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Merlin G. Butler - One of the best experts on this subject based on the ideXlab platform.
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The Frequency of Uniparental Disomy in Prader-Willi Syndrome
2010Co-Authors: Maria J. Mascari, Merlin G. Butler, Wayne Gottlieb, Peter K. Rogan, David A. Waller, John A.l. Armour, Alec J. Jeffreys, Roger L. Ladda, Robert D. NichollsAbstract:Abstract Background. Prader—Willi Syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader—Willi Syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader—Willi Syndrome. Methods. We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader—Willi Syndrome who had no cytogenetically visible deletion. We also studied their parents. Three pat...
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Prader-Willi Syndrome: are there population differences?
Clinical Genetics, 2008Co-Authors: Merlin G. Butler, David D. Weaver, F. John MeaneyAbstract:A 15 1/2-year-old black female with features consistent with the Prader-Willi Syndrome is reported. This is the second case report of a black individual and the first case of a black female with the Prader-Willi Syndrome. There is an apparent paucity of blacks reported with this condition. Whether this difference is a true difference or represents under-reporting is not known. We urge reporting of individuals representing other racial groups with this disorder and suggest population studies to determine the incidence as well as the true population difference in the Prader-Willi Syndrome.
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Management of Prader-Willi Syndrome - Management of Prader-Willi Syndrome
2006Co-Authors: Merlin G. Butler, Phillip D. K. Lee, Barbara Y. WhitmanAbstract:Diagnosis and Genetics.- Clinical Findings and Natural History of Prader-Willi Syndrome.- Diagnostic Criteria for Prader-Willi Syndrome.- Molecular Genetic Findings in Prader-Willi Syndrome.- Laboratory Testing for Prader-Willi Syndrome.- Medical Physiology and Treatment.- Medical Considerations in Prader-Willi Syndrome.- Gastrointestinal System, Obesity, and Body Composition.- Growth Hormone and Prader-Willi Syndrome.- Multidisciplinary Management.- Neurodevelopmental and Neuropsychological Aspects of Prader-Willi Syndrome.- Speech and Language Disorders Associated with Prader-Willi Syndrome.- Motor and Developmental Interventions.- Educational Considerations for Children with Prader-Willi Syndrome.- Tools for Psychological and Behavioral Management.- Educational and Social Issues for Adolescents with Prader-Willi Syndrome.- Transition from Adolescence to Young Adulthood: The Special Case of Prader-Willi Syndrome.- Vocational Training for People with Prader-Willi Syndrome.- Residential Care for Adults with Prader-Willi Syndrome.- Inpatient Crisis Intervention for Persons with Prader-Willi Syndrome.- Social Work Interventions: Advocacy and Support for Families.- A National Approach to Crisis Intervention and Advocacy.- Advocacy Issues: School Discipline and Expulsion.- Advocacy Issues: Sexuality.
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C-reactive protein levels in subjects with Prader-Willi Syndrome and obesity.
Genetics in Medicine, 2006Co-Authors: Merlin G. Butler, Douglas C. Bittel, Nataliya Kibiryeva, Uttam GargAbstract:Purpose: Prader-Willi Syndrome is characterized by infantile hypotonia, feeding difficulties, hypogonadism, small hands and feet, mental deficiency, behavioral problems, and hyperphagia leading to obesity in early childhood. To date there have been no studies examining the associated risk of cardiovascular disease related to obesity in Prader-Willi Syndrome, nor of circulating biomarkers such as C-reactive protein known to be predictive of cardiovascular disease. Therefore, we have measured the levels of C-reactive protein in a descriptive study of a cohort of Prader-Willi Syndrome and comparison subjects. Methods: An immunoassay was used to quantify C-reactive protein in plasma samples from subjects with Prader-Willi Syndrome and obesity and compared to anthropometric and body composition data. Results: The mean circulating C-reactive protein concentration for 28 subjects with Prader-Willi Syndrome (13 females, 15 males; mean age 24.6 ± 11.6 years; mean body mass index 35.9 ± 11.9) was 10.3 ± 8.8 mg/L. The mean C-reactive protein concentration for 22 nonsyndromic obese subjects (16 females, 6 males; mean age 32.3 ± 12.2 years; mean body mass index 36.6 ± 10.7) was 8.8 ± 10.9 mg/L. The reported mean value for C-reactive protein was 2.6 ± 3.0 mg/L from 100 healthy adults. Conclusions: The mean C-reactive protein values were similar between the subjects with Prader-Willi Syndrome and obesity but significantly higher in Prader-Willi Syndrome and obese subjects relative to normative data. Increased levels of C-reactive protein (>3.0 mg/L) are associated with cardiovascular disease suggesting subjects with Prader-Willi Syndrome as well as obese subjects are at a similar increased risk.
