High prevalence of central adrenal insufficiency in patients with Prader-Willi syndrome

Appetite- and Weight-Regulating Neuroendocrine Circuitry in Hypothalamic Obesity

Since hypothalamic obesity (HyOb) was first described over 120 years ago by Joseph Babinski and Alfred Fröhlich, advances in molecular genetic laboratory techniques have allowed us to elucidate various components of the intricate neurocircuitry governing appetite and weight regulation connecting the hypothalamus, pituitary gland, brainstem, adipose tissue, pancreas, and gastrointestinal tract. On a background of an increasing prevalence of population-level common obesity, the number of survivors of congenital (eg, septo-optic dysplasia, Prader-Willi syndrome) and acquired (eg, central nervous system tumors) hypothalamic disorders is increasing, thanks to earlier diagnosis and management as well as better oncological therapies. Although to date the discovery of several appetite-regulating peptides has led to the development of a range of targeted molecular therapies for monogenic obesity syndromes, outside of these disorders these discoveries have not translated into the development of efficacious treatments for other forms of HyOb. This review aims to summarize our current understanding of the neuroendocrine physiology of appetite and weight regulation, and explore our current understanding of the pathophysiology of HyOb.

Endocrine features of Prader-Willi syndrome: a narrative review focusing on genotype-phenotype correlation

Prader-Willi syndrome (PWS) is a complex genetic disorder caused by three different types of molecular genetic abnormalities. The most common defect is a deletion on the paternal 15q11-q13 chromosome, which is seen in about 60% of individuals. The next most common abnormality is maternal disomy 15, found in around 35% of cases, and a defect in the imprinting center that controls the activity of certain genes on chromosome 15, seen in 1-3% of cases. Individuals with PWS typically experience issues with the hypothalamic-pituitary axis, leading to excessive hunger (hyperphagia), severe obesity, various endocrine disorders, and intellectual disability. Differences in physical and behavioral characteristics between patients with PWS due to deletion versus those with maternal disomy are discussed in literature. Patients with maternal disomy tend to have more frequent neurodevelopmental problems, such as autistic traits and behavioral issues, and generally have higher IQ levels compared to those with deletion of the critical PWS region. This has led us to review the pertinent literature to investigate the possibility of establishing connections between the genetic abnormalities and the endocrine disorders experienced by PWS patients, in order to develop more targeted diagnostic and treatment protocols. In this review, we will review the current state of clinical studies focusing on endocrine disorders in individuals with PWS patients, with a specific focus on the various genetic causes. We will look at topics such as neonatal anthropometry, thyroid issues, adrenal problems, hypogonadism, bone metabolism abnormalities, metabolic syndrome resulting from severe obesity caused by hyperphagia, deficiencies in the GH/IGF-1 axis, and the corresponding responses to treatment.

Hormonal Imbalances in Prader-Willi and Schaaf-Yang Syndromes Imply the Evolution of Specific Regulation of Hypothalamic Neuroendocrine Function in Mammals

The hypothalamus regulates fundamental aspects of physiological homeostasis and behavior, including stress response, reproduction, growth, sleep, and feeding, several of which are affected in patients with Prader-Willi (PWS) and Schaaf-Yang syndrome (SYS). PWS is caused by paternal deletion, maternal uniparental disomy, or imprinting defects that lead to loss of expression of a maternally imprinted region of chromosome 15 encompassing non-coding RNAs and five protein-coding genes; SYS patients have a mutation in one of them, MAGEL2. Throughout life, PWS and SYS patients suffer from musculoskeletal deficiencies, intellectual disabilities, and hormonal abnormalities, which lead to compulsive behaviors like hyperphagia and temper outbursts. Management of PWS and SYS is mostly symptomatic and cures for these debilitating disorders do not exist, highlighting a clear, unmet medical need. Research over several decades into the molecular and cellular roles of PWS genes has uncovered that several impinge on the neuroendocrine system. In this review, we will discuss the expression and molecular functions of PWS genes, connecting them with hormonal imbalances in patients and animal models. Besides the observed hormonal imbalances, we will describe the recent findings about how the loss of individual genes, particularly MAGEL2, affects the molecular mechanisms of hormone secretion. These results suggest that MAGEL2 evolved as a mammalian-specific regulator of hypothalamic neuroendocrine function.

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.

Premature adrenarche in Prader-Willi syndrome is associated with accelerated pre-pubertal growth and advanced bone age

OBJECTIVES

Prader-Willi syndrome (PWS) is characterized by obesity, growth hormone deficiency, hypogonadism, and a high prevalence of premature adrenarche despite reported hypothalamic-pituitary-adrenal axis dysfunction. While idiopathic premature adrenarche is associated with accelerated pre-pubertal growth and advanced bone age, the consequences of elevated adrenal androgens on growth and bone maturation in PWS remain unknown. This study therefore sought to describe age-related changes in dehydroepiandrosterone sulfate (DHEAS) and their effects on growth and bone maturation in PWS.

METHODS

This retrospective observational study included 62 children with PWS. Simple and multiple regression models were constructed to relate age and BMI-SDS with DHEAS levels. Height velocity was compared to age and sex-based norms with t-tests and two-way ANOVA. Patterns in bone age Z-score were examined with two-way ANOVA, and the contributions of age, BMI-SDS, and DHEAS to bone age Z-score were analyzed with multiple regression.

RESULTS

DHEAS levels rose earlier and were less strongly correlated with age in males and females with PWS (R²=0.12 and 0.30) compared to healthy controls (R²=0.89 and 0.88) in a pattern unrelated to BMI-SDS (adjusted R²=0.076, p=0.10 for age, and 0.29 for BMI-SDS). Mid-childhood height velocity was increased in males and preserved in females with PWS before declining at the age of expected puberty (p<0.0001). Peri-adrenarchal bone age was advanced in a manner associated with DHEAS but not BMI-SDS (p<0.0001; adjusted R²=0.48, p=0.0014 for DHEAS, and 0.78 for BMI-SDS).

CONCLUSIONS

An obesity-independent increase in adrenal androgens is associated with accelerated mid-childhood growth and bone maturation in PWS.

