Childhood growth hormone treatment: challenges, opportunities, and considerations

With long standing demand and popularity, growth hormone treatments continue to be a topic of interest for paediatric endocrinologists and general paediatricians due to ongoing issues regarding their long-term effects, the safety of childhood treatment, and the introduction of long-acting growth hormone preparations in the past decade. Moreover, uncertainty regarding how to approach individual patients and their treatment indications remains, particularly concerning tailored treatment goals and objectives; this uncertainty is further complicated by the multitude of approved indications that surpass substitution therapy. The paediatric endocrinologist thus grapples with pertinent questions, such as what defines reasonable treatment goals for each individual given their indications, and when (and how) to initiate the necessary discussions about risks and benefits with patients and their families. The aim of this Review is to offer advanced physiological concepts of growth hormone function, map out approved paediatric indications for treatment along with evidence on their effects and safety, highlight controversies and complexities surrounding childhood growth hormone treatment, and discuss the potential of long-acting growth hormone and future directions in the realm of childhood growth hormone treatment.

Long-term effect of growth hormone on sleep-disordered breathing in Malaysian children with Prader-Willi syndrome: a retrospective study

STUDY OBJECTIVES

The effect of recombinant human growth hormone (rhGH) on sleep-disordered breathing (SDB) in Malaysian children with Prader-Willi syndrome (PWS) is under-investigated. We determined (1) the short- and long-term effects of rhGH and (2) factors associated with worsening SDB in children with PWS receiving rhGH.

METHODS

This retrospective study included children with PWS (with and without rhGH) who had undergone at least 1 polysomnography. Outcomes measured were the presence of SDB before and after starting rhGH and the progress of SDB with and without rhGH. Serial insulin-like growth factor 1 (IGF-1) measurements were recorded.

RESULTS

One-hundred and thirteen polysomnograms were analyzed. The majority (92.3%) of initial polysomnograms showed SDB, with a median (interquartile range) apnea-hypopnea index of 5.0 (2.6, 16.3) events/h. The age for receiving rhGH was a median (IQR) of 1.9 (0.7, 3.4) years. One-third (36.8%) had worsening SDB after initiating rhGH, which was associated with higher IGF-1 levels post-rhGH (P = .007). After a median of 5 years of rhGH, 73.6% maintained or reduced their positive airway pressure settings. Without rhGH, 80% had increased their positive airway pressure settings. Worsening SDB while on rhGH was associated with higher body mass index, lower rhGH dose, higher IGF-1 levels, and non-15q deletion.

CONCLUSIONS

The majority of Malaysian children with PWS had SDB. At initiation of rhGH, one-third of patients had worsening SDB, associated with increased IGF-1 levels. Stabilization of SDB was more frequently seen in those receiving long-term rhGH. Worsening SDB while on rhGH was associated with a higher body mass index, receiving a lower dose of rhGH, higher IGF-1 levels, and non-15q deletion.

CITATION

Tan YT, Azanan MS, Hng SY, et al. Long-term effect of growth hormone on sleep-disordered breathing in Malaysian children with Prader-Willi syndrome: a retrospective study. J Clin Sleep Med. 2024;20(8):1291-1299.

The outcomes of growth hormone therapy in the obstructive sleep apnea parameters of Prader-Willi syndrome patients: a systematic review

PURPOSE

Prader-Willi syndrome is a serious genetic condition, capable of causing endocrinological imbalance, which has as one of its main treatments the growth hormone therapy. However, this therapy still causes some uncertainty concerning its effects on the respiratory parameters of those patients, especially in cases of obstructive sleep apnea, therefore, presenting a need for the analysis of the relationship between the therapy and the otolaryngologic condition.

METHODS

A systematic review following the PRISMA model was developed, with searches for keywords made in the databases PubMed (MEDLINE), Scopus, and Web of Science and registration in the PROSPERO platform (CRD42023404250).

RESULTS

Three randomized controlled trials were considered eligible for inclusion in the review. None of the studies demonstrated statistically significant modifications in the obstructive sleep apnea parameters of Prader-Willi patients related to the growth hormone administration.

CONCLUSIONS

Growth hormone therapy is safe for Prader-Willi syndrome patients when analyzing their obstructive sleep apnea parameters.

Hypoventilation in patients with Prader-Willi syndrome across the pediatric age

OBJECTIVES

Few data on alveolar hypoventilation in Prader-Willi syndrome (PWS) are available and the respiratory follow-up of these patients is not standardized. The objectives of this study were to evaluate the prevalence of alveolar hypoventilation in children with PWS and identify potential risk factors.

STUDY DESIGN

This retrospective study included children with PWS recorded by polysomnography (PSG) with transcutaneous carbon dioxide pressure (PtcCO2) or end-tidal CO2 (ETCO2) measurements, between 2007 and 2021, in a tertiary hospital center. The primary outcome was the presence of alveolar hypoventilation defined as partial pressure of carbon dioxide (pCO2) ≥ 50 mmHg during ≥2% of total sleep time (TST) or more than five consecutive minutes.

RESULTS

Among the 57 included children (38 boys, median age 4.8 years, range 0.1-15.6, 60% treated with growth hormone [GH], 37% obese), 19 (33%) had moderate-to-severe obstructive sleep apnea syndrome (defined as obstructive apnea-hypopnea index ≥5/h) and 20 (35%) had hypoventilation. The median (range) pCO2 max was 49 mmHg (38-69). Among the children with hypoventilation, 25% were asymptomatic. Median age and GH treatment were significantly higher in children with hypoventilation compared to those without. There was no significant difference in terms of sex, BMI, obstructive or central apnea-hypopnea index between both groups.

CONCLUSION

The frequency of alveolar hypoventilation in children and adolescents with PWS is of concern and may increase with age and GH treatment. A regular screening by oximetry-capnography appears to be indicated whatever the sex, BMI, and rate of obstructive or central apneas.

Vagal Asystoles in a Boy With Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a genetic hormonal disorder of the hypothalamic-pituitary-axis resulting in mental retardation, muscle hypotonia, hypogonadism, and hyperphagia leading to significant obesity. Cardiovascular morbidity and mortality in adult patients with PWS is higher than in healthy controls and mainly secondary to massive obesity. In childhood, mortality may result from respiratory or gastrointestinal illnesses. We present a case of a 10-year-old boy with PWS who experienced recurrent and asymptomatic episodes of sinus pauses caused by the ingestion of large gulps of apple juice, which could be provoked and reproduced. The asystoles could not be provoked by any other vagal maneuvers and an initial diagnostic workup revealed no indication for structural heart disease. Because of the asymptomatic character of the asystoles, no treatment was initially provided. When he re-presented 3 months later after a clinically relevant syncope at school, pacemaker therapy was initiated, and he has demonstrated no subsequent sinus pauses or syncopes. Regarding the rising awareness of subtle cardiac alterations including autonomic dysfunction and electrocardiogram changes in young patients with PWS and especially the occurrence of unexplained sudden deaths in childhood that may be precipitated by arrhythmia, we suggest that the utility of periodic screening for arrhythmia risk should be evaluated in children with PWS.

Pediatric Sleep Respiratory Disorders: A Narrative Review of Epidemiology and Risk Factors

Sleep is a fundamental biological necessity, the lack of which has severe repercussions on the mental and physical well-being in individuals of all ages. The phrase "sleep-disordered breathing (SDB)" indicates a wide array of conditions characterized by snoring and/or respiratory distress due to increased upper airway resistance and pharyngeal collapsibility; these range from primary snoring to obstructive sleep apnea (OSA) and occur in all age groups. In the general pediatric population, the prevalence of OSA varies between 2% and 5%, but in some particular clinical conditions, it can be much higher. While adenotonsillar hypertrophy ("classic phenotype") is the main cause of OSA in preschool age (3-5 years), obesity ("adult phenotype") is the most common cause in adolescence. There is also a "congenital-structural" phenotype that is characterized by a high prevalence of OSA, appearing from the earliest ages of life, supported by morpho-structural abnormalities or craniofacial changes and associated with genetic syndromes such as Pierre Robin syndrome, Prader-Willi, achondroplasia, and Down syndrome. Neuromuscular disorders and lysosomal storage disorders are also frequently accompanied by a high prevalence of OSA in all life ages. Early recognition and proper treatment are crucial to avoid major neuro-cognitive, cardiovascular, and metabolic morbidities.

