Behaviour in mucopolysaccharide disorders

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.

Fragile X syndrome: lifespan developmental implications for those without as well as with intellectual disability

PURPOSE OF REVIEW

Advances in developmental neuropsychiatry and the mental health needs of people with intellectual disability are creating ever greater understanding of the critical associations between human genome variations and psychological functioning throughout lifespan and across the entire intellectual ability spectrum. This review highlights the recent developments and their clinical implications for people with fragile X syndrome.

RECENT FINDINGS

There is substantial evidence for individuals of all ages and intellectual abilities being prone to psychological profiles determined not only by having a fragile X gene full mutation, but also by having premutations and intermediate alleles. The importance of these genetic contributors to mental life, if anything, increases with age. Premutation carriers are prone to neurodegenerative mid-life fragile X tremor-ataxia syndrome. Women with premutations experience premature ovarian insufficiency. Imbalances in the (gamma amino butyrie acid)-glutamate mediated postsynaptic cascade central neuronal pathways are a current focus of psychopharmacological enquiry, giving the hope of syndrome-specific medical treatments.

SUMMARY

Findings from genetic, neurological, biochemical, psychological and pharmacological research are combining to revolutionize understanding of the pathogenesis of developmental and psychological disabilities affecting individuals with fragile X syndrome irrespective of age, intelligence level and gene mutation status. Results of syndrome-specific medication trials are awaited.

Psychiatric and behavioral manifestations of lysosomal storage disorders

The different lysosomal storage disorders (LSDs) manifest with a wide spectrum of clinical presentations. Most of these disorders are typically diagnosed early in life, due to the severity of the associated phenotypes. However, it is important to appreciate that some of the LSDs present later in adolescence or adulthood. The diverse findings triggering the initial diagnosis, as well as the range of manifestations arising later during the disease course, contribute to the complexity of these issues. Clinical presentations occurring at a more advanced age, especially psychiatric and behavioral manifestations, can be overlooked or misdiagnosed. This review describes different psychiatric and behavioral manifestations encountered in individuals with LSDs, including psychosis, schizophrenia, mood disorders, aggressiveness, early-onset dementia, and conduct disorder. Twelve different disorders are presented, including descriptions of their associated biochemical abnormalities, clinical presentations, pathology, epidemiology, and genetics. In addition, discussions of neurocognitive, behavioral, and psychiatric findings are outlined for each disorder. A greater awareness of these features may help to reduce missed diagnoses, to avoid unnecessary, invasive and expensive testing, and to facilitate an earlier detection of these rare disorders. Earlier diagnosis can enable the implementation of appropriate interventions and improve genetic counseling.

Diagnosis of Caprine Mucopolysaccharidosis Type IIID by Real-Time Polymerase Chain Reaction-Based Genotyping

Mucopolysaccharidosis type IIID is caused by a deficiency of N-acetylglucosamine-6-sulfatase, which is one of the enzymes involved in the catabolism of heparin sulfate. Simple molecular marker assays underpin modern routine animal breeding and research activities worldwide. With the rapid growth of single nucleotide polymorphism (SNP) resources for many important animal genetic disorders, the availability of routine assays for genotyping SNPs is of increased importance. In the current study, real-time polymerase chain reaction (PCR) is demonstrated to provide a valuable approach as a rapid and accurate alternative to a previously developed gel-based PCR as a straightforward and efficient assay for the diagnosis of caprine mucopolysaccharidosis IIID.

Clinical overview of children with mucopolysaccharidosis type III A and effect of Risperidone treatment on children and their mothers psychological status