The transition from pediatric to adult care in individuals with Prader-Willi syndrome

Prader-Willi syndrome (PWS), the most common form of syndromic obesity, is a complex neurodevelopmental genetic disorder including obesity with hyperphagia, endocrine and metabolic disorders and also psychiatric disorders. The most frequent endocrine disturbances include hypogonadism and growth hormone (GH) deficiency. Hypothyroidism and central adrenal insufficiency can also be observed but are less frequent. The transition of individuals with PWS from adolescence to adult life is challenging because of multiple comorbidities and complex disabilities. Individuals and caregivers face psychological, medical and social issues. This period of profound changes is thus prone to disruptions, and the main risks being the worsening of the medical situation and loss to follow-up of the individuals. Medical care may be poorly adapted to the needs of individuals because of a lack of knowledge concerning the syndrome and also lack of the necessary specific skills. A multidisciplinary panel composed of several experts in PWS met in November 2021 during an European Reference Network on Rare Endocrine Conditions (Endo-ERN) webinar. They presented complementary aspects of PWS from the perspective of the transition including psychiatric, pediatric and adult endocrinological and parent's and patient's points of view and shed light on the best way to approach this pivotal period.

Clinical Indications for Growth Hormone Therapy

Growth hormone (GH) is an injectable medication originally used to replace the deficiency of the hormone, but has expanded to treating conditions that may reduce growth and adult height even when the body maintains endogenous GH production. In the United States, there are 8 Food and Drug Administration (FDA)-approved indications for pediatric GH therapy: GH deficiency, Prader-Willi Syndrome, small for gestational age (SGA) without catch-up growth, idiopathic short stature, Turner syndrome, SHOX gene haploinsufficiency, Noonan Syndrome, and chronic renal insufficiency. We characterize the growth patterns and effects of GH treatment in each of these indications. We also review patterns of growth that warrant referral to a pediatric endocrinologist, as well as safety updates. This review is intended to guide practitioners on the initial evaluation and management of patients with short stature, and the indications for GH therapy.

Central adrenal insufficiency screening with morning plasma cortisol and ACTH levels in Prader-Willi syndrome

OBJECTIVES

Prader-Willi syndrome (PWS) is a complex genetic disorder with severe hypotonia, failure to thrive, childhood obesity, hypogonadism/hypogenitalism and learning/behavioral problems with endocrine-related growth and other hormone deficiencies. The prevalence of central adrenal insufficiency (CAI) using dynamic testing ranges from rare to 60%. We compared routine morning plasma cortisol (MPC) and ACTH levels in large cohorts of PWS and control children to address CAI.

METHODS

Retrospective analysis of MPC and ACTH levels was undertaken in 128 PWS growth hormone (GH)-treated children under medical care before considering dynamic testing for CAI and 128 non-syndromic control children with short stature evaluated for GH deficiency.

RESULTS

The average MPC level in PWS was 9.7 ± 3.7 μg/dL with no difference in age, gender or PWS genetic subtype and 13.4 ± 5.7 μg/dL in the control group. MPC levels were significantly lower (p < 0.05) in PWS but in the normal range. The morning plasma ACTH level in the PWS group was 22.1 ± 8.0 pg/mL with one individual having an initial low plasma ACTH level (8 pg/mL), but normal upon repeat.

CONCLUSIONS

MPC levels in PWS are normal and comparable with control children, without evidence or increased risk of CAI. Lower but normal MPC levels were seen in PWS and suggestive of reduced local regeneration of cortisol from cortisone in adipose tissue by the GH-IGF-I system. Hence, MPC measures alone or in combination with ACTH should be considered for initial screening for CAI in PWS but prior to dynamic testing.

Progression of Obstructive Sleep Apnea Syndrome in Pediatric Patients with Prader-Willi Syndrome

Obstructive sleep apnea syndrome (OSAS) is one of the most common comorbidities in patients with Prader-Willi syndrome (PWS) and causes significant consequences. This observational study was conducted to investigate the progression of OSAS in pediatric patients with PWS, who had not undergone upper airway surgery, through a longitudinal follow-up of their annual polysomnography results. Annual body mass index (BMI), BMI z-score, sleep efficiency and stages, central apnea index (CAI), obstructive apnea-hypopnea index (OAHI), and oxygen saturation nadir values were longitudinally analyzed. At enrollment, of 22 patients (10 boys and 12 girls) aged 11.7 ± 3.9 years, 20 had OSAS. During the 4-year follow-up, only two patients had a spontaneous resolution of OSAS. The average BMI and BMI z-score increased gradually, but CAI and OAHI showed no significant differences. After statistical adjustment for sex, age, genotype, growth hormone use, and BMI z-score, OAHI was associated with the BMI z-score and deletion genotype. In conclusion, OSAS is common in patients with PWS, and rarely resolved spontaneously. Watchful waiting may not be the best OSAS management strategy. Weight maintenance and careful selection of surgical candidates are important for OSAS treatment in patients with PWS.

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.

Prenatal and Neonatal Characteristics of Children with Prader-Willi Syndrome

Objective: Prader-Willi syndrome (PWS) is a rare genetic syndrome with a wide spectrum of clinical features in early life. Late diagnoses are still present. We characterized the perinatal and neonatal features of PWS, compared them with those of healthy newborns and assessed the prenatal and neonatal differences between the genetic subtypes. Design: A cohort study in children with PWS. The prevalence of variables was compared with healthy infants (PLUTO cohort) and to population statistics from literature. Patients: 244 infants with PWS and 365 healthy infants. Measurements: Data on prenatal and neonatal variables in both cohorts. Population statistics were collected through an extensive literature search. Results: A higher prevalence of maternal age >35 years was found in PWS compared to healthy infants and population statistics, and the highest maternal age was found in the mUPD group. Higher prevalence of polyhydramnios, caesarean section, labour induction and breech presentation, and lower birth weight SDS was found in PWS compared to healthy infants. High prevalences of decreased fetal movements (78.5%), hypotonia (100%), cryptorchism (95.9%) and poor sucking/tube feeding (93.9%) were found in PWS. Conclusions: This study presents an overview of prenatal and neonatal variables in infants with PWS compared to healthy infants. Our findings may increase clinical awareness of the early perinatal signs of PWS by obstetricians, neonatologists and all those involved in infant care, enabling early diagnosis and start of multidisciplinary treatment.

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.

