June-Anne Gold

Nutritional Phases in Prader–Willi Syndrome

Prader–Willi syndrome (PWS) is a complex neurobehavioral condition which has been classically described as having two nutritional stages: poor feeding, frequently with failure to thrive (FTT) in infancy (Stage 1), followed by hyperphagia leading to obesity in later childhood (Stage 2). We have longitudinally followed the feeding behaviors of individuals with PWS and found a much more gradual and complex progression of the nutritional phases than the traditional two stages described in the literature. Therefore, this study characterizes the growth, metabolic, and laboratory changes associated with the various nutritional phases of PWS in a large cohort of subjects. We have identified a total of seven different nutritional phases, with five main phases and sub‐phases in phases 1 and 2. Phase 0 occurs in utero, with decreased fetal movements and growth restriction compared to unaffected siblings. In phase 1 the infant is hypotonic and not obese, with sub‐phase 1a characterized by difficulty feeding with or without FTT (ages birth—15 months; median age at completion: 9 months). This phase is followed by sub‐phase 1b when the infant grows steadily along a growth curve and weight is increasing at a normal rate (median age of onset: 9 months; age quartiles 5–15 months). Phase 2 is associated with weight gain—in sub‐phase 2a the weight increases without a significant change in appetite or caloric intake (median age of onset 2.08 years; age quartiles 20–31 months;), while in sub‐phase 2b the weight gain is associated with a concomitant increased interest in food (median age of onset: 4.5 years; quartiles 3–5.25 years). Phase 3 is characterized by hyperphagia, typically accompanied by food‐seeking and lack of satiety (median age of onset: 8 years; quartiles 5–13 years). Some adults progress to phase 4 which is when an individual who was previously in phase 3 no longer has an insatiable appetite and is able to feel full. Therefore, the progression of the nutritional phases in PWS is much more complex than previously recognized. Awareness of the various phases will aid researchers in unraveling the pathophysiology of each phase and provide a foundation for developing rational therapies. Counseling parents of newly diagnosed infants with PWS as to what to expect with regard to these nutritional phases may help prevent or slow the early‐onset of obesity in this syndrome.

Mitochondrial dysfunction in CA1 hippocampal neurons of the UBE3A deficient mouse model for Angelman syndrome

Angelman syndrome (AS) is a severe neurological disorder caused by a deficiency of ubiquitin protein ligase E3A (UBE3A), but the pathophysiology of the disease remains unknown. We now report that in the brains of AS mice in which the maternal UBE3A allele is mutated (m-) and the paternal allele is potentially inactivated by imprinting (p+) (UBE3A m-\p+), the mitochondria are abnormal and exhibit a partial oxidative phosphorylation (OXPHOS) defect. Electron microscopy of the hippocampal region of the UBE3A m-\p+ mice (n=6) reveals small, dense mitochondria with altered cristae, relative to wild-type littermates (n=6) and reduced synaptic vesicle density. The specific activity of OXPHOS complex III is reduced in whole brain mitochondria in UBE3A m-\p+ (n=5) mice versus wild-type littermates (n=5). Therefore, mitochondrial dysfunction may contribute to the pathophysiology of Angelman syndrome.

Growth Charts for Non-Growth Hormone Treated Prader-Willi Syndrome

OBJECTIVE: The goal of this study was to generate and report standardized growth curves for weight, height, head circumference, and BMI for non–growth hormone–treated white male and female US subjects with Prader-Willi syndrome (PWS) between 3 and 18 years of age and develop standardized growth charts. METHODS: Anthropometric measures (N = 133) were obtained according to standard methods from 120 non–growth hormone–treated white subjects (63 males and 57 females) with PWS between 3 and 18 years of age. Standardized growth curves were developed for the third, 10th, 25th, 50th, 75th, 90th, and 97th percentiles by using the LMS method for weight, height, head circumference, and BMI for PWS subjects along with the normative third, 50th, and 97th percentiles from national and international growth data. The LMS smoothing procedure summarized the distribution of the anthropometric variables at each age using three parameters: power of the Box-Cox transformation λ (L), median μ (M) and coefficient of variation δ (S). RESULTS: Weight, height, head circumference, and BMI standardized growth charts representing 7 percentile ranges were developed from 120 non–growth hormone–treated white male and female US subjects with PWS (age range: 3–18 years) and normative third, 50th, and 97th percentiles from national and international data. CONCLUSIONS: We encourage the use of syndrome-specific growth standards to examine and evaluate subjects with PWS when monitoring growth patterns and determining nutritional and obesity status. These variables can be influenced by culture, individual medical care, diet intervention, and physical activity plans.

