Sleep disturbances in Rett syndrome: Impact and management including use of sleep hygiene practices

The sleep problems in individuals with Rett syndrome and their caregivers

LAY ABSTRACT

Sleep problems are common and impactful among individuals with Rett syndrome (RTT) and their caregivers. We examined the sleep patterns of 29 RTT patients and their primary caregivers using various assessment tools. The study found that a majority of the patients experienced sleep disturbances, with younger patients showing more sleep difficulties. Caregivers also reported poor sleep quality. The findings emphasize the need to address sleep problems in RTT management, as improving sleep quality can positively impact the well-being of individuals with RTT and their caregivers.

Associations between genotype, phenotype and behaviours measured by the Rett syndrome behaviour questionnaire in Rett syndrome

INTRODUCTION

Rett syndrome (RTT) is a rare neurodevelopmental disorder with developmental impairments, comorbidities, and abnormal behaviours such as hand stereotypies and emotional features. The Rett Syndrome Behaviour Questionnaire (RSBQ) was developed to describe the behavioural and emotional features of RTT. Little is known how RSBQ scores are associated with genetic and clinical characteristics in RTT. This study investigated relationships between genotype, age, walking, hand function, sleep, and RSBQ total and subscale scores in RTT.

METHODS

This is a cross-sectional analysis of data collected in the Australian Rett Syndrome Database and the International Rett Syndrome Phenotype Database. Parent caregivers completed the RSBQ and Sleep Disturbance Scale for Children [subscales for disorders of initiating and maintaining sleep (DIMS), disorders of excessive somnolence (DOES)], and provided information on age, variant type, functional abilities (mobility, hand function), seizure frequency and gastrointestinal problems. Associations between the RSBQ scores and the independent variables were modelled using linear regression.

RESULTS

Data were available for 365 individuals with RTT [median (range) age 17.8 (2.9-51.9) years, 2 males]. Compared to adults, 2- to 12-year-old children had higher mean Total, Night-time Behaviour and Fear/Anxiety scores. Compared to individuals with a C-terminal deletion, individuals with the p.Arg255* variant had higher mean Total and Night-time Behaviours scores, whereas the p.Arg294* variant had higher mean Mood scores. Individuals with intermediate mobility and hand function abilities had a higher mean Total score. Total RSBQ and subscale scores were similar across categories for seizures, constipation, and reflux, but were higher with abnormal DIMS and abnormal DOES scores.

CONCLUSION

Except for associations with sleep, the RSBQ measures the behavioural phenotype rather than clinical severity in RTT, as traditionally conceptualised in terms of functional abilities and comorbidities. When designing clinical trials, the RSBQ needs to be complemented by other outcome measures to assess specific core functions and associated comorbidities in RTT.

Burden of illness in Rett syndrome: initial evaluation of a disorder-specific caregiver survey

BACKGROUND

Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder associated with multiple neurologic impairments. Previous studies have shown challenges to the quality of life of individuals with RTT and their caregivers. However, instruments applied to quantify disease burden have not adequately captured the impact of these impairments on affected individuals and their families. Consequently, an international collaboration of stakeholders aimed at evaluating Burden of Illness (BOI) in RTT was organized.

METHODS

Based on literature reviews and qualitative interviews with parents of children and adults with RTT, a caregiver questionnaire was constructed to evaluate 22 problems (inclusive of core characteristics, functional impairments, and comorbidities) often experienced with RTT, rated mainly with a 5-level Likert scale. The questionnaire was administered anonymously online to an international sample of 756 caregivers (predominantly parents) of girls and women with RTT. Descriptive statistics were used to identify problems of high frequency and impact on affected individuals and caregivers. Chi-square tests characterized the relationship between problem severity and impact responses, while nonparametric ANOVAs of raw and z-score adjusted scores identified agreement between severity and impact on individual and caregiver. Secondary inferential tests were used to determine the roles of age, clinical type, and country of residence on BOI in RTT.

RESULTS

There was variability in reported frequency of problems, with the most prevalent, severe and impactful being those related to the core features of RTT (i.e., communication and fine and gross motor impairments). Chi-square analyses demonstrated interdependence between severity and impact responses, while ANOVAs showed that many problems had disproportionately greater impact than severity, either on affected individuals (e.g., hand stereotypies) or their caregivers (e.g., sleep difficulties, seizures, pain, and behavioral abnormalities). With certain exceptions (e.g., breath-holding, seizures), age, clinical type, or country of residence did not influence these BOI profiles.

CONCLUSIONS

Our data demonstrate that core features and related impairments are particularly impactful in RTT. However, problems with mild severity can also have disproportionate impact on affected individuals and, particularly, on their caregivers. Future analyses will examine the role of factors such as treatment outcomes, healthcare services, and healthcare provider's perspectives, in these BOI profiles.

