Prader-Willi Syndrome: The More We Know, the Less We Know.

Prader-Willi syndrome (PWS) is a complex genetic neurodevelopmental disorder with multisystem impact and a unique behavior profile that evolves over the life span. Beyond the primary care needs of all children and adults, the unique medical concerns and management needs of those with PWS are best served in a multidisciplinary academic center. Our PWS center has provided care for individuals with PWS and their families since 1981. Our growth hormone studies contributed to growth hormone supplementation becoming standard of care in this country. Here, in collaboration with the primary care provider, early childhood intervention programs, schools and local parent organizations, solid, patient-centered care for affected individuals and their families can be provided across the life-span. The purpose of this article is to provide a brief overview of PWS and the attendant medical and behavior management challenges attendant to the disorder.

Effects of MetAP2 inhibition on hyperphagia and body weight in Prader-Willi syndrome: A randomized, double-blind, placebo-controlled trial.

AIMS: There are no treatments for the extreme hyperphagia and obesity in Prader-Willi syndrome (PWS). The bestPWS clinical trial assessed the efficacy, safety and tolerability of the methionine aminopeptidase 2 (MetAP2) inhibitor, beloranib. MATERIALS AND METHODS: Participants with PWS (12-65 years old) were randomly assigned (1:1:1) to biweekly placebo, 1.8 mg beloranib or 2.4 mg beloranib injection for 26 weeks at 15 US sites. Co-primary endpoints were the changes in hyperphagia [measured by Hyperphagia Questionnaire for Clinical Trials (HQ-CT); possible score 0-36] and weight by intention-to-treat. ClinicalTrials.gov registration: NCT02179151. RESULTS: One-hundred and seven participants were included in the intention-to-treat analysis: placebo (n = 34); 1.8 mg beloranib (n = 36); or 2.4 mg beloranib (n = 37). Improvement (reduction) in HQ-CT total score was greater in the 1.8 mg (mean difference -6.3, 95% CI -9.6 to -3.0; P = .0003) and 2.4 mg beloranib groups (-7.0, 95% CI -10.5 to -3.6; P = .0001) vs placebo. Compared with placebo, weight change was greater with 1.8 mg (mean difference - 8.2%, 95% CI -10.8 to -5.6; P < .0001) and 2.4 mg beloranib (-9.5%, 95% CI -12.1 to -6.8; P < .0001). Injection site bruising was the most frequent adverse event with beloranib. Dosing was stopped early due to an imbalance in venous thrombotic events in beloranib-treated participants (2 fatal events of pulmonary embolism and 2 events of deep vein thrombosis) compared with placebo. CONCLUSIONS: MetAP2 inhibition with beloranib produced statistically significant and clinically meaningful improvements in hyperphagia-related behaviours and weight loss in participants with PWS. Although investigation of beloranib has ceased, inhibition of MetAP2 is a novel mechanism for treating hyperphagia and obesity.

Intranasal Carbetocin Reduces Hyperphagia, Anxiousness, and Distress in Prader-Willi Syndrome: CARE-PWS Phase 3 Trial.

CONTEXT: Prader-Willi syndrome (PWS) is a rare genetic disorder characterized by endocrine and neuropsychiatric problems including hyperphagia, anxiousness, and distress. Intranasal carbetocin, an oxytocin analog, was investigated as a selective oxytocin replacement therapy. OBJECTIVE: To evaluate safety and efficacy of intranasal carbetocin in PWS. DESIGN: Randomized, double-blind, placebo-controlled phase 3 trial with long-term follow-up. SETTING: Twenty-four ambulatory clinics at academic medical centers. PARTICIPANTS: A total of 130 participants with PWS aged 7 to 18 years. INTERVENTIONS: Participants were randomized to 9.6 mg/dose carbetocin, 3.2 mg/dose carbetocin, or placebo 3 times daily during an 8-week placebo-controlled period (PCP). During a subsequent 56-week long-term follow-up period, placebo participants were randomly assigned to 9.6 mg or 3.2 mg carbetocin, with carbetocin participants continuing at their previous dose. MAIN OUTCOME MEASURES: Primary endpoints assessed change in hyperphagia (Hyperphagia Questionnaire for Clinical Trials [HQ-CT]) and obsessive-compulsive symptoms (Children's Yale-Brown Obsessive-Compulsive Scale [CY-BOCS]) during the PCP for 9.6 mg vs placebo, and the first secondary endpoints assessed these same outcomes for 3.2 mg vs placebo. Additional secondary endpoints included assessments of anxiousness and distress behaviors (PWS Anxiousness and Distress Behaviors Questionnaire [PADQ]) and clinical global impression of change (CGI-C). RESULTS: Because of onset of the COVID-19 pandemic, enrollment was stopped prematurely. The primary endpoints showed numeric improvements in both HQ-CT and CY-BOCS which were not statistically significant; however, the 3.2-mg arm showed nominally significant improvements in HQ-CT, PADQ, and CGI-C scores vs placebo. Improvements were sustained in the long-term follow-up period. The most common adverse event during the PCP was mild to moderate flushing. CONCLUSIONS: Carbetocin was well tolerated, and the 3.2-mg dose was associated with clinically meaningful improvements in hyperphagia and anxiousness and distress behaviors in participants with PWS. CLINICAL TRIALS REGISTRATION NUMBER: NCT03649477.

