeting the underlying disease to reverse symptoms. Translating findings in basic science and animal models to humans with FXS has proven difficult. These challenges have prompted the FXS field to organize to build interlocking projects and initiatives to improve consistency of supportive care, make clinical research accessible to families, generate collaborative research on natural history, outcome measures and biomarkers, and create clinical trial consortia and novel trial designs. This work has resulted in improved success in recent clinical trials, providing key steps toward regulatory approval of disease-targeted treatments for FXS. Progress in the FXS field has informed translation of transformative new disease-targeted therapies for other monogenic neurodevelopmental disorders.

Considerations for measuring individual outcomes across contexts in Down syndrome: Implications for research and clinical trials

Individuals with Down syndrome (DS) are increasingly involved in clinical trials that target developmental outcomes, like cognition and behavior. The increased focus on treatment in DS has led to ongoing discussions regarding the selection of outcome measures using syndrome-informed criteria. This discourse is warranted as clinical trials can fail if the outcome measures selected are inappropriate for individuals with DS or do not take into account the behavioral phenotype commonly associated with DS. This review focuses on the challenges present in the measurement of outcomes in DS, with a specific focus on considerations made in evaluating cognitive, language, and behavioral/psychopathology outcomes. This review also provides a summary of recommendations for assessment of outcomes in these domains as well as recommendations for future research. The impact of physical health and assessment psychometrics on the measurement of outcomes is also reviewed.

Inclusion of Individuals With Neurodevelopmental Disorders in Norm-Referenced Language Assessments

Standardized, norm-referenced language assessment tools are used for a variety of purposes, including in education, clinical practice, and research. Unfortunately, norm-referenced language assessment tools can demonstrate floor effects (i.e., a large percentage of individuals scoring at or near the lowest limit of the assessment tool) when used with some groups with neurodevelopmental disorders (NDDs), such as individuals with intellectual disability and neurogenetic syndromes. Without variability at the lower end of these assessment tools, professionals cannot accurately measure language strengths and difficulties within or across individuals. This lack of variability may be tied to poor representation of individuals with NDDs in normative samples. Therefore, the purpose of this study was to identify and examine common standardized, norm-referenced language assessment tools to report the representation of individuals with NDDs in normative samples and the range of standard/index scores provided. A systematic search identified 57 assessment tools that met inclusion criteria. Coding of the assessment manuals identified that most assessment tools included a “disability” or “exceptionality” group in their normative sample. However, the total number of individuals in these groups and the number of individuals with specific NDDs was small. Further, the characteristics of these groups (e.g., demographic information; disability type) were often poorly defined. The floor standard/index scores of most assessment tools were in the 40s or 50s. Only four assessment tools provided a standard score lower than 40. Findings of this study can assist clinicians, educators, and researchers in their selections of norm-referenced assessment tools when working with individuals with NDDs.

Attention/Deficit Hyperactivity Disorder in Adolescent and Young Adult Males With Fragile X Syndrome

This study characterized the rates of attention-deficit/hyperactivity disorder (ADHD) in adolescent and young adult males with fragile X syndrome (FXS) using a multi-method approach integrating a DSM-based parent interview (Children's Interview for Psychiatric Syndromes; P-ChIPS, Fristad et al., 1998) and a parent rating scale (Child Behavior Checklist; CBCL, Achenbach, 2001). Thirty-one males with FXS, aged 16-24 years, participated. Forty-two percent met DSM-5 criteria for ADHD and 35% exceeded the CBCL cut-offs. Agreement between the two classification methods was fair (κ = 0.38). Autism symptom severity and nonverbal cognitive ability did not predict ADHD diagnoses/symptoms. Results show high rates of ADHD in males with FXS during late adolescence and young adulthood, which are not accounted for by impaired nonverbal cognitive skills or autism symptom severity. DSM-based ADHD-specific scales are recommended over broadband symptom scales to improve accurate identification.

Effects of Soy-Based Infant Formula on Weight Gain and Neurodevelopment in an Autism Mouse Model

Mice fed soy-based diets exhibit increased weight gain compared to mice fed casein-based diets, and the effects are more pronounced in a model of fragile X syndrome (FXS; Fmr1KO). FXS is a neurodevelopmental disability characterized by intellectual impairment, seizures, autistic behavior, anxiety, and obesity. Here, we analyzed body weight as a function of mouse age, diet, and genotype to determine the effect of diet (soy, casein, and grain-based) on weight gain. We also assessed plasma protein biomarker expression and behavior in response to diet. Juvenile Fmr1KO mice fed a soy protein-based rodent chow throughout gestation and postnatal development exhibit increased weight gain compared to mice fed a casein-based purified ingredient diet or grain-based, low phytoestrogen chow. Adolescent and adult Fmr1KO mice fed a soy-based infant formula diet exhibited increased weight gain compared to reference diets. Increased body mass was due to increased lean mass. Wild-type male mice fed soy-based infant formula exhibited increased learning in a passive avoidance paradigm, and Fmr1KO male mice had a deficit in nest building. Thus, at the systems level, consumption of soy-based diets increases weight gain and affects behavior. At the molecular level, a soy-based infant formula diet was associated with altered expression of numerous plasma proteins, including the adipose hormone leptin and the β-amyloid degrading enzyme neprilysin. In conclusion, single-source, soy-based diets may contribute to the development of obesity and the exacerbation of neurological phenotypes in developmental disabilities, such as FXS.

