Sleep disturbance in Sanfilippo syndrome: a parental questionnaire study

Causes of death in mucopolysaccharidoses

Mucopolysaccharidoses are inherited metabolic diseases caused by mutations in genes encoding enzymes required for degradation of glycosaminoglycans. A lack or severe impairment of activity of these enzymes cause accumulation of GAGs which is the primary biochemical defect. Depending on the kind of the deficient enzyme, there are 12 types and subtypes of MPS distinguished. Despite the common primary metabolic deficit (inefficient GAG degradation), the course and symptoms of various MPS types can be different, though majority of the diseases from the group are characterized by severe symptoms and significantly shortened live span. Here, we analysed the frequency of specific, direct causes of death of patients with different MPS types, the subject which was not investigated comprehensively to date. We examined a total of 1317 cases of death among MPS patients, including 393 cases of MPS I, 418 cases of MPS II, 232 cases of MPS III, 45 cases of MPS IV, 208 cases of MPS VI, and 22 cases of MPS VII. Our analyses indicated that the most frequent causes of death differ significantly between MPS types, with cardiovascular and respiratory failures being predominant in MPS I, MPS II, and MPS VI, neurological deficits in MPS III, respiratory issues in MPS IV, and hydrops fetalis in MPS VII. Results of such studies suggest what specific clinical problems should be considered with the highest priority in specific MPS types, apart from attempts to correct the primary causes of the diseases, to improve the quality of life of patients and to prolong their lives.

Drosophila melanogaster models of MPS IIIC (Hgsnat-deficiency) highlight the role of glia in disease presentation

Sanfilippo syndrome (Mucopolysaccharidosis type III or MPS III) is a recessively inherited neurodegenerative lysosomal storage disorder. Mutations in genes encoding enzymes in the heparan sulphate degradation pathway lead to the accumulation of partially degraded heparan sulphate, resulting ultimately in the development of neurological deficits. Mutations in the gene encoding the membrane protein heparan-α-glucosaminide N-acetyltransferase (HGSNAT; EC2.3.1.78) cause MPS IIIC (OMIM#252930), typified by impaired cognition, sleep-wake cycle changes, hyperactivity and early death, often before adulthood. The precise disease mechanism that causes symptom emergence remains unknown, posing a significant challenge in the development of effective therapeutics. As HGSNAT is conserved in Drosophila melanogaster, we now describe the creation and characterisation of the first Drosophila models of MPS IIIC. Flies with either an endogenous insertion mutation or RNAi-mediated knockdown of hgsnat were confirmed to have a reduced level of HGSNAT transcripts and age-dependent accumulation of heparan sulphate leading to engorgement of the endo/lysosomal compartment. This resulted in abnormalities at the pre-synapse, defective climbing and reduced overall activity. Altered circadian rhythms (shift in peak morning activity) were seen in hgsnat neuronal knockdown lines. Further, when hgsnat was knocked down in specific glial subsets (wrapping, cortical, astrocytes or subperineural glia), impaired climbing or reduced activity was noted, implying that hgsnat function in these specific glial subtypes contributes significantly to this behaviour and targeting treatments to these cell groups may be necessary to ameliorate or prevent symptom onset. These novel models of MPS IIIC provide critical research tools for delineating the key cellular pathways causal in the onset of neurodegeneration in this presently untreatable disorder.

Sleep in people with and without intellectual disabilities: a systematic review and meta-analysis

BACKGROUND

Sleep problems are regularly reported in people with intellectual disabilities. Recent years have seen a substantial increase in studies comparing sleep in people with intellectual disabilities to control participants, with an increase in the use of validated, objective measures. Emerging patterns of differences in sleep time and sleep quality warrant pooled investigation.

METHODS

A systematic search was conducted across three databases (Ovid Embase, PsycInfo and Medline) and returned all papers comparing sleep in people with intellectual disabilities to a control group, published since the last meta-analysis on the topic. A quality framework was employed to rate the risk of bias across studies. Separate meta-analyses of sleep duration and sleep quality were conducted. Subgrouping compared findings for those studies with participants with genetic syndromes or neurodevelopmental conditions and those with heterogeneous intellectual disability.

RESULTS

Thirteen new papers were identified and combined with those from the previous meta-analysis to provide 34 papers in total. Quality of studies was generally rated highly, though sampling provided risk of bias and adaptive functioning was rarely measured. People with intellectual disability associated with genetic syndromes or neurodevelopmental conditions sleep for shorter time periods (standardised mean difference = .26) and experience worse sleep quality (standardised mean difference = .68) than their peers. People with intellectual disability of heterogeneous origin show no difference in sleep time but have poorer sleep quality. There was some evidence that age moderated these effects.

CONCLUSIONS

People with intellectual disability have poorer sleep than those without. Subtle patterns suggest that aetiology of intellectual disability moderates the topography of these difficulties, with further work needed to differentiate common and distinct mechanisms across groups.

Melatonin use in children and adolescents: A scoping review of caregiver perspectives

Despite melatonin's popularity as a pediatric sleep-aid, little has been investigated around caregivers' understanding and perception of melatonin use for their dependent. This scoping review analyzes the current literature on pediatric melatonin use, to understand how caregivers' perceptions around melatonin are shaped by their illness/medication-related beliefs, treatment experience and preferences. A literature search was conducted across Embase, Medline, PsycINFO, PubMed and Scopus, generating 184 results for screening against the inclusion criteria. Nineteen studies were retrieved, comprising of 1561 children and adolescents, aged 8.7 ± 2.3 years (range: 0-44 years), conducted primarily in the United States of America (n = 6), Canada (n = 3) and the Netherlands (n = 3). Studies were evaluated for their study design and caregiver-centered outcomes, encompassing: 1) illness/treatment-related beliefs, 2) treatment satisfaction/effectiveness, 3) treatment preference/acceptability, and 4) impact of child's sleep disturbance on caregivers' quality-of-life. Sleep disturbances necessitating melatonin use occurred alongside congenital/neurodevelopmental comorbidities in 18 studies (95%). Melatonin was commonly associated with "naturalness" and "safety". Concepts of treatment satisfaction versus effectiveness were minimally differentiated within included studies. Caregivers preferred concurrent use of melatonin and behavioral interventions for management of their dependents' sleep. Improved sleep in the dependent generally led to better quality-of-life for caregivers and their family.

