Effects of recombinant human growth hormone therapy in adults with Prader-Willi syndrome: a meta-analysis

Long-term effects of GH therapy in adult patients with Prader-Willi syndrome: a longitudinal study

Introduction

Prader-Willi syndrome (PWS) is a complex disorder resulting from the failure of expression of paternal alleles in the PWS region of chromosome 15. The PWS phenotype resembles that observed in the classic non-PWS GH deficiency (GHD), including short stature, excessive fat mass, and reduced muscle mass. To date, a small number of studies on the long-term effects of GH treatment are available in adult subjects with PWS.

Methods

In this longitudinal study, 12 obese subjects with PWS (GHD/non-GHD 6/6) were treated for a median of 17 years, with a median GH dose of 0.35 mg/day. The median age was 27.1 years. Anthropometric, body composition, hormonal, biochemical, and blood pressure variables were analyzed in all subjects.

Results

Waist circumference was significantly lower at the end of the treatment period (p-value=0.0449), while body mass index (BMI) did not differ significantly. Compared to the baseline, a highly significant reduction of Fat Mass % (FM%) was observed (p-value=0.0005). IGF-I SDS values significantly increased during GH therapy (p-value=0.0005). A slight impairment of glucose homeostasis was observed after GH therapy, with an increase in the median fasting glucose levels, while insulin, HOMA-IR, and HbA1c values remained unchanged. Considering GH secretory status, both subjects with and without GHD showed a significant increase in IGF-I SDS and a reduction of FM% after GH therapy (p-value= 0.0313 for all).

Discussion

Our results indicate that long-term GH treatment has beneficial effects on body composition and body fat distribution in adults with PWS associated with obesity. However, the increase in glucose values during GH therapy should be considered, and continuous surveillance of glucose metabolism is mandatory during long-term GH therapy, especially in subjects with obesity.

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.

Endocrine and Metabolic Illnesses in Young Adults with Prader-Willi Syndrome

Prader−Willi syndrome (PWS) is a rare genetic disorder characterized by an insatiable appetite that leads to morbid obesity. Previous studies reported health problems in adults with PWS. However, studies on younger adults are lacking, and there are no specific studies of endocrine and metabolic illness in this age group. We performed a retrospective cohort study of 68 individuals with PWS aged 19 to 34 years at Samsung Medical Center. The prevalence of endocrine and metabolic illnesses were compared with those in an age-, sex-, and BMI-matched healthy control group. Young adults with PWS had a higher prevalence of metabolic syndrome (35.3% vs. 4.4%), type 2 diabetes mellitus (50.0% vs. 5.4%), hypertension (30.8% vs. 16.1%), dyslipidemia (38.2% vs. 14.7%), decreased bone density (26.4% vs. 0.9%), and sleep apnea (32.3% vs. 4.4%) than controls (all p < 0.05). The PWS group that maintained recombinant human growth (rhGH) treatment in adulthood had a lower probability of having a BMI ≥ 30 at the last follow-up (odds ratio = 0.106 (0.012−0.948), p = 0.045). Endocrine and metabolic illnesses in individuals with PWS may have already started in the early teens; therefore, appropriate screening and early intervention are important. Better understanding of the natural history of PWS and age-related complications will lead to better-quality medical care for individuals with PWS.

Do patients with Prader-Willi syndrome have favorable glucose metabolism?

Background

In recent years, more studies have observed that patients with Prader–Willi syndrome have lower insulin levels and lower insulin resistance than body mass index-matched controls, which may suggest protected glucose metabolism.

Method

The PubMed and Web of Science online databases were searched to identify relevant studies published in the English language using the terms “Prader–Willi syndrome” with “glucose”, “insulin”, “diabetes mellitus”, “fat”, “adipo*”, “ghrelin”, “oxytocin”, “irisin” or “autonomic nervous system”.

Results

The prevalence of impaired glucose intolerance, type 2 diabetes mellitus and some other obesity-associated complications in patients with Prader–Willi syndrome tends to be lower when compared to that in general obesity, which is consistent with the hypothetically protected glucose metabolism. Factors including adipose tissue, adiponectin, ghrelin, oxytocin, irisin, growth hormone and the autonomic nervous system possibly modulate insulin sensitivity in patients with Prader–Willi syndrome.

Conclusion

Although lower insulin levels, lower IR and protected glucose metabolism are widely reported in PWS patients, the causes are still mysterious. Based on existing knowledge, we cannot determine which factor is of utmost importance and what are the underlying mechanisms, and further research is in urgent need.

Magnetically actuating implantable pump for the on-demand and needle-free administration of human growth hormone

A bolus of human growth hormone (hGH) is often prescribed for the treatment of growth hormone deficiency, which requires frequent injections in current clinical settings. This painful needle-involved delivery often results in poor patient compliance, leading to low medication adherence and poor clinical outcomes. Therefore, we propose a magnetically actuating implantable pump (MAP) that can infuse an accurate dose of hGH only at the time of non-invasive magnet application from the skin. The MAP herein could reproducibly infuse 20.6 ± 0.9 μg hGH per actuation without any leak at times without actuation. The infused amount increased proportionally with an increase in the number of actuations. When the MAP was implanted and actuated with a magnet in animals with growth hormone deficiency for 21 days, the profiles of plasma hGH concentration and insulin-like growth factor (IGF)-1, as well as changes in body weight, were similar to those observed in animals treated with conventional subcutaneous hGH injections. Therefore, we anticipate that the MAP fabricated in this study can be a non-invasive alternative to administer hGH without repeated and frequent needle injections.