A clinical-translational review of sleep problems in neurodevelopmental disabilities

Sleep disorders are very common across neurodevelopmental disorders and place a large burden on affected children, adolescents, and their families. Sleep disturbances seem to involve a complex interplay of genetic, neurobiological, and medical/environmental factors in neurodevelopmental disorders. In this review, we discuss animal models of sleep problems and characterize their presence in two single gene disorders, Rett Syndrome, and Angelman Syndrome and two more commonly occurring neurodevelopmental disorders, Down Syndrome, and autism spectrum disorders. We then discuss strategies for novel methods of assessment using wearable sensors more broadly for neurodevelopmental disorders in general, including the importance of analytical validation. An increased understanding of the mechanistic contributions and potential biomarkers of disordered sleep may offer quantifiable targets for interventions that improve overall quality of life for affected individuals and their families.

The intersection of sleep and synaptic translation in synaptic plasticity deficits in neurodevelopmental disorders

Individuals with neurodevelopmental disorders experience persistent sleep deficits, and there is increasing evidence that sleep dysregulation is an underlying cause, rather than merely an effect, of the synaptic and behavioral defects observed in these disorders. At the molecular level, dysregulation of the synaptic proteome is a common feature of neurodevelopmental disorders, though the mechanism connecting these molecular and behavioral phenotypes is an ongoing area of investigation. A role for eIF2α in shifting the local proteome in response to changes in the conditions at the synapse has emerged. Here, we discuss recent progress in characterizing the intersection of local synaptic translation and sleep and propose a reciprocal mechanism of dysregulation in the development of synaptic plasticity defects in neurodevelopmental disorders.

Healthy sleep practices for shift workers: consensus sleep hygiene guidelines using a Delphi methodology

STUDY OBJECTIVES

The unique requirements of shift work, such as sleeping and working at variable times, mean that current sleep hygiene guidelines may be inappropriate for shift workers. Current guidelines may also contradict fatigue management advice (e.g. advising against daytime napping). The present study utilized a Delphi methodology to determine expert opinion regarding the applicability of current guidelines for shift workers, the appropriateness of the term "sleep hygiene," and develop tailored guidelines for shift workers.

METHODS

The research team reviewed current guidelines and existing evidence to draft tailored guidelines. Seventeen individual guidelines, covering sleep scheduling, napping, sleep environment, bedtime routine, substances, light exposure, diet, and exercise were drafted. Experts from sleep, shift work, and occupational health fields (n = 155) were invited to review the draft guidelines using a Delphi methodology. In each round, experts voted on individual guidelines, with 70% agreement considered consensus. Where consensus was not reached, written feedback from experts was discussed and incorporated into subsequent iterations.

RESULTS

Of the experts invited, 68 (44%) agreed to participate, with 55 (35%) completing the third (final) round. Most experts (84%) agreed that tailored guidelines were required for shift workers. Consensus was reached on all guidelines after three rounds. One additional guideline (sleep inertia) and an introductory statement were developed, resulting in a final set of 18 individual guidelines, termed "healthy sleep practices for shift workers."

CONCLUSIONS

This is the first study to develop tailored sleep hygiene guidelines for shift workers. Future research should investigate the acceptability and effectiveness of these guidelines amongst shift workers.

Genotype and sleep independently predict mental health in Rett syndrome: an observational study

BACKGROUND

Rett syndrome is a genetically caused neurodevelopmental disorder associated with severe impairments and complex comorbidities. This study examined predictors of anxiety and depression in Rett syndrome, including genotype.

METHODS

The International Rett Syndrome Database, InterRett, was the data source for this observational study. Associations between genotype, functional abilities, comorbidities, anxiety and depression were estimated with univariate and multivariate regression models. An additional regression model for anxiety included use of an anxiety medication as a predictor variable.

RESULTS

The sample included 210 individuals aged 6-51 years of whom 54 (25.7%) were on psychotropic medication for anxiety or depression. Individuals with the p.Arg294* variant had the highest anxiety scores, as did those with insomnia or excessive daytime sleepiness, irrespective of anxiety medication use. Individuals with the p.Arg306Cys variant had the lowest depression scores, as did those with insomnia or excessive daytime sleepiness.

CONCLUSION

Findings indicated that genotype and sleep have implications for mental health in Rett syndrome, suggesting that anticipatory guidance and proactive management of poor sleep could improve mental health. More research is needed to understand the effects of psychometric medications, which cannot be inferred from this cross-sectional study.

Natural Course of IQSEC2-Related Encephalopathy: An Italian National Structured Survey

Pathogenic loss-of-function variants in the IQ motif and SEC7 domain containing protein 2 (IQSEC2) gene cause intellectual disability with Rett syndrome (RTT)-like features. The aim of this study was to obtain systematic information on the natural history and extra-central nervous system (CNS) manifestations for the Italian IQSEC2 population (>90%) by using structured family interviews and semi-quantitative questionnaires. IQSEC2 encephalopathy prevalence estimate was 7.0 to 7.9 × 10-7. Criteria for typical RTT were met in 42.1% of the cases, although psychomotor regression was occasionally evidenced. Genetic diagnosis was occasionally achieved in infancy despite a clinical onset before the first 24 months of life. High severity in both the CNS and extra-CNS manifestations for the IQSEC2 patients was documented and related to a consistently adverse quality of life. Neurodevelopmental delay was diagnosed before the onset of epilepsy by 1.8 to 2.4 years. An earlier age at menarche in IQSEC2 female patients was reported. Sleep disturbance was highly prevalent (60 to 77.8%), with mandatory co-sleeping behavior (50% of the female patients) being related to de novo variant origin, younger age, taller height with underweight, better social interaction, and lower life quality impact for the family and friends area. In conclusion, the IQSEC2 encephalopathy is a rare and likely underdiagnosed developmental encephalopathy leading to an adverse life quality impact.