Mucopolysaccharidosis IIIA (MPS IIIA) is a lysosomal storage disorder characterized by progressive mental deterioration and severe behavioral problems. We conducted an open-label, crossover study of the efficacy and safety of Risperidone on behavioral disorder in children with MPS IIIA. A total of 12 patients (5.5+/-2.2 years) with enzymatic diagnosis of MPS IIIA were randomly assigned to receive Risperidone (0.125-2mg/d) for 6 months. The hyperactivity and disruptive behavior level of children before and after treatment was evaluated regarding the scores from Turgay DSM IV Based Child and Adolescent Behavior Disorders Screening and Rating Scale (T-DSM-IV-S). Clinic Global Impression Scale - Severity (CGIS-S) was used for all cases for determining the psychiatric disorder severity. The anxiety and depression levels of mothers before and after treatment were evaluated using Hamilton Anxiety Scale (HAM-A) and Beck Depression Inventory (BDI). The adverse effects were evaluated by monitoring weight, serum prolactin, glucose and lipid levels. The response to the treatment was measured by decrease in values of CGI-S (from 6+/-1.12 to 2.91+/-0.66, p=0.001). According to T-DSM-IV-S scores the best improvement was observed in hyperactivity scores (16.25+/-8.57/11.58+/-7.26, p=0.001), followed by opposition/defiance (6.66+/-5.92/5.08+/-4.88, p=0.032), and conduct disorder scores (1.00+/-1.85/0.41+/-.99, p=0.67). No clinically relevant elevations in weight and serum prolactin, glucose or lipid levels have been documented (p>0.05). There was a significant decrease in anxiety and depression scores of mothers (HAM-A: 20.33+/-8.28/17.91+/-6.89, BDI: 23.58+/-7.14/20.5+/-5.93, p<0.001). To our knowledge, research on the pharmacological treatment of MPS IIIA with Risperidone has not been reported. According to our data, Risperidone appeared to be safe and effective in MPS IIIA patients.

Multidisciplinary management of Hunter syndrome

Hunter syndrome is a rare, X-linked disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase. In the absence of sufficient enzyme activity, glycosaminoglycans accumulate in the lysosomes of many tissues and organs and contribute to the multisystem, progressive pathologies seen in Hunter syndrome. The nervous, cardiovascular, respiratory, and musculoskeletal systems can be involved in individuals with Hunter syndrome. Although the management of some clinical problems associated with the disease may seem routine, the management is typically complex and requires the physician to be aware of the special issues surrounding the patient with Hunter syndrome, and a multidisciplinary approach should be taken. Subspecialties such as otorhinolaryngology, neurosurgery, orthopedics, cardiology, anesthesiology, pulmonology, and neurodevelopment will all have a role in management, as will specialty areas such as physiotherapy, audiology, and others. The important management topics are discussed in this review, and the use of enzyme-replacement therapy with recombinant human iduronate-2-sulfatase as a specific treatment for Hunter syndrome is presented.

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-related breathing in children with mucopolysaccharidosis

BACKGROUND

The mucopolysaccharidoses (MPSs), a group of genetic lysosomal storage disorders, are associated with significant morbidity. Secondarily to specific associated anatomical abnormalities, MPS is associated with sleep disordered breathing (SDB), specifically obstructive sleep apnoea (OSA) that may confer additional morbidity. Few studies have examined SDB in children with MPS using full polysomnography (PSG) and thus the exact prevalence and severity of SDB is unknown. Further, successful treatments for SDB in this population have not been explored.

OBJECTIVES

This study evaluated both SDB and the efficacy of treatments offered to children with MPS using PSG data.

PATIENTS AND METHODS

A retrospective chart review was conducted on all children with MPS and a history of suspected OSA who were referred to the Hospital for Sick Children, Toronto. Both baseline and follow up treatment PSG data were analysed. PSG data recorded included obstructive apnoea-hypopnoea index (OAHI) and central apnoea index (CAI).

RESULTS

Fourteen patients (10 male) underwent a baseline PSG. Three of 14 children on ERT were excluded from the main analyses. The median (range) baseline parameters of the population (n = 11) were recorded. The age was 5.2 years (0.8-17.8) and the body mass index (BMI) was 19.9 (13.7-22.2). The OAHI was 6.6 (0.0-54.8); the CAI was 0.6 (0.0-2.6). Seven of 11 (64%) had evidence for OSA and 3/7 children were classified as having severe OSA (OAHI > 10). Of these, 5/7 children underwent treatment for OSA with 3/5 children showing a significant reduction in their OAHI. Further, the 2 patients on ERT therapy with OSA were also both successfully treated.