Hypothalamic syndrome

Hypothalamic syndrome (HS) is a rare disorder caused by disease-related and/or treatment-related injury to the hypothalamus, most commonly associated with rare, non-cancerous parasellar masses, such as craniopharyngiomas, germ cell tumours, gliomas, cysts of Rathke's pouch and Langerhans cell histiocytosis, as well as with genetic neurodevelopmental syndromes, such as Prader-Willi syndrome and septo-optic dysplasia. HS is characterized by intractable weight gain associated with severe morbid obesity, multiple endocrine abnormalities and memory impairment, attention deficit and reduced impulse control as well as increased risk of cardiovascular and metabolic disorders. Currently, there is no cure for this condition but treatments for general obesity are often used in patients with HS, including surgery, medication and counselling. However, these are mostly ineffective and no medications that are specifically approved for the treatment of HS are available. Specific challenges in HS are because the syndrome represents an adverse effect of different diseases, and that diagnostic criteria, aetiology, pathogenesis and management of HS are not completely defined.

One Year of Recombinant Human Growth Hormone Treatment in Adults with Prader-Willi Syndrome Improves Body Composition, Motor Skills and Brain Functional Activity in the Cerebellum

We compared body composition, biochemical parameters, motor function, and brain neural activation in 27 adults with Prader-Willi syndrome and growth-hormone deficiency versus age-and sex-matched controls and baseline versus posttreatment values of these parameters after one year of recombinant human growth hormone (rhGH) treatment. To study body composition, we analyzed percentage of fat mass, percentage of lean mass, and muscle-mass surrogate variables from dual X-ray absorptiometry. Biochemical parameters analyzed included IGF-I, glucose metabolism, and myokines (myostatin, irisin, and IL6). To explore muscle function, we used dynamometer-measured handgrip strength, the Timed Up and Go (TUG) test, and the Berg Balance Scale (BBS). To study brain activation, we acquired functional magnetic resonance images during three motor tasks of varying complexity. After one year of treatment, we observed an increase in lean mass and its surrogates, a decrease in fat mass, improvements in TUG test and BBS scores, and increased neural activation in certain cerebellar areas. The treatment did not significantly worsen glucose metabolism, and no side-effects were reported. Our findings support the benefits of rhGH treatment in adults with Prader-Willi syndrome and growth-hormone deficiency on body composition and suggest that it may also improve balance and brain neural activation.

Circulating insulin-like growth factor 1 levels are reduced in very young children with Prader-Willi syndrome independent of anthropometric parameters and nutritional status

OBJECTIVE

Insulin growth factor-1 (IGF-1) is used to evaluate growth hormone (GH) sufficiency and is decreased in children with Prader-Willi syndrome (PWS). Although IGF-1 is negatively affected by body size and nutritional status, both of which are impaired in PWS children, these variables are typically not considered when assessing IGF-1 levels in these subjects. Here, we compared IGF-1 levels in PWS children to controls matched for age, sex, anthropometric parameters, and nutritional status.

DESIGN/PATIENTS/MEASUREMENTS

The retrospective analysis included genetically diagnosed PWS subjects (n = 65, median age; 14.0 months) and controls (n = 111, 14.3 months) matched for age, sex, anthropometric parameters (height-standard deviation score [SDS], weight-SDS, body mass index-SDS), and serum albumin levels, a marker for nutritional status. IGF-1 SDS was compared between PWS subjects and controls after adjustment for confounding variables. The GH provocation test was performed in 29 PWS subjects, and IGF-1 SDS was compared between GH-sufficient (n = 20) and GH-deficient (n = 9) subjects. Spearman's rank correlation coefficient was performed to investigate the association between age and IGF-1 SDS. None had received GH or levothyroxine treatment.

RESULTS

After adjustment for confounding variables, IGF-1 SDS was significantly lower in PWS subjects than controls (-1.56 vs. -1.01, p = .003), while it was not different between GH-sufficient and GH-deficient PWS subjects. Correlation analysis failed to show an association between age and IGF-1 SDS both in control and PWS groups.

CONCLUSIONS

IGF-1 SDS is lower in very young children with PWS independent of anthropometric parameters and nutritional status, suggesting the presence of hypothalamic dysfunction of GH secretion.

Diabetes Mellitus in Prader-Willi Syndrome: Natural History during the Transition from Childhood to Adulthood in a Cohort of 39 Patients

Type 2 diabetes mellitus (T2DM) affects 20% of patients with Prader-Willi syndrome (PWS), with many cases diagnosed during the transition period. Our aim was to describe the natural history of T2DM in patients with PWS before the age of 25 years and to develop screening and preventive strategies. Thirty-nine patients followed in the French PWS Reference Center were included (median age 25.6 years [23.7; 31.7]). Twenty-one had been treated with growth hormone (GH), fifteen had not, and three had an unknown status. The median age at T2DM diagnosis was 16.8 years (11–24) and the median BMI was 39 kg/m² [34.6; 45], with 34/35 patients living with obesity. The patients displayed frequent psychiatric (48.3% hospitalization,) and metabolic (56.4% hypertriglyceridemia,) comorbidities and a parental history of T2DM (35.7%) or overweight (53.6%) compared to the PWS general population. There was no difference in BMI and metabolic complications between the GH-treated and non-GH-treated groups at T2DM diagnosis. Patients with PWS who develop early T2DM have severe obesity, a high frequency of psychiatric and metabolic disorders, and a family history of T2DM and overweight. These results underline the need for early identification of patients at risk, prevention of obesity, and repeated blood glucose monitoring during the transition period.