Sanfilippo syndrome: consensus guidelines for clinical care

Sanfilippo syndrome is a group of rare, complex, and progressive neurodegenerative lysosomal storage disorders that is characterized by childhood dementia. The clinical management of patients with progressive neurological decline and multisystem involvement requires a multidisciplinary team with experience in the management of neurodegenerative disorders. Best practice guidelines for the clinical management of patients with these types of rare disorders are critical to ensure prompt diagnosis and initiation of appropriate care. However, there are no published standard global clinical care guidelines for patients with Sanfilippo syndrome. To address this, a literature review was conducted to evaluate the current evidence base and to identify evidence gaps. The findings were reviewed by an international steering committee composed of clinical experts with extensive experience in managing patients with Sanfilippo syndrome. The goal was to create a consensus set of basic clinical guidelines that will be accessible to and informed by clinicians globally, as well as providing a practical resource for families to share with their local care team who may not have experience with this rare disease. This review distills 178 guideline statements into an easily digestible document that provides evidence-based, expert-led recommendations for how to approach common management challenges and appropriate monitoring schedules in the care of patients with Sanfilippo syndrome.

An observational, prospective, multicenter, natural history study of patients with mucopolysaccharidosis type IIIA

Mucopolysaccharidosis type IIIA (MPS IIIA, also known as Sanfilippo syndrome) is a rare genetic lysosomal storage disease characterized by early and progressive neurodegeneration resulting in a rapid decline in cognitive function affecting speech and language, adaptive behavior, and motor skills. We carried out a prospective observational study to assess the natural history of patients with MPS IIIA, using both standardized tests and patient-centric measures to determine the course of disease progression over a 2-year period. A cohort of 23 patients (7 girls, 16 boys; mean age 28-105 months at baseline) with a confirmed diagnosis of MPS IIIA were assessed and followed up at intervals of 3-6 months; cognitive function was measured using Bayley Scales of Infant and Toddler Development 3rd edition (BSID-III) to derive cognitive development quotients (DQ). Daily living, speech/language development and motor skills were measured using the Vineland Adaptive Behavior Scale (VABS-II). Sleep-wake patterns, behavior and quality-of-life questionnaires were also reported at each visit using parent/caregiver reported outcome tools. All patients had early onset severe MPS IIIA, were diagnosed before 74 months of age, and had cognitive scores below normal developmental levels at baseline. Patients less than 40 months of age at baseline were more likely to continue developing new skills over the first 6-12 months of follow-up. There was a high variability in cognitive developmental age (DA) in patients between 40 and 70 months of age; two-thirds of these patients already had profound cognitive decline, with a DA ≤10 months. The highest cognitive DA achieved in the full study cohort was 34 months. Post hoc, patients were divided into two groups based on baseline cognitive DQ (DQ ≥50 or <50). Cognitive DQ decreased linearly over time, with a decrease from baseline of 30.1 and 9.0 points in patients with cognitive DQ ≥50 at baseline and cognitive DQ <50 at baseline, respectively. Over the 2-year study, VABS-II language scores declined progressively. Motor skills, including walking, declined over time, although significantly later than cognitive decline. No clear pattern of sleep disturbance was observed, but night waking was common in younger patients. Pain scores, as measured on the quality-of-life questionnaire, increased over the study period. The findings of this study strengthen the natural history data on cognitive decline in MPS IIIA and importantly provide additional data on endpoints, validated by the patient community as important to treat, that may form the basis of a multidomain endpoint capturing the disease complexity.

Oxidative Stress in Mucopolysaccharidoses: Pharmacological Implications

Although mucopolysaccharidoses (MPS) are caused by mutations in genes coding for enzymes responsible for degradation of glycosaminoglycans, storage of these compounds is crucial but is not the only pathomechanism of these severe, inherited metabolic diseases. Among various factors and processes influencing the course of MPS, oxidative stress appears to be a major one. Oxidative imbalance, occurring in MPS and resulting in increased levels of reactive oxidative species, causes damage of various biomolecules, leading to worsening of symptoms, especially in the central nervous system (but not restricted to this system). A few therapeutic options are available for some types of MPS, including enzyme replacement therapy and hematopoietic stem cell transplantation, however, none of them are fully effective in reducing all symptoms. A possibility that molecules with antioxidative activities might be useful accompanying drugs, administered together with other therapies, is discussed in light of the potential efficacy of MPS treatment.

Sleep-related hypermotor epilepsy in a patient with mucopolysaccharidosis type III

Both non-epileptic sleep disturbances and epilepsy are common in patients with mucopolysaccharidoses (MPS), so diagnosis of sleep-related hypermotor epilepsy in these patients is a tackling issue. We present a case of an adult patient with MPS IIIB (Sanfilippo syndrome), who presented with numerous nocturnal events of sudden awakening and hypermotor behavior, which had been previously regarded as parasomnias. Overnight video-EEG captured numerous stereotypical seizures with ictal pattern in the frontal regions, which led the diagnosis of SHE. The patient was started with carbamazepine, which resulted in a substantial reduction in the number of seizures. Our report provides further support for use of overnight video-EEG in the differential diagnosis of sleep-related disorders in MPS, yet true incidence of SHE in MPS patients remains unknown.

Novel therapies for mucopolysaccharidosis type III

Mucopolysaccharidosis type III (MPS III) or Sanfilippo disease is an orphan inherited lysosomal storage disease and one of the most common MPS subtypes. The classical presentation is an infantile-onset neurodegenerative disease characterised by intellectual regression, behavioural and sleep disturbances, loss of ambulation, and early death. Unlike other MPS, no disease-modifying therapy has yet been approved. Here, we review the numerous approaches of curative therapy developed for MPS III from historical ineffective haematopoietic stem cell transplantation and substrate reduction therapy to the promising ongoing clinical trials based on enzyme replacement therapy or adeno-associated or lentiviral vectors mediated gene therapy. Preclinical studies are presented alongside the most recent translational first-in-man trials. In addition, we present experimental research with preclinical mRNA and gene editing strategies. Lessons from animal studies and clinical trials have highlighted the importance of an early therapy before extensive neuronal loss. A disease-modifying therapy for MPS III will undoubtedly mandate development of new strategies for early diagnosis.

Parent Experiences of Sanfilippo Syndrome Impact and Unmet Treatment Needs: A Qualitative Assessment

Introduction

Sanfilippo syndrome (MPS III) is a rare, degenerative condition characterized by symptoms impacting cognitive ability, mobility, behavior, and quality of life. Currently there are no approved therapies for this severe life-limiting disease. Integrating patient and caregiver experience data into drug development and regulatory decision-making has become a priority of the Food and Drug Administration and rare disease patient communities.