The clinical and sleep manifestations in children with FOXG1 syndrome

FOXG1 syndrome is a rare neurodevelopmental disorder associated with severe cognitive dysfunction, autistic behavior, and early-onset hyperkinetic movement disorders. Patients have also been reported to experience sleep disturbances. However, these findings are mainly based on subjective caregivers' reports, and limited by small case numbers. Moreover, no studies using objective evaluation tools, such as actigraphy, have been reported. We analyzed the clinical and sleep manifestations of children with FOXG1 syndrome registered in the International FOXG1 Research Foundation registry database. A total of 258 individuals with FOXG1 syndrome were included in this research. 132 (51.16%) had sleep disturbances. The more impaired of language acquisitions (absence of speech, OR: 3.99, 95%CI = 1.69-9.42, p = 0.002), hyperkinetic movement disorders (OR: 2.64, 95%CI = 1.34-5.20 p = 0.005) and feeding difficulties (OR: 2.81, 95% CI = 1.52-5.19, p = 0.001) were significantly associated with an increase in odds of sleep disturbance after adjusting for age, sex, and antiepileptic drugs. We also performed sleep studies on six individuals with FOXG1 syndrome using The Children's Sleep Habits Questionnaire (CSHQ), the Sleep Disturbance Scale for Children (SDSC), and 7-day data from Actiwatch. The Pittsburgh Sleep Quality Index (PSQI) and 7-day data from Actiwatch were also used to evaluate the sleep condition of their parents. The CSHQ scores revealed bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night-waking, and parasomnia. Sleep-wake transition disorders and disorders of initiating and maintaining sleep were also suggested by the SDSC scores. The children's actigraphy revealed short sleep durations, impaired sleep efficiency, longer wake after sleep onset, and frequent night-waking. All caregivers reported significantly higher PSQI scores, mildly declined sleep efficiency, and shorter total sleep duration. Sleep disturbances, especially in initiating and maintaining sleep, are common in individuals with FOXG1 syndrome and their caregivers. Sleep disorders in patients with FOXG1 syndrome and their caregivers should be investigated.

A circuit-level biomarker of Rett syndrome based on ectopic phase-amplitude coupling during slow-wave-sleep

Rett syndrome (RTT) is a neurodevelopmental disorder characterized by loss of purposeful hand use and spoken language following an initial period of normal development. Although much is known about the genetic and molecular underpinnings of RTT, less is known about the circuit-level etiopathology. Coupling of oscillations during slow-wave-sleep (SWS) underlies important neurocognitive processes in adulthood, yet its emergence has yet to be described in early typical development (TD) or in RTT. We therefore addressed these unknowns by describing SWS cross-frequency coupling in both RTT and early TD using a retrospective study design. We found that in TD, phase-amplitude coupling (PAC) during SWS was dominated by coupling of slow-wave (0.5-2 Hz) phase to theta amplitude (5-8 Hz, "SW:T") as well as slow-wave to spindle-range (12-15 Hz, "SW:S"). Coupling exhibited characteristic vertex-prominent spatial topography, which emerged during an early developmental window. This topography failed to develop in patients with RTT due to persistent ectopic coupling. Furthermore, we found that subtypes of RTT exhibit distinct PAC topographic profiles, and that ectopic PAC correlates with clinical severity. These findings suggest that altered PAC dynamics and spatial organization during SWS may underlie the circuit-level pathophysiology of RTT and suggest that ectopic coupling may contribute to RTT pathogenesis.

Feasibility of wearable devices and machine learning for sleep classification in children with Rett syndrome: A pilot study

Sleep is vital to many processes involved in the well-being and health of children; however, it is estimated that 80% of children with Rett syndrome suffer from sleep disorders. Caregiver reports and questionnaires, which are the current method of studying sleep, are prone to observer bias and missed information. Polysomnography is considered the gold standard for sleep analysis but is labor and cost-intensive and limits the frequency of data collection for sleep disorder studies. Wearable digital health technologies, such as actigraphy devices, have shown potential and feasibility as a method for sleep analysis in Rett syndrome, but have not been validated against polysomnography. Furthermore, the collected accelerometer data has limitations due to the rigidity, periodic limb movement, and involuntary muscle contractions prevalent in Rett syndrome. Heart rate and electrodermal activity, along with other physiological signals, have been linked to sleep stages and can be utilized with machine learning to provide better resistance to noise and false positives than actigraphy. This research aims to address the gap in Rett syndrome sleep analysis by comparing the performance of a machine learning model utilizing both accelerometer data and physiological data features to the gold-standard polysomnography for sleep analysis in Rett syndrome. Our analytical validation pilot study (n = 7) found that using physiological and accelerometer features, our machine learning models can differentiate between awake, non-rapid eye movement sleep, and rapid eye movement sleep in Rett syndrome children with an accuracy of 85.1% when using an individual model. Additionally, this work demonstrates that it is feasible to use digital health technologies in Rett syndrome, even at a young age, without data loss or interference from repetitive movements that are characteristic of Rett syndrome.