CONCLUSIONS

Children with MPS have a high prevalence of significant OSA and thus should be carefully screened for OSA using full polysomnography and treated accordingly.

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.

Open field locomotor activity and anxiety-related behaviors in mucopolysaccharidosis type IIIA mice

Mucopolysaccharidosis (MPS) IIIA, or Sanfilippo syndrome, is a lysosomal storage disorder characterized by severe and progressive neuropathology. Following an asymptomatic period, patients may present with sleep disturbances, cognitive decline, aggressive tendencies and hyperactivity. A naturally-occurring mouse model of MPS IIIA also exhibits many of these behavioral features and has been recently back-crossed onto a C57BL/6 genetic background. To more thoroughly characterize the behavioral phenotype of congenic MPS IIIA mice, we assessed exploratory activity and unconditioned anxiety-related behavior in the elevated plus maze (EPM) and open field locomotor activity. Although MPS IIIA male mice were less active in the EPM at 18 and 20 weeks of age, they were more likely to explore the open arms than their normal counter-parts suggesting reduced anxiety. Repeated EPM testing reduced exploration of the open arms in MPS IIIA mice. In the open field test, significant reductions in activity were evident in naïve-tested male MPS IIIA mice from 10 weeks of age. Female normal and MPS IIIA mice displayed similar exploratory activity in the open field test. These differences in anxiety and locomotor activity will allow us to evaluate the efficacy of therapeutic regimes for MPS IIIA as a forerunner to developing safe and effective therapies for Sanfilippo patients.

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.

Long-term outcomes of adaptive functions for children with mucopolysaccharidosis I (Hurler syndrome) treated with hematopoietic stem cell transplantation

Advances in medical treatment have prolonged the lives of children with Hurler syndrome or mucopolysaccharidosis I requiring increased attention to the assessment of their long-term outcomes and functional abilities. Adaptive functions are critical for understanding functional outcomes after treatment and developing focused interventions. We investigated the development of various adaptive functions in children who have had hematopoietic stem cell transplant (HSCT) for Hurler syndrome and risk factors that are associated with the development of these functions. We examined the development of 41 children who had 3 or more Vineland Adaptive Behavior Scales records assessed before and after transplant. Communication, daily living skills, socialization, and motor functions were measured. While standard scores decline over time, development of skills continue with a slower than average rate compared with peers. A cross-sectional nontransplanted comparison group showed more deficits after age 2 years than the transplanted group. In contrast to cognitive ability, age at transplant was not significantly associated with ultimate adaptive level. Baseline cognitive level before HSCT and growth of cognition after HSCT were associated with adaptive functions especially for communication and daily living skills. Socialization was predicted by cumulative medical risk factors, likely due to restricted social exposure in children with complicated transplant courses. Overall, measurement of adaptive behaviors demonstrated that HSCT allows long-term slow improvement of functional outcomes for children with Hurler syndrome. Children with Hurler syndrome with good cognitive levels before HSCT and continued growth of cognition after HSCT show good adaptive functions. Although cognitive and orthopedic problems as well as medical complications limit adaptive ability, identifying these problems early allow beneficial targeted interventions.

Neurofibromatosis and Attentional Deficits: An Illustrative Example of the Common Association of Medical Causes with Behavioural Syndromes, Implications for General Child Mental Health Services

   Neurofibromatosis type 1 (NF1) is a common autosomal dominant gene disorder. In addition to well described physical and cognitive features certain behavioural patterns have been reported. Clear association has been shown between NF1 and attention deficit hyperactivity disorder (ADHD), with up to half of children with NF1 fulfilling DSM-IV diagnostic criteria for ADHD. This article aims to increase awareness among child mental health workers of the common link between genetic conditions (like NF1) and ADHD, thus improving diagnosis and intervention.

Sleep disturbance in Sanfilippo syndrome: a parental questionnaire study

AIMS

To determine the incidence, manifestations, and best management of sleep disturbance in Sanfilippo syndrome (mucopolysaccharidosis (MPS) type III).

METHODS

Families were ascertained through the MPS societies of Australasia, the UK, and the USA. Questionnaires were sent by mail and were answered anonymously. Identical questions regarding sleep disturbance were asked about unaffected siblings to provide control data. Sleep disturbance was quantified by a total sleep disturbance score.

