Delta power robustly predicts cognitive function in Angelman syndrome

Objective

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by loss of function of the maternally inherited UBE3A gene in neurons. Promising disease‐modifying treatments to reinstate UBE3A expression are under development and an early measure of treatment response is critical to their deployment in clinical trials. Increased delta power in EEG recordings, reflecting abnormal neuronal synchrony, occurs in AS across species and correlates with genotype. Whether delta power provides a reliable biomarker for clinical symptoms remains unknown.

Methods

We analyzed combined EEG recordings and developmental assessments in a large cohort of individuals with AS (N = 82 subjects, 133 combined EEG and cognitive assessments, 1.08–28.16 years; 32F) and evaluated delta power as a biomarker for cognitive function, as measured by the Bayley Cognitive Score. We examined the robustness of this biomarker to varying states of consciousness, recording techniques and analysis procedures.

Results

Delta power predicted the Bayley Scale cognitive score (P < 10⁻⁵, R² = 0.9374) after controlling for age (P < 10⁻²⁴), genotype:age (P < 10⁻¹¹), and repeat assessments (P < 10⁻⁸), with the excellent fit on cross validation (R² = 0.95). There were no differences in model performance across states of consciousness or bipolar versus average montages (ΔAIC < 2). Models using raw data excluding frontal channels outperformed other models (ΔAIC > 4) and predicted performance in expressive (P = 0.0209) and receptive communication (P < 10⁻³) and fine motor skills (P < 10⁻⁴).

Interpretation

Delta power is a simple, direct measure of neuronal activity that reliably correlates with cognitive function in AS. This electrophysiological biomarker offers an objective, clinically relevant endpoint for treatment response in emerging clinical trials.

Aberrant aggressive behavior in a mouse model of Angelman syndrome

Angelman syndrome (AS) is a genetic neurodevelopmental disorder due to the absence of the E3-ligase protein, UBE3A. Inappropriate social interactions, usually hyper-sociability, is a part of that syndrome. In addition, clinical surveys and case reports describe aggressive behavior in AS individuals as a severe difficulty for caretakers. A mouse model for AS recapitulates most of the human AS phenotypes. However, very few studies utilized this mouse model for investigating affiliative social behavior, and not even a single study examined aggressive behavior. Hence, the aim of the herein study was to examine affiliative and aggressive social behavior. For that, we utilized a battery of behavioral paradigms, and performed detailed analyses of these behaviors. AS mice exhibited a unique characteristic of reduced habituation towards a social stimulus in comparison to their wild-type (WT) littermates. However, overall there were no additional marked differences in affiliative social behavior. In contrast to the mild changes in affiliative behavior, there was a striking enhanced aggression in the AS mice compared to their WT littermates. The herein findings emphasize the use of AS mouse model in characterizing and measuring inappropriate aggressive behavior, and suggests these as tools for investigating therapeutic interventions aimed at attenuating aggressive behavior.

Brief Report: Challenging Behaviors in Toddlers and Preschoolers with Angelman, Prader-Willi, and Williams Syndromes

Children with neurogenetic syndromes (NGS) experience comorbid challenging behaviors and psychopathology. We examined challenging behaviors in 86 toddlers and preschoolers across three NGS [Angelman syndrome (AS), Prader-Willi syndrome (PWS), and Williams syndrome (WS)] and 43 low-risk controls (LRC), using the Child Behavior Checklist for Ages 1½-5. Challenging behavior profiles differed across NGS, with generally elevated behaviors in AS and WS, but not PWS, relative to LRC. Withdrawn and autism spectrum symptoms were particularly elevated in AS. Although several profiles were similar to those previously reported in older children and adults, we also observed inconsistencies that suggest non-linear developmental patterns of challenging behaviors. These findings underscore the importance of characterizing early challenging behaviors to inform atypical phenotypic development and targeted intervention.

A behavioral test battery for mouse models of Angelman syndrome: a powerful tool for testing drugs and novel Ube3a mutants

Background

Angelman syndrome (AS) is a neurodevelopmental disorder caused by mutations affecting UBE3A function. AS is characterized by intellectual disability, impaired motor coordination, epilepsy, and behavioral abnormalities including autism spectrum disorder features. The development of treatments for AS heavily relies on the ability to test the efficacy of drugs in mouse models that show reliable, and preferably clinically relevant, phenotypes. We previously described a number of behavioral paradigms that assess phenotypes in the domains of motor performance, repetitive behavior, anxiety, and seizure susceptibility. Here, we set out to evaluate the robustness of these phenotypes when tested in a standardized test battery. We then used this behavioral test battery to assess the efficacy of minocycline and levodopa, which were recently tested in clinical trials of AS.

Methods

We combined data of eight independent experiments involving 111 Ube3a mice and 120 wild-type littermate control mice. Using a meta-analysis, we determined the statistical power of the subtests and the effect of putative confounding factors, such as the effect of sex and of animal weight on rotarod performance. We further assessed the robustness of these phenotypes by comparing Ube3a mutants in different genetic backgrounds and by comparing the behavioral phenotypes of independently derived Ube3a-mutant lines. In addition, we investigated if the test battery allowed re-testing the same animals, which would allow a within-subject testing design.

Results

We find that the test battery is robust across different Ube3a-mutant lines, but confirm and extend earlier studies that several phenotypes are very sensitive to genetic background. We further found that the audiogenic seizure susceptibility phenotype is fully reversible upon pharmacological treatment and highly suitable for dose-finding studies. In agreement with the clinical trial results, we found that minocycline and levodopa treatment of Ube3a mice did not show any sign of improved performance in our test battery.

Conclusions

Our study provides a useful tool for preclinical drug testing to identify treatments for Angelman syndrome. Since the phenotypes are observed in several independently derived Ube3a lines, the test battery can also be employed to investigate the effect of specific Ube3a mutations on these phenotypes.