Negative impact of insomnia and daytime sleepiness on quality of life in individuals with the cyclin-dependent kinase-like 5 deficiency disorder

Cyclin-dependent kinase-like 5 (CDKL5) gene pathogenic variants result in CDKL5 deficiency disorder (CDD). Early onset intractable epilepsy and severe developmental delays are prominent symptoms of CDD. Comorbid sleep disturbances are a major concerning symptom for families. We aimed to explore the relationship between insomnia, daytime sleepiness, sleep medications and quality of life in children with CDD. Caregivers of 129 children with CDD in the International CDKL5 Disorder Database completed the Quality-of-Life Inventory-Disability (QI-Disability) questionnaire and "Disorders of Maintaining Sleep" (DIMS) and the "Disorders of Excessive Somnolence" (DOES) items of the Sleep Disturbance Scale for Children. Adjusting for covariates, a unit increase in DOES score was associated with reduced quality of life total (coefficient -3.06, 95% confidence interval [CI] 1.35-7.80), physical health (coefficient -7.20, 95% CI -10.64, -3.76) and negative emotions (coefficient -3.90, 95% CI -7.38, -0.42) scores. Adjusting for covariates, a unit increase in DIMS score was associated with reduced negative emotions (coefficient -6.02, 95% CI -10.18, -2.86). Use of sleep medications had small influences on the effect sizes. This study highlights the importance of sleep problems as a determinant of quality of life in children with CDD, consistent with effects observed for other groups of children with intellectual disability. Excessive daytime sleepiness was particularly associated with detrimental effects on quality of life. Further research in optimal behavioural and pharmaceutical management of sleep problems for this population is required.

A meta-review of standard polysomnography parameters in Rett Syndrome

Rett Syndrome (RTT, OMIM 312750), a unique rare neurodevelopmental disorder, mostly affects females and causes severe multi-disabilities including poor sleep. This meta-analysis systematically reviewed the polysomnographic (PSG) data of individuals with RTT on both sleep macrostructure and sleep respiratory indexes and compared them to literature normative values. Studies were collected from PubMed, Web of Science, PsycINFO, Ebsco, Scopus, and Cochrane Library till 26 April 2022. Across 13 included studies, the 134 selected RTT cases were mostly females being MECP2 (n = 41) and CDKL5 (n = 4) positive. They were further stratified by gene, age, and clinical features. Findings of comparison with literature normative values suggested shorter total sleep time (TST) and sleep onset latency (SOL), twice as long wake after sleep onset (WASO) with lower sleep efficiency (SEI) in RTT, as well as increased non-rapid eye movement stage 3 (stage N3) and decreased rapid eye movement sleep. Based on limited data per stratifications, we found in RTT cases <5 years old lower stage N3, and in RTT cases >5 years old less WASO and more WASO in the epileptic strata. However, meta-results generated from studies designed with comparison groups only showed lower stage N1 in RTT than in healthy comparison, together with similar SEI and stage N3 to primary snoring subjects. For sleep respiratory indexes, severe disordered sleep breathing was confirmed across roughly all RTT strata. We are the first study to meta-analyze PSG data of subjects with RTT, illustrating shorter TST and aberrant sleep staging in RTT that may vary with age or the presence of epilepsy. Severe nocturnal hypoxemia with apneic events was also demonstrated. More studies are needed to explore and elucidate the pathophysiological mechanisms of these sleep findings in the future.

Breathing Abnormalities During Sleep and Wakefulness in Rett Syndrome: Clinical Relevance and Paradoxical Relationship With Circulating Pro-oxidant Markers

Background

Breathing abnormalities are common in Rett syndrome (RTT), a pervasive neurodevelopmental disorder almost exclusively affecting females. RTT is linked to mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Our aim was to assess the clinical relevance of apneas during sleep-wakefulness cycle in a population with RTT and the possible impact of apneas on circulating oxidative stress markers.

Methods

Female patients with a clinical diagnosis of typical RTT (n = 66), MECP2 gene mutation, and apneas were enrolled (mean age: 12.5 years). Baseline clinical severity, arterial blood gas analysis, and red blood cell count were assessed. Breathing was monitored during the wakefulness and sleep states (average recording time: 13 ± 0.5 h) with a portable polygraphic screening device. According to prevalence of breath holdings, the population was categorized into the wakefulness apnea (WA) and sleep apnea (SA) groups, and apnea-hypopnea index (AHI) was calculated. The impact of respiratory events on oxidative stress was assessed by plasma and intra-erythrocyte non-protein-bound iron (P-NPBI and IE-NPBI, respectively), and plasma F2-isoprostane (F2-IsoP) assays.