Acute stress response of the HPA-axis in children with Prader-Willi syndrome: new insights and consequences for clinical practice

Background

Prader-Willi syndrome (PWS) is associated with hypothalamic dysfunction. It has been reported that the HPA axis might show a delayed response during acute stress, and it is unknown whether the response of the HPA-axis during acute stress changes with age in children with PWS.

Aim

To investigate the HPA-axis response during an overnight single-dose metyrapone (MTP) test in children with PWS and to assess if the response changes with age, whether it is delayed and if it changes with repeated testing over time. In addition, we evaluated different cut-off points of ACTH and 11-DOC levels to assess stress-related central adrenal insufficiency (CAI).

Methods

An overnight single-dose MTP test was performed in 93 children with PWS. Over time, 30 children had a second test and 11 children a third one. Children were divided into age groups (0-2 years, 2-4 years, 4-8 years and > 8 years).

Results

Most children did not have their lowest cortisol level at 7.30h, but at 04.00h. Their ACTH and 11-DOC peaks appeared several hours later, suggesting a delayed response. When evaluated according to a subnormal ACTH peak (13-33 pmol/L) more children had an subnormal response compared to evaluation based on a subnormal 11-doc peak (< 200 nmol/L). The percentage of children with a subnormal ACTH response ranged from 22.2 to 70.0% between the age groups, while the percentage of a subnormal 11-DOC response ranged from 7.7 to 20.6%. When using the ACTH peak for diagnosing acute-stress-related CAI, differences between age groups and with repeated testing over time were found, whereas there was no age difference when using the 11-DOC peak.

Conclusion

Early morning ACTH or 11-DOC levels are not appropriate to determine acute stress-related CAI in children with PWS, thus multiple measurements throughout the night are needed for an accurate interpretation. Our data suggest a delayed response of the HPA-axis during acute stress. Using the 11-DOC peak for the test interpretation is less age-dependent than the ACTH peak. Repeated testing of the HPA-axis over time is not required, unless clinically indicated.

Preserved Sleep for the Same Level of Respiratory Disturbance in Children with Prader-Willi Syndrome

Debate remains as to how to balance the use of recombinant human growth hormone (rhGH) as an important treatment in Prader-Willi syndrome (PWS) with its potential role in obstructive sleep apnea. This single-center, retrospective study assessed differences in overnight polysomnography results between children with and without PWS and changes in respiratory parameters before and after the initiation of rhGH treatment in those with PWS. Compared with age-, sex-, and body-mass-index-matched controls (n = 87), children with PWS (n = 29) had longer total sleep time (434 ± 72 vs. 365 ± 116 min; p < 0.01), higher sleep efficiency (86 ± 7 vs. 78 ± 15%; p < 0.05), and lower arousal events (8.1 ± 4.5 vs. 13.0 ± 8.9 events/h; p < 0.05). Mean oxygen saturation was lower in PWS children (94.3 ± 6.0 vs. 96.0 ± 2.0%; p < 0.05), with no other differences in respiratory parameters between groups. Eleven children with PWS (38%) met the criteria for further analyses of the impact of rhGH; polysomnography parameters did not change with treatment. Compared with other children undergoing polysomnography, children with PWS had more favorable markers of sleep continuity and lower oxygen saturation for the same level of respiratory disturbance. rhGH administration was not associated with changes in respiratory parameters in PWS.

Diagnosis and management of sleep disorders in Prader-Willi syndrome

Clinical experience and a growing body of evidence suggest that sleep disturbances are common in people with Prader-Willi syndrome (PWS). PWS is a rare neuroendocrine disorder characterized by early hypotonia and feeding difficulties; developmental delays; endocrinopathies; and behavioral concerns, especially rigidity, anxiety, and behavioral outbursts. PWS is also characterized by decreased resting energy expenditure and transition to hyperphagia and obesity. We propose that, for many people with PWS, clinical diagnosis and management of sleep disorders is an unmet need. We present current information to suggest disordered sleep is a significant burden for individuals with PWS and often overlooked. While central and obstructive sleep apnea are more widely recognized in PWS, other sleep disorders have increasingly gained recognition, including hypersomnia, narcolepsy-like phenotypes, and insomnia. Sleep disorders can impact behavior, cognition, and quality of life and health for individuals with PWS. Our goal is to bring sleep disorders to the forefront of therapeutic intervention for patients with PWS. This paper presents a review of the literature and recommendations for clinical practice based on published research and our clinical experience as sleep specialists, geneticists, psychiatrists, pediatricians, otolaryngologists, and pulmonologists with extensive experience with this patient population. We recommend that management of sleep be considered an integral part of successful medical management of PWS. Further research concerning sleep problems in PWS is urgently needed to develop best practices and work toward a consensus statement for medical management to meet the needs of people with PWS.

CITATION

Duis J, Pullen LC, Picone M, et al. Diagnosis and management of sleep disorders in Prader-Willi syndrome. J Clin Sleep Med. 2022;18(6):1687-1696.

Approach to the Patient With Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a rare, multisystemic, genetic disorder involving the hypothalamus. It is caused by loss of expression of paternally inherited genes in chromosome 15 q11-13 region. The estimated incidence is around 1 in 20.000 births. PWS is characterized by a complex lifelong trajectory involving neurodevelopmental, nutritional, endocrine, metabolic, and behavioral changes. The major symptoms are hypotonia, short stature, hypogonadism, and eating disorders ranging from anorexia in infancy to hyperphagia, a deficit of satiety, and a high risk of severe obesity. The patients display intellectual disability comprising cognitive deficit, delayed motor and language development, learning deficits, impaired social skills, and emotional regulation. Behavioral features including temper outbursts, anxiety, obsessive-compulsive symptoms and rigidity are common and become more apparent with increasing age. Almost all have hypogonadism and growth hormone deficiency. Central adrenal insufficiency is rare whereas central hypothyroidism occurs in up to 30% of children with PWS. The prevalence of obesity increases with age from almost none in early childhood to more than 90% in adulthood. Up to 25% of adults with obesity have type 2 diabetes. Obesity and its complications are the major causes of comorbidity and mortality in PWS. As there is no specific treatment, care consists of comprehensive management of feeding disorders, a restricted, controlled diet, regular exercise, hormone substitution, and screening and treatment of comorbidities. Here we present the course of PWS from birth to adulthood in 2 patients and discuss their symptoms in relation to the literature.

Sleep Disorders in Adults with Prader–Willi Syndrome: Review of the Literature and Clinical Recommendations Based on the Experience of the French Reference Centre

Prader–Willi syndrome (PWS) is a rare, genetic, multisymptomatic, neurodevelopmental disease commonly associated with sleep alterations, including sleep-disordered breathing and central disorders of hypersomnolence. Excessive daytime sleepiness represents the main manifestation that should be addressed by eliciting the detrimental effects on quality of life and neurocognitive function from the patients’ caregivers. Patients with PWS have impaired ventilatory control and altered pulmonary mechanics caused by hypotonia, respiratory muscle weakness, scoliosis and obesity. Consequently, respiratory abnormalities are frequent and, in most cases, severe, particularly during sleep. Adults with PWS frequently suffer from sleep apnoea syndrome, sleep hypoxemia and sleep hypoventilation. When excessive daytime sleepiness persists after adequate control of sleep-disordered breathing, a sleep study on ventilatory treatment, followed by an objective measurement of excessive daytime sleepiness, is recommended. These tests frequently identify central disorders of hypersomnolence, including narcolepsy, central hypersomnia or a borderline hypersomnolent phenotype. The use of wake-enhancing drugs (modafinil, pitolisant) is discussed in multidisciplinary expert centres for these kinds of cases to ensure the right balance between the benefits on quality of life and the risk of psychological and cardiovascular side effects.