RESULTS

A total of 141 responses were received; 91.5% of children with Sanfilippo syndrome had sleep disturbance and this was significantly higher than for their unaffected sibs; 77.5% of parents had used medication for this problem, with melatonin and antihistamines being most commonly used. Melatonin and benzodiazepines were reported as the most efficacious. Many different environmental modifications had been employed for this problem and some parents reported success with behavioural therapies.

CONCLUSIONS

Sleep disturbance is common, severe, and difficult to manage in Sanfilippo syndrome. Based on the parental responses and its safety profile, melatonin is the first line drug that should be tried. Behavioural therapy should be tried in all with Sanfilippo syndrome and sleep disturbance.

Impaired memory and olfactory performance in NaSi-1 sulphate transporter deficient mice

In the present study, NaSi-1 sulphate transporter knock-out (Nas1-/-) mice, an animal model of hyposulphataemia, were examined for spatial memory and learning in a Morris water maze, and for olfactory function in a cookie test. The Nas1-/- mice displayed significantly (P<0.05) increased latencies to find an escape platform in the reversal learning trials at 2 days but not 1 day after the last acquisition trial in a Morris water maze test, suggesting that Nas1-/- mice may have proactive memory interference. While the wild-type (Nas1+/+) mice showed a significant (P<0.02) decrease in time to locate a hidden food reward over four trials after overnight fasting, Nas1-/- mice did not change their performance, resulting in significantly (P<0.05) higher latencies when compared to their Nas1+/+ littermates. There were no significant differences between Nas1-/- and Nas1+/+ mice in the cookie test after moderate food deprivation. In addition, both Nas1-/- and Nas1+/+ mice displayed similar escape latencies in the acquisition phase of the Morris water maze test, suggesting that learning, motivation, vision and motor skills required for the task may not be affected in Nas1-/- mice. This is the first study to demonstrate an impairment in memory and olfactory performance in the hyposulphataemic Nas1-/- mouse.

Psychiatric symptoms of children and adolescents with juvenile neuronal ceroid lipofuscinosis

BACKGROUND

Juvenile neuronal ceroid lipofuscinosis (JNCL) is one of the most common neurodegenerative disorders in childhood and adolescence. The clinical picture includes diverse and complex psychiatric symptoms that are difficult to treat. Only symptomatic treatment is available. To improve symptomatic therapy, it is important to recognize the symptoms. The purpose of this study was to identify predominant psychiatric symptoms in patients with JNCL.

METHODS

The study included 27 patients with JNCL with and without psychotropic treatment. The mean age was 15.2 (range 9-21) years. Characteristic psychiatric symptoms in this patient group were clarified by using the following standardized questionnaires filled in by parents, teachers and the patients themselves: Child Behavior Checklist (CBCL), Teacher Report Form (TRF) and Children's Depression Inventory (CDI). The symptoms were recorded for the entire study group and compared between patients with and without psychotropic treatment and between genders.

RESULTS

The patients had a large number of psychiatric symptoms according to the CBCL and TRF. The most commonly reported symptoms were social, thought, attention problems, somatic complaints and aggressive behaviour. Patients receiving psychotropic medication had more psychiatric symptoms according to the CBCL and TRF. Moreover, female patients had more problems than male patients according to the CBCL. The total psychiatric symptom score was at clinical or borderline range for psychiatric disturbance in 74% of patients. The number of depressive symptoms reported by the patients themselves was low.

CONCLUSIONS

JNCL patients suffer from a multitude of psychiatric symptoms. To improve drug choice and dosage, a thorough evaluation of these symptoms by standardized methods is needed before initiating treatment. Progress and possible adverse effects of treatment should be monitored on a regular basis.