Mental Health and Well-Being in Mothers of Children With Rare Genetic Syndromes Showing Chronic Challenging Behavior: A Cross-Sectional and Longitudinal Study

It is well documented that mothers of children with challenging behavior (CB) experience elevated levels of stress and that this persists over time, but less is known about the experience of mothers of children with rare genetic syndromes. This article describes 2 studies, 1 cross-sectional and 1 longitudinal, comparing well-being in mothers of children with Angelman, Cornelia de Lange and Cri du Chat syndrome who have either shown chronic CB ( n = 18) or low/no CB ( n = 26) in the preceding 7 years. The presence of chronic, long-term CB increased maternal stress but not depression or anxiety, and did not influence positive well-being. Stress relating specifically to their child's genetic syndrome reduced with age, highlighting the need for further exploration in this area.

Sleep in children with Angelman syndrome: Parental concerns and priorities

Angelman syndrome is a rare genetic syndrome, in which sleep disturbances are reported for 20-80% of individuals (Williams et al., 2006). This interview study delineated parental perceptions of sleep problems experienced by children with Angelman syndrome and the impact on parental sleep quality, health and wellbeing. The nature of desired interventions was also explored. Semi-structured interviews were completed with parents of 50 children, aged 16 months-15 years with Angelman syndrome who experienced current or historic sleep problems; predominantly night waking and settling problems. Parents were concerned by the impact of their child's sleep quality upon their own ability to function during the day. The importance of considering parental experiences was evidenced by variability in coping e.g. despite the persistence of sleep problems 20% of parents did not feel the need for any additional support. Amongst a range of types of further support desired, 27% cited further support with a behavioural intervention, and information about the trajectory of sleep problems in Angelman syndrome (18%). The results suggest that behavioural interventions supporting both children and parents in improving their sleep quality and well-being, and longitudinal research into sleep problems should be prioritised.

A Comparative Study of Sociability in Angelman, Cornelia de Lange, Fragile X, Down and Rubinstein Taybi Syndromes and Autism Spectrum Disorder

Few comparative studies have evaluated the heterogeneity of sociability across a range of neurodevelopmental disorders. The Sociability Questionnaire for People with Intellectual Disability (SQID) was completed by caregivers of individuals with Cornelia de Lange (n = 98), Angelman (n = 66), Fragile X (n = 142), Down (n = 117) and Rubinstein Taybi (n = 88) syndromes and autism spectrum disorder (ASD; n = 107). Between groups and age-band (<12yrs; 12-18yrs; >18yrs) comparisons of SQID scores were conducted. Rates of behaviors indicative of selective mutism were also examined. Fragile X syndrome achieved the lowest SQID scores. Cornelia de Lange, ASD, and Fragile X groups scored significantly lower than Angelman, Down and Rubinstein Taybi groups. Selective mutism characteristics were highest in Cornelia de Lange (40%) followed by Fragile X (17.8%) and ASD (18.2%). Age-band differences were identified in Cornelia de Lange and Down syndrome.

Parents' perceptions of communication patterns and effectiveness of use of augmentative and alternative communication systems by their children with Angelman syndrome

PURPOSE

The author describes communication patterns and outcomes of augmentative and alternative communication (AAC) intervention for individuals with Angelman syndrome.

METHOD

Parents self-administered a web-based survey using Qualtrics software. A series of rating scales and closed questions were used to gather information about individuals' current methods of communication, including AAC devices they were using. Individuals' uses of their single most advanced AAC devices were further explored in terms of associated importance, usefulness, success, acceptance, and functional outcomes.

RESULTS

Nonsymbolic methods of communication proved to be very important to individuals, as did electronic AAC devices, although to a lesser extent. Individuals tended to have access to more than one electronic device concurrently. Although numerous devices were cited, mobile technologies, particularly iPads, were especially prevalent. This represented a significant change from a previous investigation. Overall, device use was perceived to be frequently important, accepted, successful, and useful in relation to 8 different factors, although ratings across a series of 19 functional outcomes varied. Differences were noted on several measures when individuals' ages and educational placements were considered.

CONCLUSION

Results suggest a changing landscape in terms of types of devices used, particularly with respect to mobile technologies, and show clear evidence that device use is often, although not uniformly, associated with positive outcomes.

The prevalence of aggression in genetic syndromes: a review

Research into behavioural phenotypes identifies both environmental and organic factors as influencing aggression in children and adults with genetic disorders associated with intellectual disability. However, in contrast to self-injury there is a paucity of research that compares aggression across relevant syndromes. The primary aim of this review is to examine the association between aggression and genetic syndromes by analysis of prevalence studies. The review also examines the literature on the form of the behaviour and influence of environmental factors. Results imply that certain syndrome groups (Cri du Chat, Smith-Magenis, Prader-Willi, Angelman, Cornelia de Lange, and Fragile X syndromes; estimates over 70%) evidence a stronger association with aggression than others (e.g. Williams and Down syndromes; estimates below 15%). However, the strength of association is difficult to quantify due to methodological differences between studies. The results from examining form and environmental influences highlight the importance of phenotype-environment interactions. Research employing group comparison designs is warranted and future work on the assessment and intervention of aggression in genetic syndromes should consider the importance of phenotype-environment interactions.

Discrimination training reduces high rate social approach behaviors in Angelman syndrome: proof of principle

This proof of principle study was designed to evaluate whether excessively high rates of social approach behaviors in children with Angelman syndrome (AS) can be modified using a multiple schedule design. Four children with AS were exposed to a multiple schedule arrangement, in which social reinforcement and extinction, cued using a novel stimulus, were alternated. Twenty-five to 35 discrimination training sessions were conducted and levels of approach behaviors were measured before and after the discrimination training for two children. All four participants evidenced discrimination between conditions of reinforcement and extinction after 16-20 teaching sessions as indicated by lower rates of social approach behaviors in the presence of the S(Δ) for extinction. Reversal effects for the two children for whom this design was implemented were evident. The results demonstrate that after repeated training, the use of a novel stimulus can serve as a cue for children with AS to discriminate adult availability. This is a potentially effective component of a broader intervention strategy but highlights the need for sustained teaching procedures within this population.

