Autistic-like symptomatology in Prader-Willi syndrome: a review of recent findings

An Exploratory Analysis on the 2D:4D Digit Ratio and Its Relationship with Social Responsiveness in Adults with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a genetic disorder produced by a lack of expression of paternally derived genes in the 15q11-13 region. Research has generally focused on its genetic and behavioral expression, but only a few studies have examined epigenetic influences. Prenatal testosterone or the maternal testosterone-to-estradiol ratio (MaTtEr) has been suggested to play an important role in the development of the 'social brain' during pregnancy. Some studies propose the 2D:4D digit ratio of the hand as an indirect MaTtEr measure. The relationship between social performance and MaTtEr has been studied in other neurodevelopmental conditions such as Autism Spectrum Disorder (ASD), but to our best knowledge, it has never been studied in PWS. Therefore, our study aims to clarify the possible existence of a relationship between social performance-as measured using the Social Responsiveness Scale (SRS)-and MaTtEr levels using the 2D:4D ratio. We found that, as a group, PWS individuals have shorter index and ring fingers than the control group, but no significant difference in the 2D:4D ratios. The 2D:4D ratio showed a correlation only with Restricted Interests and Repetitive Behavior Subscale, where a positive correlation only for male individuals with PWS was found. Considering only PWS with previous GH treatment during childhood/adolescence (PWS-GH), index and ring fingers did not show differences in length with the control group, but the 2D:4D ratio was significantly higher in the right or dominant hand compared to controls.

Linking oxytocin and arginine vasopressin signaling abnormalities to social behavior impairments in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a genetic neurodevelopmental disorder. Global hypothalamic dysfunction is a core feature of PWS and has been implicated as a driver of many of PWS's phenotypic characteristics (e.g., hyperphagia-induced obesity, hypogonadism, short stature). Although the two neuropeptides (i.e., oxytocin [OXT] and arginine vasopressin [AVP]) most implicated in mammalian prosocial functioning are of hypothalamic origin, and social functioning is markedly impaired in PWS, there has been little consideration of how dysregulation of these neuropeptide signaling pathways may contribute to PWS's social behavior impairments. The present article addresses this gap in knowledge by providing a comprehensive review of the preclinical and clinical PWS literature-spanning endogenous neuropeptide measurement to exogenous neuropeptide administration studies-to better understand the roles of OXT and AVP signaling in this population. The preponderance of evidence indicates that OXT and AVP signaling are indeed dysregulated in PWS, and that these neuropeptide pathways may provide promising targets for therapeutic intervention in a patient population that currently lacks a pharmacological strategy for its debilitating social behavior symptoms.

Relationship Between Sensory Processing and Autism Spectrum Disorder-Like Behaviors in Prader-Willi Syndrome

The relationship between sensory processing and ASD-like and associated behaviors in patients with Prader-Willi Syndrome (PWS) remains relatively unexplored. Examining this relationship, 51 adults with PWS were administered the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS), Short Sensory Profile (SSP-J), Food-Related Problem Questionnaire (FRPQ), and Aberrant Behavior Checklist (ABC-J). Based on SSP-J z-scores, participants were classified into three severity groups. Analysis of variance was performed to compare the behavioral scores of these three groups. Statistically significant group differences were observed in PARS (p = .006, ηp2 = .194) and ABC-J (p = .006, ηp2 = .193) scores. Our findings suggest that the level of sensory processing may predict ASD-like and aberrant behaviors in adults with PWS, implying the importance of a proper assessment for early intervention.

Equivocal expression of emotions in children with Prader-Willi syndrome: what are the consequences for emotional abilities and social adjustment?

Background

People with Prader-Willi Syndrome (PWS) experience great difficulties in social adaptation that could be explained by disturbances in emotional competencies. However, current knowledge about the emotional functioning of people with PWS is incomplete. In particular, despite being the foundation of social adaptation, their emotional expression abilities have never been investigated. In addition, motor and cognitive difficulties - characteristic of PWS - could further impair these abilities.

Method

To explore the expression abilities of children with PWS, twenty-five children with PWS aged 5 to 10 years were assessed for 1) their emotional facial reactions to a funny video-clip and 2) their ability to produce on demand the facial and bodily expressions of joy, anger, fear and sadness. Their productions were compared to those of two groups of children with typical development, matched to PWS children by chronological age and by developmental age. The analyses focused on the proportion of expressive patterns relating to the target emotion and to untargeted emotions in the children’s productions.

Results

The results showed that the facial and bodily emotional expressions of children with PWS were particularly difficult to interpret, involving a pronounced mixture of different emotional patterns. In addition, it was observed that the emotions produced on demand by PWS children were particularly poor and equivocal.

Conclusions

As far as we know, this study is the first to highlight the existence of particularities in the expression of emotions in PWS children. These results shed new light on emotional dysfunction in PWS and consequently on the adaptive abilities of those affected in daily life.

A study of voice and non-voice processing in Prader-Willi syndrome

Background

Prader-Willi syndrome (PWS) is a rare and complex neurodevelopmental disorder of genetic origin. It manifests itself in endocrine and cognitive problems, including highly pronounced hyperphagia and severe obesity. In many cases, impaired acquisition of social and communication skills leads to autism spectrum features, and individuals with this syndrome are occasionally diagnosed with autism spectrum disorder (ASD) using specific scales. Given that communicational skills are largely based on vocal communication, it is important to study human voice processing in PWS.

We were able to examine a large number of participants with PWS (N = 61) recruited from France’s national reference center for PWS and other hospitals. We tested their voice and nonvoice recognition abilities, as well as their ability to distinguish between voices and nonvoices in a free choice task. We applied the hierarchical drift diffusion model (HDDM) with Bayesian estimation to compare decision-making in participants with PWS and controls.

Results

We found that PWS participants were impaired on both voice and nonvoice processing, but displayed a compensatory ability to perceive voices. Participants with uniparental disomy had poorer voice and nonvoice perception than participants with a deletion on chromosome 15. The HDDM allowed us to demonstrate that participants with PWS need to accumulate more information in order to make a decision, are slower at decision-making, and are predisposed to voice perception, albeit to a lesser extent than controls.

Conclusions

The categorization of voices and nonvoices is generally preserved in participants with PWS, though this may not be the case for the lowest IQ.

Preliminary Characterization of Parent-Child Interaction in Preschoolers With Prader-Willi Syndrome: The Relationship Between Engagement and Parental Stress

Early parent-child interactions (PCI) impact social cognitive development. Relatedly, children with various developmental disorders exhibit abnormal parental attachment relationships. Parental characteristics and behaviors can impact PCI and socioemotional development as well. No research has examined the parent-child dynamic in Prader-Willi syndrome (PWS), a neurodevelopmental disorder that presents with social cognitive deficits. This article provides a preliminary characterization of PCI quality and parenting stress in 17 PWS parent-child dyads, children ages 3-5 years, in comparison to 20 typically developing children and their parent. Results suggest early PCI disruption in preschoolers with PWS and their parents report increased levels of stress in various domains. These findings have important implications not only on parent well-being in PWS but its impact on child development.