Oxytocin treatment in children with Prader–Willi syndrome: A double-blind, placebo-controlled, crossover study

Prader–Willi syndrome (PWS) is a rare, complex multisystem genetic disorder which includes hypothalamic dysfunction, hyperphagia, cognitive and behavioral problems, increased anxiety, and compulsive behaviors. Individuals with PWS have a deficit of oxytocin producing neurons in the paraventricular nucleus of the hypothalamus. Oxytocin plays a role in regulation of feeding behaviors, social interactions, and emotional reactivity, which are all issues that significantly affect the quality of life for individuals with this syndrome. We performed a double‐blind, placebo‐controlled, crossover study in 24 children with PWS at three academic institutions using 5 days of intranasal oxytocin (IN‐OT) or 5 days of intranasal placebo spray, followed by a 4 week washout period, and then patients returned for 5 days of treatment with the alternate source. Questionnaires, including the Aberrant Behavior Checklist, Social Responsiveness Scale, Repetitive Behavior Scale − Revised, and the Hyperphagia Questionnaire, as well as Clinical Global Impression scales were administered. Blood testing for sodium, potassium, and glucose levels on days 2, 4, and 6, and a 24 hr diet recall. All scales factor improvement from Day 3 to Day 6 favored oxytocin over placebo. No single factor showed a statistically significant difference (P < 0.05) between groups at Day 6. The drug effect appeared to be diminished at Day 14. There was no evidence of a difference between oxytocin and placebo in safety lab parameters, 60 min post dose vital signs, weight, or diet parameters. The results from this study suggest that low dose intranasal oxytocin is safe for individuals with PWS and may result in reduction in appetite drive, and improvements in socialization, anxiety, and repetitive behaviors. Further, long‐term studies with a larger population of participants are necessary to confirm these findings. The results of this study are encouraging that oxytocin may be a safe and effective treatment for many of the issues that negatively impact individuals with PWS.

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.

Frequency of Prader-Willi syndrome in births conceived via assisted reproductive technology

PURPOSE Prader-Willi syndrome is an imprinting disorder characterized by typical facial, physical, and cognitive/behavioral features, resulting from lack of paternally expressed genes on chromosome 15q11.2-q13. Studies have suggested an increased risk of other imprinting disorders in children conceived by assisted reproductive techniques. This study was designed to determine the association between assisted reproductive technology and Prader-Willi syndrome. METHODS Data on individuals with Prader-Willi syndrome were collected from three distinct sources and the proportion of assisted reproductive technology births analyzed. RESULTS The proportions of assisted reproductive technology births in the Prader-Willi Syndrome Association (USA), Rare Diseases Clinical Research Network, and University of California, Irvine Medical Center populations were 1.0% (18/1,736), 1.0% (1/98), and 2.0% (1/50), respectively (overall 1.1%; population frequency for the United States was 1.0%). Of note, 2.4% (45/1,898) of participants were co-twins (11 born after assisted reproductive technology procedures); US twin frequency is 1.6% (P = 0.007). The proportion of individuals with maternal disomy 15/imprinting defects born after assisted reproductive technology was higher than that in the total sample, 55.6% (10/18) and 34.5% (431/1,250), respectively. CONCLUSION This study found no association between assisted reproductive technology and Prader-Willi syndrome. There was an increased frequency of twinning. The number of individuals with maternal disomy 15/imprinting defect was nearly double in the assisted reproductive technology group as compared with the total Prader-Willi syndrome participants.Purpose:Prader–Willi syndrome is an imprinting disorder characterized by typical facial, physical, and cognitive/behavioral features, resulting from lack of paternally expressed genes on chromosome 15q11.2–q13. Studies have suggested an increased risk of other imprinting disorders in children conceived by assisted reproductive techniques. This study was designed to determine the association between assisted reproductive technology and Prader–Willi syndrome.Methods:Data on individuals with Prader–Willi syndrome were collected from three distinct sources and the proportion of assisted reproductive technology births analyzed.Results:The proportions of assisted reproductive technology births in the Prader-Willi Syndrome Association (USA), Rare Diseases Clinical Research Network, and University of California, Irvine Medical Center populations were 1.0% (18/1,736), 1.0% (1/98), and 2.0% (1/50), respectively (overall 1.1%; population frequency for the United States was 1.0%). Of note, 2.4% (45/1,898) of participants were co-twins (11 born after assisted reproductive technology procedures); US twin frequency is 1.6% (P = 0.007). The proportion of individuals with maternal disomy 15/imprinting defects born after assisted reproductive technology was higher than that in the total sample, 55.6% (10/18) and 34.5% (431/1,250), respectively.Conclusion:This study found no association between assisted reproductive technology and Prader–Willi syndrome. There was an increased frequency of twinning. The number of individuals with maternal disomy 15/imprinting defect was nearly double in the assisted reproductive technology group as compared with the total Prader–Willi syndrome participants.Genet Med 16 2, 164–169.