Prader-Willi syndrome: an update on obesity and endocrine problems

Prader-Willi syndrome (PWS) is a rare complex genetic disorder that results from a lack of expression of the paternally inherited chromosome 15q11-q13. PWS is characterized by hypotonia and feeding difficulty in early infancy and development of morbid obesity aggravated by uncontrolled hyperphagia after childhood and adolescent. Dysmorphic facial features, delayed motor and language development, various degrees of cognitive impairment, and behavioral problems are common in PWS. Without early, intensive nutritional therapy along with behavioral modification, PWS patients develop severe obesity associated with type 2 diabetes, obstructive sleep apnea, right-side heart failure, and other obesity-related metabolic complications. Hypothalamic dysfunction in PWS can lead to several endocrine disorders, including short stature with growth hormone deficiency, hypothyroidism, central adrenal insufficiency, and hypogonadism. In this review, we discuss the natural history of PWS and the mechanisms of hyperphagia and obesity. We also provide an update on obesity treatments and recommendations for screening and monitoring of various endocrine problems that can occur in PWS.

Long-term cortisol levels in hair of children and adolescents with Prader-Willi Syndrome

CONTEXT

Prader-Willi syndrome (PWS) is characterized by hypothalamic dysfunction. In children with PWS, stress-induced central adrenal insufficiency (CAI) has been described, however, daily life cortisol production may be normal. Hair cortisol concentration (HCC) is a marker of long-term systemic cortisol production. Cortisol awakening response (CAR) is the increase in cortisol level after awakening. A negative CAR might suggest hypothalamic-pituitary-adrenal (HPA)-axis reactivity problems. Little is known about HCC and CAR in children with PWS.

OBJECTIVE

To investigate long-term cortisol levels in hair and CAR in children with PWS.

DESIGN

Cross-sectional study.

PATIENTS

41 children with PWS.

SETTING

Dutch PWS Reference Center.

MAIN OUTCOME MEASURES

HCC and salivary cortisol measured by LCMS.

RESULTS

Median (IQR) HCC was 1.90 (1.02-3.30) pg/mg at a median (IQR) age of 14.5 (8.20-19.0) years, with median HCC in age-matched references being 2.63 pg/mg. Five patients (13.2%) had HCC < 2.5th percentile for age and these patients had a repeatedly negative CAR. Median HCC was significantly lower in patients with negative CAR than in patients with normal CAR (1.00 (0.22-1.59) vs. 2.25 (1.47-3.26) pg/mg, p = 0.007). One patient had both HCC < 2.5th percentile and repeatedly low morning salivary cortisol levels and negative CAR, and was diagnosed with adrenal insufficiency by overnight metyrapone test.

CONCLUSIONS

HCC were normal in the majority of children with PWS. Our data suggest that children with HCC < 2.5th percentile and (repeatedly) negative CAR might possibly have adrenal insufficiency or delayed HPA-axis responsiveness.

Clinical Characteristics and Growth Hormone Treatment in Patients with Prader-Willi Syndrome

OBJECTIVE

To investigate clinical characteristics and response to growth hormone (GH) treatment in patients with Prader-Willi syndrome (PWS) in Turkey.

METHODS

The data of 52 PWS patients from ten centers was retrospectively analyzed. A nation-wide, web-based data system was used for data collection. Demographic, clinical, genetic, and laboratory data and follow-up information of the patients were evaluated.

RESULTS

The median age of patients at presentation was 1.5 years, and 50% were females. Genetic analysis showed microdeletion in 69.2%, uniparental disomy in 11.5%, imprinting defect in 1.9% and methylation abnormality in 17.3%. Hypotonia (55.7%), feeding difficulties (36.5%) and obesity (30.7%) were the most common complaints. Cryptorchidism and micropenis were present in 69.2% and 15.3% of males, respectively. At presentation, 25% had short stature, 44.2% were obese, 9.6% were overweight and 17.3% were underweight. Median age of obese patients was significantly higher than underweight patients. Central hypothyroidism and adrenal insufficiency were present in 30.7% and 4.7%, respectively. Hypogonadism was present in 75% at normal age of puberty. GH treatment was started in 40% at a mean age of 4.7±2.7 years. After two years of GH treatment, a significant increase in height SDS was observed. However, body mass index (BMI) standard deviation (SDS) remained unchanged.

CONCLUSION

The most frequent complaints were hypotonia and feeding difficulty at first presentation. Obesity was the initial finding in 44.2%. GH treatment was started in less than half of the patients. While GH treatment significantly increased height SDS, BMI SDS remained unchanged, possibly due to the relatively older age at GH start.

Patients with PWS and related syndromes display differentially methylated regions involved in neurodevelopmental and nutritional trajectory

Background

Prader–Willi syndrome is a rare genetic neurodevelopmental disorder caused by a paternal deficiency of maternally imprinted gene expression located in the chromosome 15q11–q13 region. Previous studies have demonstrated that several classes of neurodevelopmental disorders can be attributed to either over- or under-expression of specific genes that may lead to impairments in neuronal generation, differentiation, maturation and growth. Epigenetic changes that modify gene expression have been highlighted in these disorders. One recent study focused on epigenetic analysis and compared patients with PWS with patients with other imprinting disorders. No study, however, has yet focused on epigenetics in patients with PWS specifically by comparing the mutations associated with this syndrome.

Objective

This study investigated the epigenetic modifications in patients with PWS and patients with PWS-related disorders caused by inactivation of two genes of the PWS chromosomal region, SNORD116 and MAGEL2. Our approach also aimed to compare the epigenetic modifications in PWS and PWS-related disorders.

Methods

We compared genome-wide methylation analysis (GWAS) in seven blood samples from patients with PWS phenotype (five with deletions of the PWS locus, one with a microdeletion of SNORD116 and one with a frameshift mutation of MAGEL2 presenting with Schaaf–Yang syndrome), as well as two control patients. Controls were infants that had been studied for suspicion of genetic diseases that was not confirmed by the genetic analysis and the clinical follow-up.

Results

The analysis identified 29,234 differentially methylated cytosines, corresponding to 5,308 differentially methylated regions (DMRs), which matched with 2,280 genes. The DMRs in patients with PWS were associated with neurodevelopmental pathways, endocrine dysfunction and social and addictive processes consistent with the key features of the PWS phenotype. In addition, the separate analysis for the SNORD116 and MAGEL2 deletions revealed that the DMRs associated with the SNORD116 microdeletion were found in genes implicated in metabolic pathways and nervous system development, whereas MAGEL2 mutations mostly concerned genes involved in macromolecule biosynthesis.

Conclusion

The PWS is associated with epigenetic modifications with differences in SNORD116 and MAGEL2 mutations, which seem to be relevant to the different associated phenotypes.

Hair glucocorticoids in adults with intellectual disabilities and depressive symptoms pre- and post-bright light therapy: First explorations

BACKGROUND

Depressive symptoms and stress are common in adults with intellectual disabilities. Our aim was to explore long-term biological stress levels, assessed by hair cortisol (HairF) and cortisone (HairE) concentrations, in adults with intellectual disabilities and depressive symptoms and to investigate the effects of bright light therapy (BLT) on hair glucocorticoids.