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Prader-Willi Syndrome: Clinical and Genetic Findings.
The Endocrinologist, 2000Co-Authors: Merlin G. Butler, Travis ThompsonAbstract:Abstract Since the initial medical description by Prader, Labhart and Willi in 1956 of individuals with overlapping features, the Prader-Willi Syndrome has become recognized as a classical but sporadic genetic Syndrome. Prader-Willi Syndrome is the most common genetic cause of life-threatening obesity in humans. It is estimated that there are 350,000-400,000 people with this Syndrome worldwide. Prader-Willi Syndrome Association USA knows of more than 3,400 persons with Prader-Willi Syndrome in the USA out of an approximate 17,000-22,000. Prader-Willi Syndrome with an incidence of 1 in 10,000 to 25,000 individuals and Angelman Syndrome, an entirely different clinical condition, were the first examples in humans of genetic imprinting. Genetic imprinting or the differential expression of genetic information depending on the parent of origin plays a significant role in other conditions including malignancies.
Elisabeth M. Dykens - One of the best experts on this subject based on the ideXlab platform.
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Strategies and correlates of jigsaw puzzle and visuospatial performance by persons with Prader-Willi Syndrome.
American Journal on Mental Retardation, 2008Co-Authors: Brian N. Verdine, Georgene L. Troseth, Robert M. Hodapp, Elisabeth M. DykensAbstract:Abstract Some individuals with Prader-Willi Syndrome exhibit strengths in solving jigsaw puzzles. We compared visuospatial ability and jigsaw puzzle performance and strategies of 26 persons with Prader-Willi Syndrome and 26 MA-matched typically developing controls. Individuals with Prader-Willi Syndrome relied on piece shape. Those in the control group used a different, picture-focused strategy. Individuals with Prader-Willi Syndrome performed better than did the control group on an achromatic interlocking puzzle, whereas scores on puzzles with pictures (interlocking or noninterlocking) did not differ. Visuospatial scores related to performance on all puzzles in the control group and on the noninterlocking puzzle in the Prader-Willi Syndrome group. The most proficient jigsaw puzzlers with Prader-Willi Syndrome tended to be older and have shape-based strategies.
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Psychiatric disorders in Prader-Willi Syndrome: epidemiology and management.
CNS Drugs, 2003Co-Authors: Elisabeth M. Dykens, Bhavik ShahAbstract:Although people with intellectual disabilities are at increased risk for psychiatric disorders, the type and rate of these problems differ between those with different causes for their retardation. In this paper, we review behavioural and psychiatric problems in persons with Prader-Willi Syndrome, a disorder caused by a paternally derived deletion at chromosome 15(q11-q13) in about 70% of affected patients, and by maternal uniparental disomy in the majority of the remaining patients. In addition to the Syndrome’s characteristic hyperphagia and food seeking, individuals with Prader-Willi Syndrome also have increased risks of nonfood, compulsive behaviours. These include skin picking, which is highly prevalent, as well as more variable rates of hoarding, redoing and concerns with symmetry, exactness, cleanliness, ordering and arranging. Relative to others with mental retardation, persons with Prader-Willi Syndrome are at a marked increased risk for developing full-blown, obsessive-compulsive disorder. In addition, many people with Prader-Willi Syndrome show increased rates of tantrums, oppositionality and aggression. Recent findings suggest that they also have an increased risk of psychotic disorder or affective illness with a psychotic component, especially young adult patients and those with the maternal uniparental disomy as opposed to paternal deletion. Dietary approaches include a reduced-calorie diet and increased physical activity, as well as close supervision around food and keeping food locked away. To date, neither CNS stimulants nor anorectic agents have been effective in treating hyperphagia, in part because hyperphagia in Prader-Willi Syndrome is attributed to decreased satiation as opposed to increased hunger. Treatment for compulsivity and maladaptive behaviours include: behavioural programming; a structured, predictable routine; extra help with transitions; family support; and pharmacotherapy. Although formal drug studies have yet to be conducted, SSRIs have been effective in reducing skin picking, compulsivity and aggressive episodes in some individuals with Prader-Willi Syndrome. Atypical antipsychotics have also proven helpful in persons with psychotic features or extreme aggression and impulsivity. Largely on the basis of case studies, the risks and benefits of these and other drugs in Prader-Willi Syndrome are reviewed. Drug trials that move beyond case studies and that assess the relative efficacy of behavioural treatments alone or in combination with pharmacotherapy are sorely needed.