Food-Related Brain Activation Measured by fMRI in Adults with Prader-Willi Syndrome

(1) Background: Prader–Willi syndrome (PWS) is characterized by hyperphagia, resulting in morbid obesity if not controlled. The primary aim of this study was to investigate whether PWS patients show altered activation of brain areas involved in hunger. As a secondary objective, we assessed whether there is an association between these brain areas and several endocrine and metabolic factors in the fasting state. (2) Methods: 12 PWS adults and 14 healthy controls (siblings) performed a food-related experimental task after an overnight fast while brain activation in regions of interest was measured by functional MRI. (3) Results: In controls, significantly more activation was found in the left insula (p = 0.004) and the bilateral fusiform gyrus (p = 0.003 and 0.013) when the individuals were watching food as compared to non-food pictures, which was absent in PWS patients. Moreover, in PWS adults watching food versus non-food pictures a significant negative correlation for glucose and right amygdala activation (p_fwe = 0.007) as well as a positive correlation for leptin and right anterior hippocampus/amygdala activation (p_fwe = 0.028) was demonstrated. No significant associations for the other hormonal and metabolic factors were found. (4) Conclusions: PWS individuals show aberrant food-related brain activation in the fasting state. Leptin is associated with activation within the neural motivation/reward circuitry, while the opposite is true for glucose.

Growth Hormone Treatment for Adults With Prader-Willi Syndrome: A Meta-Analysis

CONTEXT

Features of Prader-Willi syndrome (PWS) overlap with features of growth hormone (GH) deficiency, like small hands and feet, short stature, increased body fat, and low muscle mass and strength. In children with PWS, GH treatment (GHt) improves physical health and cognition. GHt has become the standard of care in PWS children, but in adults this is not yet the case.

OBJECTIVE

This work aims to provide an overview of the current knowledge on GHt in PWS adults.

METHODS

Medline, Embase, and the Cochrane Central Register of Controlled Trials databases were searched. Study selection included randomized clinical trials (RCTs) and nonrandomized (un)controlled trials (NRCTs) that reported data for adults with PWS, who received GHt for at least 6 months. Data on body composition, body mass index (BMI), cardiovascular end points, bone, cognitive function, quality of life, and safety were extracted.

RESULTS

Nine RCTs and 20 NRCTs were included. Body composition improved during 12 months of GHt with an increase in mean (95% CI) lean body mass of 1.95 kg (0.04 to 3.87 kg) and a reduction of mean (95% CI) fat mass of -2.23% (-4.10% to -0.36%). BMI, low-density lipoprotein cholesterol levels, fasting glucose levels, and bone mineral density did not change during GHt. There were no major safety issues.

CONCLUSION

GHt appears to be safe and improves body composition in adults with PWS. Because poor body composition is closely linked to the observed high incidence of cardiovascular morbidity in adults with PWS, improving body composition might reduce cardiovascular complications in this vulnerable patient group.

Effects of Childhood Multidisciplinary Care and Growth Hormone Treatment on Health Problems in Adults with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a complex hypothalamic disorder. Features of PWS include hyperphagia, hypotonia, intellectual disability, and pituitary hormone deficiencies. The combination of growth hormone treatment and multidisciplinary care (GHMDc) has greatly improved the health of children with PWS. Little is known about the effects of childhood GHMDc on health outcomes in adulthood. We retrospectively collected clinical data of 109 adults with PWS. Thirty-nine had received GHMDc during childhood and adolescence (GHMDc+ group) and sixty-three had never received growth hormone treatment (GHt) nor multidisciplinary care (GHMDc− group). Our systematic screening revealed fewer undetected health problems in the GHMDc+ group (10%) than in the GHMDc− group (84%). All health problems revealed in the GHMDc+ group had developed between the last visit to the paediatric and the first visit to the adult clinic and/or did not require treatment. Mean BMI and the prevalence of diabetes mellitus type 2 were significantly lower in the GHMDc+ group compared to the GHMDc− group. As all patients who received GHt were treated in a multidisciplinary setting, it is unknown which effects are the result of GHt and which are the result of multidisciplinary care. However, our data clearly show that the combination of both has beneficial effects. Therefore, we recommend continuing GHMDc after patients with PWS have reached adult age.

Growth Hormone (GH) Treatment Decreases Plasma Kisspeptin Levels in GH-Deficient Adults with Prader-Willi Syndrome

Obesity and growth hormone (GH)-deficiency are consistent features of Prader-Willi syndrome (PWS). Centrally, kisspeptin is involved in regulating reproductive function and can stimulate hypothalamic hormones such as GH. Peripherally, kisspeptin signaling influences energy and metabolic status. We evaluated the effect of 12-month GH treatment on plasma kisspeptin levels in 27 GH-deficient adult PWS patients and analyzed its relationship with metabolic and anthropometric changes. Twenty-seven matched obese subjects and 22 healthy subjects were also studied. Before treatment, plasma kisspeptin concentrations in PWS and obese subjects were similar (140.20 (23.5-156.8) pg/mL vs. 141.96 (113.9-165.6) pg/mL, respectively, p = 0.979)) and higher (p = 0.019) than in healthy subjects (124.58 (107.3-139.0) pg/mL); plasma leptin concentrations were similar in PWS and obese subjects (48.15 (28.80-67.10) ng/mL vs. 33.10 (20.50-67.30) ng/mL, respectively, p = 0.152) and higher (p < 0.001) than in healthy subjects (14.80 (11.37-67.30) ng/mL). After GH therapy, lean body mass increased 2.1% (p = 0.03), total fat mass decreased 1.6% (p = 0.005), and plasma kisspeptin decreased to levels observed in normal-weight subjects (125.1(106.2-153.4) pg/mL, p = 0.027). BMI and leptin levels remained unchanged. In conclusion, 12-month GH therapy improved body composition and decreased plasma kisspeptin in GH deficient adults with PWS. All data are expressed in median (interquartile range).