METHOD

Scalp hair samples (n = 14) were retrospectively examined at baseline and post-BLT (10.000 and 300 lux). Liquid chromatography-tandem mass spectrometry was used to measure hair glucocorticoids.

RESULTS

A significant correlation was found between baseline HairF and depression scores (r = .605, p = .028). Post-intervention HairE levels were significantly increased ([95% CI: 11.2-17.4 pg/mg], p = .003), in particular after dim light (300 lux) ([95% CI: 10.0-18.3 pg/mg], p = .020).

CONCLUSIONS

This study showed that retrospectively examining biological levels of stress in adults with intellectual disabilities seems a potentially promising and objective method to gain insight in the stress level of adults with intellectual disabilities.

Endocrine disorders in Prader-Willi syndrome: a model to understand and treat hypothalamic dysfunction

Prader-Willi syndrome is a rare genetic neurodevelopmental disorder resulting from the loss of expression of maternally imprinted genes located in the paternal chromosomal region, 15q11-13. Impaired hypothalamic development and function is the cause of most of the phenotypes comprising the developmental trajectory of Prader-Willi syndrome: from anorexia at birth to excessive weight gain preceding hyperphagia, and early severe obesity with hormonal deficiencies, behavioural problems, and dysautonomia. Growth hormone deficiency, hypogonadism, hypothyroidism, premature adrenarche, corticotropin deficiency, precocious puberty, and glucose metabolism disorders are the main endocrine dysfunctions observed. Additionally, as a result of hypothalamic dysfunction, oxytocin and ghrelin systems are impaired in most patients. Standard pituitary and gonadal hormone replacement therapies are required. In this Review, we discuss Prader-Willi syndrome as a model of hypothalamic dysfunction, and provide a comprehensive description of the accumulated knowledge on genetics, pathophysiology, and treatment approaches of this rare disorder.

Benefits of multidisciplinary care in Prader-Willi syndrome

Introduction: Prader-Willi syndrome (PWS) is the most well-known condition of genetic obesity. Over the past 20 years, advances have been achieved in the diagnosis and treatment of PWS with a significant improvement in prognosis.Areas covered: This review focuses on the benefits of multidisciplinary approach in children and adolescents with PWS. In particular, the neonatologist and geneticist play a key role in early diagnosis and the clinical follow-up of the PWS patient must be guaranteed by a team including pediatric endocrinologist, psychologist, nutritionist/dietician, neurologist/neuropsychiatrist, sleep specialist, ears, nose and throat specialist (ENT), lung specialist, dentist, orthopedist and ophthalmologist and, eventually, gastroenterologist. We searched PubMed and critically summarized what has been reported in the last 10 years on PWS.Expert opinion: The multidisciplinary care in association with an early diagnosis and GH treatment postpones overweight development and decreases prevalence of obesity in individuals with PWS. Further prognostic improvements are expected through the selection of teams particularly experienced in the management of individuals with PWS and the discovery of new drugs.

Hair cortisol-a method to detect chronic cortisol levels in patients with Prader-Willi syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a multisymptomatic, rare, genetic, neurodevelopmental disorder in adults mainly characterized by hyperphagia, cognitive dysfunction, behavioral problems and risk of morbid obesity. Although endocrine insufficiencies are common, hypocortisolism is rare and knowledge on long-term cortisol concentrations is lacking. The aim of this study was to evaluate long-term cortisol levels in PWS by measurements of hair cortisol.

METHODS

Twenty-nine adults with PWS, 15 men and 14 women, median age 29 years, median BMI 27 kg/m², were included. Scalp hair samples were analyzed for cortisol content using liquid-chromatography tandem-mass spectrometry. In addition, a questionnaire on auxology, medication and stress were included. For comparison, 105 age- and sex-matched participants from the population-based Lifelines Cohort study were included as controls. The mean hair cortisol between the groups were compared and associations between BMI and stress were assessed by a generalized linear regression model.

RESULTS

In the PWS group large variations in hair cortisol was seen. Mean hair cortisol was 12.8 ± 25.4 pg/mg compared to 3.8 ± 7.3 pg/mg in controls (p = 0.001). The linear regression model similarly showed higher cortisol levels in patients with PWS, which remained consistent after adjusting for BMI and stress (p = 0.023). Furthermore, hair cortisol increased with BMI (p = 0.012) and reported stress (p = 0.014).

CONCLUSION

Long-term cortisol concentrations were higher in patients with PWS compared to controls and increased with BMI and stress, suggesting an adequate cortisol response to chronic stress. Hair cortisol demonstrate promising applications in the context of PWS treatment and disease management.

Loss of MAGEL2 in Prader-Willi syndrome leads to decreased secretory granule and neuropeptide production

Prader-Willi syndrome (PWS) is a developmental disorder caused by loss of maternally imprinted genes on 15q11-q13, including melanoma antigen gene family member L2 (MAGEL2). The clinical phenotypes of PWS suggest impaired hypothalamic neuroendocrine function; however, the exact cellular defects are unknown. Here, we report deficits in secretory granule (SG) abundance and bioactive neuropeptide production upon loss of MAGEL2 in humans and mice. Unbiased proteomic analysis of Magel2pΔ/m+ mice revealed a reduction in components of SG in the hypothalamus that was confirmed in 2 PWS patient-derived neuronal cell models. Mechanistically, we show that proper endosomal trafficking by the MAGEL2-regulated WASH complex is required to prevent aberrant lysosomal degradation of SG proteins and reduction of mature SG abundance. Importantly, loss of MAGEL2 in mice, NGN2-induced neurons, and human patients led to reduced neuropeptide production. Thus, MAGEL2 plays an important role in hypothalamic neuroendocrine function, and cellular defects in this pathway may contribute to PWS disease etiology. Moreover, these findings suggest unanticipated approaches for therapeutic intervention.

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.

Central Adrenal Insufficiency Is Rare in Adults With Prader-Willi Syndrome

CONTEXT

Prader-Willi syndrome (PWS) is associated with several hypothalamic-pituitary hormone deficiencies. There is no agreement on the prevalence of central adrenal insufficiency (CAI) in adults with PWS. In some countries, it is general practice to prescribe stress-dose hydrocortisone during physical or psychological stress in patients with PWS. Side effects of frequent hydrocortisone use are weight gain, osteoporosis, diabetes mellitus, and hypertension-already major problems in adults with PWS. However, undertreatment of CAI can cause significant morbidity-or even mortality.