Behavioral deficits in an Angelman syndrome model: effects of genetic background and age

Angelman syndrome (AS) is a severe neurodevelopmental disorder associated with disruption of maternally inherited UBE3A (ubiquitin protein ligase E3A) expression. At the present time, there is no effective treatment for AS. Mouse lines with loss of maternal Ube3a (Ube3a(m-/p+)) recapitulate multiple aspects of the clinical AS profile, including impaired motor coordination, learning deficits, and seizures. Thus, these genetic mouse models could serve as behavioral screens for preclinical efficacy testing, a critical component of drug discovery for AS intervention. However, the severity and consistency of abnormal phenotypes reported in Ube3a(m-/p+) mice can vary, dependent upon age and background strain, which is problematic for the detection of beneficial drug effects. As part of an ongoing AS drug discovery initiative, we characterized Ube3a(m-/p+) mice on either a 129S7/SvEvBrd-Hprt(b-m2) (129) or C57BL/6J (B6) background across a range of functional domains and ages to identify reproducible and sufficiently large phenotypes suitable for screening therapeutic compounds. The results from the study showed that Ube3a(m-/p+) mice have significant deficits in acquisition and reversal learning in the Morris water maze. The findings also demonstrated that Ube3a(m-/p+) mice exhibit motor impairment in a rotarod task, hypoactivity, reduced rearing and marble-burying, and deficient fear conditioning. Overall, these profiles of abnormal phenotypes can provide behavioral targets for evaluating effects of novel therapeutic strategies relevant to AS.

Evaluation of a behavioral treatment package to reduce sleep problems in children with Angelman Syndrome

The purpose of this investigation was to evaluate the effectiveness of a behavioral treatment package to reduce chronic sleep problems in children with Angelman Syndrome. Participants were five children, 2-11 years-of-age. Parents maintained sleep diaries to record sleep and disruptive nighttime behaviors. Actigraphy was added to provide independent evaluations of sleep-wake activity. The treatment package targeted the sleep environment, the sleep-wake schedule, and parent-child interactions during sleep times. Treatment was introduced sequentially, across families, and evaluated in an interrupted time series, multiple baseline design. Data show that prior to treatment, baseline rates of nighttime disruptive behavior were stable or increasing and none of the participants were falling to sleep independently. With the introduction of treatment, all participants quickly learned to initiate sleep independently. Gradual reductions were reported in disruptive behaviors and these improvements were sustained over time. Results were replicated with two participants when treatment was withdrawn and reinstated. Changes in disruptive bedtime behaviors and in sleep onset were found to be statistically significant. Parents indicated high satisfaction with the treatment. A behavioral treatment package was found to be effective with five children with long histories of significant sleep-related behavior problems. These results suggest that behavioral treatment may be a reasonable way to address sleep problems in some children with Angelman Syndrome.

Sleep in children and adolescents with Angelman syndrome: association with parent sleep and stress

BACKGROUND

Sleep concerns are common in children with Angelman syndrome, with 20-80% of individuals having a decreased sleep need and/or abnormal sleep-wake cycles. The impact of these sleep behaviours on parental sleep and stress is not known.

METHOD

Through the use of standardised questionnaires, wrist actigraphy and polysomnography, we defined the sleep behaviours of 15 children/adolescents with Angelman syndrome and the association of the child/adolescents sleep behaviours on parental sleep behaviours and parental stress.

RESULTS

Both children/adolescents and their parents exhibited over 1 h of wake time after sleep onset and fragmented sleep. Prolonged sleep latency in the child was associated with parent insomnia and daytime sleepiness. Additionally, variability in child total sleep time was associated with parental stress.

CONCLUSIONS

Poor sleep in children/adolescents with Angelman syndrome was associated with poor parental sleep and higher parental stress. Further work is warranted to identify the underlying causes of the poor sleep, and to relate these findings to daytime functioning, behaviour and the family unit.

Psychological well-being in parents of children with Angelman, Cornelia de Lange and Cri du Chat syndromes

BACKGROUND

The current study focuses on mothers and fathers of children with three rare genetic syndromes that are relatively unexplored in terms of family experience: Angelman syndrome, Cornelia de Lange syndrome and Cri du Chat syndrome.

METHOD

Parents of children with Angelman syndrome (n =15), Cornelia de Lange syndrome (n = 16) and Cri du Chat syndrome (n = 18), and a matched comparison group of parents of children with autism and intellectual disabilities (n = 20) completed questionnaires on both psychological distress (stress, anxiety, depression) and positive psychological functioning.

RESULTS

Parents of children with Angelman syndrome consistently reported the highest levels of psychological distress, and parents of children with Cornelia de Lange syndrome the lowest, with parents of children with Cri du Chat syndrome and autism scoring between these two. Positive psychological functioning was similar across the four aetiology groups.

CONCLUSIONS

Parents of children with rare genetic syndromes are at risk for high levels of stress and mental health problems. Methodological issues and the practical applications of these results are discussed.

Effects of adult familiarity on social behaviours in Angelman syndrome

BACKGROUND

Individuals with Angelman syndrome appear strongly motivated by social contact, but there have been few studies that have examined the relationship between sociability and familiarity. In this study we compared social behaviour in Angelman syndrome when in contact with mothers and strangers.

METHODS

We systematically manipulated adult familiarity, eye contact and speech to examine the effect on social approach behaviours in children with Angelman syndrome. Eleven children (deletion 15q11-13) participated and were observed during interactions with their mother and an unfamiliar adult, while adult eye contact and talking were manipulated. Laughing and smiling, looking and social approach were observed.

RESULTS

There was no effect of familiarity on laughing and smiling or eye contact. Participants showed more social approach towards their mother than the unfamiliar adult but only when their mother was looking at them.

CONCLUSIONS

In Angelman syndrome, looking at adults, laughing and smiling appear to be unaffected by the familiarity of the adult. However, approach behaviours are more common with mothers than strangers. The function of the approach behaviours might be to increase investment from the primary caregiver.