Sleep-disordered breathing in Australian children with Prader-Willi syndrome following initiation of growth hormone therapy

AIM

In children with Prader-Willi syndrome (PWS), growth hormone (GH) improves height and body composition; however, may be associated with worsening sleep-disordered breathing (SDB). Some studies have reported less SDB after GH initiation, but follow-up with polysomnography is still advised in most clinical guidelines.

METHODS

This retrospective, multicentre study, included children with PWS treated with GH at seven PWS treatment centres in Australia over the last 18 years. A paired analysis comparing polysomnographic measures of central and obstructive SDB in the same child, before and after GH initiation was performed with Wilcoxon signed-rank test. The proportion of children who developed moderate/severe obstructive sleep apnoea (OSA) was calculated with their binomial confidence intervals.

RESULTS

We included 112 patients with available paired data. The median age at start of GH was 1.9 years (range 0.1-13.5 years). Median obstructive apnoea hypopnoea index (AHI) at baseline was 0.43/h (range 0-32.9); 35% had an obstructive AHI above 1.0/h. Follow-up polysomnography within 2 years after the start of GH was available in 94 children who did not receive OSA treatment. After GH initiation, there was no change in central AHI. The median obstructive AHI did not increase significantly (P = 0.13), but 12 children (13%, CI_95% 7-21%) developed moderate/severe OSA, with clinical management implications.

CONCLUSIONS

Our findings of a worsening of OSA severity in 13% of children with PWS support current advice to perform polysomnography after GH initiation. Early identification of worsening OSA may prevent severe sequelae in a subgroup of children.

Adrenal insufficiency in patients with Prader-Willi syndrome

The generalized dysfunction of the hypothalamic-pituitary axis in patients with Prader-Willi syndrome (PWS) is the most likely cause of hypogonadism, inadequate growth hormone secretion, excessive appetite and associated obesity, impaired body temperature regulation, and hypothyroidism. The syndrome is also related to an increased risk of central adrenal insufficiency, although its prevalence remains unknown. The results of the studies in which different methods of pharmacological stimulation were used do not provide conclusive outcomes. As a result, there are no clear guidelines with regard to diagnosis, prevention, or long-term care when adrenal insufficiency is suspected in patients with PWS. Currently, most patients with PWS are treated with recombinant human growth hormone (rhGH). It has been confirmed that rhGH therapy has a positive effect on growth, body composition, body mass index (BMI), and potentially on psychomotor development in children with PWS. Additionally, rhGH may reduce the conversion of cortisone to cortisol through inhibition of 11β-hydroxysteroid dehydrogenase type 1. However, its influence on basal adrenal function and adrenal stress response remains unexplained in children with PWS. This paper reviews the literature related to the hypothalamic-pituitary-adrenal axis dysfunction in the PWS patient population with a focus on children.

Sleep Disorders in Children with Prader Willi Syndrome: Current Perspectives

Children with Prader-Willi syndrome (PWS) face a multitude of potential health challenges including life-threatening obesity, endocrinopathies, behavioral and emotional dysregulation, developmental delays, and sleep disorders. In the current perspective piece, we provide a focused review of the condition's etiology and clinical findings, as well as a more in-depth discussion of sleep disorders frequently associated with PWS. In particular, we highlight and discuss difficult clinical scenarios frequently encountered by the pediatric sleep physician caring for this patient population, including diagnosis and treatment of complex sleep-related breathing disorders, considerations for sleep apnea surgery, the interplay between growth hormone and sleep apnea, diagnostic challenges in hypersomnia/narcolepsy, and current and emerging therapies for hypersomnia/narcolepsy. Overall, although there are many areas that need further research, sleep disorders remain a fruitful target for improving quality of life of children with PWS and their families.

Health Problems in Individuals With PWS Are Associated With Lower Quality of Life for Their Parents: A Snapshot in the Brazilian Population

Prader-Willi syndrome (PWS) is a complex genetic disorder requiring interdisciplinary team monitoring and intensive care by parents. So far there is little information on people with PWS in Brazil. Our aim was to describe health problems and treatments used by people with PWS in Brazil and their relationship to their parents' quality of life. Parents answered questionnaires about their child's medical and exercise history, behavior problems, sociodemographic characteristics, and their own quality of life. Results: The responses of the participants showed similar health problems as in other countries. Anxiety and tantrums were the behavioral problems most commonly cited by parents. Parents of people with PWS had lower scores in respect of quality of life than the Brazilian population. Behavioral problems in individuals with PWS were negatively associated with their parents' quality of life. Behavioral and medical conditions in the children were associated with reduced quality of life in the parents. We conclude that heath care should not only be directed toward those with PWS, but also their parents.

Sleep-disordered breathing in school-aged children with Prader-Willi Syndrome

STUDY OBJECTIVES

Studies of sleep-disordered breathing (SDB) in children with Prader-Willi syndrome (PWS) have focused on early childhood and growth hormone (GH)-naïve children, but little is known about older children, including those on long term GH therapy. This study aimed to describe the nature and prevalence of SDB in school-aged children with PWS in the growth hormone era.

METHODS

This retrospective single-center chart review included children aged 6-18 years with PWS who had overnight polysomnography not involving respiratory support over five years (2012-2017). The main outcome measures were the presence of obstructive sleep apnea, central sleep apnea or hypoventilation defined by an elevated PCO₂ as per standard pediatric criteria.

RESULTS

Seventeen children (8 male, median age 11.6y, range 6.6-16.1y) were included. Fifteen demonstrated SDB of different types: central sleep apnea (18%), obstructive sleep apnea (24%), both obstructive and central sleep apnea (29%), or hypoventilation without obstructive or central sleep apnea (18%). Twelve (71%) children had evidence of hypoventilation. Those with hypoventilation had a higher central apnea-hypopnea index (AHI) but no difference in the obstructive AHI, age, sex, growth parameters, or the presence of scoliosis or sleep-related symptoms compared to those without hypoventilation.

CONCLUSIONS

Sleep-related hypoventilation is common in school-aged children with PWS. The presence of central sleep apnea, including the quantification of central hypopneas, but not obstructive sleep apnea or clinical factors predicted the presence of hypoventilation. Long-term polysomnography surveillance in children with PWS should include identification of central hypopneas and measurement of continuous pCO₂.

The consequences of hyperphagia in people with Prader-Willi Syndrome: A systematic review of studies of morbidity and mortality

Prader-Willi Syndrome (PWS) is a multi-system genetically determined neurodevelopmental disorder and the commonest cause of syndromal obesity. The development of hyperphagia in early childhood is part of the phenotype arising as a result of an impaired neural response to food intake and the inability to regulate food intake in line with energy needs. Severe obesity develops if access to food is not controlled. In this review we evaluate the evidence for increased morbidity and mortality in PWS in order to establish the extent to which it is directly related to the obesity; a consequence of the eating behaviour itself independent of obesity; or associated with other characteristics of the syndrome. Medline, Cochrane, PsychINFO, CINAHL, Web of Science and Scopus databases were used to systematically identify published material on PWS and hyperphagia and syndrome-related morbidity and mortality. One hundred and ten key papers were selected. Data on 500 people with PWS indicated that the average age of death was 21 years and obesity was, as expected, a significant factor. However, the behaviour of hyperphagia itself, independent of obesity, was also important, associated with choking, gastric rupture, and/or respiratory illness. Other syndrome-related factors increased the risk for, and seriousness of, co-morbid illness or accidents. We conclude that improving life-expectancy largely depends on managing the immediate non-obesity and obesity-related consequences of the hyperphagia, through improved support. The development of new treatments that significantly reduce the drive to eat are likely to decrease morbidity and mortality improving quality of life and life expectancy.