Behavioural abnormalities of the hyposulphataemic Nas1 knock-out mouse

We recently generated a sodium sulphate cotransporter knock-out mouse (Nas1-/-) which has increased urinary sulphate excretion and hyposulphataemia. To examine the consequences of disturbed sulphate homeostasis in the modulation of mouse behavioural characteristics, Nas1-/- mice were compared with Nas1+/- and Nas1+/+ littermates in a series of behavioural tests. The Nas1-/- mice displayed significantly (P < 0.001) decreased marble burying behaviour (4.33 +/- 0.82 buried) when compared to Nas1+/+ (7.86 +/- 0.44) and Nas1+/- (8.40 +/- 0.37) animals, suggesting that Nas1-/- mice may have decreased object-induced anxiety. The Nas1-/- mice also displayed decreased locomotor activity by moving less distance (1.53 +/- 0.27 m, P < 0.05) in an open-field test when compared to Nas1+/+ (2.31 +/- 0.24 m) and Nas1+/- (2.15 +/- 0.19 m) mice. The three genotypes displayed similar spatiotemporal and ethological behaviours in the elevated-plus maze and open-field test, with the exception of a decreased defecation frequency by the Nas1-/- mice (40% reduction, P < 0.01). There were no significant differences between Nas1-/- and Nas1+/+ mice in a rotarod performance test of motor coordination and in the forced swim test assessing (anti-)depressant-like behaviours. This is the first study to demonstrate behavioural abnormalities in the hyposulphataemic Nas1-/- mice.

Melatonin supplementation for severe and intractable sleep disturbance in young people with genetically determined developmental disabilities: short review and commentary

Serious childhood developmental disabilities are common, and are debilitating for the individual and their family. Increasingly these are being shown to have genetic bases. Associated challenging behaviours are frequent, one of the commonest being severe and intractable sleep disturbance. This is associated with daytime behaviour problems, poor developmental and academic progress, and substantial familial psychopathology. Social and behavioural approaches ("sleep hygiene" measures) have, to an extent, revolutionised management; however, many individuals remain unresponsive. Modern medications therefore play increasingly important complementary roles in conjunction with psychological, educational, and social strategies. This paper reviews evidence for the frequency and severity of sleep disturbance in children and young people with severe intractable neurodevelopmental disabilities. The potential benefits of judicious and carefully monitored use of medication are described, with a focus on the importance of melatonin as a sleep inducer. It is concluded that melatonin is a potentially useful and safe adjunct to psychological and social approaches for severe sleep disturbance in this client group.

Sleep disorders in Sanfilippo syndrome: a polygraphic study

OBJECTIVE

A high prevalence of sleep disorders is reported in patients affected by Mucopolysaccharidosis III (Sanfilippo syndrome). These disorders have never been investigated by prolonged, objective, and instrumental evaluations. The present work is based on sleep duration and structure in Sanfilippo patients.

STUDY DESIGN

The features of sleep/wake cycle in 6 Sanfilippo patients and 6 healthy controls were evaluated by means of sleep diaries and 48 hour ambulatory EEG and polygraphic recordings. Statistical analysis was performed by means of the U-test (Mann-Whitney).

RESULTS

Four out of six Sanfilippo patients, the oldest patients in our sample, showed an extremely irregular sleep pattern, with several sleep episodes of inconstant duration, irregularly distributed along 24 hours. The two younger patients showed sleep maintenance insomnia with several nocturnal awakenings.

CONCLUSIONS

These results suggest that sleep disruption in Sanfilippo syndrome consists of an irregular sleep/wake pattern, which at its onset might appear as a disorder of initiating or maintaining sleep. This could explain why same patients do not respond to conventional hypnotics. The present observation might suggest attempting therapies aimed at resynchronization, such as behavioral treatment, light therapy or melatonin.

Sleep disturbance in mucopolysaccharidosis type III (Sanfilippo syndrome): a survey of managing clinicians

Sanfilippo syndrome (mucopolysaccharidosis type III) is the commonest mucoploysaccharidosis. It causes neurodegeneration with often profound sleep and behavioral disturbance. Management of the sleep disturbance is difficult and inconsistent. In this study, we surveyed clinicians with particular expertise in the management of individuals with mucopolysaccharidoses. We found that sleep problems are almost universal in this patient population and that no one treatment is consistently viewed as beneficial. Among the clinicians surveyed, melatonin is reported as the medication most likely to be of benefit. Benzodiazepines, chloral hydrate, antihistamines and antipsychotic agents are overall reported as less efficacious. The major side-effect of the medications as a group was reported to be daytime somnolence. Based on this study, recommendations are given regarding the approach to sleep disturbance in Sanfilippo syndrome.