The prevalence and phenomenology of self-injurious and aggressive behaviour in genetic syndromes

BACKGROUND

Self-injurious and aggressive behaviours are reported as components of some behavioural phenotypes but there are few studies comparing across syndrome groups. In this study we examined the prevalence of these behaviours and the associated person characteristics in seven genetic syndromes.

METHODS

Questionnaire data on self-injury and aggression, mood, hyperactivity, autism spectrum disorder and repetitive behaviour were collected on Angelman (AS, n=104), Cornelia de Lange (CdLS, 101), Cri du Chat (CdCS, 58), Fragile X (FXS, 191), Lowe (LS, 56), Prader-Willi (PWS, 189) and Smith-Magenis (SMS, 42) syndromes.

RESULTS

A significantly higher prevalence of self-injury was evident in CdCS, CdLS, FXS, PWS, LS and SMS. The prevalence of aggression was significantly heightened in AS and SMS. Self-injury was associated with repetitive and impulsive behaviour in CdLS, FXS, PWS and LS. Impulsivity and overactivity were significantly higher in those showing aggression across all syndrome groups.

CONCLUSIONS

These data quantify the risk for self-injury and aggression in the syndromes studied with implications for early intervention. The associations between these behaviours and person characteristics both within and between syndromes warrant further research.

Adaptive behaviour in Angelman syndrome: its profile and relationship to age

BACKGROUND

Angelman syndrome (AS) is a neurodevelopmental disorder usually caused by an anomaly in the maternally inherited chromosome 15. The main features are severe intellectual disability, speech impairment, ataxia, epilepsy, sleep disorder and a behavioural phenotype that reportedly includes happy disposition, attraction to/fascination with water and hypermotoric behaviour.

METHOD

We studied the level of adaptive behaviour and the adaptive behavioural profile in the areas of 'motor skills', 'language and communication', 'personal life skills' and 'community life skills' in a group of 25 individuals with genetically confirmed AS, to determine whether there is a specific adaptive behaviour profile.

RESULTS AND CONCLUSIONS

None of the individuals, whatever their chronological age, had reached a developmental age of 3 years. A specific adaptive behaviour profile was found, with 'personal life skills' emerging as relative strengths and 'social and communication skills' as weaknesses.

Maternal parenting stress in families with a child with Angelman syndrome or Prader-Willi syndrome

BACKGROUND

Parenting stress was investigated in mothers with a child with Angelman syndrome (AS) or Prader-Willi syndrome (PWS), which are genetically related.

METHOD

Mothers of 24 children with AS and 23 children with PWS (2-12 years) completed the Nijmegen Parenting Stress Index-Short, Developmental Behaviour Checklist, and Vineland Screener 0-12.

RESULTS

Parenting stress was high for 58% of AS and 26% of PWS cases. For both syndromes, no relationship existed with the child's gender, age, or behavioural problems. In PWS there was no effect on level of functioning. Overall, more mothers with a child with AS perceived high parenting stress. When children showed low levels of behavioural problems this difference was contained. However, when children exhibited severe behavioural problems, parenting stress was the same for both syndromes.

CONCLUSION

In AS professional family support is essential, since parenting is stressful for many mothers. In PWS, this is especially the case when behavioural problems are present.

Experimental functional analysis of aggression in children with Angelman syndrome

BACKGROUND

Kinship theory suggests that genomic imprinting could account for phenotypic behaviors that increase (in the case of Angelman syndrome) or decrease (for Prader-Willi syndrome) the drive to access social resources (adult contact) depending on the imprinting parent-of-origin. Difficult to manage behaviors, such as aggression that is common in Angelman syndrome, could serve the function of increasing social interaction. We hypothesise that the commonly reported aggressive behavior in children with Angelman syndrome will be attention maintained.

METHODS

Experimental functional analysis was carried out with twelve children with Angelman syndrome caused by either a deletion (n=10) or uniparental disomy (n=2). The relative increase and decrease of aggressive behaviors was observed in response to experimentally manipulated levels of adult attention and demand. Laughing and smiling, crying and frowning, and physical initiation with an adult were also measured.

RESULTS

Aggression was seen in ten of the twelve children. One child evidenced a pattern of aggression across conditions consistent with maintenance by attention, three children showed higher levels of aggression during social interaction and two children showed escape motivated aggression.

DISCUSSION

With the exception of one child the results did not confirm the hypothesis. However, the pattern of increased aggression in the high social contact condition combined with evidence of positive affect during this condition suggests aggression may serve to both maintain and initiate social contact and this interpretation is consistent with previous research. The negative results may also have been influenced by the age of the children and the low levels of observed aggression.

Behavioural flexibility in individuals with Angelman syndrome, Down syndrome, non-specific intellectual disability and Autism spectrum disorder

BACKGROUND

Little is known about behavioural flexibility in children and adults with Angelman syndrome and whether people with this syndrome have more or less problems in being behaviourally flexible as compared with other people.

METHOD

Behavioural flexibility scores were assessed in 129 individuals with Angelman syndrome using 11 items from the Behavioural Flexibility Rating Scale-Revised (Green et al. 2007). Level of behavioural flexibility scores in individuals with Angelman syndrome (N = 129) was compared with that of people with non-specific intellectual disability (ID) (N = 90), Down syndrome (N = 398) and Autism spectrum disorder (N = 235).

RESULTS

Comparative analyses show that individuals with Angelman syndrome were more flexible than those with non-specific ID (P < 0.001) and those with Autism spectrum disorder (P < 0.01). There were no differences in behavioural flexibility scores between individuals with Angelman syndrome and those with Down syndrome (P = 0.94).

CONCLUSION

It is concluded that individuals with Angelman syndrome are comparatively flexible in their behaviour.

Preference for water-related items in Angelman syndrome, Down syndrome and non-specific intellectual disability

BACKGROUND

Few case controlled studies have been published on the behavioural phenotype of Angelman syndrome (AS). Little is yet known about preferences in individuals with AS.

METHOD

Preferences for water-related items and non-water-related items were assessed in 27 individuals with AS and two matched groups of participants, one with Down syndrome (DS) and the other with non-specific intellectual disabilities (NS), using an adapted Dutch version of the Choice Assessment Scale (Matson et al., 1999).