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Are jigsaw puzzle skills 'spared' in persons with Prader-Willi Syndrome?
Journal of Child Psychology and Psychiatry, 2002Co-Authors: Elisabeth M. DykensAbstract:Background: This three-part study examines previous clinical impressions that people with Prader-Willi Syndrome have unusual jigsaw puzzle and word search skills. Results: Children with Prader-Willi Syndrome showed relative strengths on standardized visual-spatial tasks (Object Assembly, Triangles, VMI) in that their scores were significantly higher than age- and IQ-matched peers with mixed mental retardation, but below those of age-matched normal children with average IQs. In striking contrast, children with Prader-Willi Syndrome scored on par with normal peers on word searches, and they far outperformed them on the jigsaw puzzles, placing more than twice as many pieces as the typically-developing group. Within Prader-Willi Syndrome, puzzle proficiency was not predicted by age, IQ, gender, degree of obesity, or obsessive-compulsive symptoms, but by genetic subtypes of this disorder. Conclusions: Findings are discussed in relation to splinter skills in autism, and to cases with autism and chromosome 15 anomalies that include the Prader-Willi region.
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Prader-Willi Syndrome: Genetic, Behavioral, and Treatment Issues
Child and Adolescent Psychiatric Clinics of North America, 1996Co-Authors: Elisabeth M. Dykens, Suzanne B. CassidyAbstract:Prader-Willi Syndrome is a complex developmental disorder caused in most cases by absence of paternally derived genes on chromosome 15. Although best known for causing hyperphagia and increased risks of obesity, Prader-Willi Syndrome actually involves a wide range of physical and behavioral problems. This article reviews genetic and physical features of Prader-Willi Syndrome as well as the Syndrome’s significant behavioral and psychiatric vulnerabilities. Treatment recommendations also are made.
Robert D. Nicholls - One of the best experts on this subject based on the ideXlab platform.
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The Frequency of Uniparental Disomy in Prader-Willi Syndrome
2010Co-Authors: Maria J. Mascari, Merlin G. Butler, Wayne Gottlieb, Peter K. Rogan, David A. Waller, John A.l. Armour, Alec J. Jeffreys, Roger L. Ladda, Robert D. NichollsAbstract:Abstract Background. Prader—Willi Syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader—Willi Syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader—Willi Syndrome. Methods. We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader—Willi Syndrome who had no cytogenetically visible deletion. We also studied their parents. Three pat...
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The frequency of uniparental disomy in Prader-Willi Syndrome. Implications for molecular diagnosis.
New England Journal of Medicine, 1992Co-Authors: Maria J. Mascari, Merlin G. Butler, Wayne Gottlieb, Peter K. Rogan, David A. Waller, John A.l. Armour, Alec J. Jeffreys, Roger L. Ladda, Robert D. NichollsAbstract:BACKGROUND: Prader-Willi Syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader-Willi Syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader-Willi Syndrome. METHODS: We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader-Willi Syndrome who had no cytogenetically visible deletion. We also studied their parents. Three patients with Prader-Willi Syndrome who had a cytogenetic deletion served as controls. RESULTS: In 18 of the 30 patients without a cytogenetic deletion (60 percent), we demonstrated the presence of maternal uniparental disomy for chromosome 15 and its association with advanced maternal age. In another eight patients (27 percent), we identified large molecular deletions. The remaining four patients (13 percent) had evidence of normal biparental inheritance for chromosome 15; three of these patients were the only ones in the study who had some atypical clinical features. CONCLUSIONS: In about 20 percent of all cases, Prader-Willi Syndrome results from the inheritance of both copies of chromosome 15 from the mother (maternal uniparental disomy). With the combined use of cytogenetic and molecular techniques, the genetic basis of Prader-Willi Syndrome can be identified in up to 95 percent of patients.