Face processing and exploration of social signals in Prader-Willi syndrome: a genetic signature

BACKGROUND

Faces are critical social cues that must be perfectly processed in order to engage appropriately in everyday social interactions. In Prader-Willi Syndrome (PWS), a rare genetic disorder characterized by cognitive and behavioural difficulties including autism spectrum disorder, the literature referring to face processing is sparse. Given reports of poor social interactions in individuals with PWS, we sought to assess their face and emotion recognition skills during eyetracking recordings.

RESULTS

Compared with controls, patients with PWS performed more poorly on face/emotion recognition. We observed atypical facial exploration by patients with maternal disomy. These patients looked preferentially at the mouth region, whereas patients with a deletion and controls were more attracted to the eye region. During social scenes, the exploration became more atypical as the social content increased.

CONCLUSIONS

Our comprehensive study brings new insights into the face processing of patients with PWS. Atypical facial exploration was only displayed by patients with the maternal disomy subtype, corresponding to their higher rate of autism spectrum disorder. This finding strongly argues in favor of early identification of this genetic subgroup in order to optimize care by implementing tailored interventions for each patient as soon as possible.

HERCing: Structural and Functional Relevance of the Large HERC Ubiquitin Ligases

Homologous to the E6AP carboxyl terminus (HECT) and regulator of chromosome condensation 1 (RCC1)-like domain-containing proteins (HERCs) belong to the superfamily of ubiquitin ligases. HERC proteins are divided into two subfamilies, Large and Small HERCs. Despite their similarities in terms of both structure and domains, these subfamilies are evolutionarily very distant and result from a convergence phenomenon rather than from a common origin. Large HERC genes, HERC1 and HERC2, are present in most metazoan taxa. They encode very large proteins (approximately 5,000 amino acid residues in a single polypeptide chain) that contain more than one RCC1-like domain as a structural characteristic. Accumulating evidences show that these unusually large proteins play key roles in a wide range of cellular functions which include neurodevelopment, DNA damage repair, and cell proliferation. To better understand the origin, evolution, and function of the Large HERC family, this minireview provides with an integrated overview of their structure and function and details their physiological implications. This study also highlights and discusses how dysregulation of these proteins is associated with severe human diseases such as neurological disorders and cancer.

PRADER-WILLI SYNDROME: WHAT IS THE GENERAL PEDIATRICIAN SUPPOSED TO DO? - A REVIEW

OBJECTIVE

To carry out a review about Prader-Willi Syndrome based on the most recent data about the subject and to give recommendation for the general pediatricians for early diagnoses and follow-up.

DATA SOURCES

Scientific articles in the PubMed and SciELO databases. The research was not limited to a specific time period and included all articles in such databases.

DATA SYNTHESIS

The Prader-Willi Syndrome (PWS) is a rare genetic disorder resulting from the loss of imprinted gene expression within the paternal chromosome 15q11-q13. PWS is characterized by endocrine abnormalities, such as growth hormone (GH) deficiency, obesity, central adrenal insufficiency, hypothyroidism, hypogonadism and complex behavioral and intellectual difficulties. PWS individuals also may present other comorbidities, such as sleep disorders, scoliosis, constipation, dental issues and coagulation disorders. The follow-up protocol of the Children's Institute at Universidade de São Paulo is based on four main pillars: diet, exercise, recombinant human growth hormone (rhGH) therapy and behavioral and cognitive issues. The diet must include a caloric restriction of 900 kcal/day, according to the Prader-Willi Eating Pyramid and exercise plan is focused on daily aerobic exercises and postural therapy. The rhGH therapy is highly recommended by the international scientific literature and must be started as soon as the diagnostic is made. The management of behavioral issues is based on strategies to establish routine and rules.

CONCLUSIONS

If the general pediatrician becomes more familiar with PWS, the diagnosis and treatment will start earlier, which is essential to improve the quality of life and care for these individuals.

Oxytocin and Prader-Willi Syndrome

In the chapter, we explore the relationship between the peptide hormone, oxytocin (OT), and behavioral and metabolic disturbances observed in the genetic disorder Prader-Willi Syndrome (PWS). Phenotypic and genotypic characteristics of PWS are described, as are the potential implications of an abnormal OT system with respect to neural development including the possible effects of OT dysfunction on interactions with other regulatory mediators, including neurotransmitters, neuromodulators, and hormones. The major behavioral characteristics are explored in the context of OT dysfunction, including hyperphagia, impulsivity, anxiety and emotion dysregulation, sensory processing and interoception, repetitive and restrictive behaviors, and dysfunctional social cognition. Behavioral overlaps with autistic spectrum disorders are discussed. The implications of OT dysfunction on the mechanisms of reward and satiety and their possible role in informing behavioral characteristics are also discussed. Treatment implications and future directions for investigation are considered.

Exploring autism symptoms in an Australian cohort of patients with Prader-Willi and Angelman syndromes

Background

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are neurodevelopmental disorders that are caused by abnormal expression of imprinted genes in the 15q11-13 region. Dysregulation of genes located in this region has been proposed as a susceptibility factor for autism spectrum disorder (ASD) in both disorders.

Methods

This study aimed to explore symptoms of ASD in 25 PWS and 19 AS individuals aged between 1 and 39 years via objective assessment. Participants completed the Autism Diagnostic Observation Schedule-2nd Edition (ADOS-2) and a developmentally or age-appropriate intellectual functioning assessment. All participants had their genetic diagnosis confirmed using DNA methylation analysis and microarray testing of copy number changes within the 15q11-13 region.

Results

Participants with PWS had significantly higher overall and social affect calibrated severity scores (CSS) on the ADOS-2 compared to AS participants (p = .0055 and .0015, respectively), but the two groups did not differ significantly on CSS for the repetitive and restricted behaviour domain.

Conclusions

PWS cases presented with greater symptoms associated with ASD compared to individuals with AS. Mental health issues associated with PWS may contribute to elevated symptoms of ASD, particularly in adolescents and adults with PWS.

Electronic supplementary material

The online version of this article (10.1186/s11689-018-9242-0) contains supplementary material, which is available to authorized users.

Incidental memory for faces in children with different genetic subtypes of Prader-Willi syndrome

The present study examined the effects of genetic subtype on social memory in children (7–16 years) with Prader–Willi syndrome (PWS). Visual event-related potentials (ERPs) during a passive viewing task were used to compare incidental memory traces for repeated vs single presentations of previously unfamiliar social (faces) and nonsocial (houses) images in 15 children with the deletion subtype and 13 children with maternal uniparental disomy (mUPD). While all participants perceived faces as different from houses (N170 responses), repeated faces elicited more positive ERP amplitudes (‘old/new’ effect, 250–500ms) only in children with the deletion subtype. Conversely, the mUPD group demonstrated reduced amplitudes suggestive of habituation to the repeated faces. ERP responses to repeated vs single house images did not differ in either group. The results suggest that faces hold different motivational value for individuals with the deletion vs mUPD subtype of PWS and could contribute to the explanation of subtype differences in the psychiatric symptoms, including autism symptomatology.