Towards Kinase Inhibitor Therapies for Fragile X Syndrome: Tweaking Twists in the Autism Spectrum Kinase Signaling Network

Absence of the Fragile X Mental Retardation Protein (FMRP) causes autism spectrum disorders and intellectual disability, commonly referred to as the Fragile X syndrome. FMRP is a negative regulator of protein translation and is essential for neuronal development and synapse formation. FMRP is a target for several post-translational modifications (PTMs) such as phosphorylation and methylation, which tightly regulate its cellular functions. Studies have indicated the involvement of FMRP in a multitude of cellular pathways, and an absence of FMRP was shown to affect several neurotransmitter receptors, for example, the GABA receptor and intracellular signaling molecules such as Akt, ERK, mTOR, and GSK3. Interestingly, many of these molecules function as protein kinases or phosphatases and thus are potentially amendable by pharmacological treatment. Several treatments acting on these kinase-phosphatase systems have been shown to be successful in preclinical models; however, they have failed to convincingly show any improvements in clinical trials. In this review, we highlight the different protein kinase and phosphatase studies that have been performed in the Fragile X syndrome. In our opinion, some of the paradoxical study conclusions are potentially due to the lack of insight into integrative kinase signaling networks in the disease. Quantitative proteome analyses have been performed in several models for the FXS to determine global molecular processes in FXS. However, only one phosphoproteomics study has been carried out in Fmr1 knock-out mouse embryonic fibroblasts, and it showed dysfunctional protein kinase and phosphatase signaling hubs in the brain. This suggests that the further use of phosphoproteomics approaches in Fragile X syndrome holds promise for identifying novel targets for kinase inhibitor therapies.

Design and outcome measures of LAVENDER, a phase 3 study of trofinetide for Rett syndrome

INTRODUCTION

Rett syndrome (RTT) is a debilitating neurodevelopmental disorder with no approved treatments. Trofinetide is a synthetic analog of glycine-proline-glutamate, the N-terminal tripeptide of insulin-like growth factor 1. In a phase 2, placebo-controlled trial in 82 females with RTT aged 5-15 years, a significant (p ≤ 0.042) improvement over placebo was observed with the highest trofinetide dose (200 mg/kg twice daily [BID]) on three measures: Rett Syndrome Behavior Questionnaire (RSBQ), Clinical Global Impression-Improvement (CGI-I), and RTT-Clinician Domain Specific Concerns-Visual Analog Scale (RTT-DSC-VAS). Trofinetide was well tolerated at all doses (50, 100, and 200 mg/kg BID). A phase 3 trial utilizing disease-specific and novel scales was designed to investigate the efficacy and safety of trofinetide in girls and women with RTT.

METHODS

This 12-week, double-blind, randomized, placebo-controlled study (LAVENDER; NCT04181723) will evaluate trofinetide in 187 females, aged 5-20 years, with RTT. Co-primary endpoints are the RSBQ and CGI-I scales. Clinical domains of the CGI-I include communication, ambulation, hand use, seizures, attentiveness, and social (eye contact) and autonomic (breathing) aspects. Secondary endpoints will leverage four novel RTT-specific clinician ratings (derived from the RTT-DSC-VAS) of hand function, ambulation, ability to communicate, and verbal communication, and existing scales, to evaluate other core symptoms of RTT, quality of life and caregiver burden. A 40-week, open-label extension study will follow.

DISCUSSION

This study was designed using disease-specific scales optimized to demonstrate changes in core symptoms of RTT and may provide the first phase 3 data demonstrating drug efficacy in individuals with RTT.

TRIAL REGISTRATION

Clinicaltrials.govNCT04181723.

Providing a parent-administered outcome measure in a bilingual family of a father and a mother of two adolescents with ASD: brief report

There is a need for psychometrically sound outcome measures for treatment studies that have a low burden for families and that are available in multiple languages. We have developed a language assessment in English and Spanish that parents can administer to their children at home via telehealth-delivered procedures. The current case study presents descriptive data on a single family of two parent-child dyads. Both the mother and father from a single family were trained in their primary language (Spanish) on how to administer the Expressive Language Sampling - Narration (ELS-N) in their secondary language (English) to their two English-speaking monolingual sons with ASD through telehealth-delivered procedures. Both parents learned to administer the procedures to a predetermined level of fidelity. Extension to a larger sample of bilingual families is needed for this home-based, parent-administered test; however, the present results suggest feasibility even when the language of training and administration differ.

Evidence for Three Subgroups of Female FMR1 Premutation Carriers Defined by Distinct Neuropsychiatric Features: A Pilot Study

Over 200 Cytosine-guanine-guanine (CGG) trinucleotide repeats in the 5' untranslated region of the Fragile X mental retardation 1 (FMR1) gene results in a "full mutation," clinically Fragile X Syndrome (FXS), whereas 55 - 200 repeats result in a "premutation." FMR1 premutation carriers (PMC) are at an increased risk for a range of psychiatric, neurocognitive, and physical conditions. Few studies have examined the variable expression of neuropsychiatric features in female PMCs, and whether heterogeneous presentation among female PMCs may reflect differential presentation of features in unique subgroups. In the current pilot study, we examined 41 female PMCs (ages 17-78 years) and 15 age-, sex-, and IQ-matched typically developing controls (TDC) across a battery of self-report, eye tracking, expressive language, neurocognitive, and resting state EEG measures to determine the feasibility of identifying discrete clusters. Secondly, we sought to identify the key features that distinguished these clusters of female PMCs. We found a three cluster solution using k-means clustering. Cluster 1 represented a psychiatric feature group (27% of our sample); cluster 2 represented a group with executive dysfunction and elevated high frequency neural oscillatory activity (32%); and cluster 3 represented a relatively unaffected group (41%). Our findings indicate the feasibility of using a data-driven approach to identify naturally occurring clusters in female PMCs using a multi-method assessment battery. CGG repeat count and its association with neuropsychiatric features differ across clusters. Together, our findings provide important insight into potential diverging pathophysiological mechanisms and risk factors for each female PMC cluster, which may ultimately help provide novel and individualized targets for treatment options.

