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

State-of-the-art therapies for fragile X syndrome

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

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.

From wings to whiskers to stem cells: why every model matters in fragile X syndrome research

Fragile X syndrome (FXS) is caused by epigenetic silencing of the X-linked fragile X messenger ribonucleoprotein 1 (FMR1) gene located on chromosome Xq27.3, which leads to the loss of its protein product, fragile X messenger ribonucleoprotein (FMRP). It is the most prevalent inherited form of intellectual disability and the highest single genetic cause of autism. Since the discovery of the genetic basis of FXS, extensive studies using animal models and human pluripotent stem cells have unveiled the functions of FMRP and mechanisms underlying FXS. However, clinical trials have not yielded successful treatment. Here we review what we have learned from commonly used models for FXS, potential limitations of these models, and recommendations for future steps.

A holistic approach to fragile X syndrome integrated guidance for person-centred care

BACKGROUND

The Fragile X community has expressed a desire for centralised, national guidelines in the form of integrated guidance for Fragile X Syndrome (FXS).

METHODS

This article draws on existing literature reviews, primary research and clinical trials on FXS, a Fragile X Society conference workshop and first-hand experience of clinicians who have worked with those living with FXS over many years.

RESULTS

The article scopes proposed integrated guidance over the life course, including appendices of symptoms, comorbidities and referral options for FXS and Fragile X Premutation Associated Conditions.

CONCLUSION

Integrated guidance would provide an authoritative source for doctors, health professionals, therapists, care workers, social workers, educators, employers, families and those living with FXS, so that a holistic, person-centred approach can be taken across the United Kingdom to garner the best outcomes for those with FXS.

Analyzing the Quality of Life in Individuals with Fragile X Syndrome in Relation to Sleep and Mental Health

The purpose of this paper was to examine the physical, emotional, social and school functioning domains of quality of life of individuals with Fragile X Syndrome, in relation to mental health and sleep patterns to gain a better understanding of how these aspects are affected by the disorder. This study included 119 individuals with Fragile X Syndrome who were given different cognitive examinations by a neuropsychologist or by parent-proxy questionnaires. This study focused on the Pediatric Quality of Life Inventory (PedsQoL), the Anxiety, Depression and Mood Scale (ADAMS), the Children's Sleep Habits Questionnaire (CSHQ), but did include other cognitive tests (Vineland Adaptive Behaviour Scales, Nonverbal IQ, Autism Diagnostic Observation Schedule). We identified significant associations between decreases in emotional, social and school domains of PedsQoL and the ADAMS subtests of Generalized Anxiety, Manic/Hyperactivity and Obsessive/Compulsivity, with the subtest of Depressed Mood having associations with lower physical and emotional domains. We also identified a significant impact between CSHQ subtests of Sleep Anxiety, Night Wakings, Daytime Sleepiness, and Parasomnia with the emotional and school domains of PedsQoL. There were associations connecting school functioning with Bedtime Resistance, and additional associations connecting emotional functioning with Sleep Duration and Sleep Onset Delay. Physical functioning was also associated with Sleep Anxiety. Our study shows how mental health and sleep defects impact improper sleep patterns and mental health which leads to decreases in the quality of life for individuals with FXS, and how it is important to screen for these symptoms in order to alleviate issues.

Exploring an objective measure of overactivity in children with rare genetic syndromes

BACKGROUND

Overactivity is prevalent in several rare genetic neurodevelopmental syndromes, including Smith-Magenis syndrome, Angelman syndrome, and tuberous sclerosis complex, although has been predominantly assessed using questionnaire techniques. Threats to the precision and validity of questionnaire data may undermine existing insights into this behaviour. Previous research indicates objective measures, namely actigraphy, can effectively differentiate non-overactive children from those with attention-deficit hyperactivity disorder. This study is the first to examine the sensitivity of actigraphy to overactivity across rare genetic syndromes associated with intellectual disability, through comparisons with typically-developing peers and questionnaire overactivity estimates.