Autistic, Aberrant, and Food-Related Behaviors in Adolescents and Young Adults with Prader-Willi Syndrome: The Effects of Age and Genotype

The effects of age and genotype were examined, with regard to the severity of aberrant, autistic, and food-related behaviors in Prader-Willi syndrome (PWS), with an emphasis on the contrast between adolescents and young adults. The Aberrant Behavior Checklist Japanese version (ABC-J), the Food Related Problem Questionnaire (FRPQ), and the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS) were administered to 65 PWS patients, including 20 adolescents (ages 12 to 17) and 45 young adults (ages 18 to 29). Significant differences (Mann-Whitney U tests) were found in ABC-J (p = 0.004) and PARS (p = 0.021), with lower scores in adolescents than in young adults. While DEL subgroups showed no significant differences between the two age groups in ABC-J (p = 0.063) and PARS (p = 0.134), mUPD subgroups showed a statistically significant difference in terms of ABC-J (p = 0.007). No significant differences were found between adolescents and young adults, in terms of FRPQ (p = 0.163). These results suggest that aberrant and autistic behaviors follow a marked worsening trend from around the age of 18. On the other hand, food-related behaviors give no sign of change at this transitory stage. Young adults with mUPD were found to be significantly more severe than adolescents with mUPD, in terms of aberrant behaviors.

Aberrant, autistic, and food-related behaviors in adults with Prader-Willi syndrome. The comparison between young adults and adults

This study aims to explore the differences of age as well as genotype in regards to the severity of behavioral symptoms in Prader-Willi syndrome (PWS), with emphasis on the comparison between youngadults and adults.The Food Related Problem Questionnaire (FRPQ), the Aberrant Behavior Checklist Japanese Version (ABC-J), and the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS) were administered to 46 PWS patients, including 33 young adults (ages 18-28) and 13 adults(ages 30-45). To examine the differences between young adults and adults, Mann-Whitney U tests were conducted. Statistically significant differences were found in ABC-J (p = .027) and PARS (p = .046), with higher scores in young adults than adults. Such differences between the two age groups were still true for the subgroups having a paternal chromosome 15q deletion (DEL) for ABC-J (p = .050) and part of PARS ("Problematic behavior"; p = .007). By contrast, there was no significant differences between young adults and adults regarding FRPQ (p = .65).These results suggest that aberrant behaviors decline from around the ages of thirty, in PWS patients in general and in DEL subgroups in particular, while food-related behaviors give no indication of diminishing in spite of developmental growth.

A model to characterize psychopathological features in adults with Prader-Willi syndrome

High prevalence of behavioral and psychiatric disorders in adults with Prader-Willi Syndrome (PWS) has been reported in last few years. However, data are confusing and often contradictory. In this article, we propose a model to achieve a better understanding of the psychopathological features in adults with PWS. The study is based on clinical observations of 150 adult inpatients, males and females. Non-parametric statistics were performed to analyse the association of psychopathological profiles with genotype, gender and age. We propose a model of psychiatric disorders in adults with PWS based on cognitive, emotional and behavioural issues. This model defines four psychopathological profiles: Basic, Impulsive, Compulsive, and Psychotic. The Basic profile is defined by traits and symptoms that are present in varying degrees in all persons with PWS. In our cohort, this Basic profile corresponds to 55% of the patients. The rest show, in addition to these characteristics, salient features of impulsivity (Impulsive profile, 19%), compulsivity (Compulsive profile, 7%), or psychosis (Psychotic profile, 19%). The analysis of factors associated with different profiles reveals an effect of genotype on Basic and Psychotic profiles (Deletion: 70% Basic, 9% Psychotic; Non-deletion: 23% Basic, 43% Psychotic) and a positive correlation between male sex and impulsivity, unmediated by sex hormone treatment. This is a clinical study, based on observation proposing an original model to understand the psychiatric and behavioural disorders in adults with PWS. Further studies are needed in order to test the validity of this model.

Diagnoses and characteristics of autism spectrum disorders in children with Prader-Willi syndrome

BACKGROUND

A small percentage of people with autism spectrum disorders (ASD) have alterations in chromosome 15q11.2-q3, the critical region for Prader-Willi syndrome (PWS). Data are limited, however, on the rates and characteristics of ASD in PWS. Previous estimates of ASD in PWS (25 to 41%) are questionable as they are based solely on autism screeners given to parents. Inaccurate diagnoses of ASD in PWS can mislead intervention and future research.

METHODS

One hundred forty-six children and youth with PWS aged 4 to 21 years (M = 11) were assessed with the Autism Diagnostic Observation Schedule-2 (ADOS-2). An expert clinical team-made best-estimate ASD diagnoses based on ADOS-2 videotapes, calibrated severity scores, and children's developmental histories and indices of current functioning. Children were also administered the Kaufman Brief Intelligence Test-2, and parents completed the Repetitive Behavior Scale-Revised and Vineland Adaptive Behavior Scales. Scores were compared across children with PWS + ASD versus PWS only. The performance of an ASD screener, the Social Communication Questionnaire (SCQ) and the ADOS-2 were evaluated in relation to best-estimate diagnoses.

RESULTS

Best-estimate diagnoses of ASD were made in 18 children, or 12.3% of the sample, and the majority of them had the maternal uniparental disomy (mUPD) PWS genetic subtype. Compared to the PWS-only group, children with PWS + ASD had lower verbal and composite IQ's and adaptive daily living and socialization skills, as well as elevated stereotypies and restricted interests. Regardless of ASD status, compulsivity and insistence on sameness in routines or events were seen in 76-100% of children and were robustly correlated with lower adaptive functioning. The SCQ yielded a 29-49% chance that screen-positive cases will indeed have ASD. The ADOS-2 had higher sensitivity, specificity and predictive values. Communication problems were seen in children who were ADOS-2 positive but deemed not to have ASD by the clinical team.

CONCLUSIONS

Autism screeners should not be the sole index of probable ASD in PWS; children need to be directly observed and evaluated. Compulsivity and insistence on sameness are salient in PWS and likely impede adaptive functioning. Most children with PWS only evidenced sub-threshold problems in social interactions that could signal risks for other psychopathologies.

Investigating Autism-Related Symptoms in Children with Prader-Willi Syndrome: A Case Study

Prader-Willi syndrome (PWS), a rare genetic disorder caused by the lack of expression of paternal genes from chromosome 15q11-13, has been investigated for autism spectrum disorder (ASD) symptomatology in various studies. However, previous findings have been variable, and no studies investigating ASD symptomatology in PWS have exclusively studied children. We aimed to characterize social communication functioning and other ASD-related symptoms in children with PWS, and assessed agreement across measures and rates of ASD diagnosis. Measures included the Autism Diagnostic Observation Schedule-2 (ADOS-2), the Social Communication Questionnaire (SCQ), Social Responsiveness Scale-2 (SRS-2), Social Skills Improvement System-Rating Scales (SSIS-RS), and the Vineland Adaptive Behavioral Scales-II (VABS-II). General adaptive and intellectual skills were also assessed. Clinical best estimate (CBE) diagnosis was determined by an experienced developmental pediatrician, based on history and review of all available study measures, and taking into account overall developmental level. Participants included 10 children with PWS, aged 3 to 12 years. Three of the 10 children were male and genetic subtypes were two deletion (DEL) and eight uniparental disomy (UPD) (with a total of 6 female UPD cases). Although 8 of the 10 children exceeded cut-offs on at least one of the ASD assessments, agreement between parent questionnaires (SCQ, SRS-2, SSIS-RS) and observational assessment (ADOS-2) was very poor. None of the children were assigned a CBE diagnosis of ASD, with the caveat that the risk may have been lower because of the predominance of girls in the sample. The lack of agreement between the assessments emphasizes the complexity of interpreting ASD symptom measures in children with PWS.

