Prader-Willi syndrome: a review of clinical, genetic, and endocrine findings

Oxytocin and Animal Models for Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental conditions characterized by deficits in social communication and by repetitive and stereotypic patterns of behaviors, with no pharmacological treatments available to treat these core symptoms. Oxytocin is a neuropeptide that powerfully regulates mammalian social behavior and has been shown to exert pro-social effects when administered intranasally to healthy human subjects. In the last decade, there has been a significant interest in using oxytocin to treat social behavior deficits in ASD. However, little attention has been paid to whether the oxytocin system is perturbed in subgroups of individuals with ASD and whether these individuals are likely to benefit more from an oxytocin treatment. This oversight may in part be due to the enormous heterogeneity of ASD and the lack of methods to carefully probe the OXT system in human subjects. Animal models for ASD are valuable tools to clarify the implication of the oxytocin system in ASD and can help determine whether perturbation in this system should be considered in future clinical studies as stratifying biomarkers to inform targeted treatments in subgroups of individuals with ASD. In this chapter, we review the literature on genetic- and environmental-based animal models for ASD, in which perturbations in the oxytocin system and/or the effect of oxytocin administration on the ASD-associated phenotype have been investigated.

Diagnosis and treatment of GH deficiency in Prader-Willi syndrome

Prader-Willi syndrome (PWS) results from under-expression of the paternally-derived chromosomal region 15q11-13. Growth failure is a recognized feature of PWS, and both quantitative and qualitative defects of the GH/IGF-I axis revealing GH deficiency (GHD) have been demonstrated in most children with PWS. In PWS adults, criteria for GHD are biochemically fulfilled in 8-38% of the studied cohorts. Published data support benefits of early institution of GH therapy (GHT) in PWS children, with positive effects on statural growth, body composition, metabolic homeostasis, and neurocognitive function. Like in pediatric PWS, GHT also yields beneficial effects on lean and body fat, exercise capacity, and quality of life of PWS adults. Although GHT has been generally administered safely in PWS children and adults, careful surveillance of risks is mandatory during prolonged GH replacement for all PWS individuals.

Prader-Willi Syndrome due to an Unbalanced de novo Translocation t(15;19)(q12;p13.3)

Prader-Willi syndrome (PWS) is a complex, multisystem genetic disorder characterized by endocrine, neurologic, and behavioral abnormalities. We report the first case of an unbalanced de novo reciprocal translocation of chromosomes 15 and 19, 45,XY,-15,der(19)t(15;19)(q12;p13.3), resulting in monosomy for the PWS critical chromosome region. Our patient had several typical features of PWS including infantile hypotonia, a poor suck and feeding difficulties, tantrums, skin picking, compulsions, small hands and feet, and food seeking, but not hypopigmentation, a micropenis, cryptorchidism or obesity as common findings seen in PWS at the time of examination at 6 years of age. He had seizures noted from 1 to 3 years of age and marked cognitive delay. High-resolution SNP microarray analysis identified an atypical PWS type I deletion in chromosome 15 involving the proximal breakpoint BP1. The deletion extended beyond the GABRB3 gene but was proximal to the usual distal breakpoint (BP3) within the 15q11q13 region, and GABRA5, GABRG3, and OCA2 genes were intact. No deletion of band 19p13.3 was detected; therefore, the patient was not at an increased risk of tumors from the Peutz-Jeghers syndrome associated with a deletion of the STK11 gene.

Causes of death in Prader-Willi syndrome: Prader-Willi Syndrome Association (USA) 40-year mortality survey

BACKGROUND

Prader-Willi syndrome (PWS) is a rare, complex, neurodevelopmental genetic disorder that is associated with hyperphagia and morbid obesity in humans and leads to a shortened life expectancy. This report summarizes the primary causes of death and evaluates mortality trends in a large cohort of individuals with PWS.

METHODS

The US Prader-Willi Syndrome Association (PWSA (USA)) syndrome-specific database of death reports was collected through a cursory bereavement program for PWSA (USA) families using a brief survey created in 1999. Causes of death were descriptively characterized and statistically examined using Cox proportional hazards.

RESULTS

A total of 486 deaths were reported (263 males, 217 females, 6 unknown) between 1973 and 2015, with mean age of 29.5 ± 16 years (2 months-67 years); 70% occurred in adulthood. Respiratory failure was the most common cause, accounting for 31% of all deaths. Males were at increased risk for presumed hyperphagia-related accidents/injuries and cardiopulmonary factors compared to females. PWS maternal disomy 15 genetic subtype showed an increased risk of death from cardiopulmonary factors compared to the deletion subtype.