OBJECTIVE

To prevent both over- and undertreatment with hydrocortisone, we assessed the prevalence of CAI in a large international cohort of adults with PWS. As the synacthen test shows variable results in PWS, we only use the metyrapone test (MTP) and insulin tolerance test (ITT).

DESIGN

Metyrapone test or ITT in adults with PWS (N = 82) and review of medical files for symptoms of hypocortisolism related to surgery (N = 645).

SETTING

Outpatient clinic.

PATIENTS OR OTHER PARTICIPANTS

Eighty-two adults with genetically confirmed PWS.

MAIN OUTCOME MEASURE

For MTP, 11-deoxycortisol > 230 nmol/L was considered sufficient. For ITT, cortisol > 500 nmol/L (Dutch, French, and Swedish patients) or > 450 nmol/L (British patients) was considered sufficient.

RESULTS

Central adrenal insufficiency was excluded in 81 of 82 patients. Among the 645 patients whose medical files were reviewed, 200 had undergone surgery without perioperative hydrocortisone treatment. None of them had displayed any features of hypocortisolism.

CONCLUSIONS

Central adrenal insufficiency is rare (1.2%) in adults with PWS. Based on these results, we recommend against routinely prescribing hydrocortisone stress-doses in adults with PWS.

Prader-Willi syndrome: endocrine manifestations and management

Prader-Willi syndrome (PWS) is a genetic disorder caused by the absence of gene expression in the 15q11.2-q13 paternal chromosome. Patients with PWS develop hypothalamic dysfunction that can lead to various endocrine changes such as: obesity, growth hormone deficiency, hypogonadism, hypothyroidism, adrenal insufficiency and low bone mineral density. In addition, individuals with PWS have increased risk of developing type 2 diabetes mellitus. This review summarizes and updates the current knowledge about the prevention, diagnosis and treatment of endocrine manifestations associated with Prader Willi syndrome, especially diagnosis of growth hormone deficiency, management and monitoring of adverse effects; diagnosis of central adrenal insufficiency and management in stressful situations; screening for central hypothyroidism; research and treatment of hypogonadism; prevention and treatment of disorders of glucose metabolism. Careful attention to the endocrine aspects of PWS contributes significantly to the health of these individuals. Arch Endocrinol Metab. 2020;64(3):223-34.

Requirements for improving health and well-being of children with Prader-Willi syndrome and their families

Prader-Willi syndrome (PWS) is a rare genetic condition with multi-system involvement. The literature was reviewed to describe neurodevelopment and the behavioural phenotype, endocrine and metabolic disorders and respiratory and sleep functioning. Implications for child and family quality of life were explored. Challenging behaviours contribute to poorer well-being and quality of life for both the child and caregiver. Recent evidence indicates healthy outcomes of weight and height can be achieved with growth hormone therapy and dietary restriction and should be the current target for all individuals with PWS. Gaps in the literature included therapies to manage challenging behaviours, as well as understanding the effects of growth hormone on respiratory and sleep function. New knowledge regarding the transition of children and families from schooling and paediatric health services to employment, accommodation and adult health services is also needed. Developing a national population-based registry could address these knowledge gaps and inform advocacy for support services that improve the well-being of individuals with PWS and their families.

Prader- Willi syndrome: An uptodate on endocrine and metabolic complications

Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, low lean body mass, muscular hypotonia, mental retardation, behavioral abnormalities, dysmorphic features, and excessive appetite with progressive obesity. It is caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13. This genetic disorder has an estimated prevalence that ranges between 1/10,000-1/30,000. Hypothalamic dysfunction is a common finding in PWS and it has been implicated in several manifestations of this syndrome such as hyperphagia, temperature instability, high pain threshold, sleep disordered breathing, and multiple endocrine abnormalities. These include growth hormone deficiency, central adrenal insufficiency, hypogonadism, hypothyroidism, and obesity often complicated by type 2 diabetes. The aim of this manuscript is to overview the current literature on metabolic and endocrine complications of PWS, focusing on human studies and providing insights on the physio pathological mechanisms. A careful management of metabolic and endocrine complications can contribute to improve quality of life, prevent complications, and prolong life expectancy of PW patients.

PRADER-WILLI SYNDROME: WHAT IS THE GENERAL PEDIATRICIAN SUPPOSED TO DO? - A REVIEW

OBJECTIVE

To carry out a review about Prader-Willi Syndrome based on the most recent data about the subject and to give recommendation for the general pediatricians for early diagnoses and follow-up.

DATA SOURCES

Scientific articles in the PubMed and SciELO databases. The research was not limited to a specific time period and included all articles in such databases.

DATA SYNTHESIS

The Prader-Willi Syndrome (PWS) is a rare genetic disorder resulting from the loss of imprinted gene expression within the paternal chromosome 15q11-q13. PWS is characterized by endocrine abnormalities, such as growth hormone (GH) deficiency, obesity, central adrenal insufficiency, hypothyroidism, hypogonadism and complex behavioral and intellectual difficulties. PWS individuals also may present other comorbidities, such as sleep disorders, scoliosis, constipation, dental issues and coagulation disorders. The follow-up protocol of the Children's Institute at Universidade de São Paulo is based on four main pillars: diet, exercise, recombinant human growth hormone (rhGH) therapy and behavioral and cognitive issues. The diet must include a caloric restriction of 900 kcal/day, according to the Prader-Willi Eating Pyramid and exercise plan is focused on daily aerobic exercises and postural therapy. The rhGH therapy is highly recommended by the international scientific literature and must be started as soon as the diagnostic is made. The management of behavioral issues is based on strategies to establish routine and rules.

CONCLUSIONS

If the general pediatrician becomes more familiar with PWS, the diagnosis and treatment will start earlier, which is essential to improve the quality of life and care for these individuals.

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.

Prader-Willi Syndrome - Clinical Genetics, Diagnosis and Treatment Approaches: An Update

BACKGROUND

Prader-Willi Syndrome (PWS) is a neurodevelopmental genomic imprinting disorder with lack of expression of genes inherited from the paternal chromosome 15q11-q13 region usually from paternal 15q11-q13 deletions (about 60%) or maternal uniparental disomy 15 or both 15s from the mother (about 35%). An imprinting center controls the expression of imprinted genes in the chromosome 15q11-q13 region. Key findings include infantile hypotonia, a poor suck, failure to thrive and hypogonadism/hypogenitalism. Short stature and small hands/feet due to growth and other hormone deficiencies, hyperphagia and marked obesity occur in early childhood, if uncontrolled. Cognitive and behavioral problems (tantrums, compulsions, compulsive skin picking) are common.