Results

Significant prevalence of obstructive apneas with values of AHI &gt; 15 was present in 69.7% of the population with RTT. The group with SA showed significantly increased AHI values &gt; 15 (p = 0.0032), total breath holding episodes (p = 0.007), and average SpO2 (p = 0.0001) as well as lower nadir SpO2 (p = 0.0004) compared with the patients with WAs. The subgroups of patients with WA and SA showed no significant differences in arterial blood gas analysis variables (p &gt; 0.089). Decreased mean cell hemoglobin (MCH) (p = 0.038) was observed in the group with WAs. P-NPBI levels were significantly higher in the group with WA than in that with SAs (p = 0.0001). Stepwise multiple linear regression models showed WA being related to nadir SpO2, average SpO2, and P-NPBI (adjusted R2 = 0.613, multiple correlation coefficient = 0.795 p &lt; 0.0001), and P-NPBI being related to average SpO2, blood PaCO2, red blood cell mean corpuscular volume (MCV), age, and topiramate treatment (adjusted R2 = 0.551, multiple correlation coefficient = 0.765, p &lt; 0.0001).

Conclusion

Our findings indicate that the impact of apneas in RTT is uneven according to the sleep-wakefulness cycle, and that plasma redox active iron represents a potential novel therapeutic target.

Sleep Disorders in Rett Syndrome and Rett-Related Disorders: A Narrative Review

Rett Syndrome (RTT) is a rare and severe X-linked developmental brain disorder that occurs primarily in females, with a ratio of 1:10.000. De novo mutations in the Methyl-CpG Binding protein 2 (MECP2) gene on the long arm of X chromosome are responsible for more than 95% cases of classical Rett. In the remaining cases (atypical Rett), other genes are involved such as the cyclin-dependent kinase-like 5 (CDKL5) and the forkhead box G1 (FOXG1). Duplications of the MECP2 locus cause MECP2 duplication syndrome (MDS) which concerns about 1% of male patients with intellectual disability. Sleep disorders are common in individuals with intellectual disability, while the prevalence in children is between 16 and 42%. Over 80% of individuals affected by RTT show sleep problems, with a higher prevalence in the first 7 years of life and some degree of variability in correlation to age and genotype. Abnormalities in circadian rhythm and loss of glutamate homeostasis play a key role in the development of these disorders. Sleep disorders, epilepsy, gastrointestinal problems characterize CDKL5 Deficiency Disorder (CDD). Sleep impairment is an area of overlap between RTT and MECP2 duplication syndrome along with epilepsy, regression and others. Sleep dysfunction and epilepsy are deeply linked. Sleep deprivation could be an aggravating factor of epilepsy and anti-comitial therapy could interfere in sleep structure. Epilepsy prevalence in atypical Rett syndrome with severe clinical phenotype is higher than in classical Rett syndrome. However, RTT present a significant lifetime risk of epilepsy too. Sleep disturbances impact on child's development and patients' families and the evidence for its management is still limited. The aim of this review is to analyze pathophysiology, clinical features, the impact on other comorbidities and the management of sleep disorders in Rett syndrome and Rett-related syndrome.

Literature Cases Summarized Based on Their Polysomnographic Findings in Rett Syndrome

Rett syndrome (RTT) is a severe and rare neurodevelopmental disorder affecting mostly girls. In RTT, an impaired sleep pattern is a supportive criterion for the diagnosis, yet little is known regarding the sleep structure and sleep respiratory events. Aiming to delineate sleep by aggregating RTT case (series) data from published polysomnographic studies, seventy-four RTT cases were collected from eleven studies up until 6 February 2022 (PROSPERO: CRD 42020198099). We compared the polysomnographic data within RTT stratifications and to a typically developing population. MECP2 cases demonstrated shortened total sleep time (TST) with increased stage N3 and decreased REM sleep. In cases with CDKL5 mutations, TST was longer and they spent more time in stage N1 but less in stage N3 than those cases affected by MECP2 mutations and a typically developing population. Sleep-disordered breathing was confirmed by the abnormal apnea/hypopnea index of 11.92 ± 23.67/h TST in these aggregated cases. No association of sleep structure with chronological age was found. In RTT, the sleep macrostructure of MECP2 versus CDKL5 cases showed differences, particularly regarding sleep stage N3. A severe REM sleep propensity reduction was found. Aberrant sleep cycling, possibly characterized by a poor REM ‘on switch’ and preponderance in slow and high-voltage sleep, is proposed.