CONCLUSIONS

These findings highlight the heightened vulnerability to obesity and hyperphagia-related mortality in PWS. Future research is needed to address critical vulnerabilities such as gender and genetic subtype in the cause of death in PWS.Genet Med advance online publication 17 November 2016.

Effect of cessation of GH treatment on cognition during transition phase in Prader-Willi syndrome: results of a 2-year crossover GH trial

BACKGROUND

Patients with Prader-Willi syndrome (PWS) have a cognitive impairment. Growth hormone (GH) treatment during childhood improves cognitive functioning, while cognition deteriorates in GH-untreated children with PWS. Cessation of GH treatment at attainment of adult height (AH) might deteriorate their GH-induced improved cognition, while continuation might benefit them. We, therefore, investigated the effects of placebo versus GH administration on cognition in young adults with PWS who were GH-treated for many years during childhood and had attained AH.

METHOD

Two-year, randomized, double-blind, placebo-controlled cross-over study in 25 young adults with PWS. Cross-over intervention with placebo and GH (0.67 mg/m2/day), both during 1 year.

RESULTS

Total (TIQ), verbal (VIQ) and performance IQ (PIQ) did not deteriorate during 1 year of placebo, compared to GH treatment (p > 0.322). Young adults with a lower TIQ had significantly more loss of TIQ points during placebo versus GH, in particular VIQ decreased more in those with a lower VIQ. The effect of placebo versus GH on TIQ, VIQ and PIQ was not different for gender or genotype.

CONCLUSIONS

Compared to GH treatment, 1 year of placebo did not deteriorate cognitive functioning of GH-treated young adults with PWS who have attained AH. However, patients with a lower cognitive functioning had more loss in IQ points during placebo versus GH treatment. The reassuring finding that 1 year of placebo does not deteriorate cognitive functioning does, however, not exclude a gradual deterioration of cognitive functioning on the long term.

TRIAL REGISTRATION

ISRCTN24648386 , NTR1038 , Dutch Trial Register, www.trialregister.nl . Registered 16 August 2007.

Subclinical dysphagia in persons with Prader-Willi syndrome

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc.

Benefits and limitations of prenatal screening for Prader-Willi syndrome

This review summarizes the status of genetic laboratory testing in Prader-Willi syndrome (PWS) with different genetic subtypes, most often a paternally derived 15q11-q13 deletion and discusses benefits and limitations related to prenatal screening. Medical literature was searched for prenatal screening and genetic laboratory testing methods in use or under development and discussed in relationship to PWS. Genetic testing includes six established laboratory diagnostic approaches for PWS with direct application to prenatal screening. Ultrasonographic, obstetric and cytogenetic reports were summarized in relationship to the cause of PWS and identification of specific genetic subtypes including maternal disomy 15. Advances in genetic technology were described for diagnosing PWS specifically DNA methylation and high-resolution chromosomal SNP microarrays as current tools for genetic screening and incorporating next generation DNA sequencing for noninvasive prenatal testing (NIPT) using cell-free fetal DNA. Positive experiences are reported with NIPT for detection of numerical chromosomal problems (aneuploidies) but not for structural problems (microdeletions). These reports will be discussed along with future directions for genetic screening of PWS. In summary, this review describes and discusses the status of established and ongoing genetic testing options for PWS applicable in prenatal screening including NIPT and future directions for early diagnosis in PWS. © 2016 John Wiley & Sons, Ltd.

Prader-Willi syndrome and atypical submicroscopic 15q11-q13 deletions with or without imprinting defects