Sleep disordered breathing in patients with Prader willi syndrome: Impact of underlying genetic mechanism

INTRODUCTION

Sleep-disordered breathing (SDB) is common in children with PWS. In the current study, we aimed to evaluate the severity of SDB in patients with PWS using polysomnography (PSG), and assess the effect of the underlying genetic mechanism on PSG parameters.

METHODS

Children with PWS, referred to our sleep laboratory between March 2016 and January 2020 were enrolled. PSG parameters, demographic data, body mass index (BMI), and symptoms related to SDB were recorded. The effect of non-invasive ventilation strategies and the outcome of therapy on PSG parameters were evaluated.

RESULTS

In our study, 64.5% of the patients had severe sleep apnea syndrome (total apnea hypopnea index (AHI) ≥10 events/hour). 22.6% had significantly high (>5 events/hour) central sleep apnea. Patients with a deletion had significantly lower initial and mean SaO₂, longer sleep time SaO₂ under 90%, oxygen desaturation % and total AHI when compared to those with uniparental disomy. PSG parameters were similar between patients who did or didn't receive growth hormone treatment.

CONCLUSION

The majority of the PWS patients had severe sleep apnea syndrome characterized mainly by hypopneas which were accompanied by central apneas. There was a more severe impact on oxygen parameters and total AHI in patients with deletions.

Effects of Growth Hormone Treatment on Sleep-Related Parameters in Adults With Prader-Willi Syndrome

CONTEXT

Prader-Willi syndrome (PWS) is a rare, genetic, multisymptom, neurodevelopmental disease due to lack of the expression of the paternal genes in the q11 to q13 region of chromosome 15. The main characteristics of PWS are muscular hypotonia, hyperphagia, obesity, behavioral problems, cognitive disabilities, and endocrine deficiencies, including growth hormone (GH) deficiency. Sleep apnea and abnormal sleep patterns are common in PWS. GH treatment might theoretically have a negative impact on respiration.

OBJECTIVE

Here we present the effect of GH treatment on polysomnographic measurements.

METHODS

Thirty-seven adults, 15 men and 22 women, with confirmed PWS were randomly assigned to 1 year of GH treatment (n = 19) or placebo (n = 18) followed by 2 years of GH treatment to all. Polysomnographic measurements were performed every 6 months. A mixed-effect regression model was used for comparison over time in the subgroup that received GH for 3 years.

RESULTS

At baseline median age was 29.5 years, body mass index 27.1, insulin-like growth factor 115 µg/L, apnea-hypopnea index (AHI) 1.4 (range, 0.0-13.9), and sleep efficiency (SE) 89.0% (range, 41.0%-99.0%). No differences in sleep or respiratory parameters were seen between GH- and placebo-treated patients. SE continuously improved throughout the study, also after adjustment for BMI, and the length of the longest apnea increased. AHI inconsistently increased within normal range.

CONCLUSION

SE improved during GH treatment and no clinical, significantly negative impact on respiration was seen. The etiology of breathing disorders is multifactorial and awareness of them should always be present in adults with PWS with or without GH treatment.

Prader-Willi syndrome: Hormone therapies

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder linked to the lack of expression of specific maternally imprinted genes located in the chromosomal region 15q11-q13. Impaired hypothalamic development and function explain most of the phenotype that is characterized by a specific trajectory from anorexia at birth to excessive weight gain at later ages, which is accompanied by hyperphagia and early severe obesity, as well as by other hormonal deficiencies, behavioral deficits, and dysautonomia. In almost all patients, their endocrine dysfunction involves growth hormone deficiency and hypogonadism, which originate from a combination of both peripheral and hypothalamic origin, central hypothyroidism in 40%, precocious adrenarche in 30% of the cases, and in rare cases, also adrenocorticotropin deficiency and precocious puberty. In addition, the oxytocin (OXT) and ghrelin systems are impaired in most patients and involved in a poor suckling response at birth, and hyperphagia with food addiction, poor social skills, and emotional dysregulation. Current hormonal replacement treatments are the same as used in classical hormonal deficiencies, and recombinant human GH treatment is registered since 2000 and has dramatically changed the phenotype of these children. OXT and OXT analogue treatments are currently investigated as well as new molecules targeting the ghrelin system. The severe condition of PWS can be seen as a model to improve the fine description and treatments of hypothalamic dysfunction.

Sleep-Disordered Breathing in Children with Prader-Willi Syndrome in Relation to Growth Hormone Therapy Onset

OBJECTIVE

The aim of this study was to consider sleep apnea in Prader-Willi syndrome (PWS) children depending on age at growth hormone (GH) therapy onset.

STUDY DESIGN

We analyzed longitudinally cardiorespiratory polygraphy of 62 PWS children (aged 0-2.5 years at baseline). Twenty-one children (Group A) started GH-therapy during and 41 children (Group B) after their first year of life. Data were acquired before, at 3 and 6 months, then 1.2, 2.2, and 3.2 years after GH onset. Outcomes were determined with the obstructive apnea hypopnea index (OAHI), central apnea index (CAI), oxygen desaturation index (ODI), and by measuring obstructive sleep apnea (OSA) and peripheral blood oxygen saturation (SpO2).

RESULTS

We observed no significant differences in OAHI, CAI, ODI, and SpO2 depending on treatment onset. At baseline, 5/21 patients (23.8%) in Group A versus 15/41 patients (36.6%) in Group B showed pathological sleep apnea (OAHI ≥1.5). Pathological OSA increased significantly in Group A during the first 3 months of therapy but dropped below baseline after 1 year in both groups. ODI changed during GH therapy in both groups (from 4.0 to 2.6 in Group A, and 3.6 to 1.6 in Group B; baseline to 3.2 years; p < 0.05).

CONCLUSIONS

OSA in PWS children appears to develop independently of treatment onset. Treatment may therefore safely be initiated early but should be accompanied by regular sleep analysis.

Sleep disorders in Prader-Willi syndrome, evidence from animal models and humans

Prader-Willi Syndrome (PWS) is a complex genetic disorder with multiple cognitive, behavioral and endocrine dysfunctions. Sleep alterations and sleep disorders such as Sleep-disordered breathing and Central disorders of hypersomnolence are frequently recognized (either isolated or in comorbidity). The aim of the review is to highlight the pathophysiology and the clinical features of sleep disorders in PWS, providing the basis for early diagnosis and management. We reviewed the genetic features of the syndrome and the possible relationship with sleep alterations in animal models, and we described sleep phenotypes, diagnostic tools and therapeutic approaches in humans. Moreover, we performed a meta-analysis of cerebrospinal fluid orexin levels in patients with PWS; significantly lower levels of orexin were detected in PWS with respect to control subjects (although significantly higher than the ones of narcoleptic patients). Sleep disorders in humans with PWS are multifaceted and are often the result of different mechanisms. Since hypothalamic dysfunction seems to partially influence metabolic, respiratory and sleep/wake characteristics of this syndrome, additional studies are required in this framework.

Neurodevelopmental Disorders Commonly Presenting with Sleep Disturbances

There are multiple disorders of neurodevelopment that present with co-occurring sleep disturbances. Many of these neurodevelopmental disorders (NDD) include sleep disturbances in their diagnostic criteria. Neurobiological, genetic, and environmental factors overlap to cause different sleep disorders in individuals with NDD. Caregivers often present reporting either insomnia or hypersomnia, and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. It is crucial that clinicians understand the different presentations of sleep disturbances in individuals with NDD.