Improving clinical trial readiness to accelerate development of new therapeutics for Rett syndrome

Rett syndrome is associated with severe functional impairments and many comorbidities, each in urgent need of treatments. Mutations in the MECP2 gene were identified as causing Rett syndrome in 1999. Over the past 20 years there has been an abundance of preclinical research with some studies leading to human clinical trials. Despite this, few viable therapeutic options have emerged from this investment of effort. Reasons for this lack of success as they relate both to preclinical research and the clinical trial landscape are discussed. Considering what needs to be done to promote further success in the field, we take a positive and constructive approach and introduce the concept of clinical trial readiness and its necessary ingredients for Rett syndrome. These include: listening to the needs of families; support from advocacy groups; optimising use of existing clinic infrastructures and available natural history data; and, finally, the validation of existing outcome measures and/or the development and validation of new measures. We conclude by reiterating the need for a collaborative and coordinated approach amongst the many different stakeholder groups and the need to engage in new types of trial design which could be much more efficient, less costly and much less burdensome on families.

Evaluating Sleep Disturbances in Children With Rare Genetic Neurodevelopmental Syndromes

BACKGROUND

Adequate sleep is important for proper neurodevelopment and positive health outcomes. Sleep disturbances are more prevalent in children with genetically determined neurodevelopmental syndromes compared with typically developing counterparts. We characterize sleep behavior in Rett (RTT), Angelman (AS), and Prader-Willi (PWS) syndromes to identify effective approaches for treating sleep problems in these populations. We compared sleep-related symptoms across individuals with these different syndromes with each other, and with typically developing controls.

METHODS

Children were recruited from the Rare Diseases Clinical Research Network consortium registries; unaffected siblings were enrolled as related controls. For each participant, a parent completed multiple sleep questionnaires including Pediatric Sleep Questionnaire (Sleep-Disordered Breathing), Children's Sleep Habits Questionnaire (CSHQ), and Pediatric Daytime Sleepiness Scale.

RESULTS

Sleep data were analyzed from 714 participants, aged two to 18 years. Young children with AS had more reported sleep problems than children with RTT or PWS. Older children with RTT had more reported daytime sleepiness than those with AS or PWS. Finally, all individuals with RTT had more evidence of sleep-disordered breathing when compared with individuals with PWS. Notably, typically developing siblings were also reported to have sleep problems, except for sleep-related breathing disturbances, which were associated with each of the genetic syndromes.

CONCLUSIONS

Individuals with RTT, AS, and PWS frequently experience sleep problems, including sleep-disordered breathing. Screening for sleep problems in individuals with these and other neurogenetic disorders should be included in clinical assessment and managements. These data may also be useful in developing treatment strategies and in clinical trials.

Proteomic and transcriptional changes associated with MeCP2 dysfunction reveal nodes for therapeutic intervention in Rett syndrome

Mutations in the methyl-CpG binding protein 2 (MECP2) gene cause Rett syndrome (RTT), an X-linked neurodevelopmental disorder predominantly impacting females. MECP2 is an epigenetic transcriptional regulator acting mainly to repress gene expression, though it plays multiple gene regulatory roles and has distinct molecular targets across different cell types and specific developmental stages. In this review, we summarize MECP2 loss-of-function associated transcriptome and proteome disruptions, delving deeper into the latter which have been comparatively severely understudied. These disruptions converge on multiple biochemical and cellular pathways, including those involved in synaptic function and neurodevelopment, NF-κB signaling and inflammation, and the vitamin D pathway. RTT is a complex neurological disorder characterized by myriad physiological disruptions, in both the central nervous system and peripheral systems. Thus, treating RTT will likely require a combinatorial approach, targeting multiple nodes within the interactomes of these cellular pathways. To this end, we discuss the use of dietary supplements and factors, namely, vitamin D and polyunsaturated fatty acids (PUFAs), as possible partial therapeutic agents given their demonstrated benefit in RTT and their ability to restore homeostasis to multiple disrupted cellular pathways simultaneously. Further unravelling the complex molecular alterations induced by MECP2 loss-of-function, and contextualizing them at the level of proteome homeostasis, will identify new therapeutic avenues for this complex disorder.

Determinants of sleep problems in children with intellectual disability

Children with intellectual disabilities are more likely to experience sleep disorders of insomnia, excessive daytime sleepiness and sleep breathing disorders than typically developing children. The present study examined risk factors for these sleep disorders in 447 children (aged 5-18 years), diagnosed with an intellectual disability and comorbid autism spectrum disorder, cerebral palsy, Down syndrome or Rett syndrome. Primary caregivers reported on their child's sleep using the Sleep Disturbance Scale for Children (SDSC), as well as medical comorbidities and functional abilities. Multivariate linear and logistic regressions were used to examine the effects of these factors on SDSC t scores and a binary indicator, respectively for the relevant subscales. Receiving operating characteristic curves were generated for each logistic regression model to determine their ability to discriminate between poor and good sleep. Comorbidities rather than functional abilities were associated with poorer sleep. In particular, recurrent pain, frequent seizures, frequent coughing, constipation and prescription of sleep medications were associated with abnormal sleep across the entire sample, but predictors differed between diagnostic groups. The present study suggests that comorbidities are more strongly associated with quality of sleep than functional impairments. The present study provides new information on potential associations between frequent coughing, prescription sleep medications and sleep quality that should be further investigated.