We report a 20 year follow up on a Caucasian female, now 26 years of age, with Prader-Willi syndrome (PWS) harboring an atypical 15q11-q13 submicroscopic deletion of 100-200 kb in size first detected in 1996 involving the imprinting center, SNRPN gene and surrounding region. PWS is a rare complex disorder caused by the loss of paternally expressed genes in the 15q11-q13 region. With high resolution chromosomal microarray and methylation - specific MLPA analysis, we updated the genetic findings on our patient and found a 209,819bp deletion including the SNURF-SNRPN gene complex which includes the imprinting center and the SNORD116 region. We compared with four other similarly reported individuals in the literature with atypical submicroscopic deletions within this region but without imprinting center involvement to better characterize the specific genetic lesions causing PWS clinical findings. Clinically, our patient met the diagnostic criteria of PWS including infantile hypotonia, a poor suck with feeding difficulties, global developmental delays and later food foraging, childhood obesity, small hands and skin picking. Small atypical deletions of comparable sizes were seen in the 15q11-q13 region in all five cases and similar behavioral/physical characteristics were found despite an imprinting defect in our patient. These results further support an overlapping critical deletion region involving the non-coding snoRNA SNORD116 in common in the five individuals playing a key role in contributing to the PWS phenotype.

Growth Charts for Prader-Willi Syndrome During Growth Hormone Treatment

The purpose of the current study was to develop syndrome-specific standardized growth curves for growth hormone-treated Prader-Willi syndrome (PWS) individuals aged 0 to 18 years. Anthropometric growth-related measures were obtained on 171 subjects with PWS who were treated with growth hormone for at least 40% of their lifespan. They had no history of scoliosis. PWS standardized growth curves were developed for 7 percentile ranges using the LMS method for weight, height, head circumference, weight/length, and BMI along with normative 3rd, 50th, and 97th percentiles plotted using control data from the literature and growth databases. Percentiles were plotted on growth charts for comparison purposes. Growth hormone treatment appears to normalize stature and markedly improves weight in PWS compared with standardized curves for non-growth hormone-treated PWS individuals. Growth chart implications and recommended usage are discussed.

Induced pluripotent stem cells (iPSC) created from skin fibroblasts of patients with Prader-Willi syndrome (PWS) retain the molecular signature of PWS

Prader-Willi syndrome (PWS) is a syndromic obesity caused by loss of paternal gene expression in an imprinted interval on 15q11.2-q13. Induced pluripotent stem cells were generated from skin cells of three large deletion PWS patients and one unique microdeletion PWS patient. We found that genes within the PWS region, including SNRPN and NDN, showed persistence of DNA methylation after iPSC reprogramming and differentiation to neurons. Genes within the PWS minimum critical deletion region remain silenced in both PWS large deletion and microdeletion iPSC following reprogramming. PWS iPSC and their relevant differentiated cell types could provide in vitro models of PWS.

Feeding, eating and behavioral disturbances in Prader-Willi syndrome and non-syndromal obesity

BACKGROUND

Although most individuals with Prader-Willi syndrome (PWS) are obese, little is known about the impact of obesity-related psychosocial factors in PWS. In the present study we compared feeding, eating, and behavioral disturbances in children and adolescents with PWS, peers with non-syndromal obesity, and normal weight controls.

METHODS

Twelve persons with PWS, aged 7-22 years, age- and gender-matched obese and normal weight individuals were analyzed regarding parental feeding practices, eating disturbances, and behavioral problems via standardized questionnaires.

RESULTS

Parents of individuals with PWS reported significantly more restrictive feeding and monitoring than did parents of obese or normal weight children without PWS (p<0.05). Social problems were more common in the obese and the PWS group than in the normal-weight group (p<0.05). Behavioral problems were significantly correlated with parental restrictive feeding practices.

CONCLUSIONS

Our data show that children and adolescents with PWS are affected by psychosocial problems, and that restrictive feeding practices might be associated with more severe behavioral problems. Further studies in larger samples will be necessary to replicate these results and possibly provide new therapeutic approaches for the management of PWS.

The High Direct Medical Costs of Prader-Willi Syndrome

OBJECTIVE

To assess medical resource utilization associated with Prader-Willi syndrome (PWS) in the US, hypothesized to be greater relative to a matched control group without PWS.

STUDY DESIGN

We used a retrospective case-matched control design and longitudinal US administrative claims data (MarketScan) during a 5-year enrollment period (2009-2014). Patients with PWS were identified by Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code 759.81. Controls were matched on age, sex, and payer type. Outcomes included total, outpatient, inpatient and prescription costs.