Methods

This study assesses parents’ perceptions of their child’s Sanfilippo syndrome disease-related symptoms using a research approach that is consistent with the Center for Drug Evaluation and Research (CDER) guidance. This study was initiated by the Cure Sanfilippo Foundation, and all steps in the research process were informed by a multidisciplinary advisory committee, with an objective of informing biopharmaceutical companies and regulatory agencies. We explored caregiver burden, symptoms with greatest impact, and meaningful but unmet treatment needs. Data were collected from 25 parents through three focus groups and a questionnaire. Transcripts were coded and analyzed using inductive thematic analysis, and descriptive analysis of quantitative data was conducted.

Results

Participating parents’ children ranged in age from 4 to 36 years. Participants endorsed high caregiving burden across all stages of the disease. Analysis revealed multiple domains of unmet need that impact child and family quality of life, including cognitive-behavioral challenges in communication, relationships, behavior, anxiety, and child safety; and physical health symptoms including sleep, pain, and mobility. Participants reported placing high value on incremental benefits targeting those symptoms, and on a treatment that would slow or stop symptom progression.

Conclusion

Even modest treatment benefits for Sanfilippo syndrome were shown to be highly valued. Despite high caregiver burden, most parents expressed a willingness to “try anything,” including treatments with potentially high risk profiles, to maintain their child’s current state.

Electronic supplementary material

The online version of this article (10.1007/s40120-020-00226-z) contains supplementary material, which is available to authorized users.

Challenging behavior in mucopolysaccharidoses types I-III and day-to-day coping strategies: a cross sectional explorative study

BACKGROUND

Challenging behavior represents a core symptom in neuropathological mucopolysaccharidoses (MPS) and puts major strain on affected families. Although multimodal approaches including behavioral strategies to treatment could be valuable, there is lack of research to the effectiveness of specific measures. This explorative, cross-sectional study is aimed at the collection of parental experiences regarding effective day-to-day measures against challenging behavior in MPS and focuses on 4 major research questions: First: What is challenging behavior in MPS? Second: Which strategies are helpful in the day-to-day coping with challenging behavior? Third: How strong is parental acceptance of illness and the disorder's impact on family relationships? Fourth: What are beneficial personal and interfamilial strategies for generally coping with the disorder?

METHODS

A semi structured questionnaire was designed de novo in cooperation with affected families. 37/268 questionnaires were returned (rate: 13.8%), of which 34 (MPS I: n = 8, MPS II: n = 8; MPS III: n = 18) could be included in data analysis in accordance with inclusion criteria. Assessment of challenging symptoms was based on perceived frequency, parent- and child stress. Exploration of possible coping strategies for challenging behavior and general illness-related strain included the evaluation of perceived effectiveness. Questionnaires were completed by patient's relatives and analyzed for strategies to cope with challenging behavior and the disorder's impact. STROBE criteria were respected.

RESULTS

MPS I was reported to show lower frequency and better perceived manageability of challenging behavior than MPS II and -III. Sleep disturbance, hyperactivity, agitation, aggression and orality seemed relevant symptoms regarding frequency and/or parent stress. Reported measures were manifold, worthwhile approaches against challenging behavior appeared to be aiming at distraction, relief and environmental changes. Medication and non-medication approaches were rated similarly effective. Social exchange, private space and networking with other affected families seemed highly important for personal and interfamilial well-being.

CONCLUSIONS

Multimodal mentoring for affected families could be based on the following equivalent pillars: (1) Medication therapy for challenging behavior including evaluation of cost and benefit (2) Guided implementation and re-evaluation of specific behavioral measures against challenging behavior. (3) Psychosocial support of MPS-families, including options for strengthening parental well-being and family functioning. Trial registration This study was registered at clinicaltrials.gov prior to study start (NCT-Number: NCT03161171, Date: 2017/05/19).

Cerebellar tumour-like aggregate of glycosaminoglycans in a MPS IIIB patient: a case report

INTRODUCTION

Mucopolysaccharidosis (MPS) IIIB is a lysosomal disorder in which a deficiency in α-N-acetylglucosaminidase impairs the degradation of heparan sulphate, which accumulates in tissues causing multiple organs dysfunction. This disease is associated with significant central nervous system (CNS) abnormalities, but a presentation with a tumour-like lesion has never been reported so far.

CLINICAL PRESENTATION

The present report describes the case of a 5-year-old girl suffering from MPS IIIB who developed a cerebellar lesion with evident mass effect. She underwent surgery with a subsequent notable improvement of her clinical picture. Surprisingly, the pathological analysis revealed the lesion to have the typical MPS features.

CONCLUSION

This case would describe a neglected possible presentation of MPS IIIB with a lesion mimicking a neoplasm, which could even be successfully treated with surgery.

Molecular Bases of Neurodegeneration and Cognitive Decline, the Major Burden of Sanfilippo Disease

The mucopolysaccharidoses (MPS) are a group of diseases caused by the lysosomal accumulation of glycosaminoglycans, due to genetic deficiencies of enzymes involved in their degradation. MPS III or Sanfilippo disease, in particular, is characterized by early-onset severe, progressive neurodegeneration but mild somatic involvement, with patients losing milestones and previously acquired skills as the disease progresses. Despite being the focus of extensive research over the past years, the links between accumulation of the primary molecule, the glycosaminoglycan heparan sulfate, and the neurodegeneration seen in patients have yet to be fully elucidated. This review summarizes the current knowledge on the molecular bases of neurological decline in Sanfilippo disease. It emerges that this deterioration results from the dysregulation of multiple cellular pathways, leading to neuroinflammation, oxidative stress, impaired autophagy and defects in cellular signaling. However, many important questions about the neuropathological mechanisms of the disease remain unanswered, highlighting the need for further research in this area.

Analysis of the caregiver burden associated with Sanfilippo syndrome type B: panel recommendations based on qualitative and quantitative data

BACKGROUND

Sanfilippo syndrome type B (Sanfilippo B) belongs to a group of rare lysosomal storage diseases characterized by progressive cognitive decline from an early age, acute hyperactivity, and concomitant somatic symptoms. Caregivers face a unique set of challenges related to the complex nature of Sanfilippo B, but the burden and impact on quality of life (QoL) of caregivers is poorly defined and best practice guidance for clinicians is lacking.

METHODS

An international clinical advisors meeting was convened to discuss key aspects of caregiver burden associated with Sanfilippo B based on findings from qualitative and quantitative research undertaken to identify and quantify the nature and impact of the disease on patients and caregivers.