Twenty Years of GH Treatment in Adults with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a rare neurodevelopmental genetic disorder. In adults, the syndrome is characterised by muscular hypotonia, a different body composition with more body fat than muscle mass, hyperphagia, behavioural problems, and cognitive dysfunction. Endocrine deficiencies are common, including growth hormone (GH) deficiency. Here, we present data from a cross-sectional study in adults with PWS with a focus on the long-term safety of GH treatment. A total of 22 patients (14 men) were treated with GH for a median of 20 years. Data on body composition, hormones, and metabolic parameters were retrieved from the patients’ medical records. The median age was 27 years. The median GH dose was 0.5 mg/day. Insulin-like growth factor 1 (IGF-I) and blood lipids were normal, while fasting glucose and HbA1c were slightly elevated in three men with diabetes. Fat mass was less than fat free mass in all, though this was less pronounced in women. GH treatment did not negatively affect the metabolic profile, and none developed cardiovascular diseases or cancer. All adults on long-term GH treatment had a normal body composition and our results indicate that treatment was safe. However, PWS is a complex, multisystemic disease and continuous, individual considerations are required during GH treatment, especially in patients with risk factors for adverse effects.

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.

The use of growth hormone therapy in adults with Prader-Willi syndrome: A systematic review

OBJECTIVE

Despite clear benefits in the management of children with Prader-Willi syndrome (PWS), the role of growth hormone (GH) in adults is unclear. The aim of this study was to conduct a systematic review to evaluate the effects of GH on body composition, bone health and cardiovascular health in adults with PWS.

DESIGN

A systematic computerized literature search of the PubMed database was conducted by two independent reviewers. Inclusion criteria were individuals over the age of 16 years with a genetic diagnosis of PWS who had received GH therapy, together with assessment of body composition, bone health or cardiovascular health.

RESULTS

Twenty full-text papers met the inclusion criteria, encompassing 364 unique patients. No differences in body mass index (BMI) were noted, although 2 studies reported increased BMI after GH cessation. Data demonstrated statistically significant increases in lean body mass and reductions in percentage fat mass. Studies reported inconsistent effects of GH on cholesterol and echocardiography parameters. No studies reported differences in bone mineral density, although one reported improved bone geometry. Minor adverse events including pretibial oedema, headache and transient impaired glucose tolerance were reported in 7 studies.

CONCLUSIONS

These data suggest that GH is safe and well tolerated in adults with PWS, with evidence of improvement in body composition. Further longitudinal studies are still required to investigate the effects of GH on bone and cardiovascular health. Where GH is used in adults with PWS, this should be managed by a specialist multidisciplinary team with regular monitoring initiated.

Characteristics and relationship between hyperphagia, anxiety, behavioral challenges and caregiver burden in Prader-Willi syndrome

Objectives

Prader-Willi syndrome (PWS) is a rare genetic disorder characterized by maladaptive behaviors, amongst which hyperphagia is a life-long concern for individuals with PWS and their caregivers. The current study examined the contribution of hyperphagia and other factors to caregiver burden across lifespan, in 204 caregivers of individuals with PWS living in the US, using the Zarit Burden Interview (ZBI) and the hyperphagia questionnaire (HQ-CT).

Results

We found a strong relationship between ZBI and HQ-CT especially in individuals with PWS older than 4 y and showed that HQ-CT scores of individuals with PWS is positively correlated with ZBI scores of their caregivers. The weight status of individuals with PWS was not associated with HQ-CT and ZBI scores, except for obese individuals who had significantly higher HQ-CT scores when compared to normal weight PWS individuals. We looked at PWS symptoms and care-related issues that impacted individuals and caregivers the most. We found that care-related tasks had the biggest negative impact on caregivers of children aged 0–4 y, whereas anxiety, temper tantrums, and oppositional behaviors of older individuals with PWS had the biggest impact on their caregivers concomitant with their high caregiver burden. Finally, we assessed the variability of HQ-CT and ZBI over 6 months in a subgroup of 83 participants. Overall, neither measure differed between 6 months and baseline. Most individual’s absolute HQ-CT score changes were between 0–2 units, whereas absolute ZBI score changes were between 0–6 points. Changes in the caregiver’s or individual’s life had little or no effect on HQ-CT and ZBI scores.

Conclusions

This study demonstrates a relationship between hyperphagia and caregiver burden and sheds light on predominant symptoms in children and adolescents that likely underly PWS caregiver burden. The stability and relationship between HQ-CT and ZBI support ZBI as an additional outcome measure in PWS clinical trials.

Time for a general approval of growth hormone treatment in adults with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex, multi-system, neurodevelopmental disorder characterised by neonatal muscular hypotonia, short stature, high risk of obesity, hypogonadism, intellectual disabilities, distinct behavioural/psychiatric problems and abnormal body composition with increased body fat and a deficit of lean body mass. Growth hormone (GH) deficiency and other hormone deficiencies are common due to hypothalamic dysfunction. In children with PWS GH treatment has been widely demonstrated to improve body composition, normalise height and improve psychomotor development. In adults with PWS, GH's main effects are to maintain normal body structure and metabolism. The positive effects of GH treatment on body composition, physical fitness and beneficial effects on cardiovascular risk markers, behaviour and quality of life in adults with PWS are also well established from several studies. GH treatment is approved for treatment of children with PWS in many countries, but until recently not as a treatment in young adults in the transition period or for adults in general. In this commentary we want to draw attention to the uneven global use of GH treatment, specifically in adults with PWS, and advocate for GH treatment to be approved internationally, not just for children, but also for adults with PWS and based only on the diagnosis of genetically confirmed PWS.

Effects of growth hormone on cognitive, motor, and behavioral development in Prader-Willi syndrome children: a meta-analysis of randomized controlled trials

PURPOSE

The benefits of growth hormone (GH) therapy in Prader-Willi syndrome (PWS) children are well established, but there is still considerable controversy regarding whether GH treatment can improve cognitive, motor, and behavioral development in PWS children. The objectives of this meta-analysis were to quantitatively evaluate the effects of GH on cognitive, motor function, and behavioral development in PWS children.

METHODS

Randomized controlled trials (RCTs) examining the effects of GH on cognitive, motor, and behavioral development in PWS children were identified by searching the MEDLINE, EMBASE, and Cochrane Library databases. Intervention effects were represented by Hedges'g and pooled to calculate effect sizes using a random-effects model.