Growth hormone treatment of adults with Prader-Willi syndrome and growth hormone deficiency improves lean body mass, fractional body fat, and serum triiodothyronine without glucose impairment: results from the United States multicenter trial.

CONTEXT: GH replacement in Prader-Willi syndrome (PWS) children has well-defined benefits and risks and is used extensively worldwide. Its use in PWS adults has been limited by documentation of benefits and risks, as determined by larger multisite studies. OBJECTIVES: Our objective was to evaluate the effectiveness and safety of GH in GH-deficient genotype-positive PWS adults. DESIGN: We conducted a 12-month open-label multicenter trial with 6-month dose-optimization and 6-month stable treatment periods. SETTING: The study was conducted at outpatient treatment facilities at four U.S. academic medical centers. PATIENTS: Lean and obese PWS adults with diverse cognitive skills, behavioral traits, and living arrangements were recruited from clinical populations. INTERVENTION: Human recombinant GH (Genotropin) was initiated at 0.2 mg/d with monthly 0.2-mg increments to a maximum 1.0 mg/d, as tolerated. MAIN OUTCOMES MEASURES: Lean body mass and percent fat were measured by dual-energy x-ray absorptiometry. RESULTS: Lean body mass increased from 42.65 +/- 2.25 (se) to 45.47 +/- 2.31 kg (P < or = 0.0001), and percent fat decreased from 42.84 +/- 1.12 to 39.95 +/- 1.34% (P = 0.025) at a median final dose of 0.6 mg/d in 30 study subjects who completed 6-12 months of GH. Mean fasting glucose of 85.3 +/- 3.4 mg/dl, hemoglobin A1c of 5.5 +/- 0.2%, fasting insulin of 5.3 +/- 0.6 microU/ml, area under the curve for insulin of 60.4 +/- 7.5 microU/ml, and homeostasis model assessment of insulin resistance of 1.1 +/- 0.2 were normal at baseline in 38 study initiators, including five diabetics, and remained in normal range. Total T(3) increased 26.7% from 127.0 +/- 7.8 to 150.5 +/- 7.8 ng/dl (P = 0.021) with normalization in all subjects, including six (20%) with baseline T(3) values at least 2 sd below the mean. Mildly progressive ankle edema was the most serious treatment-emergent adverse event (five patients). CONCLUSIONS: This multicenter study demonstrates that GH improves body composition, normalizes T(3), and is well tolerated without glucose impairment in PWS genotype adults.

Benefits of long-term GH therapy in Prader-Willi syndrome: a 4-year study.

Obesity, poor growth, and hypotonia in children with Prader-Willi syndrome (PWS) are accompanied by abnormal body composition resembling a GH-deficient state. Hypothalamic dysfunction in PWS includes decreased GH secretion, suggesting a possible therapeutic role for GH treatment. While short-term benefits of treatment with GH have been shown, whether these beneficial effects are dose dependent and persist or wane with prolonged therapy remains uncertain. Effects of 24 additional months of GH treatment at varying doses (0.3, 1.0, and 1.5 mg/m(2).d) on growth, body composition, strength and agility, pulmonary function, resting energy expenditure (REE), and fat utilization were assessed in 46 children with PWS, who had previously been treated with GH therapy (1 mg/m(2).d) for 12-24 months. Percent body fat, lean muscle mass, and bone mineral density (BMD) were measured by dual x-ray absorptiometry. Indirect calorimetry was used to determine REE and to calculate respiratory quotient. A modified Bruininks-Oseretski test of physical performance evaluated strength and agility. During months 24-48 of GH therapy, continued beneficial effects on body composition (decrease in fat mass and increase in lean body mass), growth velocity, and REE occurred with GH therapy doses of 1.0 and 1.5 mg/m(2).d (P < 0.05), but not with 0.3 mg/m(2).d. BMD continued to improve at all doses of GH (P < 0.05). Prior improvements in strength and agility that occurred during the initial 24 months were sustained but did not improve further during the additional 24 months regardless of dose. Salutary and sustained GH-induced changes in growth, body composition, BMD, and physical function in children with PWS can be achieved with daily administration of GH doses > or =1 mg/m(2). Lower doses of GH, (0.3 mg/m(2).d) effective in improving body composition in GHD adults, do not appear to be effective in children with PWS at sustaining improvement in body composition.