RESULTS

Providing care for patients with Sanfilippo B impinges on all aspects of family life, evolving as the patient ages and the disease progresses. Important factors contributing toward caregiver burden include sleep disturbances, impulsive and hyperactive behavior, and communication difficulties. Caregiver burden remained high throughout the life of the patient and, coupled with the physical burden of daily care, had a cumulative impact that generated significant psychological stress.

CONCLUSION

A Sanfilippo-specific QoL questionnaire is needed that is directed at caregiver needs and burden and best practice management of these domains.

Neurobehavioral phenotypes of neuronopathic mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of lysosomal multisystemic, chronic, and progressive diseases characterized by the storage of glycosaminoglycans (GAGs) that may affect the central nervous system. Neuronopathic MPS such as MPS IH, MPS II, MPS IIIA–D, and MPS VII are characterized by neurocognitive regression. In severe MPS I (MPS IH, or Hurler syndrome) initial developmental trajectory is usually unremarkable but cognitive development shows a plateau by 2 to 4 years of age and then progressively regresses with aging. Patients with neuronopathic MPS II have a plateau of cognitive and adaptive development on average by 4 to 4.5 years of age, although there is significant variability, followed by progressive neurocognitive decline. In patients with classic MPS III, developmental trajectory reaches a plateau around 3 years of age, followed by regression. Sleep disturbances and behavioral problems occur early in MPS II and III with features of externalizing disorders. Acquired autism-like behavior is often observed in children with MPS III after 4–6 years of age. Impaired social and communication abilities do occur, but MPS III children do not have restricted and repetitive interests such as in autism spectrum disorder. MPS type VII is an ultra-rare neuronopathic MPS with a wide clinical spectrum from very severe with early mortality to milder phenotypes with longer survival into adolescence and adulthood. Most patients with MPS VII have intellectual disability and severely delayed speech development, usually associated with hearing impairment. Cognitive regression in neuronopathic MPS runs parallel to a significant decrease in brain tissue volume. Assessment of the developmental profile is challenging because of low cognitive abilities, physical impairment, and behavioral disturbances. Early diagnosis is crucial as different promising treatment approaches have been extensively studied in animal MPS models and are currently being applied in clinical trials.

The Unfavorable Alliance of Pain and Poor Sleep in Children with Life-Limiting Conditions and Severe Psychomotor Impairment

A high prevalence of sleep problems exists in children and adolescents with life-limiting conditions (LLC) and severe psychomotor impairment (SPMI). This study aimed to compare the impacts of various child-related (pain, epilepsy, repositioning, medical care) and environment-related (light, noise, TV/radio, open door) factors on sleep in this vulnerable population. Data were obtained through the “Sleep Questionnaire for Children with Severe Psychomotor Impairment” (SNAKE) by proxy assessment. n = 212 children (mean age: 10.4 years) were included in the analyses. Logistic and linear regression models were used to compare child- and environment-related factors against the global rating of children’s sleep quality, five SNAKE scales, children’s sleep duration, and sleep efficacy. Pain increased the risk of sleeping poorly four-fold (OR (odds ratio) = 4.13; 95% CI (confidence interval): 1.87–9.13) and predicted four sleep problems as assessed by the SNAKE. Children who needed to reposition during the night were at three times greater risk of sleeping poorly (OR = 3.08; 95% CI: 1.42–6.69). Three of the five SNAKE scales were predicted through nocturnal repositioning. Repositioning and epilepsy predicted a reduced sleep duration and low sleep efficacy. None of the environment-related factors exhibited statistically significant results. This study emphasizes the urgent need for reliable pain detection in the context of sleep disturbances in severely ill children.

Developmental and behavioral aspects of mucopolysaccharidoses with brain manifestations - Neurological signs and symptoms

The mucopolysaccharidoses (MPS) are a group of rare, inherited lysosomal storage disorders, caused by mutations in lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). The resulting accumulation of GAGs in the body leads to widespread tissue and organ dysfunction. The spectrum, severity, and progression rate of clinical manifestations varies widely between and within the different MPS types. In addition to somatic signs and symptoms, which vary between the different MPS disorders, patients with MPS I, II, III, and VII present with significant neurological signs and symptoms, including impaired cognitive abilities, difficulties in language and speech, and/or behavioral and sleep problems. To effectively manage and develop therapies that target these neurological manifestations, it is of utmost importance to have a profound knowledge of their natural history and pathophysiology. This review describes the appearance and progression of neurological signs and symptoms in patients with MPS I, II, and III, based on presentations and discussions among an international group of experts during a meeting on the brain in MPS on April 28-30, 2016, and additional literature searches on this subject.

Pathophysiology, evaluation, and management of sleep disorders in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) represent a heterogeneous group of lysosomal storage disorders, each one associated with a deficiency in one of the enzymes involved in glycosaminoglycan degradation. Sleep disorders are a frequent manifestation of all types of MPS. Underlying causes are diverse and comprised of both respiratory and central nervous system (CNS) abnormalities. Sleep disordered breathing such as obstructive sleep apnea and nocturnal hypoventilation can arise in patients with upper airway obstruction and/or with alterations in respiratory mechanics, causing restrictive pulmonary disease. MPS patients with CNS disease can also develop sleep disturbances unrelated to ventilatory impairments, often associated with severe behavioral problems or night-time epileptic seizures. The present review discusses the pathophysiology, evaluation, and management of sleep disorders in MPS based on information from a meeting on the brain in MPS, attended by an international group of experts (April 28-30, 2016, Stockholm, Sweden), and additional literature searches.

Practical management of behavioral problems in mucopolysaccharidoses disorders

The mucopolysaccharidosis (MPS) disorders are caused by deficiencies of specific lysosomal enzymes, resulting in progressive glycosaminoglycan (GAG) accumulation in cells and tissues throughout the body. Excessive GAG storage can lead to a variety of somatic manifestations as well as primary and secondary neurological symptoms. Behavioral problems (like hyperactivity, attention difficulties, and severe frustration) and sleeping problems are typical primary neurological symptoms of MPS caused by GAG accumulation in neurons, and are frequently observed in patients with MPS I, II, III, and VII. As these problems often place a significant burden on the family, proper management is important. This review summarizes current insights into behavioral and sleeping problems in MPS disorders and the most optimal management approaches, as presented and discussed during a meeting of an international group of experts with extensive experience in managing and treating MPS.

Recommendations on clinical trial design for treatment of Mucopolysaccharidosis Type III

Background

Mucopolysaccharidosis type III is a progressive, neurodegenerative lysosomal storage disorder for which there is currently no effective therapy. Though numerous potential therapies are in development, there are several challenges to conducting clinical research in this area. We seek to make recommendations on the approach to clinical research in MPS III, including the selection of outcome measures and trial endpoints, in order to improve the quality and impact of research in this area.