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The frequency of uniparental disomy in Prader-Willi Syndrome. Implications for molecular diagnosis.
The New England journal of medicine, 1992Co-Authors: Maria J. Mascari, Merlin G. Butler, Wayne Gottlieb, Peter K. Rogan, David A. Waller, John A.l. Armour, Alec J. Jeffreys, Roger L. Ladda, Robert D. NichollsAbstract:Abstract Background. Prader—Willi Syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader—Willi Syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader—Willi Syndrome. Methods. We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader—Willi Syndrome who had no cytogenetically visible deletion. We also studied their parents. Three pat...
Suzanne B. Cassidy - One of the best experts on this subject based on the ideXlab platform.
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Prader-Willi Syndrome
Genetics in Medicine, 2011Co-Authors: Suzanne B. Cassidy, Stuart Schwartz, Jennifer L. Miller, Daniel J. DriscollAbstract:Prader-Willi Syndrome is characterized by severe infantile hypotonia with poor suck and failure to thrive; hypogonadism causing genital hypoplasia and pubertal insufficiency; characteristic facial features; early-childhood onset obesity and hyperphagia; developmental delay/mild intellectual disability; short stature; and a distinctive behavioral phenotype. Sleep abnormalities and scoliosis are common. Growth hormone insufficiency is frequent, and replacement therapy provides improvement in growth, body composition, and physical attributes. Management is otherwise largely supportive. Consensus clinical diagnostic criteria exist, but diagnosis should be confirmed through genetic testing. Prader-Willi Syndrome is due to absence of paternally expressed imprinted genes at 15q11.2-q13 through paternal deletion of this region (65–75% of individuals), maternal uniparental disomy 15 (20–30%), or an imprinting defect (1–3%). Parent-specific DNA methylation analysis will detect >99% of individuals. However, additional genetic studies are necessary to identify the molecular class. There are multiple imprinted genes in this region, the loss of which contribute to the complete phenotype of Prader-Willi Syndrome. However, absence of a small nucleolar organizing RNA gene, SNORD116, seems to reproduce many of the clinical features. Sibling recurrence risk is typically
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Prader Willi Syndrome
Genetics in Medicine, 2011Co-Authors: Suzanne B. Cassidy, Stuart Schwartz, Jennifer L. Miller, Daniel J. DriscollAbstract:Prader-Willi Syndrome is characterized by severe infantile hypotonia with poor suck and failure to thrive; hypogonadism causing genital hypoplasia and pubertal insufficiency; characteristic facial features; early-childhood onset obesity and hyperphagia; developmental delay/mild intellectual disability; short stature; and a distinctive behavioral phenotype. Sleep abnormalities and scoliosis are common. Growth hormone insufficiency is frequent, and replacement therapy provides improvement in growth, body composition, and physical attributes. Management is otherwise largely supportive. Consensus clinical diagnostic criteria exist, but diagnosis should be confirmed through genetic testing. Prader-Willi Syndrome is due to absence of paternally expressed imprinted genes at 15q11.2-q13 through paternal deletion of this region (65–75% of individuals), maternal uniparental disomy 15 (20–30%), or an imprinting defect (1–3%). Parent-specific DNA methylation analysis will detect >99% of individuals. However, additional genetic studies are necessary to identify the molecular class. There are multiple imprinted genes in this region, the loss of which contribute to the complete phenotype of Prader-Willi Syndrome. However, absence of a small nucleolar organizing RNA gene, SNORD116, seems to reproduce many of the clinical features. Sibling recurrence risk is typically <1%, but higher risks may pertain in certain cases. Prenatal diagnosis is available. Genet Med 2012:14(1):10–26.