Concurrent Associations between Expressive Language Ability and Independence in Adolescents and Adults with Fragile X Syndrome

BACKGROUND

Few individuals with fragile X syndrome (FXS) successfully meet adult normative expectations in education, employment, peer relations, and habitation, although there is within-syndrome variability in this regard. The primary goal of this study was to determine whether expressive language skills contribute to the capacity for independent functioning in adulthood even after controlling for nonverbal cognitive ability.

METHODS

Participants were 18- to 23-year-olds with FXS. Expressive language was assessed using the psychometrically validated Expressive Language Sampling (ELS) conversation and narration procedures. The language produced was transcribed and analyzed to yield measures of expressive vocabulary, syntax, and intelligibility. Parents concurrently completed questionnaires on the independent functioning of the participants with FXS.

RESULTS

All three ELS measures were significantly corelated with multiple measures of independence. The magnitudes of the correlations were reduced when nonverbal IQ was controlled through partial correlation. Nonetheless, many of the partial correlations were medium to large and several were statistically significant.

CONCLUSIONS

Expressive language skills appear to contribute uniquely to the capacity for independence, although longitudinal data are needed to evaluate the possibility of a bidirectional relationship between these domains. Thus, language intervention may be a prerequisite for preparing youth with FXS for an independent adult life.

An "Omic" Overview of Fragile X Syndrome

Fragile X syndrome (FXS) is a neurodevelopmental disorder associated with a wide range of cognitive, behavioral and medical problems. It arises from the silencing of the fragile X mental retardation 1 (FMR1) gene and, consequently, in the absence of its encoded protein, FMRP (fragile X mental retardation protein). FMRP is a ubiquitously expressed and multifunctional RNA-binding protein, primarily considered as a translational regulator. Pre-clinical studies of the past two decades have therefore focused on this function to relate FMRP's absence to the molecular mechanisms underlying FXS physiopathology. Based on these data, successful pharmacological strategies were developed to rescue fragile X phenotype in animal models. Unfortunately, these results did not translate into humans as clinical trials using same therapeutic approaches did not reach the expected outcomes. These failures highlight the need to put into perspective the different functions of FMRP in order to get a more comprehensive understanding of FXS pathophysiology. This work presents a review of FMRP's involvement on noteworthy molecular mechanisms that may ultimately contribute to various biochemical alterations composing the fragile X phenotype.

Spoken language outcome measures for treatment studies in Down syndrome: feasibility, practice effects, test-retest reliability, and construct validity of variables generated from expressive language sampling

BACKGROUND

The purpose of this study was to evaluate expressive language sampling (ELS) as a procedure for generating spoken language outcome measures for treatment research in Down syndrome (DS). We addressed (a) feasibility, (b) practice effects across two short-term administrations, (c) test-retest reliability across two short-term administrations, (d) convergent and discriminant construct validity, and (e) considered comparisons across the conversation and narration contexts.

METHOD

Participants were 107 individuals with DS between 6 and 23 years of age who presented with intellectual disability (IQ < 70). The utility of ELS procedures designed to collect samples of spoken language in conversation and narration were evaluated separately. Variables of talkativeness, vocabulary, syntax, utterance planning, and articulation quality, derived from transcripts segmented into C-units (i.e., an independent clause and its modifiers), were considered. A 4-week interval was used to assess practice effects and test-retest reliability. Standardized direct assessments and informant report measures were collected to evaluate construct validity of the ELS variables.

RESULTS

Low rates of noncompliance were observed; youth who were under 12 years of age, had phrase-level speech or less, and had a 4-year-old developmental level or less were at particular risk for experiencing difficulty completing the ELS procedures. Minimal practice effects and strong test-retest reliability across the 4-week test-retest interval was observed. The vocabulary, syntax, and speech intelligibility variables demonstrated strong convergent and discriminant validity. Although significant correlations were found between the variables derived from both the conversation and narration contexts, some differences were noted.

CONCLUSION

The ELS procedures considered were feasible and yielded variables with adequate psychometric properties for most individuals with DS between 6 and 23 years old. That said, studies of outcome measures appropriate for individuals with DS with more limited spoken language skills are needed. Context differences were observed in ELS variables suggest that comprehensive evaluation of expressive language is likely best obtained when utilizing both contexts.

Increased aperiodic gamma power in young boys with Fragile X Syndrome is associated with better language ability

Background

The lack of robust and reliable clinical biomarkers in Fragile X Syndrome (FXS), the most common inherited form of intellectual disability, has limited the successful translation of bench-to-bedside therapeutics. While numerous drugs have shown promise in reversing synaptic and behavioral phenotypes in mouse models of FXS, none have demonstrated clinical efficacy in humans. Electroencephalographic (EEG) measures have been identified as candidate biomarkers as EEG recordings of both adults with FXS and mouse models of FXS consistently exhibit alterations in resting state and task-related activity. However, the developmental timing of these EEG differences is not known as thus far EEG studies have not focused on young children with FXS. Further, understanding how EEG differences are associated with core symptoms of FXS is crucial to successful use of EEG as a biomarker, and may improve our understanding of the disorder.