RESULTS

Individuals with AS showed a higher preference for water-related items compared to individuals in both comparison groups, substantiating previous reports which have suggested that individuals with AS are fascinated with water.

CONCLUSIONS

Knowledge about preferences in individuals with AS, especially with regard to water-related objects and activities, is important in person-centred planning of daytime activities and training programs for this group.

Angelman syndrome revisited

OBJECTIVES

Angelman syndrome (AS) is characterized by severe mental retardation, epilepsy, absent speech, dysmorphic facial features, and a characteristic behavioral phenotype. It is caused by deficiency of gene expression from maternally derived chromosome 15q11-q13.

STUDY DESIGN

The authors present the clinical picture of 9 children (median age, 4.9 years; range, 1 to 10 years) with confirmed Angelman syndrome. The patients complied with the international consensus criteria for AS and were consecutively investigated for psychomotor development, epilepsy, and electroencephalogram (EEG) profiles.

RESULTS

The median age at diagnosis was 3.9 years. The motor milestones were delayed. Median developmental quotient level was 26. All patients but 1 experienced predominantly polymorphic seizures. In 4 cases, the epilepsy was refractory to treatment. The EEG of all patients displayed an abnormal sleep pattern and generalized abnormalities, with a maximum over the posterior areas.

CONCLUSIONS

Milder or less typical phenotypes of AS may remain undiagnosed, leading to an overall underdiagnosis of the disease. The EEG shows no clear relation to genotype, clinical picture, or to the presence and severity of epilepsy. AS should be considered in the differential diagnosis of children with severe cryptogenic epilepsy and a characteristic configuration of clinical features.

Identification of novel deletions of 15q11q13 in Angelman syndrome by array-CGH: molecular characterization and genotype–phenotype correlations

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by mental retardation, absent speech, ataxia, and a happy disposition. Deletions of the 15q11q13 region are found in approximately 70% of AS patients. The deletions are sub-classified into class I and class II based on their sizes of approximately 6.8 and approximately 6.0, respectively, with two different proximal breakpoints and a common distal breakpoint. Utilizing a chromosome 15-specific comparative genomic hybridization genomic microarray (array-CGH), we have identified, determined the deletion sizes, and mapped the breakpoints in a cohort of 44 cases, to relate those breakpoints to the genomic architecture and derive more precise genotype-phenotype correlations. Interestingly four patients of the 44 studied (9.1%) had novel and unusually large deletions, and are reported here. This is the first report of very large deletions of 15q11q13 resulting in AS; the largest deletion being >10.6 Mb. These novel deletions involve three different distal breakpoints, two of which have been earlier shown to be involved in the generation of isodicentric 15q chromosomes (idic15). Additionally, precise determination of the deletion breakpoints reveals the presence of directly oriented low-copy repeats (LCRs) flanking the recurrent and novel breakpoints. The LCRs are adequate in size, orientation, and homology to enable abnormal recombination events leading to deletions and duplications. This genomic organization provides evidence for a common mechanism for the generation of both common and rare deletion types. Larger deletions result in a loss of several genes outside the common Angelman syndrome-Prader-Willi syndrome (AS-PWS) critical interval, and a more severe phenotype.

Environmental influences on the behavioral phenotype of Angelman syndrome

Using observational methods, we examined the social influences on laughing and smiling behavior in children with Angelman syndrome by systematically manipulating aspects of social interaction. Seven boys and 4 girls who were between 4 and 11 years of age and who had a confirmed maternal deletion of chromosome 15q11-q13 completed the study. Each child was observed while repeatedly exposed to three conditions in which parameters of social interaction were manipulated. Laughing and smiling behavior varied across all children and was significantly heightened in a condition involving adult speech, touch, smiling, laughing, and eye contact. The findings highlight the importance of examining environmental and social influences on purported phenotypic behavior in genetic syndromes.

[Behavioral phenotypes and cognitive characteristics in mental retardation]

The authors in a review article deal with characteristic cognitive and behavioral features appearing in mental retardations, which later are referred as behavioral phenotypes. Nyhan (1972) introduced the term "behavioral phenotype" to describe outwardly observable behavior so characteristic of children with genetic disorders that its presence suggests the underlying genetic condition. The behavioral phenotype is a characteristic pattern of motor, cognitive, linguistic and social abnormalities that is consistently associated with a biological/neurodevelopmental disorder. This does not mean that the behavior is present in all instances but that the probability of its occurrence is increased. In the future, more may be learned about brain mechanisms and gene-brain interactions by comparing those with behavioral involvement with others with the same syndrome but without the behavioral features.

Brief Report: Visual-Spatial Deficit in a 16-year-old Girl with Maternally Derived Duplication of Proximal 15q

Duplications of chromosome 15 may be one of the most common single genetic causes of autism spectrum disorders (ASD), aside from fragile X. Most of the cases are associated with maternally derived interstitial duplication involving 15q11-13. This case report describes a female proband with a maternally derived interstitial duplication of proximal 15q. She did not exhibit any symptoms of ASD apart from some developmental delay. By adolescence, she showed mild dysmorphism, a discrepant profile on the Wechsler Intelligence Scale for Children (Verbal IQ = 87; Performance IQ = 65) and a major deficit in visual-spatial abilities affecting fine motor skills, mathematical reasoning, visual memory and some global reading tasks. This is one of the first reports of a child with a maternal duplication who exhibits a visual-spatial deficit without ASD.

A long-term population-based clinical and morbidity profile of Angelman syndrome in Western Australia: 1953-2003

PURPOSE

To investigate the incidence, clinical presentation and associated comorbidities of Angelman syndrome (AS) in Western Australia, with establishment of an information database for the disorder.

METHODS

Data were collected from Disability Services Commission files, supplemented by datasets provided by the Western Australian Data Linkage Unit. The analysis was retrospective and quantitative.