RESULTS

After matching and application of inclusion/exclusion criteria, we identified 2030 patients with PWS (1161 commercial, 38 Medicare supplemental, and 831 Medicaid). Commercially insured patients with PWS (median age 10 years) had 8.8-times greater total annual direct medical costs than their counterparts without PWS (median age 10 years: median costs $14 907 vs $819; P < .0001; mean costs: $28 712 vs $3246). Outpatient care comprised the largest portion of medical resource utilization for enrollees with and without PWS (median $5605 vs $675; P < .0001; mean $11 032 vs $1804), followed by mean annual inpatient and medication costs, which were $10 879 vs $1015 (P < .001) and $6801 vs $428 (P < .001), respectively. Total annual direct medical costs were ∼42% greater for Medicaid-insured patients with PWS than their commercially insured counterparts, an increase partly explained by claims for Medicaid Waiver day and residential habilitation.

CONCLUSION

Direct medical resource utilization was considerably greater among patients with PWS than members without the condition. This study provides a first step toward quantifying the financial burden of PWS posed to individuals, families, and society.

Disorders of Sleep and Ventilatory Control in Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is an imprinted genetic disorder conferred by loss of paternal gene expression from chromosome 15q11.2-q13. Individuals with PWS have impairments in ventilatory control and are predisposed toward sleep disordered breathing due to a combination of characteristic craniofacial features, obesity, hypotonia, and hypothalamic dysfunction. Children with PWS progress from failure to thrive during infancy to hyperphagia and morbid obesity during later childhood and onward. Similarly, the phenotype of sleep disordered breathing in PWS patients also evolves over time from predominantly central sleep apnea in infants to obstructive sleep apnea (OSA) in older children. Behavioral difficulties are common and may make establishing effective therapy with continuous positive airway pressure (CPAP) more challenging when OSA persists after adenotonsillectomy. Excessive daytime sleepiness (EDS) is also common in patients with PWS and may continue after OSA is effectively treated. We describe here the characteristic ventilatory control deficits, sleep disordered breathing, and excessive daytime sleepiness seen in individuals with PWS. We review respiratory issues that may contribute to sudden death events in PWS patients during sleep and wakefulness. We also discuss therapeutic options for treating sleep disordered breathing including adenotonsillectomy, weight loss, and CPAP. Lastly, we discuss the benefits and safety considerations related to growth hormone therapy.

Growth hormone therapy for Prader-willi syndrome: challenges and solutions

Prader-Willi syndrome (PWS) is characterized by a dysregulation of growth hormone (GH)/insulin-like growth factor I axis, as the consequence of a complex hypothalamic involvement. PWS' clinical picture seems to resemble the classic non-PWS GH deficiency (GHD), including short stature, excessive body fat, decreased muscle mass, and impaired quality of life. GH therapy is able to ameliorate the phenotypic appearance of the syndrome, as well as to improve body composition, physical strength, and cognitive level. In this regard, however, some pathophysiologic and clinical questions still remain, representing a challenge to give the most appropriate care to PWS patients. Data about the prevalence of GHD in PWS children are not unequivocal, ranging from 40% to 100%. In this context, to establish whether the presence (or not) of GHD may have a different effect on clinical course during GH therapy may be helpful. In addition, the comparison of GH effects in PWS children diagnosed as small for gestational age with those obtained in subjects born appropriate for gestational age is of potential interest for future trials. Emerging information seems to demonstrate the maintenance of beneficial effects of GH therapy in PWS subjects after adolescent years. Thus, GH retesting after achievement of final height should be taken into consideration for all PWS patients. However, it is noteworthy that GH administration exerts positive effects both in PWS adults with and without GHD. Another critical issue is to clarify whether the genotype-phenotype correlations may be relevant to specific outcome measures related to GH therapy. Moreover, progress of our understanding of the role of GH replacement and concomitant therapies on bone characteristics of PWS is required. Finally, a long-term surveillance of benefits and risks of GH therapy is strongly recommended for PWS population, since most of the current studies are uncontrolled and of short duration.

Higher plasma orexin A levels in children with Prader-Willi syndrome compared with healthy unrelated sibling controls