Tubulin Polymerization Promoting Protein Affects the Circadian Timing System in C57Bl/6 Mice

The circadian timing system (CTS) is a complex set of cyclic cellular mechanisms which serve to synchronize discrete cell groups across multiple organ systems to adapt the bodys physiology to a (roughly) 24-hour clock. Many genes and hormones have been shown to be strongly associated with the CTS, some of which include the genes Bmal1, Period1, Period2, Cryptochrome1, and Cryptochrome2, and the hormone melatonin. Previous data suggest that microtubule dynamics play an important role in melatonin function as it relates to the CTS in vitro, though this relationship has never been explored in vivo. The purpose of this study was to determine whether disruption of microtubule regulation in C57Bl/6 mice results in measurable changes to the CTS. To study the potential effects of microtubule dynamics on the CTS in vivo, we utilized a mouse model of microtubule instability, knocked out for the tubulin polymerization promoting protein gene (Tppp -/-), comparing them to their wild type (WT) littermates in three categories: locomotor activity (in light/dark and dark/dark photoperiods), serial clock gene expression, and serial serum melatonin concentration. These comparisons showed differences in all three categories, including significant differences in locomotor characteristics under dark/dark conditions. Our findings support and extend previous reports that microtubule dynamics are a modulator of circadian rhythm regulation likely through a mechanism involving melatonin induced phase shifting.

The effect of functioning on Quality of Life Inventory-Disability measured quality of life is not mediated or moderated by parental psychological distress

PURPOSE

The measurement of quality of life (QOL) in children with intellectual disability often relies upon proxy report via caregivers. The current study investigated whether caregiver psychological distress mediates or moderates the effects of impairment on their ratings of QOL in children with intellectual disability.

METHODS

Caregivers of 447 children with an intellectual disability reported their child's day-to-day functioning, their own psychological distress using the Kessler Psychological Distress Scale, and the Quality of Life Inventory-Disability (QI-Disability), a measure of QOL for proxy report of a child's observable behaviours that indicate quality of life. Linear regression was used to assess the effects of the child's functional abilities on their QI-Disability score and causal mediation analysis to estimate the extent to which these effects were mediated by caregivers' psychological distress.

RESULTS

A minority of caregivers (n = 121, 27.1%) reported no psychological distress. Lower day-to-day functional abilities, such as being fully dependent on others to manage their personal needs were associated with lower total QOL scores. There was no significant mediation effect of caregiver psychological distress on the association between child functioning and total QOL scores. Moderation analyses revealed small and largely nonsignificant interaction coefficients, indicating that caregiver psychological distress did not influence the strength of the relationship between child functioning and total QOL scores.

CONCLUSION

Caregiver psychological distress did not mediate or moderate the relationship between the level of functional abilities and QOL in children with intellectual disability. QI-Disability measured observable child behaviours which may reduce the influence of caregiver factors on the accurate measure of QOL for children with intellectual disability.

Phenotypes in adult patients with Rett syndrome: results of a 13-year experience and insights into healthcare transition

BACKGROUND

Rett syndrome is a complex genetic disorder with age-specific manifestations and over half of the patients surviving into middle age. However, little information about the phenotype of adult individuals with Rett syndrome is available, and mainly relies on questionnaires completed by caregivers. Here, we assess the clinical manifestations and management of adult patients with Rett syndrome and present our experience in transitioning from the paediatric to the adult clinic.

METHODS

We analysed the medical records and molecular data of women aged ≥18 years with a diagnosis of classic Rett syndrome and/or pathogenic variants in MECP2, CDKL5 and FOXG1, who were in charge of our clinic.

RESULTS

Of the 50 women with classic Rett syndrome, 94% had epilepsy (26% drug-resistant), 20% showed extrapyramidal signs, 40% sleep problems and 36% behavioural disorders. Eighty-six % patients exhibited gastrointestinal problems; 70% had scoliosis and 90% low bone density. Breathing irregularities were diagnosed in 60%. None of the patients had cardiac issues. CDKL5 patients experienced fewer breathing abnormalities than women with classic Rett syndrome.

CONCLUSION

The delineation of an adult phenotype in Rett syndrome demonstrates the importance of a transitional programme and the need of a dedicated multidisciplinary team to optimise the clinical management of these patients.

Sleep problems in Rett syndrome animal models: A systematic review

Due to the discovery of Rett Syndrome (RTT) genetic mutations, animal models have been developed. Sleep research in RTT animal models may unravel novel neural mechanisms for this severe neurodevelopmental heritable rare disease. In this systematic literature review we summarize the findings on sleep research of 13 studies in animal models of RTT. We found disturbed efficacy and continuity of sleep in all genetically mutated models of mice, cynomolgus monkeys, and Drosophila. Models presented highly fragmented sleep with distinct differences in 24-hr sleep/wake cyclicity and circadian arrhythmicity. Overall, animal models mimic sleep complaints reported in individuals with RTT. However, contrary to human studies, in mutant mice, attenuated sleep delta waves, and sleep apneas in non-rapid eye movement sleep were reported. Future studies may focus on sleep structure and EEG alterations, potential central mechanisms involved in sleep fragmentation and the occurrence of sleep apnea across different sleep stages. Given that locomotor dysfunction is characteristic of individuals with RTT, studies may consider to integrate its potential impact on the behavioral analysis of sleep.