METHODS

A secondary analysis of actigraphy data and overactivity estimates from The Activity Questionnaire (TAQ) was conducted for children aged 4-15 years with Smith-Magenis syndrome (N=20), Angelman syndrome (N=26), tuberous sclerosis complex (N=16), and typically-developing children (N=61). Actigraphy data were summarized using the M10 non-parametric circadian rhythm variable, and 24-hour activity profiles were modelled via functional linear modelling. Associations between actigraphy data and TAQ overactivity estimates were explored. Differences in actigraphy-defined activity were also examined between syndrome and typically-developing groups, and between children with high and low TAQ overactivity scores within syndromes.

RESULTS

M10 and TAQ overactivity scores were strongly positively correlated for children with Angelman syndrome and Smith-Magenis syndrome. M10 did not substantially differ between the syndrome and typically-developing groups. Higher early morning activity and lower evening activity was observed across all syndrome groups relative to typically-developing peers. High and low TAQ group comparisons revealed syndrome-specific profiles of overactivity, persisting throughout the day in Angelman syndrome, occurring during the early morning and early afternoon in Smith-Magenis syndrome, and manifesting briefly in the evening in tuberous sclerosis complex.

DISCUSSION

These findings provide some support for the sensitivity of actigraphy to overactivity in children with rare genetic syndromes, and offer syndrome-specific temporal descriptions of overactivity. The findings advance existing descriptions of overactivity, provided by questionnaire techniques, in children with rare genetic syndromes and have implications for the measurement of overactivity. Future studies should examine the impact of syndrome-related characteristics on actigraphy-defined activity and overactivity estimates from actigraphy and questionnaire techniques.

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 (ABCFX). A 5-class solution yielded the most clinically meaningful, pharmacotherapy independent behavioral groups with distinctive SCQ, SRS-2, and ABCFX profiles, and adequate non-overlap (≥ 71%): "Mild" (31%), "Moderate without Social Impairment" (32%), "Moderate with Social Impairment" (7%), "Moderate with Disruptive Behavior" (20%), and "Severe" (9%). Our findings support FXS subtyping, for improving clinical management and therapeutic development.

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.

Behavioural sleep problems in children and adults with intellectual disabilities: An integrative literature review

BACKGROUND

People with intellectual disabilities are more likely to experience sleep problems, which can affect quality of life, physical health, mental health and well-being.

METHODS

An integrative literature review was conducted to investigate what is known about behavioural sleep disturbances in people with an intellectual disability. The search used the following databases: Scopus, PsycInfo and Cinahl, to find papers published since 2015.

RESULTS

Within intellectual disability research, sleep appears as a common issue due to its high prevalence, negative relationships with an individual's physical and mental health, their quality of life, and impact of sleep problems on family or carers. The growing evidence base appears to support the use of behavioural, lifestyle and pharmacological interventions to improve sleep in people with an intellectual disability.

CONCLUSION

A wide array of literature provides evidence that people with intellectual disabilities are affected by and need support with their sleep.

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

Descriptive analysis of seizures and comorbidities associated with fragile X syndrome

BACKGROUND

Fragile X syndrome is characterized by a myriad of physical features, behavioral features, and medical problems. Commonly found behavioral features are hyperactivity, anxiety, socialization difficulties, and ASD. There is also a higher incidence than in the general population of strabismus, otitis media, and mitral valve prolapse. In addition, one of the most common medical problems associated with FXS is an increased risk of seizures. A subset of individuals carrying the full mutation of the FMR1 gene and diagnosed with fragile X syndrome (FXS) are reported to experience seizures, mostly during the first 10 years of their life span.

METHODS

As part of a larger project to identify genetic variants that modify the risk of seizures, we collected clinical information from 49 carriers with FXS who experienced seizures and 46 without seizures. We compared seizure type and comorbid conditions based on the source of data as well as family history of seizures.

RESULTS

We found that the concordance of seizure types observed by parents and medical specialists varied by type of seizure. The most common comorbid condition among those with seizures was autism spectrum disorder (47% per medical records vs. 33% per parent report compared with 19% among those without seizures per parent report); the frequency of other comorbid conditions did not differ among groups. We found a slightly higher frequency of family members who experienced seizures among the seizure group compared with the nonseizure group.