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder associated with maladaptive social behavior, hyperphagia, and morbid obesity. Orexin A is a hypothalamic neuropeptide important as a homeostatic regulator of feeding behavior and in energy metabolism through actions in the lateral hypothalamus. Dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia seen in PWS and we sought to assess orexin A levels in PWS relative to controls children. Morning fasting plasma orexin A levels were analyzed in 23 children (aged 5-11 years) with genetically confirmed PWS and 18 age and gender matched healthy unrelated siblings without PWS. Multiplex immune assays utilized the Milliplex Human Neuropeptide Magnetic panel and the Luminex platform. Natural log-transformed orexin A data were analyzed using general linear model adjusting for diagnosis, gender, age, total body fat and body mass index (BMI). Plasma orexin A levels were significantly higher (P < 0.006) in children with PWS (average ±SD = 1028 pg/ml ± 358) compared with unrelated siblings (average ±SD = 609 pg/ml ± 351; P < 0.001). Orexin A levels correlated with age in females and were significantly elevated in PWS even after these effects were controlled. These findings support the hypothesis that dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia in PWS. Further studies are warranted to better understand the complex relationship between orexin A levels and the problematic behaviors consistently found in individuals with PWS. © 2016 Wiley Periodicals, Inc.

New Perspectives on Genomic Imprinting, an Essential and Multifaceted Mode of Epigenetic Control in the Developing and Adult Brain

Mammalian evolution entailed multiple innovations in gene regulation, including the emergence of genomic imprinting, an epigenetic regulation leading to the preferential expression of a gene from its maternal or paternal allele. Genomic imprinting is highly prevalent in the brain, yet, until recently, its central roles in neural processes have not been fully appreciated. Here, we provide a comprehensive survey of adult and developmental brain functions influenced by imprinted genes, from neural development and wiring to synaptic function and plasticity, energy balance, social behaviors, emotions, and cognition. We further review the widespread identification of parental biases alongside monoallelic expression in brain tissues, discuss their potential roles in dosage regulation of key neural pathways, and suggest possible mechanisms underlying the dynamic regulation of imprinting in the brain. This review should help provide a better understanding of the significance of genomic imprinting in the normal and pathological brain of mammals including humans.

MECHANISMS IN ENDOCRINOLOGY: Novel genetic causes of short stature

The fast technological development, particularly single nucleotide polymorphism array, array-comparative genomic hybridization, and whole exome sequencing, has led to the discovery of many novel genetic causes of growth failure. In this review we discuss a selection of these, according to a diagnostic classification centred on the epiphyseal growth plate. We successively discuss disorders in hormone signalling, paracrine factors, matrix molecules, intracellular pathways, and fundamental cellular processes, followed by chromosomal aberrations including copy number variants (CNVs) and imprinting disorders associated with short stature. Many novel causes of GH deficiency (GHD) as part of combined pituitary hormone deficiency have been uncovered. The most frequent genetic causes of isolated GHD are GH1 and GHRHR defects, but several novel causes have recently been found, such as GHSR, RNPC3, and IFT172 mutations. Besides well-defined causes of GH insensitivity (GHR, STAT5B, IGFALS, IGF1 defects), disorders of NFκB signalling, STAT3 and IGF2 have recently been discovered. Heterozygous IGF1R defects are a relatively frequent cause of prenatal and postnatal growth retardation. TRHA mutations cause a syndromic form of short stature with elevated T3/T4 ratio. Disorders of signalling of various paracrine factors (FGFs, BMPs, WNTs, PTHrP/IHH, and CNP/NPR2) or genetic defects affecting cartilage extracellular matrix usually cause disproportionate short stature. Heterozygous NPR2 or SHOX defects may be found in ∼3% of short children, and also rasopathies (e.g., Noonan syndrome) can be found in children without clear syndromic appearance. Numerous other syndromes associated with short stature are caused by genetic defects in fundamental cellular processes, chromosomal abnormalities, CNVs, and imprinting disorders.

Single Gene and Syndromic Causes of Obesity: Illustrative Examples

Obesity is a significant health problem in westernized societies, particularly in the United States where it has reached epidemic proportions in both adults and children. The prevalence of childhood obesity has doubled in the past 30 years. The causation is complex with multiple sources, including an obesity promoting environment with plentiful highly dense food sources and overall decreased physical activity noted for much of the general population, but genetic factors clearly play a role. Advances in genetic technology using candidate gene approaches, genome-wide association studies, structural and expression microarrays, and next generation sequencing have led to the discovery of hundreds of genes recognized as contributing to obesity. Polygenic and monogenic causes of obesity are now recognized including dozens of examples of syndromic obesity with Prader-Willi syndrome, as a classical example and recognized as the most common known cause of life-threatening obesity. Genetic factors playing a role in the causation of obesity will be discussed along with the growing evidence of single genes and the continuum between monogenic and polygenic obesity. The clinical and genetic aspects of four classical but rare obesity-related syndromes (ie, Prader-Willi, Alström, fragile X, and Albright hereditary osteodystrophy) will be described and illustrated in this review of single gene and syndromic causes of obesity.