Anxiety and depression symptomatology in adult siblings of individuals with different developmental disability diagnoses

Factors predicting the emotional well-being of adult siblings of those with developmental disability (DD) remain under-researched. In this study adult siblings of individuals with Down's syndrome (DS), autism (ASD), Prader-Willi syndrome (PWS) and those with DD but with unknown aetiology (DUA) were compared with each other and a closely-matched control group to ascertain if sibling disability type made a difference to anxiety and/or depression levels. Also considered was the interactive effect of gender, age, parental and sibling educational attainment levels, socio-economic status and birth order on anxiety and depression outcomes. With the exception of siblings of those with DS, adult siblings of those with ASD, PWS and DUA reported significantly higher levels of anxiety and depression than the control group. There were some predictive effects of the demographic variables upon anxiety and depression but none common to all disability types and no moderating effects of demographic factors were found. Consequently other solutions must be found as to why this important group of people have elevated rates of anxiety and depression in comparison to the general population.

Deficits in voice and multisensory processing in patients with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare neurodevelopmental and genetic disorder that is characterized by various expression of endocrine, cognitive and behavioral problems, among which a true obsession for food and a deficit of satiety that leads to hyperphagia and severe obesity. Neuropsychological studies have reported that PWS display altered social interactions with a specific weakness in interpreting social information and in responding to them, a symptom closed to that observed in autism spectrum disorders (ASD). Based on the hypothesis that atypical multisensory integration such as face and voice interactions would contribute in PWS to social impairment we investigate the abilities of PWS to process communication signals including the human voice. Patients with PWS recruited from the national reference center for PWS performed a simple detection task of stimuli presented in an uni-o or bimodal condition, as well as a voice discrimination task. Compared to control typically developing (TD) individuals, PWS present a specific deficit in discriminating human voices from environmental sounds. Further, PWS present a much lower multisensory benefits with an absence of violation of the race model indicating that multisensory information do not converge and interact prior to the initiation of the behavioral response. All the deficits observed in PWS were stronger for the subgroup of patients suffering from Uniparental Disomy, a population known to be more sensitive to ASD. Altogether, our study suggests that the deficits in social behavior observed in PWS derive at least partly from an impairment in deciphering the social information carried by voice signals, face signals, and the combination of both. In addition, our work is in agreement with the brain imaging studies revealing an alteration in PWS of the "social brain network" including the STS region involved in processing human voices.

Model mice for 15q11-13 duplication syndrome exhibit late-onset obesity and altered lipid metabolism

Copy number variations on human chromosome 15q11-q13 have been implicated in several neurodevelopmental disorders. A paternal loss or duplication of the Prader-Willi syndrome/Angelman syndrome (PWS/AS) region confers a risk of obesity, although the mechanism remains a mystery due to a lack of an animal model that accurately recreates the obesity phenotype. We performed detailed analyses of mice with duplication of PWS/AS locus (6 Mb) generated by chromosome engineering and found that animals with a paternal duplication of this region (patDp/+) show late-onset obesity, high sensitivity for high-fat diet, high levels of blood leptin and insulin without an increase in food intake. We show that prior to becoming obese, young patDp/+ mice already had enlarged white adipocytes. Transcriptome analysis of adipose tissue revealed an up-regulation of Secreted frizzled-related protein 5 (Sfrp5), known to promote adipogenesis. We additionally generated a new mouse model of paternal duplication focusing on a 3 Mb region (3 Mb patDp/+) within the PWS/AS locus. These mice recapitulate the obese phenotypes including expansion of visceral adipose tissue. Our results suggest paternally expressed genes in PWS/AS locus play a significant role for the obesity and identify new potential targets for future research and treatment of obesity.

Learning by observation and learning by doing in Prader-Willi syndrome

BACKGROUND

New competencies may be learned through active experience (learning by doing) or observation of others' experience (learning by observation). Observing another person performing a complex action accelerates the observer's acquisition of the same action, limiting the time-consuming process of learning by doing. Here, we compared learning by observation and learning by doing in individuals with Prader-Willi syndrome (PWS). It is hypothesized that PWS individuals could show more difficulties with learning by observation than learning by doing because of their specific difficulty in interpreting and using social information.

METHODS

The performance of 24 PWS individuals was compared with that of 28 mental age (MA)- and gender-matched typically developing (TD) children in tasks of learning a visuo-motor sequence by observation or by doing. To determine whether the performance pattern exhibited by PWS participants was specific to this population or whether it was a nonspecific intellectual disability effect, we compared the PWS performances with those of a third MA- and gender-matched group of individuals with Williams syndrome (WS).

RESULTS

PWS individuals were severely impaired in detecting a sequence by observation, were able to detect a sequence by doing, and became as efficient as TD children in reproducing an observed sequence after a task of learning by doing. The learning pattern of PWS children was reversed compared with that of WS individuals.

CONCLUSIONS

The observational learning deficit in PWS individuals may be rooted, at least partially, in their incapacity to understand and/or use social information.

QOL in caregivers of Japanese patients with Prader-Willi syndrome with reference to age and genotype

This study aimed to measure quality of life (QOL) of the primary family caregivers for patients with Prader–Willi syndrome (PWS). Comparisons were made between caregivers' QOL in regard to their dependents' genotype and age group. The participants with PWS consisted of 22 children (aged from 6 to 12 years) and 23 adolescents (aged from 13 to 19 years), including 6 children and 7 adolescents with maternal uniparental disomy (mUPD) and 16 children and 16 adolescents with deletion (DEL). The QOL of the primary family caregiver for each patient was assessed using the Japanese version of the WHOQOL-BREF. To examine the effect that age (children vs. adolescents) and genotype (DEL vs. mUPD) have on the QOL of caregivers, a two-way ANOVA was conducted, followed by the Bonferroni procedure to test the simple main effects. The two age groups and the two genotypes of PWS were used as independent variables and the total QOL of caregivers as a dependent variable. The two-way ANOVA (F(1, 41) = 6.98, P < 0.05), followed by the Bonferroni procedure, showed the following: the total QOL of caregivers of DEL adolescents showed little difference from that with DEL children, but the QOL of caregivers for mUPD adolescents was shown to be lower than that with mUPD children along with that of caregivers with DEL adolescents. There is hence a growing tendency for the deterioration in the QOL of caregivers to manifest itself later in the patients' adolescence, found mainly with mUPD patients. © 2014 The Authors. American Journal of Medical Genetics Published by Wiley Periodicals, Inc.