CONCLUSION

This study confirms previously reported features of seizures in FXS, supports additional genetic factors, and highlights the importance of information sources, altogether contributing to a better understanding of seizures in FXS.

Melatonin Rhythm and Its Relation to Sleep and Circadian Parameters in Children and Adolescents With Autism Spectrum Disorder

Introduction

Sleep problems are prevalent among individuals with autism spectrum disorder (ASD), and a role has been attributed to melatonin in this multifactorial comorbidity.

Methods

A cross-sectional study was conducted on 41 autistic children and adolescents (9.9 ± 3.02) and 24 children and adolescents with a normal intellectual function (8.42 ± 2.43) were used as controls. Subjects were matched for sex, body mass index, and pubertal stage, and all were drug-naive. Circadian and sleep parameters were studied using an ambulatory circadian monitoring (ACM) device, and saliva samples were collected around the onset of sleep to determine dim light melatonin onset (DLMO).

Results

Prepubertal individuals with ASD presented later DLMO and an earlier decline in melatonin during adolescence. A relationship was found between melatonin and both sleep and circadian parameters. Participants and controls with later DLMOs were more likely to have delayed sleep onset times. In the ASD group, subjects with the later daytime midpoint of temperature had a later DLMO. Later melatonin peak time and DLMO time were related to lower general motor activity and lower stability of its rhythms.

Conclusion

The melatonin secretion pattern was different in individuals with ASD, and it showed a relationship with sleep and circadian parameters. Alterations in DLMO have not been previously reported in ASD with the exception of more variable DLMO timing; however, high variability in the study design and sample characteristics prevents direct comparison. The ACM device enabled the measurement of circadian rhythm, a scarcely described parameter in autistic children. When studied in combination with other measures such as melatonin, ACM can offer further knowledge on sleep problems in ASD.

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 (FMR1) 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.gov. While we have reviewed the biological importance of the fragile X mental retardation protein (FMRP), the FXS phenotype, and current diagnosis techniques, the emphasis of this review is on clinical interventions. Early non-pharmacological interventions in combination with pharmacotherapy and targeted treatments aiming to reverse dysregulated brain pathways are the mainstream of treatment in FXS. Overall, early diagnosis and interventions are fundamental to achieve optimal clinical outcomes in FXS.

Sleep disturbances correlate with behavioral problems among individuals with Wiedemann-Steiner syndrome

Wiedemann-Steiner syndrome (WSS) is a rare genetic disorder caused by mutation in KMT2A and characterized by neurodevelopmental delay. This study is the first prospective investigation to examine the sleep and behavioral phenotypes among those with WSS through parent-informant screening inventories. A total of 24 parents of children/adults with WSS (11F, Mean age = 12.71 years, SD = 8.17) completed the Strengths and Difficulties Questionnaire (SDQ) and 22 of these caregivers also completed the Modified Simonds and Parraga Sleep Questionnaire (MSPSQ). On average, the majority of those with WSS (83%) were rated to show borderline to clinical level of behavioral difficulties on the SDQ. Approximately 83% were rated in these ranges for hyperactivity, 63% for emotional problems, and 50% for conduct problems. When applying prior published clinical cut-off for risk of sleep disturbance among those with neurodevelopmental disorders, over 80% of our sample exceeded this limit on the MSPSQ. Largely, caregivers' ratings suggested restless sleep, rigid bedtime rituals, sleep reluctance and breathing through the mouth in sleep were most consistent problems observed. Partial correlations between sleep and behavioral domains showed elevated emotional problems were associated with parasomnia characteristics after controlling for age. Daytime drowsiness and activity were associated with more hyperactivity. Those with more night waking problems and delayed sleep onset were rated to show more severe conduct problems. Overall, these findings suggest dysfunctional sleep behaviors, hyperactivity, and affective problems are part of the neurobehavioral phenotype of WSS. Routine clinical care for those affected by WSS should include close monitoring of sleep and overactive behaviors.