Zebrafish Models of Prader-Willi Syndrome: Fast Track to Pharmacotherapeutics

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder characterized by an insatiable appetite, leading to chronic overeating and obesity. Additional features include short stature, intellectual disability, behavioral problems and incomplete sexual development. Although significant progress has been made in understanding the genetic basis of PWS, the mechanisms underlying the pathogenesis of the disorder remain poorly understood. Treatment for PWS consists mainly of palliative therapies; curative therapies are sorely needed. Zebrafish, Danio rerio, represent a promising way forward for elucidating physiological problems such as obesity and identifying new pharmacotherapeutic options for PWS. Over the last decade, an increased appreciation for the highly conserved biology among vertebrates and the ability to perform high-throughput drug screening has seen an explosion in the use of zebrafish for disease modeling and drug discovery. Here, we review recent advances in developing zebrafish models of human disease. Aspects of zebrafish genetics and physiology that are relevant to PWS will be discussed, and the advantages and disadvantages of zebrafish models will be contrasted with current animal models for this syndrome. Finally, we will present a paradigm for drug screening in zebrafish that is potentially the fastest route for identifying and delivering curative pharmacotherapies to PWS patients.

Transcranial direct current stimulation reduces food-craving and measures of hyperphagia behavior in participants with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a neurodevelopmental genetic disorder characterized by intellectual disabilities and insatiable appetite with compulsive eating leading to severe obesity with detrimental health consequences. Transcranial direct current stimulation (tDCS) has been shown to modulate decision-making and cue-induced food craving in healthy adults. We conducted a pilot double blind, sham-controlled, multicenter study of tDCS modulation of food drive and craving in 10 adult PWS participants, 11 adult obese (OB) and 11 adult healthy-weight control (HWC) subjects. PWS and OB subjects received five consecutive daily sessions of active or sham tDCS over the right dorsolateral prefrontal cortex (DLPFC), while HWC received a single sham and active tDCS in a crossover design. Standardized psychometric instruments assessed food craving, drive and hyperphagia by self-report and caregiver assessment over 30 days. Robust baseline differences were observed in severity scores for the Three-Factor Eating Questionnaire (TFEQ) and Dykens Hyperphagia Questionnaire (DHQ) for PWS compared to HWC while obese participants were more similar to HWC. Active tDCS stimulation in PWS was associated with a significant change from baseline in TFEQ Disinhibition (Factor II) (Ƶ = 1.9, P < 0.05, 30 days) and Total Scores (Ƶ = 2.3, P < 0.02, 30 days), and participant ratings of the DHQ Severity (Ƶ = 1.8, P < 0.06, 5 days) and Total Scores (Ƶ = 1.9, P < 0.05, 15 days). These findings support sustained neuromodulatory effects and efficacy of tDCS to reduce food drive and behaviors impacting hyperphagia in PWS. Transcranial direct current stimulation may represent a straight-forward, low risk and low cost method to improve care, management and quality of life in PWS.

Laparoscopic sleeve gastrectomy in children and adolescents with Prader-Willi syndrome: a matched-control study

BACKGROUND

Obesity is a leading cause of mortality and morbidity in Prader-Willi syndrome (PWS).

OBJECTIVES

To study weight loss and growth after laparoscopic sleeve gastrectomy (LSG) in pediatric patients with PWS compared with those without the syndrome.

SETTING

Academic center with a standardized care pathway for pediatric bariatric surgery as a part of a prospective clinical outcome study on children and adolescents undergoing weight loss surgery.

METHODS

Clinical data of all PWS patients who underwent LSG were abstracted from our prospective database, which included all pediatric patients who underwent bariatric surgery. These data were then compared with a 1:3 non-PWS group matched for age, gender, and body mass index (BMI). Data for up to 5 years follow-up were analyzed.