RESULTS

Ten relevant studies comprising data from 302 participants were finally included. We observed no significant difference in cognitive performance between the GH treatment group and the control group (p = 0.197). GH treatment was shown to remarkably improve motor development in PWS children compared with the control treatment (p < 0.001), with moderate positive treatment effects (Hedges'g [95% CI] = 0.71 [0.38, 1.03]). There were no significant differences between the GH group and the control group based on objective assessments of behavioral development (p = 0.53).

CONCLUSIONS

The meta-analysis suggested that GH treatment had a significantly positive effect on motor development, with moderate treatment effects in PWS children; however, there was no evidence of effects on cognitive or behavioral development.

Visceral adipose tissue resides within the reference range in children with Prader-Willi syndrome receiving nutritional intervention on a regular basis

Nutritional intervention for maintaining an appropriate body composition is central to the management of Prader-Willi syndrome (PWS). Despite evidence that visceral adipose tissue (VAT) is associated with increased metabolic risks, the effects of nutritional intervention on fat distribution have not been evaluated for PWS children. We herein investigated fat distribution in 20 genetically diagnosed PWS children (9 males and 11 females); 17 of which received nutritional intervention with or without growth hormone (GH) treatment [GH-treated group (n = 8), GH-untreated group (n = 9)]. GH treatment continued for median of 4.9 years. GH treatment significantly increased height standard deviation score (SDS) whereas body weight SDS and body mass index SDS were not affected in GH-treated group. In GH-untreated group, height SDS significantly decreased during approximately 5 years of follow-up. Fat distribution was evaluated at the median age of 6.93 years in GH-treated group and 7.01 years in GH-untreated group. VAT was maintained within the reference range in both groups. Subcutaneous adipose tissue (SAT) was elevated in GH-untreated groups compared to reference values whereas it was not in GH-treated group. The remaining three subjects, who had never received nutritional intervention or GH treatment, showed increased VAT and SAT. In conclusion, nutritional intervention is beneficial in maintaining VAT within the reference range during childhood, although excessive nutritional intervention may cause unfavorable effect on linear growth.

Three years of growth hormone treatment in young adults with Prader-Willi Syndrome previously treated with growth hormone in childhood: Effects on glucose homeostasis and metabolic syndrome

CONTEXT

Growth hormone (GH) has been approved for children with Prader-Willi syndrome (PWS) and significantly improves body composition in adults with PWS. Adults with PWS are predisposed to develop impaired glucose tolerance (IGT) and diabetes mellitus type 2 (DMT2). Continuation of GH maintains body composition, but GH is known to induce insulin resistance, which might affect glucose homeostasis. Studies on long-term effects of GH treatment in adults are very limited.

OBJECTIVE

To investigate effects of 3 years of GH treatment on glucose homeostasis and prevalence of metabolic syndrome (MS) in adults with PWS.

DESIGN

Open-label, prospective study.

PATIENTS

43 young adults with PWS.

SETTING

Dutch PWS Reference Center.

MAIN OUTCOME MEASURES

Glucose and insulin during oral glucose tolerance test.

RESULTS

Estimated mean (95% CI) fasting glucose and insulin levels remained stable during 3 years of GH treatment. Glucose being 4.6 (4.4-4.8) mmol/l at start and 4.7 (4.6-4.9) mmol/l after 3 years (P = .07); insulin being 59.5 (45.2-75.8) pmol/l and 56.7 (45.2-69.6) pmol/l resp. (P = .72). Sex, ethnicity and fat mass percentage were significantly associated with fasting glucose levels, while IGF-I or GH-dose were not. Blood pressure, lipids and prevalence of MS remained stable during 3 years of GH. IGT prevalence was variable over time, six patients had IGT at start and eleven after 3 years of GH. One patient developed DMT2. However, prevalence of IGT or DMT2 was not significantly higher after 3 years than at study start.

CONCLUSIONS

Three years of GH treatment in adults with PWS does not impair glucose homeostasis and does not lead to an increased prevalence of DMT2.

Caring and living with Prader-Willi syndrome in Italy: integrating children, adults and parents' experiences through a multicentre narrative medicine research

OBJECTIVES

Prader-Willi syndrome (PWS) significantly impacts health-related quality of life; however, its relational and existential aspects remain unknown in Italian clinical and social debate. The project aimed to investigate the impact of PWS on illness experience through narrative medicine (NM) to understand the daily life, needs and resources of patients with PWS and their caregivers, and to furnish insights for clinical practice.

DESIGN AND SETTING

The project involved 10 medical centres of the Italian Network for Rare Diseases and PWS family associations and targeted underage and adult patients with PWS and their caregivers. Written interviews, composed by a sociodemographic survey and a narrative, were collected through the project's website. Three dedicated illness plots employed evocative and open words to facilitate individual expression and to encourage reflection. Narratives were analysed through NVivo software. Researchers discussed the results with the project's steering committee.

PARTICIPANTS

Twenty-one children and adolescents and 34 adults with PWS joined the project, as well as 138 caregivers. A PWS diagnosis or the caregiving of a patient with PWS older than 5 years represented the eligibility criteria, as well as the willingness to share their illness experience by writing and the ability to communicate in Italian.

RESULTS

The analysis of narratives led to understanding the PWS social and relational issues concerning diagnosis and current management, PWS daily experiences and social contexts, PWS implications in the working sphere and participants' future perspectives. Narratives demonstrated that PWS management affects relationships and work-life balance and that social stigma remains present.

CONCLUSION

The project represented the first effort to investigate the impact of PWS on illness experience in Italy through NM while considering the perspectives of patients with PWS and their caregivers. The findings indicated that a multiprofessional approach is fundamental to ensure adequate treatment and provided elements for its improvement.