OBJECTIVE

Hyperphagia and obesity with related complications are major causes of morbidity and mortality in PWS. This report will describe an accurate diagnosis with determination of specific genetic subtypes, appropriate medical management and best practice treatment approaches.

METHODS AND RESULTS

An extensive literature review was undertaken related to genetics, clinical findings and laboratory testing, clinical and behavioral assessments and summary of updated health-related information addressing the importance of early PWS diagnosis and treatment. A searchable, bulleted and formatted list of topics is provided utilizing a Table of Contents approach for the clinical practitioner.

CONCLUSION

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

Central adrenal insufficiency in children and adolescents

Central adrenal insufficiency (CAI) is a life-threatening condition caused by either pituitary disease (secondary adrenal insufficiency) or impaired hypothalamic function with inadequate CRH production (tertiary adrenal insufficiency). ACTH deficiency may be isolated or, more frequently, occur in conjunction with other pituitary hormone deficiencies and midline defects. Genetic mutations of the TBX19 causing isolated CAI are rare but a number of genes encoding transcription factors involved in hypothalamic-pituitary gland development, as well as other genes including POMC and PC1, are associated with ACTH deficiency. CAI is frequently identified in congenital, malformative, genetic, and epigenetic syndromes as well as in several acquired conditions of different etiologies. The signs and symptoms vary considerably and depend on the age of onset and the number and severity of associated pituitary defects. They may include hypoglycemia, lethargy, apnea, poor feeding, prolonged cholestatic jaundice, jitteriness, seizures, and sepsis in the neonate, or nonspecific signs such as fatigue, hypotension, vomiting and hyponatremia without hyperkalemia in children. The diagnosis of CAI relies on the measurement of morning cortisol concentrations along with dynamic test for cortisol release with different stimulating agents. Early recognition of CAI and its correct management are mandatory in order to avoid both morbidity and mortality in affected neonates, children and adolescents.

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.

Impact of transitional care on endocrine and anthropometric parameters in Prader-Willi syndrome

CONTEXT

The transition of patients with Prader-Willi syndrome (PWS) to adult life for medical care is challenging because of multiple comorbidities, including hormone deficiencies, obesity and cognitive and behavioral disabilities.

OBJECTIVE

To assess endocrine management, and metabolic and anthropometric parameters of PWS adults who received (n = 31) or not (n = 64) transitional care, defined as specialized pediatric care followed by a structured care pathway to a multidisciplinary adult team.

PATIENTS AND STUDY DESIGN

Hormonal and metabolic parameters were retrospectively recorded in 95 adults with PWS (mean ± s.d. age 24.7 ± 8.2 years, BMI: 39.8 ± 12.1 kg/m²) referred to our Reference Center and compared according to transition.

RESULTS

Among the entire cohort, 35.8% received growth hormone (GH) during childhood and 16.8% had a GH stimulation test after completion of growth. In adulthood, 14.7% were treated with GH, 56.8% received sex-hormone therapy, whereas 91.1% were hypogonadic and 37.9% had undergone valid screening of the corticotropic axis. The main reason for suboptimal endocrine management was marked behavioral disorders. Patients receiving transitional care were more likely to have had a GH stimulation test and hormonal substitutions in childhood. They also had a lower BMI, percentage of fat mass, improved metabolic parameters and fewer antidepressant treatments. Transitional care remained significantly associated with these parameters in multivariate analysis when adjusted on GH treatment.

CONCLUSION

A coordinated care pathway with specialized pediatric care and transition to a multidisciplinary adult team accustomed to managing complex disability including psychiatric troubles are associated with a better health status in adults 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.

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.

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.

Altered functional resting-state hypothalamic connectivity and abnormal pituitary morphology in children with Prader-Willi syndrome

Background

Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder, characterized by endocrine problems and hyperphagia, indicating hypothalamic-pituitary dysfunction. However, few studies have explored the underlying neurobiology of the hypothalamus and its functional connectivity with other brain regions. Thus, the aim of this study was to examine the anatomical differences of the hypothalamus, mammillary bodies, and pituitary gland as well as resting state functional connectivity of the hypothalamus in children with PWS.

Methods

Twenty-seven children with PWS (13 DEL, 14 mUPD) and 28 typically developing children were included. Manual segmentations by a blinded investigator were performed to determine the volumes of the hypothalamus, mammillary bodies, and pituitary gland. In addition, brain-wide functional connectivity analysis was performed using the obtained masks of the hypothalamus.

Results

Children with PWS showed altered resting state functional connectivity between hypothalamus and right and left lateral occipital complex, compared to healthy controls. In addition, children with PWS had on average a 50% smaller pituitary volume, an irregular shape of the pituitary, and a longer pituitary stalk. Pituitary volume did not increase in volume during puberty in PWS. No volumetric differences in the hypothalamus and mammillary bodies were found. In all subjects, the posterior pituitary bright spot was observed.

Conclusions

We report altered functional hypothalamic connectivity with lateral occipital complexes in both hemispheres, which are implicated in response to food and reward system, and absence of connectivity might therefore at least partially contribute to the preoccupation with food in PWS.

Pituitary-Adrenal Axis in Prader Willi Syndrome

PURPOSE

Prader Willi syndrome (PWS) is a rare genetic condition that has concurrent endocrinological insufficiencies. The presence of growth hormone deficiency has been well documented, but adrenal insufficiency (AI) is not widely reported. A review was conducted to investigate its prevalence and relevance in PWS in both adults and children.

METHODOLOGY

A literature review was performed with the search terms "Prader-Willi syndrome" and "adrenal insufficiency".

RESULTS

The review found studies disagree on the prevalence and method of investigation of AI in PWS. Case studies demonstrate that patients with PWS are at risk of premature death, often secondary to respiratory infections. The possibility that this may be the result of the inability to mount an effective cortisol response has been studied, with some evidence confirming AI in PWS patients. Most reports agreed AI is present in PWS, however, Farholt et al. showed no HPA axis dysfunction in adults, suggesting that perhaps it is rare in adults, and children should be the focus of further studies.

CONCLUSION

AI is present in some patients with PWS. Further research is required to ensure optimal treatment can be implemented and to prevent premature deaths related to adrenal insufficiency. Clinicians should have a low threshold for testing the adrenal axis and considering treatment for adrenal insufficiency in PWS patients.