Results

An international workshop involving academic researchers, clinical experts and industry groups was held in June 2015, with presentations and discussions on disease pathophysiology, biomarkers, potential therapies and clinical outcome measures. A set of recommendations was subsequently prepared by a working group and reviewed by all delegates. We present a series of 11 recommendations regarding the conduct of clinical research, outcome measures and management of natural history data in Mucopolysaccharidosis type III.

Conclusions

Improving the quality of clinical research in Mucopolysaccharidosis type III will require an open, collaborative and systematic approach between academic researchers, clinicians and industry. Natural history data should be published as soon as possible and ideally collated in a central repository. There should be agreement on outcome measures and instruments for evaluation of clinical outcomes to maximise the effectiveness of current and future clinical research.

Management of the behavioural manifestations of Hunter syndrome

This article reviews the behavioural manifestations of, and the strategies for managing, Hunter syndrome (mucopolysaccharidosis (MPS) type II), a rare X-linked lysosomal storage disorder caused by a deficiency of the enzyme iduronate-2-sulphatase. Hunter syndrome is generally considered to have two manifestations: an attenuated form and a severe form; in the latter, the person has pronounced cognitive decline. Infants with either phenotype usually appear normal at birth, but may show some somatic signs. Children with the severe phenotype show developmental delay and changes in behaviour patterns at about 18 months to 4 years of age. To varying degrees, patients with the severe form manifest behavioural disorders such as hyperactivity, aggression, impulsivity, anxiety and sleep disturbances. Medications, such as antipsychotics, benzodiazepines and anticonvulsants, have been tried with varying degrees of success. Behavioural management strategies may be a worthwhile approach, although published data are lacking. For sleep disturbances, behavioural modification plus melatonin or benzodiazepine may be effective treatments.

Emerging drugs for the treatment of mucopolysaccharidoses

INTRODUCTION

Despite being reported for the first time almost one century ago, only in the last few decades effective have treatments become available for the mucopolysaccharidoses (MPSs), a group of 11 inherited metabolic diseases that affect lysosomal function. These diseases are progressive, usually severe, and, in a significant number of cases, involve cognitive impairment.

AREAS COVERED

This review will not cover established treatments such as bone marrow/hematopoietic stem cell transplantation and classic intravenous enzyme replacement therapy (ERT), whose long-term outcomes have already been published (MPS I, MPS II, and MPS VI), but it instead focuses on emerging therapies for MPSs. That includes intravenous ERT for MPS IVA and VII, intrathecal ERT, ERT with fusion proteins, substrate reduction therapy, gene therapy, and other novel approaches.

EXPERT OPINION

The available treatments have resulted in improvements for several disease manifestations, but they still do not represent a cure for these diseases; thus, it is important to develop alternative methods to approach the unmet needs (i.e. bone disease, heart valve disease, corneal opacity, and central nervous system (CNS) involvement). The work in progress with novel approaches makes us confident that in 2017, when MPS will commemorate 100 years of its first report, we will be much closer to an effective cure for these challenging conditions.

Circadian profiling in two mouse models of lysosomal storage disorders; Niemann Pick type-C and Sandhoff disease

Sleep and circadian rhythm disruption is frequently associated with neurodegenerative disease, yet it is unclear how the specific pathology in these disorders leads to abnormal rest/activity profiles. To investigate whether the pathological features of lysosomal storage disorders (LSDs) influence the core molecular clock or the circadian behavioural abnormalities reported in some patients, we examined mouse models of Niemann-Pick Type-C (Npc1 mutant, Npc1(nih)) and Sandhoff (Hexb knockout, Hexb(-/-)) disease using wheel-running activity measurement, neuropathology and clock gene expression analysis. Both mutants exhibited regular, entrained rest/activity patterns under light:dark (LD) conditions despite the onset of their respective neurodegenerative phenotypes. A slightly shortened free-running period and changes in Per1 gene expression were observed in Hexb(-/-) mice under constant dark conditions (DD); however, no overt neuropathology was detected in the suprachiasmatic nucleus (SCN). Conversely, despite extensive cholesterol accumulation in the SCN of Npc1(nih) mutants, no circadian disruption was observed under constant conditions. Our results indicate the accumulation of specific metabolites in LSDs may differentially contribute to circadian deregulation at the molecular and behavioural level.

Actigraphic investigation of circadian rhythm functioning and activity levels in children with mucopolysaccharidosis type III (Sanfilippo syndrome)

BACKGROUND

Sleep disturbance is part of the behavioural phenotype of the rare genetic condition mucopolysaccharidosis (MPS) type III. A growing body of evidence suggests that underlying disturbance in circadian rhythm functioning may explain sleep problems within the MPS III population.

METHODS

Actigraphic data were recorded in eight children with MPS III over 7-10 days and compared to age-matched typically developing controls. Parameters of circadian rhythmicity and activity levels across a 24-h period were analysed.

RESULTS

Statistically and clinically significant differences between the two groups were noted. Analysis indicated that children with MPS III showed significantly increased fragmentation of circadian rhythm and reduced stability with external cues (zeitgebers), compared to controls. Average times of activity onset and offset were indicative of a phase delayed sleep-wake cycle for some children in the MPS III group. Children with MPS III had significantly higher activity levels during the early morning hours (midnight-6 am) compared to controls.

CONCLUSIONS

Results are consistent with previous research into MPS III and suggest that there is an impairment in circadian rhythm functioning in children with this condition. Implications for clinical practice and the management of sleep difficulties are discussed.

Current role of melatonin in pediatric neurology: clinical recommendations

BACKGROUND/PURPOSE

Melatonin, an indoleamine secreted by the pineal gland, plays a key role in regulating circadian rhythm. It has chronobiotic, antioxidant, anti-inflammatory and free radical scavenging properties.

METHODS

A conference in Rome in 2014 aimed to establish consensus on the roles of melatonin in children and on treatment guidelines.