Multisystem comorbidities in classic Rett syndrome: a scoping review

BACKGROUND

Rett syndrome (RTT) is a severe, progressive neurodevelopmental disorder with multisystem comorbidities that evolve across a patient's lifespan requiring attentive coordination of subspecialty care by primary care providers. A comprehensive, up-to-date synthesis of medical comorbidities in RTT would aid care coordination and anticipatory guidance efforts by healthcare providers. Our objective was to review and summarise published evidence regarding prevalence of RTT medical comorbidities across all relevant organ systems.

METHODS

Search of PubMed from January 2000 to July 2019 was performed using the search terms (Rett and MECP2 AND patient) OR (Rett and MECP2 AND cohort). Articles reporting the prevalence of clinical findings in RTT were assessed with respect to the size and nature of the cohorts interrogated and their relevance to clinical care.

RESULTS

After review of over 800 records, the multisystem comorbidities of RTT were summarised quantitatively from 18 records comprising both retrospective and prospective cohorts (31-983 subjects). Neurological comorbidities had the highest prevalence, occurring in nearly all individuals with gastrointestinal and orthopaedic concerns almost as prevalent as neurological. With the exception of low bone mineral content which was relatively common, endocrine comorbidities were seen in only around one-third of patients. Although more prevalent compared with the general population, cardiac conduction abnormalities were the least common comorbidity in RTT.

CONCLUSIONS

Effective care coordination for RTT requires knowledge of and attention to multiple comorbidities across multiple unrelated organ systems. Many issues common to RTT can potentially be managed by a primary care provider but the need for sub-specialist referral can be anticipated. Since the median life expectancy extends into the sixth decade with evolving subspecialty requirements throughout this time, paediatric providers may be tasked with continued coordination of these comorbidities or transitioning to adult medicine and specialists with experience managing individuals with complex medical needs.

Advances in understanding of Rett syndrome and MECP2 duplication syndrome: prospects for future therapies

The X-linked gene encoding MECP2 is involved in two severe and complex neurodevelopmental disorders. Loss of function of the MeCP2 protein underlies Rett syndrome, whereas duplications of the MECP2 locus cause MECP2 duplication syndrome. Research on the mechanisms by which MeCP2 exerts effects on gene expression in neurons, studies of animal models bearing different disease-causing mutations, and more in-depth observations of clinical presentations have clarified some issues even as they have raised further questions. Yet there is enough evidence so far to suggest possible approaches to therapy for these two diseases that could go beyond attempting to address specific signs and symptoms (of which there are many) and instead target the pathophysiology underlying MECP2 disorders. Further work could bring antisense oligonucleotides, deep brain stimulation, and gene therapy into the clinic within the next decade or so.

Consensus guidelines on managing Rett syndrome across the lifespan

BACKGROUND

Rett syndrome (RTT) is a severe neurodevelopmental disorder with complex medical comorbidities extending beyond the nervous system requiring the attention of health professionals. There is no peer-reviewed, consensus-based therapeutic guidance to care in RTT. The objective was to provide consensus on guidance of best practice for addressing these concerns.

METHODS

Informed by the literature and using a modified Delphi approach, a consensus process was used to develop guidance for care in RTT by health professionals.

RESULTS

Typical RTT presents early in childhood in a clinically recognisable fashion. Multisystem comorbidities evolve throughout the lifespan requiring coordination of care between primary care and often multiple subspecialty providers. To assist health professionals and families in seeking best practice, a checklist and detailed references for guidance were developed by consensus.

CONCLUSIONS

The overall multisystem issues of RTT require primary care providers and other health professionals to manage complex medical comorbidities within the context of the whole individual and family. Given the median life expectancy well into the sixth decade, guidance is provided to health professionals to achieve current best possible outcomes for these special-needs individuals.

Rett Syndrome and CDKL5 Deficiency Disorder: From Bench to Clinic

Rett syndrome (RTT) and CDKL5 deficiency disorder (CDD) are two rare X-linked developmental brain disorders with overlapping but distinct phenotypic features. This review examines the impact of loss of methyl-CpG-binding protein 2 (MeCP2) and cyclin-dependent kinase-like 5 (CDKL5) on clinical phenotype, deficits in synaptic- and circuit-homeostatic mechanisms, seizures, and sleep. In particular, we compare the overlapping and contrasting features between RTT and CDD in clinic and in preclinical studies. Finally, we discuss lessons learned from recent clinical trials while reviewing the findings from pre-clinical studies.