RESULTS

Thirty-four individuals (two deceased) were identified (19 F, 15 M), with a mean age of 21.6 years; 52.9% had an IQ < 40, with the remainder of IQ 40-69. The incidence was one in 40,000 births and mean age at diagnosis was 5.8 years. The mean age of the 23 home residents was 20.2 years compared to 27.9 years in the nine individuals in sheltered accommodation. In general, the patients exhibited a typical AS clinical presentation. A median of 5.5 (range 0-20) hospital admissions was recorded per person, with epilepsy, gastrointestinal disorders, and dental work all common reasons for admission.

CONCLUSIONS

The estimated incidence was low compared to other reports, as was the proportion of IQ < 40. AS cases required substantial levels of medical care, especially those who were epileptic. An increase in the future numbers of AS patients needing sheltered accommodation is predicted.

Preferences in individuals with Angelman syndrome assessed by a modified Choice Assessment Scale

BACKGROUND

Individuals with Angelman syndrome (AS) seem to have a strong preference for water-related items. Until present, preference assessment in AS has not been reported.

METHODS

An adapted Dutch version of the Choice Assessment Scale (CAS) was administered by parents and other caregivers to 105 individuals with AS. The CAS was adapted by adding several items related to water and by adding a sub-scale describing activities and materials that individuals may avoid or escape.

RESULTS

The five sub-scales and total scale of the modified CAS had good internal consistency. Water-related items were more often scored as preferred than non-water-related items. No associations were found between sub-scale and total scale scores and demographic characteristics (e.g. genetic subtype, age).

CONCLUSIONS

This study shows that people with AS often have strong preferences for water-related items. The modified CAS is a reliable and sensitive instrument to assess client preferences.

Atypical cases of Angelman syndrome

Angelman syndrome (AS) is a profound disorder notable for mental retardation and severe language deficits that results from lack of function of the maternally inherited copy of the UBE3A gene. Chromosome deletions of 15q11q13, paternal uniparental disomy (UPD), UBE3A gene mutations, and imprinting center defects are all commonly recognized mechanisms that disrupt the function of the maternal copy of the UBE3A gene. We report here two patients with different atypical etiologies of AS. The first patient is a 3-year-old boy with global developmental delay, severe speech deficits, seizures, and very happy disposition. Southern blot analysis for the maternal and paternal chromosome 15 methylation products showed a mosaic methylation pattern, suggesting an imprinting center defect. The second patient is a 4(1/2)-year-old boy with global developmental delay, no expressive language, microcephaly, seizures, and ataxic gait. Array-based comparative genomic hybridization (CGH) demonstrated a loss in copy number for two overlapping clones encompassing the UBE3A gene, indicating a partial deletion within UBE3A. His mother, who was adopted, had an identical pattern, suggesting that her deletion was probably on her paternally imprinted allele. These patients illustrate the expanding spectrum of molecular findings in AS, reinforce the need to maintain suspicion when clinical features suggest AS but initial testing is normal, and show the power of CGH as a tool to uncover partial UBE3A deletions.

The behavioural phenotype of Angelman syndrome

BACKGROUND

The purpose of this review is to examine the notion of a behavioural phenotype for Angelman syndrome and identify methodological and conceptual influences on the accepted presentation.

METHODS

Studies examining the behavioural characteristics associated with Angelman syndrome are reviewed and methodology is described.

RESULTS

Potential bias in the description of the phenotype emerges with the use of case and cohort studies with the absence of comparison groups. A trend in the literature from a direct gene effect to a socially mediated effect on laughter is evident.

CONCLUSION

Evidence for a behavioural phenotype of Angelman syndrome has begun to emerge. However, by adopting the concept of a 'behavioural phenotype', attention may become biased towards the underlying biological basis of the syndrome, with developmental and environmental factors being overlooked.

Effects of Social Stimuli on Laughing and Smiling in Young Children With Angelman Syndrome

The effects of social stimuli present and absent on laughing and smiling in 2 young children with Angelman syndrome were assessed via a multielement design. Results indicated that laughing and smiling for either child was unaffected by the social stimuli assessed in the social interaction condition. Results are discussed in terms of the effects of biological variables and environmental stimuli on children with specific genetic disorders across the lifespan.

Autism in Angelman syndrome: implications for autism research

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by severe mental retardation, ataxia, and a happy/sociable disposition. Maternally, but not paternally, derived defects, such as duplications, within the AS critical region result in autistic symptomatology, suggesting that the UBE3A gene might be implicated in the causation of autism. This study examined the prevalence of autism in AS in 19 children representing three known molecular classes of AS. Children were studied over the course of 1 year. Forty-two percent of this population, eight of 19 children, met criteria for autism according to the Autism Diagnostic Observation Schedule (ADOS). Parents of children who were diagnosed with autism according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV criteria as well as the ADOS - Generic, Module 1 (ADOS-G) were administered the Autism Diagnostic Interview - Revised (ADI-R). Data from the ADI-R were convergent with data from the ADOS-G in all cases. Children with comorbid autism and AS scored lower on measures of language, adaptive behavior, and cognition, and demonstrated a slower rate of improvement over the course of the study. Furthermore, they demonstrated deficits in communication and socialization that mirror those observed in children with idiopathic autism. The study highlights the phenotypic overlap between autism and AS and increases the probability that dysregulation of UBE3A may play a role in the causation of autism.

Behavioral aspects of Angelman syndrome: a case control study

Angelman syndrome (AS) is a rare congenital disorder characterized by impairments in intellectual, neurological and motor functioning and a postulated behavioral profile. This study compared behavioral characteristics of 62 individuals with genetically confirmed AS and 29 individuals with presumed AS from clinical features, with a control group of young persons with intellectual disability (ID) derived from an Australian epidemiological register. Twelve behavioral items from the developmental behavior checklist (DBC) were used for this comparison. The groups were matched for chronological age, gender, and level of ID. In the AS group, significant differences were found for 10 behaviors, with poor attention span and impulsivity being less common, and overactivity/restlessness, chewing or mouthing objects, eating non-food items, gorging food, food fads, fascination for water, hand flapping and sleep disturbance being more common. Interestingly, there was no difference in prevalence of unprovoked laughter. Comparison of the results of the genetically confirmed with the genetically unconfirmed AS cases showed no significant differences between individual behavior prevalence. These findings show that a "behavioral phenotype" of AS can be distinguished from others of similar level of ID, but it is different from that hitherto published. Abnormal food related behaviors, hyperactivity, fascination for water, hand flapping, and sleep disturbance should be included in a "behavioral phenotype" for AS. Apart from hyperactivity, "ADHD-type" behaviors are not more characteristic of AS than in ID generally. Therefore, the Consensus Criteria for the diagnosis of AS need to be reviewed.