Polysomnographic characteristics and sleep-disordered breathing in Schaaf-Yang syndrome

INTRODUCTION

Schaaf-Yang syndrome (SYS) is a genetic disorder caused by truncating variants in the MAGEL2 gene located in the maternally imprinted Prader-Willi syndrome (PWS) region at 15q11-13. The SYS phenotype shares features with PWS, a syndrome with known high incidence of sleep disorders. However, the spectrum of sleep-disorders in SYS has not been described.

METHODS

We performed a retrospective analysis of polysomnograms from 22 patients in an international SYS cohort. Sleep characteristics for individuals with the common c.1996dupC variant (n = 10) were compared to other truncating variants (n = 11).

RESULTS

We collected 33 sleep study reports from 22 patients, ages 2 months - 18.5 years (mean 6.5 years). Mean sleep efficiency was 70.5% (range 45%-93%) with arousal index 14.1/h (1.2-45/h). The mean apnea-hypopnea index (AHI) was 19.1/h (0.9-49/h) with mean obstructive AHI (oAHI) of 16.3/h (0.6-49/h). Mean central apnea index was 2.8/h (0-14/h). Mean oxygen desaturation index was 20.8/h (range 0-85/hr). Obstructive sleep apnea (OSA) was diagnosed in 81%, and 62% had moderate or severe OSA. Elevated central apnea index occurred in 9.5%. Comparison by genotype groups and age did not reveal any difference in OSA findings. Periodic limb movement index (PLMI) was elevated in 4/15 (26%).

CONCLUSION

OSA is frequently identified on polysomnography in patients with SYS. The mean PLMI is elevated compared to normative data. Patients with SYS should have routine polysomnography screening due to high risk of sleep disorders.

Sleep-disordered breathing and genetic findings in children with Prader-Willi syndrome in China

Background

Sleep-related breathing disorders are common in individuals with Prader-Willi syndrome (PWS), and can include hypersomnolence and obstructive sleep apnea, as well as central sleep breathing abnormalities that are present from infancy. Here we describe the sleep-disordered breathing (SDB) and genetic findings in patients with PWS in China.

Methods

In all, 48 patients confirmed by genetic tests were enrolled, 32 were under 2 years of age and 16 were older children. There were 37 (77.1%) patients with paternal 15q11-13 deletions, 11 (22.9%) patients with maternal uniparental disomy (mUPD), and no patients with imprinting defect (ID).

Results

Compared with infants, a significantly higher proportion of older children with PWS were overweight or obese (15/16 children vs. 4/32 infants) and children had a higher serum level of free thyroxine (FT4) (0.9±0.2 vs. 0.7±0.7) and thyroxine (T4) (9.0±2.5 vs. 7.5±1.7). Age was correlated significantly with body mass index (BMI), T4, and FT4 (r=0.626, P=0.000; r=0.426, respectively). Overall, 42 of 48 (87.5%) patients had sleep apnea on polysomnography (PSG). Infants, when compared with older children, were more likely to experience central sleep apnea (71.8% vs. 25%). In infants, there were no significant differences in the prevalence of SDB between the deletion group and the mUPD group.

Conclusions

Being overweight or obese was more common in older children with PWS. Compared with infants, a higher proportion children were overweight or obese and had higher serum levels of FT4 and T4. The prevalence of SDB was high in those with PWS, and central sleep apnea was found to be prevalent in infants. The pattern of SDB in infants with PWS was not significantly associated with the genotypes.

Prader-Willi syndrome: reflections on seminal studies and future therapies

Prader-Willi syndrome (PWS) is caused by the loss of function of the paternally inherited 15q11-q13 locus. This region is governed by genomic imprinting, a phenomenon in which genes are expressed exclusively from one parental allele. The genomic imprinting of the 15q11-q13 locus is established in the germline and is largely controlled by a bipartite imprinting centre. One part, termed the Prader-Willi syndrome imprinting center (PWS-IC), comprises a CpG island that is unmethylated on the paternal allele and methylated on the maternal allele. The second part, termed the Angelman syndrome imprinting centre, is required to silence the PWS_IC in the maternal germline. The loss of the paternal contribution of the imprinted 15q11-q13 locus most frequently occurs owing to a large deletion of the entire imprinted region but can also occur through maternal uniparental disomy or an imprinting defect. While PWS is considered a contiguous gene syndrome based on large-deletion and uniparental disomy patients, the lack of expression of only non-coding RNA transcripts from the SNURF-SNRPN/SNHG14 may be the primary cause of PWS. Patients with small atypical deletions of the paternal SNORD116 cluster alone appear to have most of the PWS related clinical phenotypes. The loss of the maternal contribution of the 15q11-q13 locus causes a separate and distinct condition called Angelman syndrome. Importantly, while much has been learned about the regulation and expression of genes and transcripts deriving from the 15q11-q13 locus, there remains much to be learned about how these genes and transcripts contribute at the molecular level to the clinical traits and developmental aspects of PWS that have been observed.

Bariatric Surgery for Monogenic Non-syndromic and Syndromic Obesity Disorders

PURPOSE OF REVIEW

The global prevalence of obesity has increased rapidly over the last decades, posing a severe threat to human health. Currently, bariatric surgery is the most effective therapy for patients with morbid obesity. It is unknown whether this treatment is also suitable for patients with obesity due to a confirmed genetic defect (genetic obesity disorders). Therefore, this review aims to elucidate the role of bariatric surgery in the treatment of genetic obesity.

RECENT FINDINGS

In monogenic non-syndromic obesity, an underlying genetic defect seems to be the most important factor determining the efficacy of bariatric surgery. In syndromic obesity, bariatric surgery result data are scarce, and even though some promising follow-up results have been reported, caution is required as patients with more severe behavioral and developmental disorders might have poorer outcomes. There is limited evidence in support of bariatric surgery as a treatment option for genetic obesity disorders; hence, no strong statements can be made regarding the efficacy and safety of these procedures for these patients. However, considering that patients with genetic obesity often present with life-threatening obesity-related comorbidities, we believe that bariatric surgery could be considered a last-resort treatment option in selected patients.

Bariatric surgery for Prader-Willi syndrome was ineffective in producing sustainable weight loss: Long term results for up to 10 years

BACKGROUND

Obesity control in Prader-Willi syndrome (PWS) is notoriously difficult. The role of bariatric surgery in PWS remains controversial as long-term data are lacking.

OBJECTIVES

To evaluate the 10-year outcomes of bariatric surgery in PWS.

METHODS

This was a prospective observational study on PWS patients who received bariatric surgery and multidisciplinary follow-up programmes for obesity control. Outcomes on weight reduction and comorbidity resolution were evaluated.

RESULTS

Between 2008 and 2013, five PWS patients (two males, mean age 19.2 ± 3.0 years) with body mass index of 47.3 ± 6.9 kg m^-2 received sleeve gastrectomy (n = 2), one anastomosis gastric bypass (n = 2), and Roux-en-Y gastric bypass (n = 1) after failing all non-operative weight loss programmes. The median follow-up was 8.4 ± 2.2 years. The best mean percentage of total weight loss (%TWL) was achieved at 2 years (24.7%). %TWL dropped to 23.3% at 3 years, 11.9% at 5 years, 4.1% at 8 years, and 0% at 10 years. Each patient had at least three comorbidities preoperatively, but none of them had resolution of any one of the comorbidities at the last follow-up.

CONCLUSIONS

Bariatric surgery could not produce sustainable long-term weight loss or comorbidity resolution in PWS. This study suggests that bariatric surgery cannot be recommended to PWS patients as a standard treatment.

Causes of death in Prader-Willi syndrome: lessons from 11 years' experience of a national reference center

Background

In the last 20 years, substantial improvements have been made in the diagnosis, treatment and management of patients with Prader-Willi syndrome (PWS). Few data on causes of death are available since those improvements were made. Our study assessed the causes of death among French patients with PWS over the first 11 years of experience of the nationwide French Reference Center for PWS (FRC-PWS).