Update on Diabetes Mellitus and Glucose Metabolism Alterations in Prader-Willi Syndrome

PURPOSE OF REVIEW

This review summarizes our current knowledge on type 2 diabetes mellitus (T2DM) and glucose metabolism alterations in Prader-Willi syndrome (PWS), the most common syndromic cause of obesity, and serves as a guide for future research and current best practice.

RECENT FINDINGS

Diabetes occurs in 10-25% of PWS patients, usually in adulthood. Severe obesity is a significant risk factor for developing of T2DM in PWS. Paradoxically, despite severe obesity, a relative hypoinsulinemia, without the expected insulin resistance, is frequently observed in PWS. The majority of PWS subjects with T2DM are asymptomatic and diabetes-related complications are infrequent. Long-term growth hormone therapy does not adversely influence glucose homeostasis in all ages, if weight gain does not occur. Early intervention to prevent obesity and the regular monitoring of glucose levels are recommended in PWS subjects. However, further studies are required to better understand the physiopathological mechanisms of T2DM in these patients.

Physical exercise and Prader-Willi syndrome: A systematic review

OBJECTIVE

The aim of this systematic review was to summarize evidence on the acute responses of individuals with Prader-Willi syndrome (PWS) to physical exercise, and on the effectiveness of long-term exercise interventions to improve the clinical manifestations of this syndrome.

DESIGN/METHODS

Relevant articles were identified in the electronic databases PubMed, Medline, CINAHL and SPORTDiscus (from inception to December 2018). Twenty-two studies including a total of 356 patients with PWS met all inclusion criteria and were included in the review.

RESULTS

Patients with PWS present with a decreased physical performance and impaired cardiorespiratory (maximal oxygen consumption, heart rate recovery after exercise) and hormonal (growth hormone release) responses to exercise. Most long-term exercise interventions have proven to decrease body mass while improving physical performance. Some benefits have also been reported in biochemical (glucose homeostasis, lipid profile) and biomechanical (gait pattern) variables, although there is controversy regarding the effects on body composition. No exercise-related adverse events have been reported in patients with PWS.

CONCLUSION

Physical exercise seems to be safe and effective for improving several phenotypes in PWS, notably physical fitness. However, further research is needed to confirm these results and especially to corroborate whether exercise per se or combined with dietary intervention is an effective coadjuvant treatment for reducing body mass in these patients.

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.

Characterization of a novel method for the production of single-span membrane proteins in Escherichia coli

The large‐scale production and isolation of recombinant protein is a central element of the biotechnology industry and many of the products have proved extremely beneficial for therapeutic medicine. Escherichia coli is the microorganism of choice for the expression of heterologous proteins for therapeutic application, and a range of high‐value proteins have been targeted to the periplasm using the well characterized Sec protein export pathway. More recently, the ability of the second mainstream protein export system, the twin‐arginine translocase, to transport fully‐folded proteins into the periplasm of not only E. coli, but also other Gram‐negative bacteria, has captured the interest of the biotechnology industry.

In this study, we have used a novel approach to block the export of a heterologous Tat substrate in the later stages of the export process, and thereby generate a single‐span membrane protein with the soluble domain positioned on the periplasmic side of the inner membrane. Biochemical and immuno‐electron microscopy approaches were used to investigate the export of human growth hormone by the twin‐arginine translocase, and the generation of a single‐span membrane‐embedded variant. This is the first time that a bonafide biotechnologically relevant protein has been exported by this machinery and visualized directly in this manner. The data presented here demonstrate a novel method for the production of single‐span membrane proteins in E. coli.

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.

Visceral adipose tissue increases shortly after the cessation of GH therapy in adults with Prader-Willi syndrome

GH therapy in pediatric patients with Prader-Willi syndrome (PWS) improves body composition, but discontinuation of GH after achieving adult height has been implicated in its deterioration. Although there is evidence for the deleterious effects of visceral adipose tissue (VAT) rather than subcutaneous adipose tissue (SAT) on the development of obesity-related complications, the effects of GH discontinuation on fat distribution in adults with PWS has not been fully investigated. Therefore, we utilized dual-energy X-ray absorptiometry (DEXA) and abdominal computed tomography (CT) to compare the fat distribution between before and 6 months or 12 months after the cessation of GH therapy in 7 adult PWS patients. GH therapy was initiated at a mean age of 4.1 ± 1.4 years and discontinued at a mean age of 18.9 ± 1.8 years. Serum IGF-1 levels were decreased by discontinuation of GH therapy. Fat mass was significantly increased 6 and 12 months after GH cessation, whereas muscle mass and bone mineral density were unchanged during both study periods. Abdominal CT analysis revealed that elevations in fat mass were due to increases in VAT rather than SAT. Circulating low-density lipoprotein (LDL) cholesterol levels were significantly elevated 6 months after GH cessation. In conclusion, discontinuation of GH therapy caused rapid increases in visceral adipose tissue and LDL cholesterol levels. These findings indicate that continuation of GH therapy may be a therapeutic option to maintain body composition; however, further studies regarding the long-term benefits and adverse effects of GH therapy in adults with PWS are required.