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Prader-Willi Syndrome
Management of Genetic Syndromes, 2005Co-Authors: Suzanne B. Cassidy, Shawn E. MccandlessAbstract:The major features of this multisystem disorder include prenatal and neonatal central hypotonia causing poor suck and infantile failure to thrive, characteristic facial appearance, developmental delay/generally mild mental retardation, childhood-onset obesity, short stature for the family, hypogonadism causing genital hypoplasia and pubertal insufficiency, and a characteristic behavior disorder. Obesity-related complications are the major cause of morbidity and mortality. The cause of Prader-Willi Syndrome is absence of paternal contribution at chromosome 15q11-13, a region involving genomic imprinting, through deletion, maternal uniparental disomy, or an imprinting defect. The specific genes involved are not yet definitively delineated. Clinical diagnostic criteria for Prader-Willi Syndrome have been published, but confirmation requires diagnostic testing, which is clinically available. Management is mostly supportive since no definitive treatment is known. Special feeding techniques are usually required to avoid or treat failure to thrive in infancy. Early infant stimulation followed by special educational resources can optimize developmental outcome. Obesity can be avoided or treated through appropriate nutrition, exercise, and environmental controls. Growth deficiency and abnormal body composition (high fat:lean body mass) respond well to growth hormone replacement. Sex hormones can be given to replace the deficient ones. Behavioral problems are treated through parenting skill enhancement, behavior modification, or psychotropic medication. Treatment of abnormal saliva secretion and sleep disturbance are also possible. Keywords: Prader-Willi Syndrome; hypotonia; obesity; hypogonadism; failure to thrive; growth hormone deficiency; mental retardation; developmental delay; dysmorphic features; sleep disturbance; diagnostic criteria; imprinting; deletion; chromosome 15; uniparental disomy
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Respiratory Sinus Arrhythmia in Patients With Prader-Willi Syndrome
Journal of Child Neurology, 1996Co-Authors: Francis J. Dimario, Jana Volpe, Lance O. Bauer, Suzanne B. CassidyAbstract:In this investigation, we sought to further test the hypothesis that parasympathetic deficiency exists among persons with Prader-Willi Syndrome, by examining respiratory sinus arrhythmia. The study sample comprised two groups of patients: 14 subjects with Prader-Willi Syndrome and 14 age- and sex-matched controls. Each subject's electrocardiogram was recorded in a quiet room and digitized by a personal computer during five 1-minute periods. RR intervals within each 1-minute period were converted to heart rate in 120 successive 0.5-second intervals. The resultant heart rate time series was converted to its underlying frequency composition by a fast Fourier transform and averaged across minutes. Respiratory sinus arrhythmia was defmed as the variability in the time series over a frequency range (0.096 to 0.48 Hz) corresponding to a range of respiratory rates from six to 30 breaths/minute. Analysis revealed significantly less variability in the heart rates of subjects with Prader-Willi Syndrome relative to a...
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Prader-Willi Syndrome: Genetic, Behavioral, and Treatment Issues
Child and Adolescent Psychiatric Clinics of North America, 1996Co-Authors: Elisabeth M. Dykens, Suzanne B. CassidyAbstract:Prader-Willi Syndrome is a complex developmental disorder caused in most cases by absence of paternally derived genes on chromosome 15. Although best known for causing hyperphagia and increased risks of obesity, Prader-Willi Syndrome actually involves a wide range of physical and behavioral problems. This article reviews genetic and physical features of Prader-Willi Syndrome as well as the Syndrome’s significant behavioral and psychiatric vulnerabilities. Treatment recommendations also are made.
Bhavik Shah - One of the best experts on this subject based on the ideXlab platform.