RESULTS AND CONCLUSION

The best evidence for efficacy is in sleep onset insomnia and delayed sleep phase syndrome. It is most effective when administered 3-5 h before physiological dim light melatonin onset. There is no evidence that extended-release melatonin confers advantage over immediate release. Many children with developmental disorders, such as autism spectrum disorder, attention-deficit/hyperactivity disorder and intellectual disability have sleep disturbance and can benefit from melatonin treatment. Melatonin decreases sleep onset latency and increases total sleep time but does not decrease night awakenings. Decreased CYP 1A2 activity, genetically determined or from concomitant medication, can slow metabolism, with loss of variation in melatonin level and loss of effect. Decreasing the dose can remedy this. Animal work and limited human data suggest that melatonin does not exacerbate seizures and might decrease them. Melatonin has been used successfully in treating headache. Animal work has confirmed a neuroprotective effect of melatonin, suggesting a role in minimising neuronal damage from birth asphyxia; results from human studies are awaited. Melatonin can also be of value in the performance of sleep EEGs and as sedation for brainstem auditory evoked potential assessments. No serious adverse effects of melatonin in humans have been identified.

An investigation of the middle and late behavioural phenotypes of Mucopolysaccharidosis Type-III

Background

Mucopolysaccharidosis type-III (MPS III) is an autosomal recessive lysosomal storage disorder. It causes progressive physical and cognitive decline and has been linked to increased incidences of behavioural problems.

Methods

Data on the behaviour and adaptive skills of 20 children with MPS III and 25 children with intellectual disability (ID) (17 included in analysis) were gathered via parental report questionnaire. The frequencies of different types of behaviour displayed by children with MPS III and children with ID were compared across two age categories.

Results

The total frequency of challenging behaviours displayed by children aged 2–9 years with MPS III and ID was not significantly different. Behaviours associated with hyperactivity, orality, unusual body movements and inattention were seen significantly more frequently in 2–9 year olds with MPS III than in those with ID. Children aged 10–15 years with MPS III showed significantly fewer problem behaviours than a contrasting group with ID. The frequency of challenging behaviours displayed by children with MPS III and their adaptive skills was found to decrease with age.

Conclusions

Behaviours relating to hyperactivity, orality, unusual body movements and inattention are part of the behavioural phenotype of the middle phase of MPS III. The late phase of MPS III is associated with low rates of problem behaviour and loss of adaptive skills. Therefore, families with a child with MPS III may benefit from a different type of clinical service when the child is aged 2–9 years, than when aged 10–15 years.

Assessment of sleep in children with mucopolysaccharidosis type III

Sleep disturbances are prevalent in mucopolysaccharidosis Type III (MPS III), yet there is a lack of objective, ecologically valid evidence detailing sleep quantity, quality or circadian system. Eight children with MPS III and eight age-matched typically developing children wore an actigraph for 7–10 days/nights. Saliva samples were collected at three time-points on two separate days, to permit analysis of endogenous melatonin levels. Parents completed a sleep questionnaire and a daily sleep diary. Actigraphic data revealed that children with MPS III had significantly longer sleep onset latencies and greater daytime sleep compared to controls, but night-time sleep duration did not differ between groups. In the MPS III group, sleep efficiency declined, and sleep onset latency increased, with age. Questionnaire responses showed that MPS III patients had significantly more sleep difficulties in all domains compared to controls. Melatonin concentrations showed an alteration in the circadian system in MPS III, which suggests that treatment for sleep problems should attempt to synchronise the sleep-wake cycle to a more regular pattern. Actigraphy was tolerated by children and this monitoring device can be recommended as a measure of treatment success in research and clinical practice.

Behavioural phenotypes of the mucopolysaccharide disorders: a systematic literature review of cognitive, motor, social, linguistic and behavioural presentation in the MPS disorders

BACKGROUND

The mucopolysaccharide disorders (MPS) are a group of recessively inherited metabolic disorders resulting in progressive physical and cognitive decline.

MATERIALS AND METHODS

MEDLINE, PsycINFO and Embase databases were searched, alongside manual screening, to identify relevant literature. Papers were included in the review if they were published in a peer reviewed journal and conducted empirical research into cognitive, motor, social or linguistic development or behaviour in one or more MPS disorders.

RESULTS

Twenty-five papers were reviewed. Two papers used methodology of a sufficiently high standard to demonstrate a behavioural phenotype; both found sleep disturbance to be part of the phenotype of MPS III. Fearfulness and sleep disturbance were frequently observed in people with MPS I and II. Cognitive and motor impairment and decline, and challenging behaviour were highly prevalent in the severe form of MPS II. Cognitive decline and severe behavioural problems relating to aggression, hyperactivity, orality, unusual affect and temper tantrums were seen in MPS III.

CONCLUSIONS

Sleep disturbance is part of the behavioural phenotype of MPS III, and challenging behaviour is highly prevalent in MPS II and MPS III, therefore the efficacy of behavioural interventions for these populations should be investigated. Further research into the behaviour and adaptive skills of children with MPS III and MPS IV is required.

Evaluation of miglustat treatment in patients with type III mucopolysaccharidosis: a randomized, double-blind, placebo-controlled study

OBJECTIVE

To evaluate the efficacy and safety of oral miglustat treatment in patients with mucopolysaccharidosis type III. The primary outcome was efficacy with improvement or stabilization in at least two domains of Vineland Adaptative Behavior Scales at 6 months. The secondary outcome measured the evolution of other cognitive tests at 12 months. The safety and tolerability were assessed throughout the study.

STUDY DESIGN

This was a randomized, double-blind, placebo-controlled, monocenter, institutional, phase IIb to III study. In case of efficacy at 6 months, the study would go on for another 6 months on an open design with all patients receiving miglustat. In the absence of efficacy at 6 months, the trial had to be continued for 6 more months with the initial design.

RESULTS

After 6 months, efficacy was not superior in patients with miglustat. The independent review board confirmed continuing the study until 12 months.

CONCLUSION

Miglustat treatment was not associated with any improvement/stabilization in behavior problems in patients with mucopolysaccharidosis type III. Miglustat has an acceptable safety profile. However, the study has confirmed that miglustat is able to pass through the blood-brain barrier without significantly decreasing ganglioside levels.