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

INTRODUCTION

Prader-Willi syndrome (PWS) is a multisystemic complex genetic disorder caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13 region. There are three main genetic subtypes in PWS: paternal 15q11-q13 deletion (65-75 % of cases), maternal uniparental disomy 15 (20-30 % of cases), and imprinting defect (1-3 %). DNA methylation analysis is the only technique that will diagnose PWS in all three molecular genetic classes and differentiate PWS from Angelman syndrome. Clinical manifestations change with age with hypotonia and a poor suck resulting in failure to thrive during infancy. As the individual ages, other features such as short stature, food seeking with excessive weight gain, developmental delay, cognitive disability and behavioral problems become evident. The phenotype is likely due to hypothalamic dysfunction, which is responsible for hyperphagia, temperature instability, high pain threshold, hypersomnia and multiple endocrine abnormalities including growth hormone and thyroid-stimulating hormone deficiencies, hypogonadism and central adrenal insufficiency. Obesity and its complications are the major causes of morbidity and mortality in PWS.

METHODS

An extensive review of the literature was performed and interpreted within the context of clinical practice and frequently asked questions from referring physicians and families to include the current status of the cause and diagnosis of the clinical, genetics and endocrine findings in PWS.

CONCLUSIONS

Updated information regarding the early diagnosis and management of individuals with Prader-Willi syndrome is important for all physicians and will be helpful in anticipating and managing or modifying complications associated with this rare obesity-related disorder.

Evaluation of the hypothalamic-pituitary-adrenal axis and its relationship with central respiratory dysfunction in children with Prader-Willi syndrome

BACKGROUND

Children with Prader-Willi Syndrome (PWS) have been considered at risk for central adrenal insufficiency (CAI). Hypothalamic dysregulation has been proposed as a common mechanism underlying both stress-induced CAI and central respiratory dysfunction during sleep.

OBJECTIVE

To evaluate CAI and sleep-related breathing disorders in PWS children.

PATIENTS AND METHODS

Retrospective study of cortisol response following either insulin tolerance test (ITT) or glucagon test (GT) in 20 PWS children, and comparison with 33 non- Growth Hormone deficient (GHD) controls. Correlation between sleep related breathing disorders and cortisol response in 11 PWS children who received both investigations.

RESULTS

In PWS children, the cortisol peak value showed a significant, inverse correlation with age (Kendall's τ = -0.411; p = 0.012). A similar though non-significant correlation was present between cortisol increase and age (τ = -0.232; p = 0.16). Similar correlations were found in controls. In only 1 of 20 PWS children (5 %), ITT was suggestive of CAI. Four patients had an elevated central apnea index but they all exhibited a normal cortisol response. No relationship was found between peak cortisol or cortisol increase and central apnea index (respectively p = 0.94 and p = 0.14) or the other studied polysomnography (PSG) parameters.

CONCLUSIONS

CAI assessed by ITT/GT is rare in PWS children. Our data do not support a link between CAI and central respiratory dysregulation.

Growth Hormone Therapy in Adults with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is characterized by hyperphagia, obesity if food intake is not strictly controlled, abnormal body composition with decreased lean body mass and increased fat mass, decreased basal metabolic rate, short stature, low muscle tone, cognitive disability, and hypogonadism. In addition to improvements in linear growth, the benefits of growth hormone therapy on body composition and motor function in children with PWS are well established. Evidence is now emerging on the benefits of growth hormone therapy in adults with PWS. This review summarizes the current literature on growth hormone status and the use of growth hormone therapy in adults with PWS. The benefits of growth hormone therapy on body composition, muscle strength, exercise capacity, certain measures of sleep-disordered breathing, metabolic parameters, quality of life, and cognition are covered in detail along with potential adverse effects and guidelines for initiating and monitoring therapy.

Long-term side effects of growth hormone treatment in children with Prader-Willi syndrome

The main motivations of growth hormone (GH) treatment of Prader-Willi syndrome (PWS) are the stimulation of growth and lean muscle mass. Furthermore GH therapy in Prader-Willi children seems to favorably affect their behavior and mental performances. It is still a matter of discussion whether GH therapy in PWS should be considered responsible for specific adverse events. The most significant of them are scoliosis and breathing disorders, the latter considered being responsible for some deaths, reported in children with PWS, mainly at the beginning of GH therapy. Obstructive sleep apnea was occasionally reported also in patients treated with GH for several years. The review reports and discusses the latest data related to side effects of long-term GH treatment in children with PWS.

Prader-Willi syndrome and growth hormone deficiency

Prader-Willi syndrome (PWS) is a rare multisystem genetic disorder demonstrating great variability with changing clinical features during patient's life. It is characterized by severe hypotonia with poor sucking and feeding difficulties in early infancy, followed by excessive eating and gradual development of morbid obesity in later infancy or early childhood. The phenotype is most probably due to hypothalamic dysfunction which is also responsible for growth hormone (GH) and thyroid-stimulating hormone (TSH) deficiencies, central adrenal insufficiency and hypogonadism. The multidimensional problems of patients with PWS can be managed with multidisciplinary approach. Reduced GH secretion, low peak GH response to stimulation, decreased spontaneous GH secretion and low serum IGF-1 levels in PWS patients have been documented in many studies. GH therapy has multiple beneficial effects on growth and body composition, motor and mental development in PWS patients. The recommended dosage for GH is 0.5-1 mg/m2/day. GH therapy should not be started in the presence of obstructive sleep apnea syndrome, adenotonsillar hypertrophy, severe obesity and diabetes mellitus. GH treatment should be considered for patients with genetically confirmed PWS in conjunction with dietary, environmental and life-style measures.

Hypoglycemia in Prader-Willi syndrome

Although mouse models of Prader-Willi syndrome (PWS) suggest that hypoglycemia may be part of this syndrome, review of the literature shows little evidence that it is an issue in humans with PWS. Both adrenal and growth hormone deficiency can be seen in PWS, and both of these hormone deficiencies are associated with increased risk for hypoglycemia. We reviewed medical records for patients with PWS seen at the University of Florida Prader-Willi Program. Children were 2 months to 5 years of age. We recorded the presence, degree, and persistence of hypoglycemia, age of first occurrence, genetic diagnosis, and gestational age. Repeated hypoglycemia was determined if individuals had multiple blood glucose (BG) values <50 mg/dl before 1 month old, or BG levels <50 mg/dl once and additional BG values <70 mg/dl after 1 year of age. Of 95 patient charts reviewed, 12 (12.6%) had recorded hypoglycemia. Six of 12 patients with hypoglycemia had documented BG levels <40 mg/dl. Seven had their first episode of hypoglycemia within the first day of life. Of these seven individuals, five had BG <40 mg/dl. Repeated hypoglycemia was noted in 10 patients (83% of all patients with hypoglycemia). Only two with hypoglycemia had documented adrenal insufficiency. Our study suggests that infants with PWS may be predisposed to hypoglycemia from birth. Additional investigation is necessary to confirm our findings and define the cause of hypoglycemia. If the presence of hypoglycemia is confirmed, early detection and treatment may result in improved neurocognitive outcomes.