Methods

Resting-state EEG was collected from FXS boys with full mutation of Fmr1 (2.5–7 years old, n = 11) and compared with both age-matched (n = 12) and cognitive-matched (n = 12) typically developing boys. Power spectra (including aperiodic and periodic components) were compared using non-parametric cluster-based permutation testing. Associations between 30 and 50 Hz gamma power and cognitive, language, and behavioral measures were evaluated using Pearson correlation and linear regression with age as a covariate.

Results

FXS participants showed increased power in the beta/gamma range (~ 25–50 Hz) across multiple brain regions. Both a reduction in the aperiodic (1/f) slope and increase in beta/gamma periodic activity contributed to the significant increase in high-frequency power. Increased gamma power, driven by the aperiodic component, was associated with better language ability in the FXS group. No association was observed between gamma power and parent report measures of behavioral challenges, sensory hypersensitivities, or adaptive behaviors.

Limitations

The study sample size was small, although comparable to other human studies in rare-genetic disorders. Findings are also limited to males in the age range studied.

Conclusions

Resting-state EEG measures from this study in young boys with FXS identified similar increases in gamma power previously reported in adults and mouse models. The observed positive association between resting state aperiodic gamma power and language development supports hypotheses that alterations in some EEG measures may reflect ongoing compensatory mechanisms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00425-x.

Structural validity of the Child Behavior Checklist (CBCL) for preschoolers with neurogenetic syndromes

BACKGROUND

Psychologists routinely use the Child Behavior Checklist for Ages 1½-5 (CBCL) to assess challenging behaviors of preschoolers with developmental disabilities. However, the CBCL has not been thoroughly validated in neurogenetic syndromes (NGS).

AIM

We investigated the structural validity of the CBCL in NGS.

METHODS

Based on 152 preschoolers with Angelman, fragile X, Prader-Willi, and Williams syndromes, we employed confirmatory factor analysis (CFA) to evaluate the goodness-of-fit of CBCL narrowband, broadband, and DSM-oriented scales.

RESULTS

CFA models largely supported the unidimensionality of most narrowband scales and the two-factor structure of internalizing and externalizing broadband scales. However, there was limited evidence for the unidimensionality of most DSM-oriented scales.

CONCLUSIONS

Psychologists may consider using the CBCL as a psychometrically sound narrowband and broadband measure of challenging behaviors but should exercise caution when interpreting DSM-oriented scales for preschoolers with NGS. Our findings underscore a continued need to enhance assessment measures for identifying early precursors of child psychopathology in pediatric populations with atypical developmental trajectories.

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 (mGluR5) in fmr1 knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR5 expression in humans with FXS exposed to NAMs might help in that effort. We used positron emission tomography (PET) to measure the mGluR5 density as a proxy of mGluR5 expression in cortical and subcortical brain regions to confirm target engagement of NAMs for mGluR5s. The density and the distribution of mGluR5 were measured in two independent samples of men with FXS (N = 9) and typical development (TD) (N = 8). We showed the feasibility of this complex study including MRI and PET, meaning that this challenging protocol can be accomplished in men with FXS with an adequate preparation. Analysis of variance of estimated mGluR5 expression showed that mGluR5 expression was significantly reduced in cortical and subcortical regions of men with FXS in contrast to age-matched men with TD.

Outcome Measures for Core Symptoms of Intellectual Disability: State of the Field

Intellectual disability (ID) is defined by impairments in intellectual and adaptive functioning. As such, tools designed to assess these domains would theoretically be ideal outcome measures for treatment trials targeting core symptoms of ID. However, measures of intellectual and adaptive functioning have rarely been used as primary outcome measures to date and further study is needed regarding their usefulness to measure change. This area of inquiry is important because promising, mechanism-modifying treatments for conditions leading to ID are being initiated. To show efficacy, these treatments need to demonstrate an impact on core features of ID. After reviewing literature on this topic, we suggest solutions to several problems outlined, including use of out-of-age-range testing, alternative metrics, and development of new measures.

A Psychometric Evaluation of the Motor-Behavioral Assessment Scale for Use as an Outcome Measure in Rett Syndrome Clinical Trials

Rett syndrome (RTT) is a neurodevelopmental disorder that primarily affects females. Recent work indicates the potential for disease modifying therapies. However, there remains a need to develop outcome measures for use in clinical trials. Using data from a natural history study (n = 1,075), we examined the factor structure, internal consistency, and validity of the clinician-reported Motor Behavior Assessment scale (MBA). The analysis resulted in a five-factor model: (1) motor dysfunction, (2) functional skills, (3) social skills, (4) aberrant behavior, and (5) respiratory behaviors. Item Response Theory (IRT) analyses demonstrated that all items had acceptable discrimination. The revised MBA subscales showed a positive relationship with parent reported items, age, and a commonly used measure of clinical severity in RTT, and mutation type. Further work is needed to evaluate this measure longitudinally and to add items related to the RTT phenotype.