Autism traits in children and adolescents with Cornelia de Lange syndrome

Cornelia de Lange syndrome (CdLS) is a cohesinopathy causing delayed growth and limb deficits. Individuals with CdLS have mild to profound intellectual disability and autistic features. This study characterizes the behavioral phenotype of children with CdLS, focusing on autistic features, maladaptive behaviors, and impact of age. Children with CdLS (5-18 years) were administered normed instruments to characterize autism features (Childhood Autism Rating Scale, CARS), maladaptive behaviors (Aberrant Behavior Checklist), and adaptive skills (Vineland Adaptive Behaviors Scales). CdLS features and severity were rated with Diagnostic Criteria for CdLS. Forty-one children with CdLS (23 females, 18 males) were classified as having "no autism" (n = 7; 17.1%), "mild autism" (n = 17; 41.4%), and "severe autism" (n = 17; 41.4%), using CARS scores. Characteristic items were abnormal emotional response, stereotypies, odd object use, rigidity, lack of verbal communication, and low intellectual functioning. Verbal communication deficits and repetitive behaviors were higher compared to sensory, social cognition, and behavior abnormalities (P ≤ 0.0001). Maladaptive behaviors associated with autism traits were stereotypies (P = 0.003), hyperactivity (P = 0.01), and lethargy (P = 0.03). Activities of daily living were significantly affected; socialization adaptive skills were a relative strength. However, with advancing age, both socialization (P < 0.0001) and communication (P = 0.001) domains declined significantly. CdLS is characterized by autistic features, notably excessive repetitive behaviors and expressive language deficits. While other adaptive skills are impacted, socialization adaptive skills are less affected. Advancing age can worsen communication and socialization deficits relative to neurotypical peers.

Autism spectrum disorders and hyperactive/impulsive behaviors in Japanese patients with Prader-Willi syndrome: a comparison between maternal uniparental disomy and deletion cases

This study aims to compare maternal uniparental disomy 15 (mUPD) and a paternal deletion of 15q11-13 (DEL) of Prader–Willi syndrome (PWS) in regard to autism spectrum disorders (ASD). Forty-five Japanese individuals with PWS were recruited from a single recruitment center. The participants consisted of 22 children (aged from 6 to 12) and 23 adolescents (aged from 13 to 19). Six children and seven adolescents were confirmed as having mUPD. Sixteen children and 16 adolescents were confirmed as having DEL. Under blindness to the participants' genotypes, a single psychologist carried out behavioral and psychological assessments, including the Wechsler Intelligence Scales, Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS), and ADHD-Rating Scale-IV (ADHD-RS-IV). Two comparisons were made: one between mUPD and DEL children and another between mUPD and DEL adolescents. In children, no significant differences were found between mUPD and DEL participants in terms of autistic (PARS childhood, P = 0.657) and impulsive behaviors (ADHD-RS-IV hyperactive/impulsive, P = 0.275). In adolescents, mUPD patients showed significantly more autistic symptomatology (PARS adolescent, P = 0.027) and significantly more impulsive behavior (ADHD-RS-IV hyperactive/impulsive, P = 0.01) than DEL patients. Our findings about Japanese PWS patients were consistent with previous researches from western countries not focused on Asian patients, indicating that mUPD cases would be more prone to ASD than DEL cases, regardless of ethnoregional differences. In addition, our data suggested that the behavioral difference between mUPD and DEL cases in terms of autistic and impulsive symptoms tend to be unrecognizable in their childhood. © 2014 The Authors. American Journal of Medical Genetics Part A Published by Wiley Periodicals, Inc.

Good cognitive performances in a child with Prader-Willi syndrome

We report the case of a child affected by Prader-Willi syndrome (PWS) with good cognitive performances and without relevant behavioral abnormalities.

The diagnosis of PWS, suspected on the basis of clinical features and past history, was confirmed by DNA methylation analysis. Additional genetic testing revealed a maternal uniparental disomy. Intellectual profile was analyzed by WISC-III and Raven’s Progressive Matrices CPM, while the behavior was evaluated by K-SADS-PL and Child Behavior Checklist/4-18 to the parents.

WISC-III test showed a Total Intelligence Quotient (T-IQ = 79) at the border level for age. The Verbal Intelligence Quotient (V-IQ) showed a lower score than the Performance Intelligence Quotient (P-IQ) (78 and 85, respectively). Raven’s Matrices CPM showed an intelligence level at 75-90° percentile for age. Concerning behavioral evaluation, a difficulty in impulse control was observed, with persistent but controllable search for food, without a clear psychopathological meaning. Also according to K-SADS-PL no areas of psychopathological dimensions were detected. In conclusion, in presence of consisting clinical features of PWS and high diagnostic suspicion, the diagnosis of PWS should be considered even in presence of a borderline IQ and in absence of psychopathological abnormalities.

Behavioral profile of adults with Prader-Willi syndrome: correlations with individual and environmental variables

Background

Maladaptive behavior has been reported as a phenotypical feature in Prader–Willi syndrome (PWS). It severely limits social adaptation and the quality of life of children and adults with the syndrome. Different factors have been linked with the intensity and form of these behavioral disturbances but there is no consensus about the cause. Consequently, there is still controversy regarding management strategies and there is a need for new data.

Methods

The behavior of 100 adults with PWS attending a dedicated center was assessed using the Developmental Behavior Checklist for Adults (DBC-A) and the PWS-specific Hyperphagia Questionnaire. The DBC-A was completed separately by trained caregivers at the center and relatives or caregivers in a natural setting. Genotype, gender, age, degree of obesity and cognitive impairment were analyzed as variables with a hypothetical influence on behavioral features.

Results

Patients showed a relatively high rate of behavioral disturbances other than hyperphagia. Disruptive and social relating were the highest scoring DBC-A subscales whereas anxiety/antisocial and self-absorbed were the lowest. When hospital caregiver and natural caregiver scores were compared, scores for the latter were higher for all subscales except for disruptive and anxiety/antisocial. These effects of institutional management were underlined. In the DBC-A, 22 items have descriptive indications of PWS behavior and were used for further comparisons and correlation analysis. In contrast to previous reports, rates of disturbed behavior were lower in patients with a deletion genotype. However, the behavioral profile was similar for both genotypes. No differences were found in any measurement when comparing type I and type II deletions. The other analyzed variables showed little relevance.

Conclusions

Significant rates of behavioral disorders were highlighted and their typology described in a large cohort of adults with PWS. The deletion genotype was related to a lower severity of symptoms. Some major behavioral problems, such as hyperphagia, may be well controlled if living circumstances are adapted to the specific requirements of individuals with PWS.

Is autism a disease of the cerebellum? An integration of clinical and pre-clinical research

Autism spectrum disorders are a group of neurodevelopmental disorders characterized by deficits in social skills and communication, stereotyped and repetitive behavior, and a range of deficits in cognitive function. While the etiology of autism is unknown, current research indicates that abnormalities of the cerebellum, now believed to be involved in cognitive function and the prefrontal cortex (PFC), are associated with autism. The current paper proposes that impaired cerebello-cortical circuitry could, at least in part, underlie autistic symptoms. The use of animal models that allow for manipulation of genetic and environmental influences are an effective means of elucidating both distal and proximal etiological factors in autism and their potential impact on cerebello-cortical circuitry. Some existing rodent models of autism, as well as some models not previously applied to the study of the disorder, display cerebellar and behavioral abnormalities that parallel those commonly seen in autistic patients. The novel findings produced from research utilizing rodent models could provide a better understanding of the neurochemical and behavioral impact of changes in cerebello-cortical circuitry in autism.