Response to growth hormone treatment in Prader-Willi syndrome: auxological criteria versus genetic diagnosis

AIM

The Australian Prader-Willi Syndrome (PWS) database was established to monitor the efficacy and safety of growth hormone (GH) treatment in PWS. This study aims to compare response to GH based on eligibility criteria.

METHODS

Comparative study: 72 children received GH on the basis of short stature or evidence of GH deficiency (pre-2009: PWS-SS) and 94 on a genetic diagnosis (post-2009: PWS-Dx). We report on mandatory patient data for GH prescription: median and standard deviation score (SDS) for height and body mass index (BMI), waist/height ratio, bone age/chronological age ratio and adverse events. Comparisons were made using non-parametric tests.

RESULTS

At baseline, the PWS-SS cohort was shorter (height SDS: -2.6 vs. -1.1, P < 0.001), had a lower BMI (0.6 vs. 1.5 SDS, P < 0.05) and greater bone age delay (bone age/chronological age: 0.7 vs. 0.9, P < 0.05) than the PWS-Dx cohort. PWS-SS parents were shorter (mid-parental height SDS: -0.13 vs. 0.28, P < 0.005). Mean change in height over 2 years was 0.9 SDS and in BMI using PWS reference standards -0.3 SDSPWS (n = 106) (year 2, height SDS: PWS-SS = -1.7, PWS-Dx = 0.1; BMI SDSPWS : PWS-SS = -1.0, PWS-Dx = -0.6). The waist/height ratio reduced (PWS-Dx: 0.60 vs. 0.56, P < 0.05) and bone age delay was unchanged over this period. No serious adverse events were reported.

CONCLUSIONS

The PWS-SS cohort represents a subgroup of the wider PWS-Dx population; however both cohorts improved height SDS with normalisation of height in the PWS-Dx cohort and lowering of BMI relative to PWS standards supporting the efficacy of treatment under the current Australian GH programme.

Current status of growth hormone therapy in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex genetic disorder characterized by muscular hypotonia, hypogonadism, short stature, hyperphagia, obesity, cognitive disabilities and behavioral problems. Body composition is abnormal and growth hormone (GH) secretion is insufficient with more body fat than lean body mass. In children with PWS treatment with GH improves height, head size, body composition and psychomotor functioning. In adults with PWS treatment with GH improves body composition, physical activity and quality of life. However, restricted diet and regular physical exercise are cornerstone treatments in PWS also during GH treatment. GH treatment should be considered in PWS patients with a genetically confirmed diagnosis. Cognitive disabilities and scoliosis are not contraindications to GH treatment. Adverse effects to GH treatment in PWS are few, but glucose metabolism and changes in respiration must be monitored carefully, especially in individuals with predispositions. GH treatment should be continued as long as benefits outweigh the risks.

Central adrenal insufficiency in young adults with Prader-Willi syndrome

OBJECTIVE

A high prevalence (60%) of central adrenal insufficiency (CAI) has been reported in Prader-Willi syndrome (PWS) using the metyrapone test. We have assessed CAI in adults with PWS using the low-dose short synacthen test (LDSST).

DESIGN

Basal cortisol and ACTH, and 30-min cortisol after the administration of 1 μg synacthen, were determined in 53 PWS adults (33 females). A peak cortisol value of ≥500 nmol/l was taken as normal. Hormonal profiles were analysed in relation to gender, genotype and phenotype. Deficient patients were retested by high-dose short synachten test (HDSST) or a repeat LDSST.

RESULTS

Mean ± SD basal cortisol and ACTH were 336·6 ± 140·7 nmol/l and 4·4 ± 3·7 pmol/l respectively. Cortisol rose to 615·4 ± 135·0 nmol/l after LDSST. Eight (15·1%) patients had a peak cortisol response <500 nmol/l, with a lower mean ± SD (range) basal cortisol of 184·9 ± 32·0 (138·0-231·7) compared with 364·1 ± 136·6 (149·0-744·5) in normal responders (P < 0·001). Seven of the eight patients underwent retesting, with 4 (7·5%) showing persistent suboptimal responses. Basal and peak cortisol correlated in females (r = 0·781, P < 0·001). Logistic regression revealed that only female gender and baseline cortisol were predictors of cortisol peaks (adjusted R square 0·505).

CONCLUSIONS

Although CAI can be part of the adult PWS phenotype, it has a lower prevalence (7·5%) than previously reported. Clinicians are advised to test PWS patient for CAI. Our study also shows that basal cortisol is closely correlated with adrenal response to stimulation, indicating that its measurement may be helpful in selecting patients for LDSST.

Endocrine manifestations and management of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex genetic disorder, caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13. In infancy it is characterized by hypotonia with poor suck resulting in failure to thrive. As the child ages, other manifestations such as developmental delay, cognitive disability, and behavior problems become evident. Hypothalamic dysfunction has been implicated in many manifestations of this syndrome including hyperphagia, temperature instability, high pain threshold, sleep disordered breathing, and multiple endocrine abnormalities. These include growth hormone deficiency, central adrenal insufficiency, hypogonadism, hypothyroidism, and complications of obesity such as type 2 diabetes mellitus. This review summarizes the recent literature investigating optimal screening and treatment of endocrine abnormalities associated with PWS, and provides an update on nutrition and food-related behavioral intervention. The standard of care regarding growth hormone therapy and surveillance for potential side effects, the potential for central adrenal insufficiency, evaluation for and treatment of hypogonadism in males and females, and the prevalence and screening recommendations for hypothyroidism and diabetes are covered in detail. PWS is a genetic syndrome in which early diagnosis and careful attention to detail regarding all the potential endocrine and behavioral manifestations can lead to a significant improvement in health and developmental outcomes. Thus, the important role of the provider caring for the child with PWS cannot be overstated.