A Double-Blind, Randomized, Placebo-Controlled Clinical Study of Trofinetide in the Treatment of Fragile X Syndrome

BACKGROUND

We analyze the safety and tolerability of trofinetide and provide a preliminary evaluation of its efficacy in adolescent and adult males with fragile X syndrome.

METHODS

This study was an exploratory, phase 2, multicenter, double-blind, placebo-controlled, parallel group study of the safety and tolerability of orally administered trofinetide in 72 adolescent and adult males with fragile X syndrome. Subjects were randomly assigned in a 1:1:1 ratio to 35 or 70 mg/kg twice daily trofinetide or placebo for 28 days. Safety assessments included adverse events, clinical laboratory tests, vital signs, electrocardiograms, physical examinations, and concomitant medications. Efficacy measurements were categorized into four efficacy domains, which related to clinically relevant phenotypic dimensions of impairment associated with fragile X syndrome.

RESULTS

Both 35 and 70 mg/kg dose levels of trofinetide were well tolerated and appeared to be generally safe. Trofinetide at the 70 mg/kg dose level demonstrated efficacy compared with placebo based on prespecified criteria. On the basis of a permutation test, the probability of a false-positive outcome for the achieved prespecified success was 0.045. In the group analysis, improvement from treatment baseline was demonstrated on three fragile X syndrome-specific outcome measures.

CONCLUSIONS

Trofinetide was well tolerated in adolescent and adult males with fragile X syndrome. Despite the relatively short duration of the study, a consistent signal of efficacy at the higher dose was observed in both caregiver and clinician assessments, based on a novel analytical model incorporating evaluation of multiple key symptom areas of fragile X syndrome. This finding suggests a potential for trofinetide treatment to provide clinically meaningful improvement in core fragile X syndrome symptoms.

Properties of beta oscillations in Dup15q syndrome

Background

Duplications of 15q11.2-q13.1 (Dup15q syndrome) are highly penetrant for autism, intellectual disability, hypotonia, and epilepsy. The 15q region harbors genes critical for brain development, particularly UBE3A and a cluster of gamma-aminobutyric acid type A receptor (GABA_AR) genes. We recently described an electrophysiological biomarker of the syndrome, characterized by excessive beta oscillations (12–30 Hz), resembling electroencephalogram (EEG) changes induced by allosteric modulation of GABA_ARs. In this follow-up study, we tested a larger cohort of children with Dup15q syndrome to comprehensively examine properties of this EEG biomarker that would inform its use in future clinical trials, specifically, its (1) relation to basic clinical features, such as age, duplication type, and epilepsy; (2) relation to behavioral characteristics, such as cognition and adaptive function; (3) stability over time; and (4) reproducibility of the signal in clinical EEG recordings.

Methods

We computed EEG power and beta peak frequency (BPF) in a cohort of children with Dup15q syndrome (N = 41, age range 9–189 months). To relate EEG parameters to clinical (study 1) and behavioral features (study 2), we examined age, duplication type, epilepsy, cognition, and daily living skills (DLS) as predictors of beta power and BPF. To evaluate stability over time (study 3), we derived the intraclass correlation coefficients (ICC) from beta power and BPF computed from children with multiple EEG recordings (N = 10, age range 18–161 months). To evaluate reproducibility in a clinical setting (study 4), we derived ICCs from beta power computed from children (N = 8, age range 19–96 months), who had undergone both research EEG and clinical EEG.

Results

The most promising relationships between EEG and clinical traits were found using BPF. BPF was predicted both by epilepsy status (R² = 0.11, p = 0.038) and the DLS component of the Vineland Adaptive Behavior Scale (R² = 0.17, p = 0.01). Beta power and peak frequency showed high stability across repeated visits (beta power ICC = 0.93, BPF ICC = 0.92). A reproducibility analysis revealed that beta power estimates are comparable between research and clinical EEG (ICC = 0.94).

Conclusions

In this era of precision health, with pharmacological and neuromodulatory therapies being developed and tested for specific genetic etiologies of neurodevelopmental disorders, quantification and examination of mechanistic biomarkers can greatly improve clinical trials. To this end, the robust beta oscillations evident in Dup15q syndrome are clinically reproducible and stable over time. With future preclinical and computational studies that will help disentangle the underlying mechanism, it is possible that this biomarker could serve as a robust measure of drug target engagement or a proximal outcome measure in future disease modifying intervention trials.

Brief Report: Assessment Experiences of Children with Neurogenetic Syndromes: Caregivers' Perceptions and Suggestions for Improvement

It is well-recognized that measurement options for diagnosing and monitoring children with neurogenetic syndromes (NGS) associated with moderate to severe intellectual impairment are limited (Berry-Kravis, Dev Med Child Neurol https://doi.org/10.1111/dmcn.13018, 2016), and caregivers experience significant concerns regarding the assessment process. However to date, these concerns have not been summarized into actionable steps for clinicians and test-makers. As such, we used a mixed methods approach to assess caregiver-derived perceptions and suggestions for improving assessments in NGS. Results indicated many shared challenges and suggestions for improvement, particularly in the domains of testing procedures and examiner communication. Integrating these suggestions into future protocols is an important next step toward improving the quality of assessment procedures for children with NGS and their families across both clinical and research contexts.