Methods

Our study relied on two sources of mortality information at national level between 2004 and 2014: The French Epidemiological Centre for the Medical Causes of Death (CépiDc) Registry and the FRC-PWS database. Causes of death were classified into seven categories: respiratory, cardiovascular, gastrointestinal, severe infection, sudden death, other causes, and unknown. Descriptive statistics were calculated separately for children (< 18 years-old) and adults (≥18 years-old).

Results

One hundred and four deaths were identified in France from 2004 to 2014. The median age at death was 30 years, ranging from less than 1 month to 58 years. Seventeen deaths occurred in patients under 18 years, with 70% of them in children under 2 years. Respiratory causes accounted for more than 50% of the deaths in patients with PWS in both children and adults. Both cause and age of death did not significantly differ according to gender or genetic subtype.

Conclusions

Patients with PWS die prematurely due to a respiratory cause in most cases at all ages. In those adult patients with data on obesity, 98% were reported to be obese.

Prader-Willi syndrome: A model for understanding the ghrelin system

Subsequent to the discovery of ghrelin as the endogenous ligand of growth hormone secretagogue receptor 1a, this unique gut peptide has been found to exert numerous physiological effects, such as appetite stimulation and lipid accumulation via the central regulating mechanisms in the hypothalamus, stimulation of gastric motility, regulation of glucose metabolism and brown fat thermogenesis, and modulation of stress, anxiety, taste sensation, reward-seeking behaviour and the sleep/wake cycle. Prader-Willi syndrome (PWS) has been described as a unique pathological state characterised by severe obesity and high circulating levels of ghrelin. It was hypothesised that hyperghrelinaemia would explain at least a part of the feeding behaviour and body composition of PWS patients, who are characterised by hyperphagia, an obsession with food and food-seeking, and increased adiposity. Initially, the link between hyperghrelinaemia and growth hormone deficiency, which is observed in 90% of the children with PWS, was not fully understood. Over the years, however, the increasing knowledge on ghrelin, PWS features and the natural history of the disease has led to a more comprehensive description of the abnormal ghrelin system and its role in the pathophysiology of this rare and complex neurodevelopmental genetic disease. In the present study, we (a) present the current view of PWS; (b) explain its natural history, including recent data on the ghrelin system in PWS patients; and (c) discuss the therapeutic approach of modulating the ghrelin system in these patients and the first promising results.

Hypoventilation disproportionate to OSAS severity in children with Prader-Willi syndrome

OBJECTIVE

To test the hypothesis that children with Prader-Willi syndrome (PWS) and obstructive sleep apnoea syndrome (OSAS) have hypercapnia for higher proportion of total sleep time (TST) than non-syndromic children with similar obstructive apnoea-hypopnoea index (OAHI).

DESIGN

Cross-sectional study.

SETTING

Two tertiary care hospitals.

PATIENTS

Patients with PWS and non-syndromic children with snoring who underwent polygraphy and were of similar age, body mass index (BMI) z-score and OAHI.

MAIN OUTCOME MEASURE

The two groups were compared regarding %TST with transcutaneous CO₂ (PtcCO₂) >50 mm Hg. The interaction between PWS diagnosis and OSAS severity (OAHI <1 episode/h vs 1-5 episodes/h vs >5 episodes/h) regarding %TST with PtcCO₂ >50 mm Hg was tested using multiple linear regression.

RESULTS

48 children with PWS and 92 controls were included (median age 2.3 (range 0.2-14.1) years vs 2.2 (0.3-15.1) years; BMI z-score 0.7±1.9 vs 0.8±1.7; median OAHI 0.5 (0-29.5) episodes/h vs 0.5 (0-33.9) episodes/h; p>0.05). The two groups did not differ in %TST with PtcCO₂ >50 mm Hg (median 0% (0-100%) vs 0% (0-81.3%), respectively; p>0.05). However, the interaction between PWS and OSAS severity with respect to duration of hypoventilation was significant (p<0.01); the estimated mean differences of %TST with PtcCO₂ >50 mm Hg between children with PWS and controls for OAHI <1 episode/h, 1-5 episodes/h and >5 episodes/h were +0.2%, +1% and +33%, respectively.

CONCLUSION

Increasing severity of upper airway obstruction during sleep in children with PWS is accompanied by disproportionately longer periods of hypoventilation when compared with non-syndromic children with similar frequency of obstructive events.

A multidisciplinary approach to the clinical management of Prader-Willi syndrome

Background

Prader–Willi syndrome (PWS) is a complex neuroendocrine disorder affecting approximately 1/15,000–1/30,000 people. Unmet medical needs of individuals with PWS make it a rare disease that models the importance of multidisciplinary approaches to care with collaboration between academic centers, medical homes, industry, and parent organizations. Multidisciplinary clinics support comprehensive, patient‐centered care for individuals with complex genetic disorders and their families. Value comes from improved communication and focuses on quality family‐centered care.

Methods

Interviews with medical professionals, scientists, managed care experts, parents, and individuals with PWS were conducted from July 1 to December 1, 2016. Review of the literature was used to provide support.

Results

Data are presented based on consensus from these interviews by specialty focusing on unique aspects of care, research, and management. We have also defined the Center of Excellence beyond the multidisciplinary clinic.

Conclusion

Establishment of clinics motivates collaboration to provide evidence‐based new standards of care, increases the knowledge base including through randomized controlled trials, and offers an additional resource for the community. They have a role in global telemedicine, including to rural areas with few resources, and create opportunities for clinical work to inform basic and translational research. As a care team, we are currently charged with understanding the molecular basis of PWS beyond the known genetic cause; developing appropriate clinical outcome measures and biomarkers; bringing new therapies to change the natural history of disease; improving daily patient struggles, access to care, and caregiver burden; and decreasing healthcare load. Based on experience to date with a PWS multidisciplinary clinic, we propose a design for this approach and emphasize the development of “Centers of Excellence.” We highlight the dearth of evidence for management approaches creating huge gaps in care practices as a means to illustrate the importance of the collaborative environment and translational approaches.

Pediatric endocrinology through syndromes

In everyday practice, a pediatric endocrinologist will face a variety of different endocrine issues (such as short or tall stature, dysthyroidism, abnormal pubertal timing or impaired glucose metabolism), which relevantly contribute to the global care of a number of syndromic conditions. On the other hand, the presence of endocrine features may assist in the diagnostic process, leading to final diagnosis of a syndromic disorder. The intention of this review is to provide a referenced overview of different genetic syndromes characterized by endocrine features, and to present a possible classification, based on whether the endocrinopathy or the syndrome is typically recognized first. Thus, the first part of the manuscript deals with the most common syndromes associated with endocrine dysfunctions, while the second part describes the conditions by which a syndrome is most frequently diagnosed after an endocrine finding. The aim is to provide a practical overview of the assessment of syndromic patients, so that they can be recognized and managed in an integrated, multidisciplinary fashion.

Contributing factors of mortality in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a multi-system disorder resulting from a lack of paternal gene expression in the 15q11.2-q13 region. Using databases compiled through response questionnaires completed by families known to the Prader-Willi Syndrome Association (USA), this study tested the hypothesis that PWS genetic subtype, BMI, age of diagnosis, clinical symptoms, and growth hormone treatment differ among deceased and living individuals with PWS. Categorical and continuous variables were compared using chi-square and two-group t tests, respectively. Deceased individuals had higher rates of clinical features, including increased weight concerns, heart problems, sleep apnea, other respiratory complications, diabetes, osteoporosis, high pain tolerance, and severe skin picking, when compared to living individuals. Meanwhile, living individuals had higher rates of growth hormone use and early puberty. Obesity and subsequent consequences are the primary contributors to increased mortality in PWS. Additional emphasis on areas to decrease mortality is needed.