A comprehensive team approach to the management of patients with Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a genetic disorder characterized by extreme obesity accompanied by other, multisystem clinical manifestations encompassing both physical and behavioral/cognitive abnormalities. The multi-dimensional problems of patients with PWS cannot be treated with a single intervention and benefit from a team approach to management to optimize outcomes. Childhood stature below target height and reduced final height are some defining characteristics of PWS, and compelling evidence from growth hormone (GH) treatment trials suggests that hypothalamic GH deficiency exists. Treatment with GH has been shown to increase height velocity in children with PWS, decrease weight-for-height index values and body fat mass, and have a positive effect on lean body mass during at least the first year of therapy. In addition to medical concerns, the behavioral manifestations, including an uncorrectable deficit in appetite control, and cognitive limitations associated with PWS, require long-term multidisciplinary management.

Growth standards of infants with Prader-Willi syndrome.

OBJECTIVE: To generate and report standardized growth curves for weight, length, head circumference, weight/length, and BMI for non-growth hormone-treated white infants (boys and girls) with Prader-Willi syndrome (PWS) between 0 and 36 months of age. The goal was to monitor growth and compare data with other infants with PWS. METHODS: Anthropometric measures (N = 758) were obtained according to standard methods and analyzed from 186 non-growth hormone-treated white infants (108 boys and 78 girls) with PWS between 0 and 36 months of age. Standardized growth curves were developed and the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles were calculated by using the LMS (refers to λ, µ, and σ) smoothing procedure method for weight, length, head circumference, weight/length, and BMI along with the normative 50th percentile using Centers for Disease Control and Prevention national growth data from 2003. The data were plotted for comparison purposes. RESULTS: Five separate standardized growth curves (weight, length, head circumference, weight/length, and BMI) representing 7 percentile ranges were developed from 186 non-growth hormone-treated white male and female infants with PWS aged 0 to 36 months, and the normative 50th percentile was plotted on each standardized infant growth curve. CONCLUSIONS: We encourage the use of these growth standards when examining infants with PWS and evaluating growth for comparison purposes, monitoring for growth patterns, nutritional assessment, and recording responses to growth hormone therapy, commonly used in infants and children with PWS.

Long-term growth hormone therapy changes the natural history of body composition and motor function in children with prader-willi syndrome.

BACKGROUND: Children with Prader-Willi syndrome (PWS) have decreased muscle mass, hypotonia, and impaired linear growth. Recombinant human GH (hGH) treatment reportedly improves body composition and physical function in children with PWS, but these studies lack long-term control data. To assess the impact of hGH therapy begun early in life on the natural history of PWS, we compared height, body composition, and strength in similar-age children with PWS naïve to hGH with those treated with hGH for 6 yr. OBJECTIVES: Forty-eight children with PWS were studied: 21 subjects (aged 6-9 yr) treated with hGH for 6 yr (beginning at 4-32 months, mean 13 +/- 6 months) were compared with 27 children of similar age (5-9 yr) prior to treatment with hGH. Percent body fat, lean body mass, carbohydrate/lipid metabolism, and motor strength were compared using analysis of covariance. RESULTS: PWS children treated with hGH demonstrated lower body fat (mean, 36.1 +/- 2.1 vs. 44.6 +/- 1.8%, P < 0.01), greater height (131 +/- 2 vs. 114 +/- 2 cm; P < 0.001), greater motor strength [increased standing broad jump 22.9 +/- 2.1 vs. 14.6 +/- 1.9 in. (P < 0.001) and sit-ups 12.4 +/- 0.9 vs. 7.1 +/- 0.7 in 30 sec (P < 0.001)], increased high-density lipoprotein cholesterol (58.9 +/- 2.6 vs. 44.9 +/- 2.3 mg/dl, P < 0.001), decreased low-density lipoprotein (100 +/- 8 vs. 131 +/- 7 mg/dl, P < 0.01), and no difference in fasting glucose or insulin. CONCLUSIONS: hGH treatment in children with PWS, begun prior to 2 yr of age, improves body composition, motor function, height, and lipid profiles. The magnitude of these effects suggests that long-term hGH therapy favorably alters the natural history of PWS to an extent that exceeds risks and justifies consideration for initiation during infancy.