Analysis of the characteristics of epilepsy in 37 patients with the molecular diagnosis of Angelman syndrome

Angelman syndrome is a genetic disorder caused by defects in the maternally inherited imprinted domain located on chromosome 15q11-q13. Most patients with Angelman syndrome present with severe mental retardation, characteristic physical appearance, behavioral traits, and severe, early-onset epilepsy. We retrospectively reviewed the medical histories of 37 patients, all with the molecular diagnosis of Angelman syndrome and at least three years of follow-up in our neurology department, for further information about their epilepsy: age of onset, type of seizures initially and during follow-up, EEG recordings, treatments and response. The molecular studies showed 87% deletions de novo, 8% uniparental, paternal disomy, and 5% imprinting defects. The median age at diagnosis was 6.5 years, with 20% having begun to manifest febrile seizures at an average age of 1.9 years. Nearly all (95%) presented with epilepsy, the majority under the age of three (76%). The most frequent seizure types were myoclonic, atonic, generalized tonic-clonic and atypical absences. At onset, two patients exhibited West syndrome. EEG recordings typical of Angelman syndrome were found in 68%. Normalization of EEG appeared in 12 patients after nine years. Control of epileptic seizures improved after the age of 8.5 years. The most effective treatments were valproic acid and clonazepam. We conclude that epilepsy was present in nearly all of our cases with Angelman syndrome, and that the EEG can be a useful diagnostic tool. On comparing the severity of epilepsy with the type of genetic alteration, we did not find any statistically significant correlations.

Sleep in Individuals With Angelman Syndrome: Parent Perceptions of Patterns and Problems

The diagnostic criteria for Angelman syndrome includes sleep disturbance as an associated characteristic. There are, however, few researchers who have examined sleep problems in this population. Our goal in this study was to better characterize the sleep patterns and problems in individuals with Angelman syndrome. Parents of 339 individuals between the ages of 3 and 22 completed a previously validated sleep questionnaire. Results confirmed that a variety of sleep problems exist in a significant portion of individuals with Angelman syndrome, most prominently in the areas of sleep initiation, sleep duration, reliance on sleep facilitators, being awakened by loud noises, and being disoriented when aroused. Developmental trends, syndrome specificity of findings, clinical implications, and directions for future research are discussed.

Thelarche variant in a girl with Angelman syndrome

A case of Angelman syndrome (AS) with thelarche variant in a 4.5-year-old girl is presented. Clinical suspicion of AS was raised at the age of 15 months when she presented with mental retardation and epilepsy, absence of speech, ataxic gait with jerky movements, hyperactivity and paroxysmal episodes of laughter. Moreover, she had facial dysmorphic features such as microbrachycephaly, mid-facial hypoplasia, macrostomia and prominent mandible. Dinucleotide repeat polymorphism (DNRP) analysis, identified absence of maternal alleles at D15S543, D15S113 and GABRB3 loci, findings consistent with AS. Studies on CYP19 locus (outside the 15q11-13 region) revealed the presence of two different alleles, thus excluding the possibility of paternal isodisomy of chromosome 15 in this patient. Breast development at the age of 4.5 years, accompanied by accelerated growth velocity and bone age suggested the diagnosis of variant thelarche. This is the second case of AS with sexual precocity reported and whether this combination is a coincidence or not remains to be clarified.

Just how happy is the happy puppet? An emotion signaling and kinship theory perspective on the behavioral phenotype of children with Angelman syndrome

The favored level of parental investment in a child may differ for genes of maternal and paternal origin in the child. This conflict can be expressed in the phenomenon of genomic imprinting that refers to situations in which the same gene is differentially expressed depending on its parent of origin. Two disorders that show the effects of genomic imprinting--both at 15q11-q13--are Angelman Syndrome (AS) which is due to the absence of expression of maternally-inherited genes and Prader-Willi syndromes (PWS) which is due to the absence of expression of paternally-inherited genes. However, although both disorders can arise from the deletion of the same genetic region, the gustatory, behavioral, and affective characteristics of AS and PWS children are remarkably distinct. Recent research inspired by kinship theory has suggested the origins of these phenotypic differences may lie in the differential investment of each parent's genome in the AS or PWS child. Specifically, it is thought that each set of parental genes have different 'ideas' regarding how the child should behave towards the mother and how much investment they should look to extract. In normal cases, the trade-off between the competing parental genomes produces a behavioral equilibrium in the child. However, in pathological instances, particularly where gene expression is one-sided, the evolved behavioral strategies favored by the contributing genome will dominate the child's behavior. To date, research in the area of genomic conflict in AS and PWS children has primarily focusing on differences in post-natal nutrition-related behaviors. The current paper extends this framework by offering an emotion and evolutionary signaling interpretation of the affective characteristics of AS children. A review of the affective characteristics of the two syndromes (PWS and AS) is presented before kinship and emotions theory are used to examine the functions that differential affect expression may serve in altering maternal investment. We expected that because the ultimate goal of paternal genes is to increase the child rearing burden of mothers, the Angelman behavioral phenotype should exhibit the emotion signaling characteristics that elicit levels of investment more consistent with paternal genetic interests. AS children display more positive, relative to negative, affect expressions (i.e. AS children laugh and smile more frequently than PWS children). In affect signaling theories, positive affect signals (i.e., smiling, laughing) have evolved to manipulate the sensory systems of receivers to increase social resources. In contrast, because the expression of some negative affects may indicate to the mother that the infant is not viable, negative affect expression is characteristically low among AS children. However, AS children may nonetheless have high levels of non-expressed anxiety because of its role in assisting the child (and its paternal genome) to maintain vigilance for changes in investment on the part of the mother. Overall, our kinship and emotion signaling analysis of AS children suggests that their global pattern of affect signaling represents one manifestation of an array of possible evolved strategies within the parental genome. Specifically, because AS exhibits the effects of paternally-inherited genes unhindered by the expression of maternally-inherited genes, the AS infant manifests a pattern of expression and non-expression that maximize maternal investment and thus paternal fitness. This theory is a significant departure from the standard but erroneous conjecture that a mother and child's inclusive fitness interests are one and the same.