Obstructive events in children with Prader-Willi syndrome occur predominantly during rapid eye movement sleep

OBJECTIVE

Children with Prader-Willi syndrome (PWS) have a high prevalence of obstructive sleep apnea syndrome (OSAS). In most typically developing children with OSAS, more obstructive apneas and hypopneas occur during rapid eye movement (REM) than during non-REM (NREM) sleep. It was hypothesized that patients with PWS are even more prone to obstructive events in REM sleep than otherwise healthy subjects with OSAS.

METHODS

Polysomnographic data of patients with PWS and of typically developing children (controls) with OSAS (apnea-hypopnea index [AHI] > 1 episode/h) were analyzed. The two groups were compared regarding obstructive AHI (OAHI), OAHI during NREM sleep (OAHInrem), OAHI during REM sleep (OAHIrem), and the OAHIrem/OAHI ratio (outcome measures). The association between PWS diagnosis and OAHIrem/OAHI was adjusted for confounders using a general linear model.

RESULTS

Twelve children with PWS (median age 7.1 years [interquartile range 3.5, 12.4 years]) and 53 controls (6.5 years [3.9, 8.7 years]) were studied. Children with PWS and controls were similar regarding OAHI (p = 0.21) and OAHInrem (p = 0.76). However, subjects with PWS had higher OAHIrem (17.6 episodes/h [5.8, 25.8 episodes/h]) and OAHIrem/OAHI (2.3 [1.5, 3.2]) than controls (5 episodes/h [1.5, 8.1 episodes/h]; p = 0.002 and 1 [0.5, 2]; p = 0.003, respectively). The association between PWS diagnosis and higher OAHIrem/OAHI persisted after adjustment for age, gender, and obesity (p = 0.009).

CONCLUSION

In children with PWS, OAHI calculated for total sleep time does not reflect OSAS severity during REM sleep, which on average can be twice as high. Mild OSAS in patients with PWS demonstrated by polygraphy without sleep staging may correspond to a moderately-to-severely increased OAHIrem.

EFFECT OF GROWTH HORMONE THERAPY IN CHILDREN WITH PRADER-WILLI SYNDROME - OUR FIRST EXPERIENCES

- Prader-Willi syndrome (PWS) is the most common cause of morbid obesity in childhood. It is the consequence of the lack of expression of genes on the paternally inherited 15q11.2-q13 region. Hyperphagia, obesity, short stature, psychomotor retardation and deterioration of behavior predominate in clinical presentation. Recombinant human growth hormone (rhGH) therapy, along with restriction of caloric intake, has become the mainstay in the management of PWS patients. Anthropometric parameters (height, body mass index (BMI)), therapy effect on carbohydrate and lipid metabolism, and occurrence of side effects were monitored in four children with PWS treated with rhGH for ≥2 years at doses of up to 1 mg/m2/day. During the follow-up, the height standard deviation score (SDS) increased in comparison with baseline values, and after ≥2 years of treatment with rhGH it was within the reference range for the general children population. BMI SDS decreased after the first year of treatment, but thereafter increased again; still, the level of BMI SDS was much better in comparison with most children with PWS of the same age and gender. RhGH therapy had no negative effect on glucose and lipid metabolism, nor caused any other adverse effect. Therapy including a customized diet for PWS, along with rhGH therapy, provided a satisfactory growth rate and prevented development of morbid obesity without side effects. This treatment approach would ensure transition of a greater number of PWS patients into adult care, where the multidisciplinary approach in care should be continued.

No central adrenal insufficiency found in patients with Prader-Willi syndrome with an overnight metyrapone test

Background Individuals with Prader-Willi syndrome (PWS) have hypothalamic dysfunction and may have central adrenal insufficiency (CAI). The prevalence of CAI in PWS remains unknown. Methods Twenty-one subjects with PWS aged 4-53 years underwent a low dose adrenocorticotropic hormone (ACTH) stimulation test (LDAST) (1 μg/m2, maximum 1 μg) followed by an overnight metyrapone test (OMT). Metyrapone (30 mg/kg, maximum 3 g) was administered at 2400 h. Cortisol, 11-deoxycortisol (11-DOC) and ACTH levels were collected the following morning at 0800 h. OMT was the standard test for comparison. Peak cortisol ≥15.5 μg/dL (427.6 nmol/L) on LDAST and 0800 h 11-DOC ≥7 μg/dL (200 nmol/L) on OMT were classified as adrenal sufficiency. Results Twenty subjects had 0800 h 11-DOC values ≥7 μg/dL on OMT indicating adrenal sufficiency. One subject had an inconclusive OMT result. Six of the 21 (29%) subjects had peak cortisol <15.5 μg/dL on LDAST. Conclusions We found no evidence of CAI based on OMT, yet 29% of our PWS population failed the LDAST. This suggests that the LDAST may have a high false positive rate in diagnosing CAI in individuals with PWS. OMT may be the preferred method of assessment for CAI in patients with PWS.

Delayed peak response of cortisol to insulin tolerance test in patients with Prader-Willi syndrome

Deaths among children with Prader-Willi syndrome (PWS) are often related to only mild or moderate upper respiratory tract infections, and many causes of death remain unexplained. Several reports have hypothesized that patients with PWS may experience latent central adrenal insufficiency. However, whether PWS subjects suffer from alteration of the hypothalamus-pituitary-adrenal (HPA) axis remains unclear. This study aimed to explore the HPA axis on PWS. We evaluated the HPA axis in 36 PWS patients (24 males, 12 females; age range, 7 months to 12 years; median age 2.0 years; interquartile range [IQR], 1.5-3.4 years) using an insulin tolerance test (ITT) in the morning between 08:00 and 11:00. For comparison, ITT results in 37 age-matched healthy children evaluated for short stature were used as controls. In PWS patients, basal levels of adrenocorticotropic hormone (ACTH) were 13.5 pg/ml (IQR, 8.3-27.5 pg/ml) and basal levels of cortisol were 18.0 μg/dl (IQR, 14.2-23.7 μg/dl). For all patients, cortisol levels at 60 min after stimulation were within the reference range (>18.1 μg/dl), with a median peak of 41.5 μg/dl (IQR, 32.3-48.6 μg/dl). Among control children, basal level of ACTH and basal and peak levels of cortisol were 10.9 (IQR, 8.5-22.0 pg/ml), 15.6 (IQR, 11.9-21.6 μg/dl), and 27.8 μg/dl (IQR, 23.7-30.5 μg/dl), respectively. Basal and peak levels of cortisol were all within normal ranges, but peak response of cortisol to ITT was delayed in the majority of PWS patients (64%). Although the mechanism remains unclear, this delay may signify the existence of central obstacle in adjustment of the HPA axis.

Treatment with growth hormone in the prader-willi syndrome

INTRODUCTION

The Prader-Willi syndrome (PWS) is a rare genetic disorder caused by absence of expression of the paternal alleles in región 15q11.2-q13. Obesity and hormonal deficiencies, especially of growth hormone (GH), are the most important signs from the therapeutic viewpoint. Recombinant GH (rGH) is effective in children and represents the mainstay in treatment; by contrast, little evidence in available in adult patients.

OBJECTIVE

To review the reported evidence on the beneficial and adverse effects of treatment with rGH in children and adults.

DESIGN

A review was made of 62 original articles published between 2000 and 2017 using the PubMed database.

RESULTS

In pediatric and adult PWS, rGH improves body morphology and composition, physical performance, cognition, psychomotor development, respiratory function, and quality of life with few adverse effects.

CONCLUSIONS

Treatment with rGH is effective and safe and improves quality of life in both children and adults with PWS.