Two years of growth hormone therapy in young children with Prader-Willi syndrome: physical and neurodevelopmental benefits.

Infants with Prader-Willi syndrome (PWS) typically display failure to thrive and decreased muscle mass with excess body fat for age. Growth hormone (GH) therapy in children with PWS improves, but does not normalize, body composition and muscle strength and agility. The objective of this study was to determine the effects of earlier GH therapy on anthropometric measurements, body composition, and psychomotor development in affected PWS infants and toddlers. Twenty-five subjects, ages 4-37 months, were randomized to 2 years of GH therapy (1 mg/m(2)/day) or 1 year of observation without GH treatment and then placed on GH (1.5 mg/m(2).day) for 1 year only. Anthropometric measurements were obtained by standard methods: percent body fat, lean body mass, and total body bone mineral density by dual x-ray absorptiometry; motor constructs of mobility and stability by the Toddler Infant Motor Evaluation; and cognitive and language function by the Capute Scales of Infant Language and Cognitive Development. GH-treated PWS subjects demonstrated normalization of length/height standard deviation scores (SDS), faster head growth, increased lean body mass accrual, and decreased percent body fat (P < 0.005 for all parameters), as well as improved language (P = 0.05) and cognitive (P = 0.02) quotient Z-scores compared with similarly aged untreated PWS subjects after 1 year into the study. PWS subjects treated before their first birthday spoke their first words at a mean age of 14.4 +/- 2.8 months and walked independently at 23.3 +/- 4.8 months. GH therapy was well-tolerated; however, one PWS subject experienced scoliosis progression. As greater benefits were seen in our study with early treatment, prompt referral to a pediatric endocrinologist for consideration of GH therapy is recommended for PWS at an early age.

The behavioral impact of growth hormone treatment for children and adolescents with Prader-Willi syndrome: a 2-year, controlled study.