Social and emotional processing in Prader-Willi syndrome: genetic subtype differences

Background

People with Prader-Willi syndrome (PWS) demonstrate social dysfunction and increased risk of autism spectrum disorder, especially those with the maternal uniparental disomy (mUPD) versus paternal deletion genetic subtype. This study compared the neural processing of social (faces) and nonsocial stimuli, varying in emotional valence, across genetic subtypes in 24 adolescents and adults with PWS.

Methods

Upright and inverted faces, and nonsocial objects with positive and negative emotional valence were presented to participants with PWS in an oddball paradigm with smiling faces serving as targets. Behavioral and event-related potential (ERP) data were recorded.

Results

There were no genetic subtype group differences in accuracy, and all participants performed above chance level. ERP responses revealed genetic subtype differences in face versus object processing. In those with deletions, the face-specific posterior N170 response varied in size for face stimuli versus inverted faces versus nonsocial objects. Persons with mUPD generated N170 of smaller amplitude and showed no stimulus differentiation. Brain responses to emotional content did not vary by subtype. All participants elicited larger posterior and anterior late positive potential responses to positive objects than to negative objects. Emotion-related differences in response to faces were limited to inverted faces only in the form of larger anterior late positive potential amplitudes to negative emotions over the right hemisphere. Detection of the target smiling faces was evident in the increased amplitude of the frontal and central P3 responses but only for inverted smiling faces.

Conclusion

Persons with the mUPD subtype of PWS may show atypical face versus object processes, yet both subtypes demonstrated potentially altered processing, attention to and/or recognition of faces and their expressions.

Expressive and receptive language in Prader-Willi syndrome: report on genetic subtype differences

Prader-Willi syndrome (PWS), most recognized for the hallmark hyperphagia and food preoccupations, is caused by the absence of expression of the paternally active genes in the q11-13 region of chromosome 15. Since the recognition of PWS as a genetic disorder, most research has focused primarily on the medical, genetic, and behavioral aspects of the syndrome. Extensive research has not been conducted on the cognitive, speech, and language abilities in PWS. In addition, language differences with regard to genetic mechanism of PWS have not been well investigated. To date, research indicates overall language ability is markedly below chronological age with expressive language more impaired than receptive language in people with PWS. Thus, the aim of the present study was to further characterize expressive and receptive language ability in 35 participants with PWS and compare functioning by genetic subtype using the Clinical Evaluation of Language Fundamentals-4 (CELF-IV). Results indicate that core language ability is significantly impaired in PWS and both expressive and receptive abilities are significantly lower than verbal intelligence. In addition, participants with the maternal uniparental disomy (mUPD) genetic subtype exhibit discrepant language functioning with higher expressive vs. receptive language abilities. Future research is needed to further examine language functioning in larger genetic subtype participant samples using additional descriptive measures. Further work should also delineate findings with respect to size of the paternal deletion (Type 1 and Type 2 deletions) and explore how overexpression of maternally expressed genes in the 15q11-13 region may relate to verbal ability.

LEARNING OUTCOMES

After reading this article, the reader will be able to: (1) summarize primary characteristics of Prader-Willi syndrome (PWS), (2) describe differentiating characteristics for the PWS genetic subtypes, (3) recall limited research regarding language functioning in PWS to date, (4) summarize potential genetic variations of language ability in Prader-Willi syndrome, and (5) summarize language ability in PWS with respect to adaptive functioning.

Epigenetic epidemiology in psychiatry: A translational neuroscience perspective

Accumulating evidence from the field of neuroscience indicates a crucial role for epigenetic regulation of gene expression in development and aging of nervous system and suggests that aberrations in the epigenetic machinery are involved in the etiology of psychiatric disorders. Epidemiologic evidence on epigenetics in psychiatry, however, is currently very sparsely available, but is consistent with a mediating role for epigenetic mechanisms in bringing together inherited and acquired risk factors into a neurodevelopmental etiological model of psychiatric disorders. Here, we review evidence from the epidemiological and neuroscience literature, and aim to converge the evidence into an etiological model of psychiatric disorders that encompasses environmental, genetic and epigenetic contributions. Given the dynamic nature of the epigenetic machinery and the potential reversibility of epigenetic modifications, future well-designed interdisciplinary and translational studies will be of key importance in order to identify new targets for prevention and therapeutic strategies.

Repetitive behavior profiles: Consistency across autism spectrum disorder cohorts and divergence from Prader-Willi syndrome

Restricted and repetitive behavior (RRB) is a group of heterogeneous maladaptive behaviors. RRB is one of the key diagnostic features of autism spectrum disorders (ASDs) and also commonly observed in Prader–Willi syndrome (PWS). In this study, we assessed RRB using the Repetitive Behavior Scale-Revised (RBS-R) in two ASD samples (University of Illinois at Chicago [UIC] and University of Florida [UF]) and one PWS sample. We compared the RBS-R item endorsements across three ASD cohorts (UIC, UF and an ASD sample from Lam, The Repetitive Behavior Scale-Revised: independent validation and the effect of subject variables, PhD thesis, 2004), and a PWS sample. We also compared the mean RBS-R subscale/sum scores across the UIC, UF and PWS samples; across the combined ASD (UIC + UF), PWS-deletion and PWS-disomy groups; and across the combined ASD sample, PWS subgroup with a Social Communication Questionnaire (SCQ) score ≥15, and PWS subgroup with a SCQ score <15. Despite the highly heterogeneous nature, the three ASD samples (UIC, UF and Lam’s) showed a similar pattern of the RBS-R endorsements, and the mean RBS-R scores were not different between the UIC and UF samples. However, higher RRB was noted in the ASD sample compared with the PWS sample, as well as in the PWS subgroup with a SCQ score ≥15 compared with the PWS subgroup with a SCQ score <15. Study limitations include a small sample size, a wide age range of our participants, and not controlling for potential covariates. A future replication study using a larger sample and further investigation into the genetic bases of overlapping ASD and RRB phenomenology are needed, given the higher RRB in the PWS subgroup with a SCQ score ≥15.

Oxytocin may be useful to increase trust in others and decrease disruptive behaviours in patients with Prader-Willi syndrome: a randomised placebo-controlled trial in 24 patients

Background

Prader-Willi syndrome (PWS) is a complex neurodevelopmental genetic disorder with hypothalamic dysfunction, early morbid obesity with hyperphagia, and specific psychiatric phenotypes including cognitive and behavioural problems, particularly disruptive behaviours and frequent temper outbursts that preclude socialization. A deficit in oxytocin (OT)-producing neurons of the hypothalamic paraventricular nucleus has been reported in these patients.

Methods

In a double-blind, randomised, placebo-controlled study, 24 adult patients with PWS received a single intranasal administration of 24 IU of OT or placebo and were tested 45 min later on social skills. Behaviours were carefully monitored and scored using an in-house grid as follows: over the two days before drug administration, on the half-day following administration, and over the subsequent two days. All patients were in a dedicated PWS centre with more than ten years of experience. Patients are regularly admitted to this controlled environment.

Results

Patients with PWS who received a single intranasal administration of OT displayed significantly increased trust in others (P = 0.02) and decreased sadness tendencies (P = 0.02) with less disruptive behaviour (P = 0.03) in the two days following administration than did patients who received placebo. In the half-day following administration, we observed a trend towards less conflict with others (p = 0.07) in the OT group compared with the placebo group. Scores in tests assessing social skills were not significantly different between the two groups.