Silent aspiration in infants with Prader-Willi syndrome identified by videofluoroscopic swallow study

Feeding intolerance in Prader-Willi syndrome (PWS) infants is well-recognized, but their swallow physiology is not well understood. Swallow dysfunction increases risks of respiratory compromise and choking, which have a high incidence in PWS. To investigate swallow pathology in PWS infants we undertook a retrospective review of videofluoroscopic swallow studies (VFSS) in infants with PWS seen at our institution. We hypothesize that VFSS will characterize swallow pathology suspected by clinical observation during a feeding evaluation and may help determine feeding safety in these infants.Retrospective review of 23 VFSS on 10 PWS infants (average age 9.7 ± 8.4 months; range 3 weeks-29 months). Logistic regression models evaluated associations between gender, genetic subtype, and growth hormone (GH) use on aspiration incidence. Polysomnographic (PSG) studies conducted on the same participant ±1 year from VFSS were examined to characterize respiratory abnormalities.There was a high rate of swallowing dysfunction (pharyngeal residue 71%, aspiration events 87%) and disordered sleep. All aspiration events were silent. There were no differences in rates of aspiration for gender, genetic subtype, or GH use.A high incidence of aspiration was identified indicating swallow dysfunction may frequently be present in infants with PWS. Comprehensive evaluation of feeding and swallowing is essential and requires a multidisciplinary approach. Providers should recognize risk factors for swallow dysfunction and consider a multidisciplinary approach to guide decision making and optimize feeding safety in PWS.

Review of Prader-Willi syndrome: the endocrine approach

Prader-Willi syndrome (PWS) is a complex genetic disorder with implications on the endocrine and neurologic systems, metabolism, and behavior. Early in life, PWS is characterized by hypotonia and failure to thrive, followed by obesity and hyperphagia. Patients with PWS develop hypothalamic dysfunction which may lead growth hormone deficiency (GHD), hypogonadism, hypothyroidism, adrenal insufficiency, and poor bone mineral density (BMD). In addition to hypothalamic dysfunction, individuals with PWS have increased risk for obesity which may be complicated by metabolic syndrome and type 2 diabetes mellitus (T2DM). In this paper, we will review the current literature pertaining to the endocrine concerns of PWS and current recommendations for screening and management of these conditions.

Survival trends from the Prader-Willi Syndrome Association (USA) 40-year mortality survey

Background

Prader-Willi syndrome (PWS) is a complex genetic disorder characterized by hyperphagia and morbid obesity with increased cardiopulmonary and hyperphagia-related mortality. Survival trends in PWS were evaluated to assess the impact of modern interventions on mortality risk.

Methods

The PWSA (USA) 40-year mortality syndrome-specific database of 486 death reports was utilized to examine survival trends in PWS and cohort effects for recent deaths (years 2000–2015, N=331) relative to deaths prior to 2000 (N=94). Cox Proportional Hazards regression modeling was applied to generate log rank statistics and Kaplan-Meier curves examining sex, cause of death and cohort.

Results

Risk for all-cause mortality in PWS was 1.5 (95%CI=1.2–1.9) times higher for the Early than the Recent era cohort reflected in female cardiac failure (HR=1.8; 95%CI=1.3–2.6), pulmonary embolism (HR=6.1; 95%CI=1.7–22), and GI-related (HR=3.2; 95%CI=1.1–7.4) causes. Accidental deaths in males increased in the Recent era cohort (HR=5.7; 95%CI=1.2–27.1) possibly due to enhanced weight management and mobility. Risk of death from respiratory failure was unchanged.

Conclusions

We report measurable increases in survival effecting cardiovascular and GI-related causes in PWS most likely attributable to earlier diagnosis and proactive interventions to prevent morbid obesity. More research is needed to address underlying vulnerability to respiratory failure, an unchanged mortality risk in PWS.

Longitudinal evaluation of sleep disordered breathing in infants with Prader-Willi syndrome

OBJECTIVE

To evaluate the course of sleep disordered breathing (SDB) in infants with Prader-Willi syndrome (PWS).

DESIGN

Retrospective longitudinal observational study.

SETTING

Sleep laboratory at The Hospital for Sick Children, Toronto, Canada.

PATIENTS

Infants with PWS.

MAIN OUTCOME MEASURES

The natural history of SDB in infants with PWS within 2 years from baseline assessment.

RESULTS

We identified 28 (12 male) infants with PWS who had a baseline polysomnography (PSG) at a median age (interquartile (IQR)) of 0.9 (0.5, 1.1) years. The median central apnoea index (CAI) at baseline was 6.6 events/hour (IQR 2.6, 12.1). Of these, 15/28 (53%) infants with PWS were diagnosed with significant central sleep apnoea (CSA) (CAI≥5 events/hour). Median age (IQR) at follow-up PSG was 2.1 (1.5, 2.6) years. The median CAI improved from 6.6 to 2.3 events/hour (p<0.0001). Only four infants with PWS had persistent CSA at the time of the follow-up PSG. Furthermore, three infants with PWS were diagnosed with mild-to-moderate obstructive sleep apnoea (OSA) that has improved at follow-up studies whereas two patients with PWS with no evidence of OSA at baseline were diagnosed with severe OSA on the follow-up PSG requiring adenotonsillectomy. The overall median obstructive apnoea-hypopnoea index was similar between baseline and follow-up studies (0.6 and 0.8, respectively, p=0.91).

CONCLUSIONS

CSA is prevalent in infants with PWS but usually improves with age. However, these patients continue to require ongoing PSG surveillance because some infants will have persistent CSA and others are at risk of developing OSA.

Growth Hormone Treatment in Children With Prader-Willi Syndrome: Three Years of Longitudinal Data in Prepubertal Children and Adult Height Data From the KIGS Database

CONTEXT

Longitudinal data of children with Prader-Willi syndrome (PWS) treated with genotropin were registered in the Pfizer International Growth Database (KIGS).

OBJECTIVE

To evaluate efficacy and safety of growth hormone (GH) treatment in a large group of children with PWS.

DESIGN

Data registered in KIGS from 1987 to 2012.

SETTING

Worldwide retrospective cohort study.

PATIENTS

Patients included 522 prepubertal children treated with GH for three years and 173 children who had reached adult height. Safety analysis included 2332 children. Intervention involved GH treatment.

MAIN OUTCOME MEASURE

Height standard deviation score (SDS), body mass index (BMI) SDS, occurrence of serious adverse events, and deaths reported in KIGS.

RESULTS

In prepubertal children, mean (standard deviation) height SDS improved to -0.31 (1.34) (P < 0.05) during three years of GH treatment. In the adolescent group, height SDS improved until the start of puberty to -0.22 (1.31) (P < 0.05) but had a loss of -0.77 (0.81) during puberty, resulting in a mean adult height SDS of -1.19 (1.37). Total height gain was 0.95 (1.32) SDS. BMI SDS increased in the prepubertal group from 1.11 (2.09) to 1.53 (1.43) (P < 0.05) and did not significantly change in the adolescent group, who had a BMI SDS at an adult height of 1.78 (1.26). KIGS contained 12 death reports.

CONCLUSIONS

GH treatment in children with PWS significantly improves linear growth. BMI remains on average below +2 SDS, in contrast to the natural course of increasing obesity in PWS. Safety should be closely monitored in children with PWS, with and without GH treatment.

Respiratory Complications in Children with Prader Willi Syndrome

Prader Willi syndrome, resulting from the partial deletion or lack of expression of a region of genes on the paternal chromosome 15, has a number of phenotypic features which predispose affected patients to ventilatory problems. These include generalised hypotonia, abnormal arousal and ventilatory responses to hypoxia and hypercapnia, scoliosis and frequently, obesity. The spectrum of the resulting respiratory complications thus runs from sleep disordered breathing, to aspiration and respiratory functional impairment. While the use of growth hormone, in conjunction with multidisciplinary clinical management, is currently the cornerstone of clinical care of these patients, concerns have been raised following reports of sudden death shortly after growth hormone initiation. This review summarizes the respiratory complications commonly seen and draws together the published literature on the impact of growth hormone in relation to various respiratory parameters, aiming to provide the reader with the necessary information to manage these patients as safely as possible.

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.

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.