INTRODUCTION: Prader-Willi syndrome (PWS) is characterized by obesity, hypotonia, hypogonadism, hyperphagia, short stature, and a neurobehavioral profile that includes cognitive deficits, learning problems, and behavioral difficulties that increase in both quantity and severity over time. PWS results from an alteration in the molecular composition of a critical region of C#15q. Morbid obesity resulting from hyperphagia is amplified by decreased energy expenditure and reduced physical activity. The hyperphagia has proven refractory to all psychopharmocologic intervention; the behavioral components are equally resistant to psychotropic intervention. PWS patients' body composition resembles that of individuals with growth hormone (GH) deficiency, including short stature and reduced lean body mass with concomitant increased fat mass. We hypothesized that GH administration to children with PWS, in addition to stimulating linear growth, would improve body composition, increase energy expenditure and fat utilization, and improve muscle strength, physical agility, and pulmonary function. Two recent reports from this study document significant positive effects of GH treatment on these children's physical parameters measured in a 2-year, controlled study. However, the behavioral impact of GH treatment in this population remains incompletely described. A psychosocial burden, including emotional, behavioral, and cognitive disturbances associated with short stature, has been previously described in a non-PWS population with GH deficiency and idiopathic short stature. An impaired quality of life and psychosocial status is also documented in otherwise normal adults with GH deficiency. In both populations, growth hormone replacement therapy (GHRT) is reported to improve alertness, activity level, endurance, irritability, tendency to worry, and extroversion resulting in better personal relationships with fewer conflicts. This report focuses on that portion of the study investigating the behavioral and psychosocial outcomes accompanying increased stature and improved physical status for persons with PWS treated with GHRT. We hypothesized that, as in other populations, GHRT for persons with PWS would have a significant positive effect on their psychosocial status as well as an improvement in their growth parameters. METHODS: A 2-year, controlled study with control group crossover in the second year was used. Fifty-four consecutive children with genetically confirmed PWS were enrolled. Patients were 4 to 16 years of age at time of enrollment, had skeletal maturation <13 for girls and <15 for boys; all but 3 participants remained prepubertal (Tanner stage 1) throughout the study. Children who had previous therapy with GH were excluded, as were children with a scoliosis >20 degrees. After a 6-month growth assessment were randomized into a 60:40 treatment:control ratio. Treatment consisted of Nutropin (Genentech), 1 mg/m2/day. A modified Offord Survey Diagnostic Instrument (SDI) was used to monitor behavior at 6-month intervals. The SDI is a 165-item behavioral checklist with items rated on a scale of 0 = Never or Not True, 1 = Sometimes or Somewhat True, and 2 = Often or Very True. The items are balanced between positively and negatively scored items. The present instrument was designed to derive diagnoses for the following Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition categories: Depression, Obsessive-Compulsive Disorder, Anxiety Disorder, Somatization Disorder, Conduct Disorder, and Attention-Deficit/Hyperactivity Disorder. The SDI was modified to include 10 items specifically inquiring about PWS (eg, denies having PWS, picks excessively at skin, nose, or other body parts). Because diagnoses are not mutually exclusive, an individual can meet criteria for 1 or more diagnostic categories. The SDI contains a second section measuring behavior functioning in the school environment, in the family, and in personal and social relationships. A wider scoring range is used and is question-specific. Parallel forms of this measure are available for parents, teachers, and the child him/herself. We gathered data from both parents and teachers at 6-month intervals. No questionnaire was scored until the completion of the entire study to avoid any possibility of an inadvertent "feedback" or "self-fulfilling prophecy" effect. All questionnaires were scored by a Bachelor's level research assistant blind to study assignment. Family stress was monitored with the Family Inventory of Life Events. At study completion, the impact of GH was measured with a 13-item summary interview adapted from Wiren et al. After completion of all final study visits, a single research assistant blind to treatment assignment interviewed all families by phone. This method was chosen to minimize any positively biased demand characteristics. RESULTS: Both between-group and within-group contrasts were computed for baseline, 12 (time 1) and 24 month (time 2) measures. Because behavioral deterioration, as well as improvement, was a possibility, a 2-tailed hypothesis test was used for all comparisons. No differences were found between treatment and control groups, nor within groups across measurement points for attentional symptoms, anxiety, obsessive-compulsive complex, violence, or psychotic symptoms. Similarly, no differences were noted between groups on depressive symptoms; however, a significant positive effect (reduction of depressive symptoms) was noted for the treatment group from baseline to time 1, and was retained at time 2. The group was divided by age, with those 11.0 years and younger comprising one group and those older the second group. This analysis indicated that the major reduction in depressive symptoms occurred in those over 11 years old. When divided by age, a second unexpected finding emerged. There was a significant increase in attention-deficit/hyperactivity disorder symptoms from baseline to 24 months in those children 11 and under, independent of treatment status. The groups were subsequently further broken down by sex and by genetic status (deletion versus disomy) with no significant findings. At no time was the expected behavioral deterioration reported. We conclude that in addition to the previously detailed improvements in physical parameters for these children, behavioral improvement, including a lack of predictable behavioral deterioration during the treatment period, is a strong argument for the use of GHRT for this difficult syndrome.

Growth hormone improves mobility and body composition in infants and toddlers with Prader-Willi syndrome.

OBJECTIVES: To determine the effect of growth hormone (GH) on body composition and motor development in infants and toddlers with Prader-Willi syndrome (PWS). STUDY DESIGN: Twenty-nine subjects with PWS (4-37 months of age) were randomized to GH treatment (1mg/m 2 /day) or observation for 12 months. Percent body fat, lean body mass, and bone mineral density were measured by dual x-ray absorptiometry; energy expenditure was measured by deuterium dilution; and motor constructs of mobility (M) and stability (S) were assessed using the Toddler Infant Motor Evaluation (TIME). RESULTS: GH-treated subjects, compared with controls, demonstrated decreased percent body fat (mean, 22.6% +/- 8.9% vs 28.5% +/- 7.9%; P < .001), increased lean body mass (mean, 9.82 +/- 1.9 kg vs 6.3 +/- 1.9 kg; P < .001), and increased height velocity Z scores (mean, 5. 0 +/- 1.8 vs 1.4 +/- 1.0; P < .001). Patients who began GH before 18 months of age showed higher mobility skill acquisition compared with controls within the same age range (mean increase in raw score, 284 +/- 105 vs 206 +/- 63; P < .05). CONCLUSIONS: GH treatment of infants and toddlers with PWS for 12 months significantly improves body composition and when begun before 18 months of age increases mobility skill acquisition. These results suggest that GH therapy instituted early in life may lessen deterioration of body composition in PWS while also accelerating motor development.