Molecular genetics of mucopolysaccharidosis type IIIA and IIIB: Diagnostic, clinical, and biological implications

Mucopolysaccharidosis (MPS) types IIIA, B, C, and D are a group of autosomal recessive lysosomal storage diseases caused by mutations in one of four genes which encode enzyme activities required for the lysosomal degradation of heparan sulfate. The progressive lysosomal storage of heparan sulfate eventually results in the clinical onset of disease, which is predominantly characterized by severe central nervous system degeneration. MPS-IIIA and MPS-IIIB involve deficiencies of heparan sulfate sulfamidase (SGSH) and alpha-N-acetylglucosaminidase (NAGLU), respectively. Both the SGSH and NAGLU genes have been cloned and characterized, thereby permitting mutation analysis of MPS-IIIA and MPS-IIIB patients. A total of 62 mutations have now been defined for MPS-IIIA consisting of 46 missense/nonsense mutations, 15 small insertions/deletions, and one splice site mutation. A total of 86 mutations have been identified in the NAGLU gene of MPS-IIIB patients; 58 missense/nonsense mutations, 27 insertions/deletions, and one splice site mutation. Most of the identified mutations in the SGSH and NAGLU genes are associated with severe clinical phenotypes. Many of the missense, nonsense, and insertion/deletion mutations have been expressed in mammalian cell lines to permit the characterization of their effects on SGSH and NAGLU activity and intracellular processing and trafficking. For MPS-IIIA and MPS-IIIB many of the reported mutations are unique making screening the general population difficult. However, molecular characterization of MPS-IIIA patients has revealed a high incidence of particular mutations of different geographical origins, which will be beneficial for the molecular diagnosis of MPS-IIIA.

Hematopoietic cell transplantation for mucopolysaccharidosis IIB (Hunter syndrome)

Hunter syndrome is an X-linked metabolic storage disorder arising from deficiency of iduronate sulfatase enzyme activity. Despite the successful use of hematopoietic cell transplantation for a variety of lysosomal and peroxisomal storage diseases, limited benefit occurs following transplantation in either the severe or mild forms of Hunter syndrome. A brief ethical commentary is provided on the case of a boy with mucopolysaccharidosis IIB (ie the mild form) who received an unrelated umbilical cord blood transplant to improve his future quality of life. Bone Marrow Transplantation (2000).

[Anatomo-pathological and ultrastructural features of mucopolysaccharidosis. Case report]

The mucopolysaccharidoses (MPS) are lysosomal storage diseases in which a specific enzyme defect causes glycosaminoglycans storage in tissues. The authors present a necropsy case of a 10 years old boy with clinical and laboratorial diagnosis of MPS. The necropsy revealed thickening of meninges, cardiac valves and hepatomegaly. The microscopical examination of the brain showed finely vacuolated histiocytes around blood vessels and meninges. Systemic deposits of vacuolated histiocytes in cardiac valves and liver were also detected. The ultrastructural examination of the brain, liver and spleen showed filamentous material accumulated in vacuolated histiocytes and hepatocytes and features neuronal storage disease.

Sleep problems in children with Sanfilippo syndrome

Sanfilippo syndrome is a rare degenerative disorder which has severe intellectual and behavioural sequelae, commonly including sleep problems. A parental questionnaire was used to gather information on the sleep patterns of 80 children with Sanfilippo syndrome (mean age 10 years 2 months). The majority were found to have sleep problems (78%). Many also exhibited other distressing and unusual night time behaviours (staying up all night, chewing the bedclothes or crying out suddenly), and a few laughed or sang. Such problems may have been more severe in those with Sanfilippo syndrome type B. In four of the families offered individually tailored behaviour-management advice there was immediate improvement, which was maintained at followup in two cases. These results demonstrate the usefulness of even such a minimal intervention, even in a very difficult population such as this.