Female mucopolysaccharidosis IIIA mice exhibit hyperactivity and a reduced sense of danger in the open field test

Reliable behavioural tests in animal models of neurodegenerative diseases allow us to study the natural history of disease and evaluate the efficacy of novel therapies. Mucopolysaccharidosis IIIA (MPS IIIA or Sanfilippo A), is a severe, neurodegenerative lysosomal storage disorder caused by a deficiency in the heparan sulphate catabolising enzyme, sulfamidase. Undegraded heparan sulphate accumulates, resulting in lysosomal enlargement and cellular dysfunction. Patients suffer a progressive loss of motor and cognitive function with severe behavioural manifestations and premature death. There is currently no treatment. A spontaneously occurring mouse model of the disease has been described, that has approximately 3% of normal enzyme activity levels. Behavioural phenotyping of the MPS IIIA mouse has been previously reported, but the results are conflicting and variable, even after full backcrossing to the C57BL/6 background. Therefore we have independently backcrossed the MPS IIIA model onto the C57BL/6J background and evaluated the behaviour of male and female MPS IIIA mice at 4, 6 and 8 months of age using the open field test, elevated plus maze, inverted screen and horizontal bar crossing at the same circadian time point. Using a 60 minute open field, we have demonstrated that female MPS IIIA mice are hyperactive, have a longer path length, display rapid exploratory behaviour and spend less time immobile than WT mice. Female MPS IIIA mice also display a reduced sense of danger and spend more time in the centre of the open field. There were no significant differences found between male WT and MPS IIIA mice and no differences in neuromuscular strength were seen with either sex. The altered natural history of behaviour that we observe in the MPS IIIA mouse will allow more accurate evaluation of novel therapeutics for MPS IIIA and potentially other neurodegenerative disorders.

Early clinical markers of central nervous system involvement in mucopolysaccharidosis type II

OBJECTIVE

To identify early clinical markers of neurologic involvement in mucopolysaccharidosis type II.

STUDY DESIGN

A retrospective review of neurobehavioral standardized assessments of patients with mucopolysaccharidosis type II evaluated at the Program for Neurodevelopmental Function in Rare Disorders was completed. Patients were grouped based on the presence or absence of central nervous system (CNS) involvement at the most recent evaluation. Differences in early signs and symptoms between resulting cohorts were tested for significance, and an index severity score was developed.

RESULTS

Between December 2002 and November 2010, clinical evaluations of 49 patients and 151 patient encounters were reviewed. Thirty-seven patients exhibited neurologic deterioration. Of the 25 signs evaluated, 7 early clinical markers were strongly correlated with subsequent cognitive dysfunction: sleep disturbance, increased activity, behavior difficulties, seizure-like behavior, perseverative chewing behavior, and inability to achieve bowel training and bladder training. A new severity score index was developed, with a score ≥3 indicating a high likelihood of developing CNS disease.

CONCLUSION

Seven early clinical markers and a severity score index of CNS involvement can be used for initial screening of children who might benefit from CNS-directed therapies.

Clinical uses of melatonin in pediatrics

This study analyzes the results of clinical trials of treatments with melatonin conducted in children, mostly focused on sleep disorders of different origin. Melatonin is beneficial not only in the treatment of dyssomnias, especially delayed sleep phase syndrome, but also on sleep disorders present in children with attention-deficit hyperactivity, autism spectrum disorders, and, in general, in all sleep disturbances associated with mental, neurologic, or other medical disorders. Sedative properties of melatonin have been used in diagnostic situations requiring sedation or as a premedicant in children undergoing anesthetic procedures. Epilepsy and febrile seizures are also susceptible to treatment with melatonin, alone or associated with conventional antiepileptic drugs. Melatonin has been also used to prevent the progression in some cases of adolescent idiopathic scoliosis. In newborns, and particularly those delivered preterm, melatonin has been used to reduce oxidative stress associated with sepsis, asphyxia, respiratory distress, or surgical stress. Finally, the administration of melatonin, melatonin analogues, or melatonin precursors to the infants through the breast-feeding, or by milk formula adapted for day and night, improves their nocturnal sleep. Side effects of melatonin treatments in children have not been reported. Although the above-described results are promising, specific studies to resolve the problem of dosage, formulations, and length of treatment are necessary.

Respiratory manifestations in mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of inherited, metabolic diseases caused by deficiency of lysosomal enzymes that degrade glycosaminoglycans (GAG). Loss of enzyme activity results in cellular accumulation of GAG fragments leading to the progressive multi-system manifestations. MPS are classified into seven clinical types based on eleven known lysosomal enzyme deficiencies of GAG metabolism. Respiratory involvement is seen in most MPS types with recurrent respiratory infections, upper and lower airway obstruction, tracheomalacia, restrictive lung disease, and sleep disturbances. Patients with airway obstruction are at high risk for anaesthetic complications. In this review, we present the respiratory manifestations in various MPS types and stages, evaluation of respiratory involvement, and treatment options for the progressive respiratory failure that occurs in MPS patients.

Circadian rhythm and suprachiasmatic nucleus alterations in the mouse model of mucopolysaccharidosis IIIB

Mucopolysaccharidosis IIIB (MPSIIIB) is a lysosomal storage disease characterised by progressive central nervous system degeneration in patients, with death usually in the late teens. Serious behavioural problems have been reported in children at the early stages of the disease, such as hyperactivity and severe sleep disturbances, which suggest alterations in circadian rhythms. We investigated the circadian rhythm of locomotor activity of young and old MPSIIIB mice, under a 24-h light-dark (LD) cycle and under constant darkness (DD), and also examined neuropeptide expression in the suprachiasmatic nucleus (SCN), site of the principal biological pacemaker. We show that MPSIIIB mice have higher activity levels during the light (resting) phase of the LD cycle, together with weaker circadian rhythms, and a longer active phase due to a late peak of activity, in both LD and DD. In addition, young MPSIIIB mice showed shorter phase delays in response to a light pulse in DD. Increased lysosomal storage, neuroinflammation and changes in the expression of Arginine Vasopressin and Vasointestinal Polypeptide, two circadian neuropeptides, were observed in the SCN, which may be in part responsible for the changes in circadian behaviour observed in MPSIIIB mice. These findings suggest an alteration of the circadian system in MPSIIIB mice, and may inform better clinical management of circadian, sleep and behavioural disturbances in patients with MPSIII.

Extrapyramidal symptoms and medication use in Mucopolysaccharidosis type III

BACKGROUND

We report the case of a 16-year-old male with Mucopolysaccharidosis III type A (Sanfilippo syndrome) who was commenced on risperidone for behaviour management. He rapidly developed extrapyramidal symptoms that have not resolved.

METHOD

The medication histories of 20 patients with Mucopolysaccharidosis III seen at a Lysosomal Storage Diseases Clinic were reviewed to determine the incidence of extrapyramidal side effects.

RESULTS

Six patients had been treated with risperidone, olanzapine, or lamotrigine. Five of these patients developed extrapyramidal side effects.

CONCLUSIONS

The incidence of extrapyramidal side effects was considerably higher than expected. We suggest that these medications be used with considerable caution in these patients.