The Prader-Willi syndrome and the Angelman syndrome

The Prader-Willi syndrome and the Angelman syndrome are characterised by a complex clinical and behavioural phenotype resulting from loss of paternal or maternal expression, respectively, of genes located on the human chromosome 15q11-13. Different molecular mechanisms leading to this imbalance have been identified, including microdeletions, intragenic mutations, uniparental disomy and imprinting centre defects. Low copy repeat gene clusters are known to flank the 15q11-13 microdeletion. They predispose to unequal crossing-over events resulting in the deletion. Involvement of multiple disease genes is strongly suspected and traditional positional cloning techniques as well as animal models are used to identify the involved genes. In this review we include the present state of art and a delineation of future approach to study the candidate genes in these two syndromes.

Case report: Angelman syndrome in an individual with a small SMC(15) and paternal uniparental disomy: a case report with reference to the assessment of cognitive functioning and autistic symptomatology

The case of a 15-year-old male with Angelman syndrome, paternal uniparental disomy of chromosome 15, and a small supernumerary marker chromosome is discussed. Assessment of cognitive functioning revealed an uneven profile of ability across different domains; in particular, receptive language ability was found to be superior to expressive language ability, whilst both gross and fine motor skills were found to be relatively well developed. Assessment using the Autism Diagnostic Observation Schedule showed very little evidence of autistic symptomatology. The patient showed an interest in social interaction and used a variety of methods to communicate, including some gestures and several single words. A clinical history revealed febrile convulsions during childhood but an absence of seizures in the previous 5 years. The patient was not hypopigmented, and height, weight, and head circumference were within the normal range for his age. The implications of these features are discussed in the context of previous work describing a milder phenotype in nondeletion cases of Angelman syndrome and work that has examined the prevalence of autism spectrum disorders amongst individuals with Angelman syndrome.

Effects of environmental events on smiling and laughing behavior in Angelman syndrome

Angelman syndrome is a neurogenetic disorder associated with unique behaviors and characteristics, including an unusually happy expression, inability to speak, ataxia, mental retardation, and abnormal EEG. Previous research has suggested that smiling and laughing behaviors in Angelman syndrome are inappropriate, excessive, and dissociated from contextual events. In the present study, the variability of smiling and laughing behaviors of 3 individuals with Angelman syndrome was examined across typical social contexts. Results indicate that laughing and smiling increased during social situations and occurred at low levels during non-social situations. The behaviors, therefore, did not occur totally inappropriately, as has been suggested. The findings illustrate the need to divert attention to the examination of environmental influences on purported phenotypic behavior in genetic syndromes.

Drowning as a cause of death in Angelman syndrome

Angelman syndrome is characterized by mental retardation, seizures, ataxia, inappropriate laughter, lack of speech, a particular facial appearance, and generally a chromosome 15q11-q13 deletion. Recently, a fascination with water and water-related activities has been reported in individuals with the syndrome. We report on a 9.6-year-old male previously diagnosed with Angelman syndrome who died unexpectedly by drowning in a shallow backyard wading pool. This case further illustrates the fascination with water by individuals with Angelman syndrome and highlights that this fascination may lead to death. We wish to alert careproviders that this fascination with water and water-related activities may contribute to death and that these individuals should be closely supervised when in the presence of water.

Behavioral phenotypes in genetic syndromes: genetic clues to human behavior

A behavioral phenotype is the characteristic cognitive, personality, behavioral, and psychiatric pattern that typifies a disorder. A number of genetic syndromes have been identified as having this type of distinctive and consistent behavior pattern. It may act as an important diagnostic sign, like a malformation or characteristic facial appearance. Such patterns are also useful for the physician's anticipatory guidance from an educational, rehabilitative, and parenting perspective. In addition, because they are the consequences of known genetic alterations, behavioral phenotypes can be potentially highly valuable clues to the identification of genes in the population that are important to determination of cognitive skills or deficits, personality determinants, behavioral abnormalities, or psychiatric disorders. The nature of a behavioral phenotype and its potential for genetic insight can be appreciated through the examples of Williams syndrome, Prader-Willi syndrome, and Angelman syndrome. The cognitive and behavioral characteristics of these disorders are distinctive. Williams syndrome is known for its association with remarkable conversational verbal abilities and excessive empathy, whereas Prader-Willi syndrome is known for temper tantrums and obsessive-compulsive features, and Angelman syndrome is associated with a constantly happy affect and hyperactivity. The genetic basis for each of these disorders is known, and the pathophysiology and genotype-phenotype correlations are beginning to provide insight into genes responsible for personality characteristics and behavioral abnormalities.

Communication profiles of individuals with Down's syndrome, Angelman syndrome and pervasive developmental disorder

The communication profiles of individuals with Down's syndrome (DS), Angelman syndrome (AS) and pervasive developmental disorder (PDD) were investigated and contrasted. Seventy-seven individuals participated in the study. A within-group analysis revealed that those with DS performed better on tacting or labelling and echoing than on manding or requesting. No other effects were found, apart from an absence of echoing in those with AS, a result that is hardly surprising. A between-groups analysis revealed no differences between the aetiological groups in terms of their use of mands or requests and tacts. Individuals with DS and PDD did not differ in their scores on echoic functioning. The implications of these findings for the study of behavioural phenotypes and for communication intervention are discussed.