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Psychiatric Disorders in Prader-Willi Syndrome
CNS Drugs, 2003Co-Authors: Elisabeth Dykens, Bhavik ShahAbstract:Although people with intellectual disabilities are at increased risk for psychiatric disorders, the type and rate of these problems differ between those with different causes for their retardation. In this paper, we review behavioural and psychiatric problems in persons with Prader-Willi Syndrome, a disorder caused by a paternally derived deletion at chromosome 15(q11-q13) in about 70% of affected patients, and by maternal uniparental disomy in the majority of the remaining patients. In addition to the Syndrome’s characteristic hyperphagia and food seeking, individuals with Prader-Willi Syndrome also have increased risks of nonfood, compulsive behaviours. These include skin picking, which is highly prevalent, as well as more variable rates of hoarding, redoing and concerns with symmetry, exactness, cleanliness, ordering and arranging. Relative to others with mental retardation, persons with Prader-Willi Syndrome are at a marked increased risk for developing full-blown, obsessive-compulsive disorder. In addition, many people with Prader-Willi Syndrome show increased rates of tantrums, oppositionality and aggression. Recent findings suggest that they also have an increased risk of psychotic disorder or affective illness with a psychotic component, especially young adult patients and those with the maternal uniparental disomy as opposed to paternal deletion. Dietary approaches include a reduced-calorie diet and increased physical activity, as well as close supervision around food and keeping food locked away. To date, neither CNS stimulants nor anorectic agents have been effective in treating hyperphagia, in part because hyperphagia in Prader-Willi Syndrome is attributed to decreased satiation as opposed to increased hunger. Treatment for compulsivity and maladaptive behaviours include: behavioural programming; a structured, predictable routine; extra help with transitions; family support; and pharmacotherapy. Although formal drug studies have yet to be conducted, SSRIs have been effective in reducing skin picking, compulsivity and aggressive episodes in some individuals with Prader-Willi Syndrome. Atypical antipsychotics have also proven helpful in persons with psychotic features or extreme aggression and impulsivity. Largely on the basis of case studies, the risks and benefits of these and other drugs in Prader-Willi Syndrome are reviewed. Drug trials that move beyond case studies and that assess the relative efficacy of behavioural treatments alone or in combination with pharmacotherapy are sorely needed.
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Psychiatric disorders in Prader-Willi Syndrome: epidemiology and management.
CNS Drugs, 2003Co-Authors: Elisabeth M. Dykens, Bhavik ShahAbstract:Although people with intellectual disabilities are at increased risk for psychiatric disorders, the type and rate of these problems differ between those with different causes for their retardation. In this paper, we review behavioural and psychiatric problems in persons with Prader-Willi Syndrome, a disorder caused by a paternally derived deletion at chromosome 15(q11-q13) in about 70% of affected patients, and by maternal uniparental disomy in the majority of the remaining patients. In addition to the Syndrome’s characteristic hyperphagia and food seeking, individuals with Prader-Willi Syndrome also have increased risks of nonfood, compulsive behaviours. These include skin picking, which is highly prevalent, as well as more variable rates of hoarding, redoing and concerns with symmetry, exactness, cleanliness, ordering and arranging. Relative to others with mental retardation, persons with Prader-Willi Syndrome are at a marked increased risk for developing full-blown, obsessive-compulsive disorder. In addition, many people with Prader-Willi Syndrome show increased rates of tantrums, oppositionality and aggression. Recent findings suggest that they also have an increased risk of psychotic disorder or affective illness with a psychotic component, especially young adult patients and those with the maternal uniparental disomy as opposed to paternal deletion. Dietary approaches include a reduced-calorie diet and increased physical activity, as well as close supervision around food and keeping food locked away. To date, neither CNS stimulants nor anorectic agents have been effective in treating hyperphagia, in part because hyperphagia in Prader-Willi Syndrome is attributed to decreased satiation as opposed to increased hunger. Treatment for compulsivity and maladaptive behaviours include: behavioural programming; a structured, predictable routine; extra help with transitions; family support; and pharmacotherapy. Although formal drug studies have yet to be conducted, SSRIs have been effective in reducing skin picking, compulsivity and aggressive episodes in some individuals with Prader-Willi Syndrome. Atypical antipsychotics have also proven helpful in persons with psychotic features or extreme aggression and impulsivity. Largely on the basis of case studies, the risks and benefits of these and other drugs in Prader-Willi Syndrome are reviewed. Drug trials that move beyond case studies and that assess the relative efficacy of behavioural treatments alone or in combination with pharmacotherapy are sorely needed.