Bringing the Laboratory Home: PANDABox Telehealth-Based Assessment of Neurodevelopmental Risk in Children

Background

Advances in clinical trials have revealed a pressing need for outcome measures appropriate for children with neurogenetic syndromes (NGS). However, the field lacks a standardized, flexible protocol for collecting laboratory-grade experimental data remotely. To address this challenge, we developed PANDABox (Parent-Administered Neurodevelopmental Assessment), a caregiver-facilitated, remotely administered assessment protocol for collecting integrated and high quality clinical, behavioral, and spectral data relevant to a wide array of research questions. Here, we describe PANDABox development and report preliminary data regarding: (1) logistics and cost, (2) caregiver fidelity and satisfaction, and (3) data quality.

Methods

We administered PANDABox to a cohort of 16 geographically diverse caregivers and their infants with Down syndrome. Tasks assessed attention, language, motor, and atypical behaviors. Behavioral and physiological data were synchronized and coded offline by trained research assistants.

Results

PANDABox required low resources to administer and was well received by families, with high caregiver fidelity (94%) and infant engagement (91%), as well as high caregiver-reported satisfaction (97% positive). Missing data rates were low for video frames (3%) and vocalization recordings (6%) but were higher for heart rate (25% fully missing and 13% partially missing) and discrete behavioral presses (8% technical issues and 19% not enough codable behavior), reflecting the increased technical demands for these activities.

Conclusion

With further development, low-cost laboratory-grade research protocols may be remotely administered by caregivers in the family home, opening a new frontier for cost-efficient, scalable assessment studies for children with NGS other neurodevelopmental disorders.

Adaptive Skills in FXS: A Review of the Literature and Evaluation of the PEDI-Computer Adaptive Test (PEDI-CAT) to Measure Adaptive Skills

As adaptive skills (AS) are dynamic and may indicate the success of an intervention, they are a common domain measured in clinical trials. Typical interview tools for measuring AS are time-consuming, and questionnaire measures often lead to inconsistent information. The present study was designed to evaluate the feasibility, validity and test-retest performance of the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) in Fragile X syndrome (FXS). The PEDI-CAT is administered via tablet and uses the item response theory to efficiently determine the items administered. The PEDI-CAT was administered to 42 individuals with FXS (27 males; 15 females) aged 1.6-50.9 years (M = 14.9; SD = 11.2), followed by the Vineland-3 (VABS-3) interview for comparison. Administration was efficient (M = 21.7 min; SD = 9.5; range 8-45 min; mode = 19). Males and females did not significantly differ on the PEDI-CAT domains, except for daily activities (t(40) = -2.22, p = 0.037). Floor effects were significant for both measures, although the PEDI-CAT showed more floor effects in the mobility (35.7%) and social-cognitive (50%) domains. PEDI-CAT daily activities, mobility, social-cognitive and responsibility domains were all significantly correlated with most of the VABS-3 domains (all rho > 0.5; p < 0.01). Test-rest of the PEDI-CAT was comparable to the VABS-3. Results suggest that the PEDI-CAT is efficient, and minimal training is needed to administer it; however, it lacks specificity and shares a high rate of floor effects with the VABS-3.

Using generalizability theory to evaluate the comparative reliability of developmental measures in neurogenetic syndrome and low-risk populations

BACKGROUND

The lack of available measures that can reliably characterize early developmental skills in children with neurogenetic syndromes (NGS) poses a significant challenge for research on early development in these populations. Although syndrome-specific measures may sometimes be necessary, a more cost- and time-efficient solution would be to identify existing measures that are appropriate for use in special populations or optimize existing measures to be used in these groups. Reliability is an important metric of psychometric rigor to consider when auditing and optimizing assessment tools for NGS. In this study, we use Generalizability Theory, an extension of classical test theory, as a novel approach for more comprehensively characterizing the reliability of existing measures and making decisions about their use in the field of NGS research.

METHODS

We conducted generalizability analyses on a popular early social communication screener, the Communication and Symbolic Behavior Scales-Infant-Toddler Checklist (CSBS-ITC), collected on 172 children (41 Angelman syndrome, 30 Prader-Willi syndrome, 42 Williams syndrome, 59 low-risk controls).

RESULTS

Overall, the CSBS-ITC demonstrated at least adequate reliability in the NGS groups included in this study, particularly for the Prader-Willi and Williams syndrome groups. However, the sources of systematic error variance in the CSBS-ITC varied greatly between the low-risk control and NGS groups. Moreover, as unassessed in previous research, the CSBS-ITC demonstrated substantial differences in variance sources among the NGS groups. Reliability of CSBS-ITC scores was highest when averaging across all measurement points for a given child and was generally similar or better in the NGS groups compared to the low-risk control group.

CONCLUSIONS

Our findings suggest that the CSBS-ITC communicates different information about the reliability of stability versus change, in low-risk control and NGS samples, respectively, and that psychometric approaches like Generalizability Theory can provide more complete information about the reliability of existing measures and inform decisions about how measures are used in research on early development in NGS.