Conclusions

This study needs to be reproduced and adapted. It nevertheless opens new perspectives for patients with PWS and perhaps other syndromes with behavioural disturbances and obesity.

Trial registration number

ClinicalTrials.gov: NCT01038570

Trajectory and outcomes of speech language therapy in the Prader-Willi syndrome (PWS): case report

The aim of this study was to describe the trajectory and the outcomes of speech-language therapy in Prader-Willi syndrome through a longitudinal study of the case of an 8 year-old boy, along four years of speech-language therapy follow-up. The therapy sessions were filmed and documental analysis of information from the child's records regarding anamnesis, evaluation and speech-language therapy reports and multidisciplinary evaluations were carried out. The child presented typical characteristics of Prader-Willi syndrome, such as obesity, hyperfagia, anxiety, behavioral problems and self aggression episodes. Speech-language pathology evaluation showed orofacial hypotony, sialorrhea, hypernasal voice, cognitive deficits, oral comprehension difficulties, communication using gestures and unintelligible isolated words. Initially, speech-language therapy had the aim to promote the language development emphasizing social interaction through recreational activities. With the evolution of the case, the main focus became the development of conversation and narrative abilities. It were observed improvements in attention, symbolic play, social contact and behavior. Moreover, there was an increase in vocabulary, and evolution in oral comprehension and the development of narrative abilities. Hence, speech-language pathology intervention in the case described was effective in different linguistic levels, regarding phonological, syntactic, lexical and pragmatic abilities.

Epigenetic impacts on neurodevelopment: pathophysiological mechanisms and genetic modes of action

Disruptions of genes that are involved in epigenetic functions are known to be causative for several mental retardation/intellectual disability (MR/ID) syndromes. Recent work has highlighted genes with epigenetic functions as being implicated in autism spectrum disorders (ASDs) and schizophrenia (SCZ). The gene-environment interaction is an important factor of pathogenicity for these complex disorders. Epigenetic modifications offer a mechanism by which we can explain how the environment interacts with, and is able to dynamically regulate, the genome. This review aims to provide an overview of the role of epigenetic deregulation in the etiopathology for neurodevelopment disease.

Association of hypomelanotic skin disorders with autism: links to possible etiologic role of vitamin-D levels in autism?

Vitamin D is crucial for several key physiological processes, including brain development, DNA repair, and regulation of many genes. Much evidence indicates prenatal and early postnatal vitamin-D deficiency increases autism risk, probably through multiple effects, including impaired brain development and increased de novo mutations. High autism rates in several genetically based hypomelanotic skin disorders are puzzling, because ultraviolet-B radiation (UVB) in sunlight acting on skin is a key source of vitamin-D, and lighter skin protects against vitamin-D deficiency, especially at high latitudes. We consider two hypotheses to help explain autism's co-morbidity with hypomelanosis. 1) Because genetic and epigenetic variants that produce hypomelanosis help protect against vitamin-D deficiency, they increase reproductive fitness of individuals who also have other autism risk factors. 2) Hypomelanotic children have increased autism risk because photosensitivity and skin-cancer concerns lead families to excessively reduce children's sun exposure. Hypothesis testing could involve studies comparing genomes, epigenetic markers, skin pigmentation, and vitamin-D levels in autistic individuals with and without hypomelanosis, their relatives and controls. Conducting such studies in samples from regions that differ widely in UVB availability would provide particularly valuable data. Support for either hypothesis would elucidate vitamin-D's role in autism and suggest vitamin-D enhancement may aid treatment and prevention of autism.

Role of UBE3A and ATP10A genes in autism susceptibility region 15q11-q13 in an Italian population: a positive replication for UBE3A

The aetiology of autism is still largely unknown despite analyses from family and twin studies demonstrating substantial genetic role in the aetiology of the disorder. Data from linkage studies and analyses of chromosomal abnormalities identified 15q11-q13 as a region of particular aetiopathogenesis interest. We screened a set of markers spanning two known imprinted, maternally expressed genes, UBE3A and ATP10A, harboured in this candidate region. We replicated evidence of linkage disequilibrium (LD) at marker D15S122, located at the 5' end of UBE3A and originally reported by Nurmi et al. (2001). The potential role of UBE3A in our family-based association study is further supported by the association of two haplotypes that include one of the alleles of D15S122 and by the transmission disequilibrium test (TDT) evidence of the same allele in a parent of origin effect analysis. In a secondary analysis, we provided the first evidence of a significant association between first word delay and psychomotor regression with the 15q11-q13 region. Our data support a potential role of UBE3A in the complex pathogenic mechanisms of autism.

Functional Assessment and Behavioral Treatment of Skin Picking in a Teenage Girl With Prader-Willi Syndrome

Skin picking is common in individuals with Prader-Willi Syndrome (PWS) but few treatment studies exist. This study reports the successful functional behavioral assessment (FBA) and treatment of skin picking in a 16-year-old female with PWS. A treatment package based on FBA results consisted of differential reinforcement for alternative and incompatible behavior, self-evaluation of progress, and reinforcement for weekly progress and participation in treatment. Pictures of wounds resulting from skin picking were taken during treatment. A total of 30 pictures were randomly selected and shown in a random order to 16 individuals unfamiliar with the study. The individuals then rated severity of the wounds displayed in the pictures. Pearson’s χ2 was used to assess changes in the ratings of severity during the course of treatment, and significant results indicate improvement over the course of intervention, χ 2(1) = 246.6, p < .001. This study adds to the very small literature on treatment of skin picking in people with PWS.

Autism spectrum disorders and epigenetics

OBJECTIVE

Current research suggests that the causes of autism spectrum disorders (ASD) are multifactorial and include both genetic and environmental factors. Several lines of evidence suggest that epigenetics also plays an important role in ASD etiology and that it might, in fact, integrate genetic and environmental influences to dysregulate neurodevelopmental processes. The objective of this review is to illustrate how epigenetic modifications that are known to alter gene expression without changing primary DNA sequence may play a role in the etiology of ASD.

METHOD

In this review, we summarize current knowledge about epigenetic modifications to genes and genomic regions possibly involved in the etiology of ASD.

RESULTS

Several genetic syndromes comorbid with ASD, which include Rett, Fragile X, Prader-Willi, Angelman, and CHARGE (Coloboma of the eye, Heart defects, Atresia of the nasal choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness), all demonstrate dysregulation of epigenetic marks or epigenetic mechanisms. We report also on genes or genomic regions exhibiting abnormal epigenetic regulation in association with either syndromic (15q11-13 maternal duplication) or nonsyndromic forms of ASD. Finally, we discuss the state of current knowledge regarding the etiologic role of environmental factors linked to both the development of ASD and epigenetic dysregulation.

CONCLUSION

Data reviewed in this article highlight a variety of situations in which epigenetic dysregulation is associated with the development of ASD, thereby supporting a role for epigenetics in the multifactorial etiologies of ASD.