Effect of genetic subtypes and growth hormone treatment on bone mineral density in Prader-Willi syndrome.

Abstract Background: Currently, there is limited information on the effects of growth hormone and of the different genetic subtypes on bone mineral density (BMD) in Prader-Willi syndrome (PWS). Methods: We evaluated BMD in 79 individuals with the common subtypes of PWS (48 with deletion and 27 with UPD) and the effect of growth hormone treatment (n=46) vs. no growth hormone treatment. Results: Forty-four percent of the individuals studied had whole body, hip, or spine BMD <–1 standard deviation (SD) and 10% had a BMD <–2 SD. BMD Z-scores and total BMD (g/cm2) of the spine were significantly higher in the growth hormone group. With each year of growth hormone treatment, these values increased by a factor of 0.207 and 0.011 (p=0.006 and 0.032), respectively. Individuals with uniparental disomy revealed higher spine BMD compared with deletion subclass; however, the differences were not significant. Conclusion: This study emphasizes the importance of evaluating bone mineralization in individuals with PWS and the beneficial effects of prolonged treatment with growth hormone. There was a trend for a higher BMD in individuals with uniparental disomy.

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.

Multicentre study of maternal and neonatal outcomes in individuals with Prader-Willi syndrome

Introduction Prader-Willi syndrome (PWS) is a complex genetic disorder associated with three different genetic subtypes: deletion of the paternal copy of 15q11-q13, maternal UPD for chromosome 15 and imprinting defect. Patients are typically diagnosed because of neonatal hypotonia, dysmorphism and feeding difficulties; however, data on the prenatal features of PWS are limited. Objective The aim of the study was to identify and compare frequencies of prenatal and neonatal clinical features of PWS among the three genetic subtypes. Methods Data from 355 patients with PWS from the Rare Diseases Clinical Research Network PWS registry were used to analyse multiple maternal and neonatal factors collected during an 8-year multisite study. Results Among our cohort of 355 patients with PWS (61% deletion, 36% UPD and 3% imprinting defect) 54% were born by caesarean section, 26% were born prematurely and 34% with a low birth weight (frequencies 32%, 9.6% and 8.1%, respectively, in the general population). Fetal movements were reported as decreased in 72%. All babies were hypotonic, and 99% had feeding difficulties. Low Apgar scores (<7) were noted in 17.7% and 5.6% of patients, respectively, compared with 1% and 1.4%, respectively, in the general population. Maternal age and pre-pregnancy weight were significantly higher in the UPD group (p=0.01 and <0.001, respectively). Conclusion We found a higher rate of perinatal complications in PWS syndrome compared with the general population. No significant differences in the genetic subtypes were noted except for a higher maternal age and pre-pregnancy weight in the UPD subgroup

Comparison of perinatal factors in deletion versus uniparental disomy in Prader-Willi syndrome

Prader–Willi syndrome (PWS) is caused by a deficiency of imprinted genes in the 15q11‐q13 region and is characterized by prenatal onset of hypotonia, poor feeding, childhood‐onset obesity, hyperphagia, short stature, facial dysmorphism, intellectual disability, and behavioral problems. We studied perinatal factors in a cohort of 64 people with PWS resulting from paternal deletion of 15q11‐q13 and maternal uniparental disomy (UPD) for chromosome 15. We recruited 34 individuals with deletion and 30 with UPD. We compared the frequency of multiple prenatal and neonatal factors with the general population as well as between the two genetic subtypes. Of the 64 individuals with PWS, fetal movements were decreased in 82.8%, 31.7% were born prematurely, 42.1% by Cesarean section, and 35.9% required oxytocin induction. Apgar scores were low in 34.6%, 96.8% had feeding difficulty, 50% needed tube feeding, and 6.2% subsequently had gastrostomy tube placement. On comparing findings in the deletion versus the UPD groups, we did not find many significant differences. We, however, found a higher maternal age, and also later age at diagnosis in the UPD versus the deletion group. PWS subjects have higher rates of perinatal complications, especially Cesarean section rate, hypotonia, and low Apgar scores compared to the general population. We did not find many differences between the genetic subtypes, except for later age of diagnosis of the UPD 15 group suggesting a milder phenotype. We also found that the mothers in the UPD were older, supporting the hypothesis that UPD results from nondisjunction associated trisomy rescue.