Evaluating Social Interactions Using the Autism Screening Instrument for Education Planning-3rd Edition (ASIEP-3): Interaction Assessment in Children and Adults with Fragile X Syndrome

An efficient and direct measure of social interactions and autism symptoms is needed for fragile X syndrome (FXS) research and clinical care. The Autism Screening Instrument for Educational Planning-Third Edition (ASIEP-3) Interaction assessment is a brief standardized measure that quantifies social responses under different conditions. The feasibility and validity of the ASIEP-3 was evaluated in 26 males and 13 females with FXS, along with cognitive testing and behavior questionnaires. The videos were scored at 10-second intervals, and the observed behaviors were scored as an interaction, independent play, no response, or aggression. In total, 39/41 participants successfully completed the ASIEP-3 (age M = 14.4 ± 10.2), with a range of cognitive abilities (abbreviated IQ (ABIQ) M = 58.9 ± 17.3, median = 50), behaviors (Aberrant Behavior Checklist (ABC) Total M = 37.00 ± 27.3), and autism diagnoses (N = 22/39). Reliable administration was demonstrated by all team members. The mean coded behaviors included interaction (40.6%), independent play (36.8%), no response (21.1%), and aggressive behavior (<10%). The interaction score was negatively correlated with the Social Communication Questionnaire (SCQ) score (p = 0.037), and the profiles differed by autism spectrum disorder (ASD) diagnosis. The intraclass correlation coefficients (ICCs) ranged from 0.79 to 0.93 for master's level and above. Administration of the ASIEP-3 was feasible for FXS across sex, age, ability, and behavior ratings by a trained research team. Reliable scoring required advanced training in the assessment of social development and FXS experience. The scores correlated to ratings and diagnoses of ASD. The ASIEP-3 shows promise to reliably index social interactions in FXS.

Delineating Repetitive Behavior Profiles across the Lifespan in Fragile X Syndrome

Restricted repetitive behaviors (RRBs) are a core area of impairment in autism spectrum disorder (ASD), but also affect several other neurodevelopmental disorders including fragile X syndrome (FXS). Current literature has begun to describe the RRB profile in FXS up through adolescence; however, little is known about the subtypes of RRBs in adolescents and adults. Further, literature on the RRB profile of females with FXS is limited. The present study examines the RRB profile across subtypes and specific items in both males and females with FXS while assessing for differences based on age, ASD diagnosis and the impact of IQ. Participants included 154 individuals with FXS (ages 2 to 50 years old). Results revealed a peak in RRB severity in FXS between 7–12 years for the majority of RRB subscales with the exception of Sensory-Motor behaviors peaking between 2 and 12 years before declining. Distinct RRB profiles in males and females with FXS emerged in addition to significant overlap among the item and subscale levels of RRBs across gender. Further, an added diagnosis of ASD significantly increased rates of RRBs across all subscale levels, but not necessarily across all items. Lastly, IQ did not solely account for the presence of RRBs in FXS, with Sensory-Motor behaviors being driven by comorbid ASD in males with FXS, and Restricted Interest behaviors being driven by comorbid ASD regardless of gender. These findings build on the current understanding of RRBs in FXS based on gender and comorbid ASD and lay important groundwork for the development of targeted behavioral and pharmacological treatments.

Language across the Lifespan in Fragile X Syndrome: Characteristics and Considerations for Assessment

While it is widely acknowledged that language development is delayed for the majority of individuals with fragile X syndrome (FXS), there has been limited research into how best to assess this area. This study aimed to deepen the understanding of standardized language assessment in FXS by addressing the three following objectives: (1) Examine the feasibility and validity of widely-used, standardized assessments in participants with FXS; (2) describe linguistic and cognitive profiles for a large sample of individuals with FXS; and (3) Compare results obtained from objective testing in clinic to those obtained using caregiver report. Results indicate that previous results indicating strong correlations between cognition and language results hold true across a wide range of ages as well as across multiple assessments, with an exception in very young children. Caregiver report tended to give lower estimates of language ability than what was found using an objectively administered assessment. Appropriate assessments remain difficult to find as a significant percentage of individuals scored at floor when scaled scores were calculated. Further, a sub-group of participants were coded for behavioral response to testing demands, the majority being able to complete a standardized assessment. These results speak to the need for assessments that provide a wider range of items so individuals can both achieve a valid score and demonstrate progress in their attainment of language skills.

Expressive language sampling as a source of outcome measures for treatment studies in fragile X syndrome: feasibility, practice effects, test-retest reliability, and construct validity

BACKGROUND

The evaluation of treatment efficacy for individuals with fragile X syndrome (FXS) or intellectual disability (ID) more generally has been hampered by the lack of adequate outcome measures. We evaluated expressive language sampling (ELS) as a procedure for generating outcome measures for treatment research in FXS. We addressed: (a) feasibility, (b) practice effects over two administrations, (c) test-retest reliability over the repeated administrations, and (d) construct validity. We addressed these issues for the full sample as well as for subgroups defined by age, IQ, and ASD status.

METHODS

Participants were 106 individuals with FXS between ages 6 and 23 years who had IQs within the range of intellectual disability (IQ < 70). ELS procedures for collecting samples in conversation and narration were followed and analyzed separately. Five measures were derived from transcripts segmented into C-units (i.e., an independent clause and its modifiers): number of C-units per minute (talkativeness), number of different word roots (vocabulary), C-unit length in morphemes (syntax), percentage of C-units containing dysfluency (utterance planning), and percentage of C-units that were fully or partly unintelligible (articulatory quality). ELS procedures were administered twice at 4-week intervals for each participant. Standardized tests and informant reports were administered and provided measures for evaluating construct validity of ELS measures.

RESULTS

We found low rates of noncompliance, suggesting the task can be completed meaningfully by most individuals with FXS, although noncompliance was higher for younger, lower IQ, and more autistic participants. Minimal practice effects and strong test-retest reliability over the 4-week interval were observed for the full sample and across the range of ages, IQs, and autism symptom severity. Evidence of convergent construct validity was observed for the measures of vocabulary, syntax, and unintelligibility for the full sample and across the range of IQ and autism symptom severity, but not for participants under age 12. Conversation and narration yielded largely similar results in all analyses.