RESULTS

The 24 PWS patients (mean age 10.7; 6<8 yr old, range 4.9-18) had a preoperative BMI of 46.2 ± 12.2 kg/m(2). All PWS patients had obstructive sleep apnea (OSA), 62% had dyslipidemia, 43% had hypertension, and 29% had diabetes mellitus. BMI change at the first, second, third, fourth, and fifth annual visits was -14.7 (n = 22 patients), -15.0 (n = 18), 12.2 (n = 13), -12.7 (n = 11), and -10.7 (n = 7), respectively, in the PWS group, whereas the non-PWS group had a BMI change of -15.9 (n = 67), -18.0 (n = 50), -18.4 (n = 47), -18.9 (n = 26), and -19.0 (n = 20), respectively. No significant difference was observed in postoperative BMI change (P = .2-.7) or growth (postoperative height z-score P value at each annual visit = .2-.8); 95% of co-morbidities in both groups were in remission or improved, with no significant difference in the rate of co-morbidity resolution after surgery (P = .73). One PWS patient was readmitted 5 years after surgery with recurrence of OSA and heart failure. No other readmissions occurred, and there were no reoperations, postoperative leaks, or other complications. No mortality or major morbidity was observed during the 5 years of follow-up. Among the PWS patients who reached their follow-up visit time points the total follow-up rate was 94.1%, whereas in the non-PWS group it was 97%. All patients who missed a follow-up visit were subsequently seen in future follow-ups, and no patient was lost to follow-up in either group.

CONCLUSIONS

PWS children and adolescents underwent effective weight loss and resolution of co-morbidities after LSG, without mortality, significant morbidity, or slowing of growth. LSG should be offered to obese PWS patients with heightened mortality particularly because no other effective alternative therapy is available.

Prader-Willi Syndrome: Clinical Genetics and Diagnostic Aspects with Treatment Approaches

BACKGROUND

Prader-Willi syndrome (PWS) is a neuro-developmental genetic disorder due to lack of expression of genes inherited from the paternal chromosome 15q11-q13 region with three main genetic subtypes. These include paternal 15q11-q13 deletion (about 70% of cases), maternal uniparental disomy 15 or both 15s from the mother (20-30% of cases), and defects in the imprinting center (1-3%) which controls the expression of imprinted genes in this chromosome region. Clinical manifestations include infantile hypotonia with a poor suck resulting in failure to thrive, short stature, small hands/feet and hypogonadism/hypogenitalism due to growth and other hormone deficiencies, hyperphagia and excessive weight gain with obesity and cognitive and behavioral problems including obsessive compulsions, tantrums and self-injury. The phenotype is likely related to hypothalamic dysfunction.

OBJECTIVE

Hyperphagia and obesity with related complications are major causes of morbidity and mortality in PWS requiring accurate diagnosis, appropriate medical management and treatment; the major objective of our report.

METHODS AND RESULTS

An extensive review of the literature was undertaken including genetics, clinical and behavioral aspects, and updated health-related information addressing the importance of early diagnosis and treatment of individuals with Prader-Willi syndrome. A searchable, bulleted and formatted list of topics related to this obesity syndrome was provided utilizing a Table of Contents approach for the clinical practitioner.

CONCLUSIONS

Physicians and other health care providers can use this review with clinical, genetic and treatment summaries divided into sections that are pertinent in the context of clinical practice. Finally, frequently asked questions by clinicians, families and other interested participants will be addressed.

Adiposopathy and epigenetics: an introduction to obesity as a transgenerational disease

BACKGROUND

To examine the contribution of generational epigenetic dysregulation to the inception of obesity and its adiposopathic consequences.

METHODS

Sources for this review included searches of PubMed, Google Scholar, and international government/major association websites using terms including adiposity, adiposopathy, epigenetics, genetics, and obesity.

RESULTS

Excessive energy storage in adipose tissue often results in fat cell and fat organ dysfunction, which may cause metabolic and fat mass disorders. The adverse clinical manifestations of obesity are not solely due to the amount of body fat (adiposity), but are also dependent on anatomical and functional perturbations (adiposopathy or 'sick fat'). This review describes extragenetic factors and genetic conditions that promote obesity. It also serves as an introduction to epigenetic dysregulation (i.e., abnormalities in gene expression that occur without alteration in the genetic code itself), which may contribute to obesity and adiposopathic metabolic health outcomes in offspring. Within the epigenetic paradigm, obesity is a transgenerational disease, with weight lost or gained by either parent potentially impacting generational risk for obesity and its complications.

CONCLUSIONS

Epigenetics may be an important contributor to the emergence of obesity and its complications as global epidemics. Although transgenerational epigenetic influences present challenges, they may also present interventional opportunities, via justifying weight management for individuals before, during, and after pregnancy and for future generations.