Analysis of Circulating Mediators of Bone Remodeling in Prader-Willi Syndrome

We tested the hypothesis that the levels of bone remodeling mediators may be altered in Prader-Willi syndrome (PWS). We assessed RANKL, OPG, sclerostin, DKK-1 serum levels, and bone metabolism markers in 12 PWS children (7.8 ± 4.3 years), 14 PWS adults (29.5 ± 7.2 years), and 31 healthy controls matched for sex and age. Instrumental parameters of bone mineral density (BMD) were also evaluated. Lumbar spine BMD Z-scores were reduced in PWS children (P < 0.01), reaching osteopenic levels in PWS adults. PWS patients showed lower 25(OH)-vitamin D serum levels than controls (P < 0.001). Osteocalcin was increased in PWS children but reduced in adults respect to controls (P < 0.005 and P < 0.01, respectively). RANKL levels were higher in both pediatric and PWS adults than controls (P < 0.004), while OPG levels were significantly reduced (P < 0.004 and P < 0.006, respectively). Sclerostin levels were increased in children (P < 0.04) but reduced in adults compared to controls (P < 0.01). DKK-1 levels did not show significant difference between patients and controls. In PWS patients, RANKL, OPG, and sclerostin significantly correlated with metabolic and bone instrumental parameters. Consistently, with adjustment for age, multiple linear regression analysis showed that BMD and osteocalcin were the most important predictors for RANKL, OPG, and sclerostin in children, and GH and sex steroid replacement treatment in PWS adults. We demonstrated the involvement of RANKL, OPG, and sclerostin in the altered bone turnover of PWS subjects suggesting these molecules as markers of bone disease and new potential pharmacological targets to improve bone health in 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.

High levels of caregiver burden in Prader-Willi syndrome

Objectives

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder that is characterized by hyperphagia, developmental delay, incomplete sexual development, mild-to-moderate intellectual disability, and a variety of challenging behavioral and psychiatric symptoms. The characteristics of PWS can be difficult for caregivers to cope with and are likely to cause significant and long- term caregiver burden. The current study examined burden in 142 caregivers of children and adults with PWS living in the US using the Zarit Burden Interview (ZBI). The study aimed to measure the level of burden in caregivers of individuals with PWS, to explore the impact of PWS on caregiver quality of life, and to assess ZBI as an indicator of that impact.

Results

Caregivers participating in this study were predominantly mothers, 30–59 years old, non-Hispanic Whites, married or in a relationship, with an annual household income slightly distributed towards higher income. Nearly 90% of the caregiver`s children with PWS lived at home. Caregivers experienced high caregiver burden with an average ZBI score of 44.4 ± 15.4. ZBI scores were highest for caregivers of teenage and young adult individuals with PWS (49.2 ± 14.6 and 49.2 ± 14.1, respectively), while those caring for older adults (>30) and the youngest age group had lower scores (38.6 ±10.5 and 34.8 ±12.5, respectively). Caregivers reported that caring for a person with PWS negatively impacted their romantic relationship, ability to work, sleep, and mood. Whereas we did not find strong correlations between family income or level of help the caregiver receives and ZBI scores, the results showed significant correlations and a linear relationship between ZBI scores and caregiver depressed mood, feelings of anxiety, negative romantic relationship impact, as well as sleep and work disruption.

Conclusions

Our study reveals that PWS incurs high caregiver burden and impacts many aspects of the lives of caregiver. We identified the ZBI as a good predictor of that impact. Our findings draw attention to the critical unmet need for support for caregivers of individuals with PWS.

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.

Body composition, adipokines, bone mineral density and bone remodeling markers in relation to IGF-1 levels in adults with Prader-Willi syndrome

Background

In patients with Prader-Willi syndrome (PWS) body composition is abnormal and alterations in appetite regulating factors, bone mineral density and insulin-like growth factor-1 (IGF-1) levels have been described. Studies in PWS adults are limited. In this study, we investigated body composition, appetite regulating peptides, bone mineral density and markers of bone remodeling in an adult PWS population. Furthermore, we investigated the association between these different parameters and IGF-1 levels because of the described similarities with growth hormone deficient patients.

Methods

In this cross-sectional observational cohort study in a university hospital setting we studied fifteen adult PWS patients. Anthropometric and metabolic parameters, IGF-1 levels, bone mineral density and bone metabolism were evaluated. The homeostasis model assessment of insulin resistance (HOMA2-IR) was calculated. Fourteen healthy siblings served as a control group for part of the measurements.

Results

In the adult PWS patients, height, fat free mass, IGF-1 and bone mineral content were significantly lower when compared to controls; body mass index (BMI), waist, waist-to-hip ratio and fat mass were higher. There was a high prevalence of osteopenia and osteoporosis in the PWS patients. Also, appetite regulating peptides and bone remodelling markers were aberrant when compared to reference values. Measurements of body composition were significantly correlated to appetite regulating peptides and high-sensitive C-reactive protein (hs-CRP), furthermore HOMA was correlated to BMI and adipokines.

Conclusion

In adults with Prader-Willi syndrome alterations in body composition, adipokines, hs-CRP and bone mineral density were demonstrated but these were not associated with IGF-1 levels. Further investigations are warranted to gain more insight into the exact pathophysiology and the role of these alterations in the metabolic and cardiovascular complications seen in PWS, so these complications can be prevented or treated as early as possible.

Circulating angiopoietin-like 8 (ANGPTL8) is a marker of liver steatosis and is negatively regulated by Prader-Willi Syndrome

ANGPTL8 is a liver-derived protein related to insulin-sensitivity. Its relationship with obesity and liver function in Prader-Willi syndrome (PWS) is unknown. The present study investigated circulating ANGPTL8 in PWS and controls with common obesity, assessing its association to liver steatosis. For this purpose, 20 obese PWS and 20 controls matched for body mass index (BMI), sex and age underwent analysis of ANGPTL8 levels, glucose and lipid metabolism. Liver function tests and degree of liver steatosis by ultrasonography (US), fat-free mass (FFM) and fat mass (FM) by dual-energy x-ray absorptiometry (DEXA) were also assessed. In comparison to controls, obese PWS showed lower values of FFM (p < 0.0001) and higher FM (p = 0.01), while harbouring higher HDL cholesterol, lower triglycerides and OGTT-derived insulin levels, as well as a lower prevalence and severity of liver steatosis. With respect to obese controls, ANGPTL8 levels were significantly lower in PWS (p = 0.007) and overall correlated with transaminase levels and the severity of liver steatosis, as well as FFM (p < 0.05 for all). By a stepwise multivariable regression analysis, ANGPTL8 levels were independently predicted by PWS status (p = 0.01) and liver steatosis (p < 0.05). In conclusion, ANGPTL8 levels are lower in PWS than obese controls and are inversely associated with the severity of liver steatosis. Further studies should investigate the potential genetic basis for this observation.