CONCLUSIONS

The findings suggest that the ELS procedures are feasible and yield measures with adequate psychometric properties for a majority of 6 to 23 years with FXS who have ID. The procedures work equally well regardless of level of ID or degree of ASD severity. The procedures, however, are more challenging and have somewhat less adequate psychometric properties for individuals with FXS under age 12.

A novel eye-tracking paradigm for indexing social avoidance-related behavior in fragile X syndrome

Fragile X syndrome (FXS) is characterized by hallmark features of gaze avoidance, reduced social approach, and social anxiety. The development of therapeutics to manage these symptoms has been hindered, in part, by the lack of sensitive outcome measures. This study investigated the utility of a novel eye-tracking paradigm for indexing social avoidance-related phenotypes. Adolescent/young adult-aged males with FXS (n = 24) and typical development (n = 23) participated in the study. Participants viewed faces displaying direct or averted gaze and the first fixation duration on the eyes was recorded as an index of initial stimulus registration. Fixation durations did not differ across the direction of gaze conditions in either group, although the control group showed longer initial fixations on the eyes relative to the FXS group. Shorter initial fixation on averted gaze in males with FXS was a robust predictor of the severity of their social avoidance behavior exhibited during a social greeting context, whereas parent-reported social avoidance symptoms were not related to performance in the semi-naturalistic context. This eye-tracking paradigm may represent a promising outcome measure for FXS clinical trials because it provides a quantitative index that closely maps onto core social avoidance phenotypes of FXS, can be completed in less than 20 min, and is suitable for use with individuals with low IQ.

A neurophysiological model of speech production deficits in fragile X syndrome

Fragile X syndrome is the most common inherited intellectual disability and monogenic cause of autism spectrum disorder. Expressive language deficits, especially in speech production, are nearly ubiquitous among individuals with fragile X, but understanding of the neurological bases for these deficits remains limited. Speech production depends on feedforward control and the synchronization of neural oscillations between speech-related areas of frontal cortex and auditory areas of temporal cortex. Interaction in this circuitry allows the corollary discharge of intended speech generated from an efference copy of speech commands to be compared against actual speech sounds, which is critical for making adaptive adjustments to optimize future speech. We aimed to determine whether alterations in coherence between frontal and temporal cortices prior to speech production are present in individuals with fragile X and whether they relate to expressive language dysfunction. Twenty-one participants with full-mutation fragile X syndrome (aged 7-55 years, eight females) and 20 healthy controls (matched on age and sex) completed a talk/listen paradigm during high-density EEG recordings. During the talk task, participants repeated pronounced short vocalizations of 'Ah' every 1-2 s for a total of 180 s. During the listen task, participants passively listened to their recordings from the talk task. We compared pre-speech event-related potential activity, N1 suppression to speech sounds, single trial gamma power and fronto-temporal coherence between groups during these tasks and examined their relation to performance during a naturalistic language task. Prior to speech production, fragile X participants showed reduced pre-speech negativity, reduced fronto-temporal connectivity and greater frontal gamma power compared to controls. N1 suppression during self-generated speech did not differ between groups. Reduced pre-speech activity and increased frontal gamma power prior to speech production were related to less intelligible speech as well as broader social communication deficits in fragile X syndrome. Our findings indicate that coordinated pre-speech activity between frontal and temporal cortices is disrupted in individuals with fragile X in a clinically relevant way and represents a mechanism contributing to prominent speech production problems in the disorder.

Vocabulary comprehension in adults with fragile X syndrome (FXS)

BACKGROUND

Receptive and expressive vocabulary in adult and adolescent males with fragile X syndrome (FXS) have been shown as significantly lower than their chronological age; however, receptive vocabulary has been considered a strength relative to mental age. This has not been formally examined, however, and data are needed to compare receptive vocabulary with other language skills and with mental age in individuals with FXS. This is especially important as vocabulary measures are sometimes used as a proxy to estimate language ability.

METHODS

This preliminary study examined receptive vocabulary, global language, and cognitive skills in 42 adults (33 males and 9 females) with FXS as a portion of the baseline evaluation prior to randomization in a clinical trial of ampakine CX516. The battery of standardized tests addressed receptive vocabulary with the Peabody Picture Vocabulary Test, Third Edition (PPVT-III), receptive and expressive language (termed henceforth as global language) via the Preschool Language Scale, Fourth Edition or the Clinical Evaluation of Language Fundamentals, Third Edition, and non-verbal cognition via the Stanford-Binet Intelligence Scales, Fourth Edition (SB-IV).

RESULTS

Results showed (1) significantly higher receptive vocabulary than global language, (2) significantly better receptive vocabulary than non-verbal cognition, (3) equivalent non-verbal cognition and global language, and (4) severity of autism symptomatology was not correlated to receptive vocabulary or global language once non-verbal cognition was removed as factor. The scores from the PPVT-III did not represent the global language skills in our sample of adults with FXS.

CONCLUSIONS

Findings from this investigation strongly suggest that the PPVT-III should not be used as a screening tool for language levels or cognitive function in clinical studies since the scores from the PPVT-III were not representative of global language or non-verbal cognitive skills in adults with intellectual disabilities. This finding is critical in order to understand how to evaluate, as well as to treat, language in individuals with FXS. Development of efficient and appropriate tools to measure language, cognition, and behavior in individuals with FXS is essential.