Sleep problems in children with neurological disorders

This review describes the complex and often reciprocal relationship between sleep problems, neurological disorders and/or intellectual disability in children. The causes of Intellectual disability (ID) discussed in this review include those conditions present from or around the time of birth, although it also considers traumatic brain injuries occurring later in development. This review discusses the patterns of sleep difficulty associated with specific disorders and summarizes the assessment and interventions, both behavioural and pharmacological, applicable to children. Many neurological disorders such as epilepsy, narcolepsy and neurorespiratory disorders vary considerably in terms of the degree of co-morbid problems and can present with a spectrum of effects on underlying cognitive or behavioural substrates including sleep function. These conditions are discussed as they provide useful insights into how disordered sleep can impact on cognitive development and behaviour. The review draws both on the literature in these areas and the extensive clinical experience of the authors.

Sanfilippo syndrome: a mini-review

Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) is an autosomal recessive disorder, caused by a deficiency in one of the four enzymes involved in the lysosomal degradation of the glycosaminoglycan heparan sulfate. Based on the enzyme deficiency, four different subtypes, MPS IIIA, B, C, and D, are recognized. The genes encoding these four enzymes have been characterized and various mutations have been reported. The probable diagnosis of all MPS III subtypes is based on increased concentration of heparan sulfate in the urine. Enzymatic assays in leukocytes and/or fibroblasts confirm the diagnosis and allow for discrimination between the different subtypes of the disease. The clinical course of MPS III can be divided into three phases. In the first phase, which usually starts between 1 and 4 years of age, a developmental delay becomes apparent after an initial normal development during the first 1-2 years of life. The second phase generally starts around 3-4 years and is characterized by severe behavioural problems and progressive mental deterioration ultimately leading to severe dementia. In the third and final stage, behavioural problems slowly disappear, but motor retardation with swallowing difficulties and spasticity emerge. Patients usually die at the end of the second or beginning of the third decade of life, although survival into the fourth decade has been reported. Although currently no effective therapy is yet available for MPS III, several promising developments raise hope that therapeutic interventions, halting the devastating mental and behavioural deterioration, might be feasible in the near future.

Development of sensory, motor and behavioral deficits in the murine model of Sanfilippo syndrome type B

BACKGROUND

Mucopolysaccharidosis (MPS) IIIB (Sanfilippo Syndrome type B) is caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop disturbances of sleep, activity levels, coordination, vision, hearing, and mental functioning culminating in early death. The murine model of MPS IIIB demonstrates lysosomal distention in multiple tissues, a shortened life span, and behavioral changes.

PRINCIPAL FINDINGS

To more thoroughly assess MPS IIIB in mice, alterations in circadian rhythm, activity level, motor function, vision, and hearing were tested. The suprachiasmatic nucleus (SCN) developed pathologic changes and locomotor analysis showed that MPS IIIB mice start their daily activity later and have a lower proportion of activity during the night than wild-type controls. Rotarod assessment of motor function revealed a progressive inability to coordinate movement in a rocking paradigm. Purkinje cell counts were significantly reduced in the MPS IIIB animals compared to age matched controls. By electroretinography (ERG), MPS IIIB mice had a progressive decrease in the amplitude of the dark-adapted b-wave response. Corresponding pathology revealed shortening of the outer segments, thinning of the outer nuclear layer, and inclusions in the retinal pigmented epithelium. Auditory-evoked brainstem responses (ABR) demonstrated progressive hearing deficits consistent with the observed loss of hair cells in the inner ear and histologic abnormalities in the middle ear.

CONCLUSIONS/SIGNIFICANCE

The mouse model of MPS IIIB has several quantifiable phenotypic alterations and is similar to the human disease. These physiologic and histologic changes provide insights into the progression of this disease and will serve as important parameters when evaluating various therapies.

Is Sanfilippo type B in your mind when you see adults with mental retardation and behavioral problems?

Sanfilippo type B is an autosomal recessive mucopolysaccharidosis (MPS IIIB) caused by deficiency of N-acetyl-alpha-D-glucosaminidase, a lysosomal enzyme involved in the degradation of heparan sulfate. It is characterized by neurologic degeneration, behavioral problems, and mental decline. Somatic features are relatively mild and patients with this disorder can reach late adulthood. It is the most common subtype of MPS in the Netherlands and probably underdiagnosed in adult persons with mental retardation (MR). In order to increase knowledge on the adult phenotype and natural history in Sanfilippo type B, we present the clinical data of 20 patients with this disorder. Sixteen of them were followed for one to three decades. Six died between 28 and 69 years of age, mainly from pneumonia and cachexia; the surviving patients were 18-63 years old. Apart from the youngest, they had lost mobility at 36-68 years. Most had developed physical problems, in particular in the 4th-6th decade of life: cardiac disease (cardiomyopathy, atrial fibrillations), arthritis, skin blistering, swallowing difficulties requiring feeding by a gastrostomy tube, and seizures. The course of the disease was dominated in most of them by challenging behavioral problems with restlessness, extreme screaming and hitting, difficult to prevent or to treat pharmaceutically. Even in absence of knowledge of the history of an elderly patient with MR, the presence of behavioral problems should prompt metabolic investigation for MPS.

Sleep disturbances in aspartylglucosaminuria (AGU): a questionnaire study

Sleep disturbances are common in many progressive metabolic encephalopathies. The possible presence of disturbed sleep-wake behaviour in the lysosomal storage disorder aspartylglucosaminuria, has not been previously studied, however. The sleep-wake behaviour of 81 patients with aspartylglucosaminuria (AGU, age 3-55 years, median 22 years; 42 female and 39 male) and 49 controls (age 2-57 years, median 18 years; 25 female and 24 male) was assessed through a postal survey. A slightly modified version of the validated Basic Nordic Sleep Questionnaire was used. Fifty-eight per cent of the AGU patients were reported to suffer daily from a sleep-related problem (controls 31%, p < 0.01). In AGU adults (age >17 years) and children (age < or =17 years), the corresponding figures were 52% and 61%, respectively (control children 22%, p < 0.05 and control adults 38%, p = 0.06). In AGU children, settling difficulties were reported to occur significantly more commonly than in control children. Children with AGU were also reported to snore more often than were the controls. Adults with this disorder were found to suffer from severely fragmented night-time sleep, which was experienced as highly distressing by the parents and other caregivers. A long night sleep period was reported to be common in the ageing AGU patients (AGU 9.5 +/- 1.7 vs controls 7.2 +/- 1.0 h, mean +/- SD, p < 0.001). Parents and caregivers also often complained about disturbing movements during sleep in AGU patients. In conclusion, both children and adults with aspartylglucosaminuria were reported to display several types of sleep disturbances significantly more commonly than healthy controls.