Clinical management of behavioral characteristics of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder caused by an abnormality on the long arm of chromosome 15 (q11-q13) that results in a host of phenotypic characteristics, dominated primarily by hyperphagia and insatiable appetite. Characteristic behavioral disturbances in PWS include excessive interest in food, skin picking, difficulty with a change in routine, temper tantrums, obsessive and compulsive behaviors, and mood fluctuations. Individuals with PWS typically have intellectual disabilities (borderline to mild/moderate mental retardation) and exhibit a higher overall behavior disturbance compared to individuals with similar intellectual disability. Due to its multisystem disorder, family members, caregivers, physicians, dieticians, and speech-language pathologists all play an important role in the management and treatment of symptoms in an individual with PWS. This article reviews current research on behavior and cognition in PWS and discusses management guidelines for this disorder.

Neurodevelopmental disorders involving genomic imprinting at human chromosome 15q11-q13

Human chromosome 15q11-q13 is subject to regulation by genomic imprinting, an epigenetic process by which genes are expressed in a parent-of-origin specific manner. Three neurodevelopmental disorders, Prader-Willi syndrome, Angelman syndrome, and 15q duplication syndrome, result from aberrant expression of imprinted genes in this region. Here, we review the current literature pertaining to mouse models and recently identified patients with atypical deletions, which shed light on the epigenetic regulation of the chromosome 15q11-q13 subregion and the genes that are responsible for the phenotypic outcomes of these disorders.

Cognitive profile in a large French cohort of adults with Prader-Willi syndrome: differences between genotypes

BACKGROUND

Prader-Willi syndrome (PWS) is a rare genetic disorder characterised by developmental abnormalities leading to somatic and psychological symptoms. These include dysmorphic features, impaired growth and sexual maturation, hyperphagia, intellectual delay, learning disabilities and maladaptive behaviours. PWS is caused by a lack of expression of maternally imprinted genes situated in the 15q11-13 chromosome region. The origin is a 'de novo' deletion in the paternal chromosome in 70% of the cases and a maternal uniparental disomy in 25%. The two main genotypes show differences, notably regarding cognitive and behavioural features, but the mechanisms are not clear. This study assessed cognitive impairment in a cohort of adults with genetically confirmed PWS, analysed their profiles of cognitive strengths and weaknesses, and compared the profiles in terms of genotype.

METHODS

Ninety-nine male and female adults participated, all inpatients on a specialised unit for the multidisciplinary care of PWS. The Wechsler Adult Intelligence Scale (WAIS-III) was administered to all patients in identical conditions by the same psychologist. Eighty-five patients were able to cope with the test situation. Their scores were analysed with non-parametric statistical tools. The correlations with sex, age and body mass index were explored. Two genotype groups were compared: deletion (n = 57) and non-deletion (n = 27).

RESULTS

The distribution of intelligence quotients in the total cohort was non-normal, with the following values (medians): Full Scale Intelligence Quotient (FSIQ): 52.0 (Q1:46.0; Q3:60.0), Verbal Intellectual Quotient (VIQ): 53.0 (Q1:48; Q3:62) and Performance Intellectual Quotient (PIQ): 52.5 (Q1:48; Q3:61). No correlation was found with sex, age or body mass index. Comparison between groups showed no significant difference in FSIQ or VIQ. PIQ scores were significantly better in the deletion group. The total cohort and the deletion group showed the VIQ = PIQ profile, whereas VIQ > PIQ was observed in the non-deletion group. The subtest scores in the two groups showed significant differences, with the deletion group scoring better in three subtests: object assembly, picture arrangement and digit symbol coding. Some relative strengths and weaknesses concerned the total cohort, but others concerned only one genotype.

DISCUSSION

We documented a global impairment in the intellectual abilities of a large sample of French PWS patients. The scores were slightly lower than those reported in most other studies. Our data confirmed the previously published differences in the cognitive profiles of the two main PWS genotypes and offer new evidence to support this hypothesis. These results could guide future neuropsychological studies to determine the cognitive processing in PWS. This knowledge is essential to improve our understanding of gene-brain-behaviour relationships and to open new perspectives on therapeutic and educational programmes.

Genetic causes of syndromic and non-syndromic autism

AIMS

Over the past decade, genetic tests have become available for numerous heritable disorders, especially those whose inheritance follows the Mendelian model. Autism spectrum disorders (ASDs) represent a group of developmental disorders with a strong genetic basis. During the past few years, genetic research in ASDs has been successful in identifying several vulnerability loci and a few cytogenetic abnormalities or single-base mutations implicated in the causation of autism.

METHOD

In this study the literature was reviewed to highlight genotype-phenotype correlations between causal gene mutations or cytogenetic abnormalities and behavioural or morphological phenotypes.

RESULTS

Based on this knowledge, practical information is offered to help clinicians pursue targeted genetic testing of individuals with autism whose clinical phenotype is suggestive of a specific genetic or genomic aetiology.

INTERPRETATION

Comprehensive research into the molecular mechanism of autism is required to aid the development of disease-specific targeted therapies. In order to transfer this recently acquired knowledge into clinical practice, it is critical to define a set of phenotypic inclusion criteria that must be met by affected probands to justify their enrolment in a specific genetic testing programme.

Autism spectrum and obsessive-compulsive disorders: OC behaviors, phenotypes and genetics

Autism spectrum disorders (ASDs) are a phenotypically and etiologically heterogeneous set of disorders that include obsessive-compulsive behaviors (OCB) that partially overlap with symptoms associated with obsessive-compulsive disorder (OCD). The OCB seen in ASD vary depending on the individual's mental and chronological age as well as the etiology of their ASD. Although progress has been made in the measurement of the OCB associated with ASD, more work is needed including the potential identification of heritable endophenotypes. Likewise, important progress toward the understanding of genetic influences in ASD has been made by greater refinement of relevant phenotypes using a broad range of study designs, including twin and family-genetic studies, parametric and nonparametric linkage analyses, as well as candidate gene studies and the study of rare genetic variants. These genetic analyses could lead to the refinement of the OCB phenotypes as larger samples are studied and specific associations are replicated. Like ASD, OCB are likely to prove to be multidimensional and polygenic. Some of the vulnerability genes may prove to be generalist genes influencing the phenotypic expression of both ASD and OCD while others will be specific to subcomponents of the ASD phenotype. In order to discover molecular and genetic mechanisms, collaborative approaches need to generate shared samples, resources, novel genomic technologies, as well as more refined phenotypes and innovative statistical approaches. There is a growing need to identify the range of molecular pathways involved in OCB related to ASD in order to develop novel treatment interventions.

The role of DNA copy number variation in schizophrenia

Schizophrenia is a major psychiatric disease with strong evidence of genetic risk factors. Recent studies based on genome-wide study of copy number variations (CNVs) have detected novel recurrent submicroscopic copy number changes, including recurrent deletions at 1q21.11, 15q11.3, 15q13.3, and the recurrent CNV at the 2p16.3 neurexin 1 locus. These schizophrenia susceptibility CNV loci demonstrate that schizophrenia is, at least in part, genetic in origin and provide the basis for further investigation of mutations associated with the disease. The studies combined have also established the role of rare and-in sporadic cases-de novo variants in schizophrenia. Furthermore, neuronal-related genes and genetic pathways are starting to emerge from the CNV loci associated with schizophrenia. Here, we review the major findings in the recent literature, which begin to unravel the genetic and biological architecture of this complex human neuropsychiatric disorder.