The Role of the Growth Hormone/Insulin-Like Growth Factor System in Visceral Adiposity

There is substantial evidence that the growth hormone (GH)/insulin-like growth factor (IGF) system is involved in the pathophysiology of obesity. Both GH and IGF-I have direct effects on adipocyte proliferation and differentiation, and this system is involved in the cross-talk between adipose tissue, liver, and pituitary. Transgenic animal models have been of importance in identifying mechanisms underlying these interactions. It emerges that this system has key roles in visceral adiposity, and there is a rationale for targeting this system in the treatment of visceral obesity associated with GH deficiency, metabolic syndrome, and lipodystrophies. This evidence is reviewed, gaps in knowledge are highlighted, and recommendations are made for future research.

Metabolic health profile in young adults with Prader-Willi syndrome: results of a 2-year randomized, placebo-controlled, crossover GH trial

CONTEXT

Patients with Prader-Willi syndrome (PWS) have an increased fat mass and decreased lean body mass. GH-treated young adults with PWS who have attained adult height benefit from continuation of growth hormone (GH) treatment, as GH maintained their improved body composition, whereas fat mass increased during the placebo period. Adults with PWS are predisposed to T2DM and cardiovascular disease. Whether GH affects metabolic health profile of this patient group is unknown.

OBJECTIVE

To investigate the effects of GH vs placebo on metabolic health, in young adults with PWS who were GH-treated for many years during childhood and had attained adult height (AH).

METHOD

A 2-year, randomized, double-blind, placebo-controlled crossover study with stratification for gender and BMI in 27 young adults with PWS. Intervention with GH (0·67 mg/m² /day) and placebo, both for 1-year duration.

RESULTS

Compared to placebo, GH treatment resulted in similar glucose and insulin levels during oral glucose tolerance test. Only fasting glucose and insulin were slightly higher during GH vs placebo (+0·2 mmol/l and +18·4 pmol/l), although both remained within normal ranges in both phases. Blood pressure and lipid profile were similar after GH vs placebo. At baseline (AH) and during GH, no patients had metabolic syndrome, while 1 developed it during placebo treatment.

CONCLUSIONS

Growth hormone treatment has no adverse effects on metabolic health profile. Thus, GH-treated young adults with PWS who have attained AH benefit from continuation of GH treatment without safety concerns regarding metabolic health.

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.

The neurobiology of the Prader-Willi phenotype of fragile X syndrome

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism, caused by a CGG expansion to greater than 200 repeats in the promoter region of FMR1 on the bottom of the X chromosome. A subgroup of individuals with FXS experience hyperphagia, lack of satiation after meals and severe obesity, this subgroup is referred to have the Prader-Willi phenotype of FXS. Prader-Willi syndrome is one of the most common genetic severe obesity disorders known and it is caused by the lack of the paternal 15q11-13 region. Affected individuals suffer from hyperphagia, lack of satiation, intellectual disability, and behavioral problems. Children with fragile X syndrome Prader-Willi phenotye and those with Prader Willi syndrome have clinical and molecular similarities reviewed here which will impact new treatment options for both disorders.

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

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

Rare Genetic Forms of Obesity: Clinical Approach and Current Treatments in 2016

Obesity results from a synergistic relationship between genes and the environment. The phenotypic expression of genetic factors involved in obesity is variable, allowing to distinguish several clinical pictures of obesity. Monogenic obesity is described as rare and severe early-onset obesity with abnormal feeding behavior and endocrine disorders. This is mainly due to autosomal recessive mutations in genes of the leptin-melanocortin pathway which plays a key role in the hypothalamic control of food intake. Melanocortin 4 receptor(MC4R)-linked obesity is characterized by the variable severity of obesity and no notable additional phenotypes. Mutations in the MC4R gene are involved in 2-3% of obese children and adults; the majority of these are heterozygous. Syndromic obesity is associated with mental retardation, dysmorphic features, and organ-specific developmental abnormalities. Additional genes participating in the development of hypothalamus and central nervous system have been regularly identified. But to date, not all involved genes have been identified so far. New diagnostic tools, such as whole-exome sequencing, will probably help to identify other genes. Managing these patients is challenging. Indeed, specific treatments are available only for specific types of monogenic obesity, such as leptin deficiency. Data on bariatric surgery are limited and controversial. New molecules acting on the leptin-melanocortin pathway are currently being developed.

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

BACKGROUND

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

OBJECTIVE

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

METHODS AND RESULTS

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

CONCLUSIONS

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

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.

Unaltered ratio of circulating levels of growth hormone/GH isoforms in adults with Prader-Willi syndrome after GHRH plus arginine administration

Human growth hormone (GH) is a heterogeneous protein hormone consisting of several isoforms, the most abundant being 22 kDa- and 20 kDa-GH. The availability of analytical methods to measure these GH isoforms might represent a valuable diagnostic tool to investigate GH hyposecretory states, including Prader-Willi syndrome (PWS), one of the most common causes of syndromic obesity. The aim of the present study was to measure circulating levels of 22 kDa- and 20 kDa-GH in PWS adults (n=14; M/F: 5/9; genotype DEL15/UPD15: 12/2; age: 19.0±3.7 years; BMI: 29.9±8.7 kg/m2) after combined GH releasing hormone (GHRH) plus arginine (ARG) administration. The results were analysed subdividing the study population in obese vs. nonobese (6/8) and GH deficient vs. nonGH deficient (GHD) (6/8) subjects, according to appropriate BMI-related diagnostic cut-off limits of GH peak response to the provocative test. Circulating levels of 22 kDa-GH were measured by a chemiluminescent method based on a detection monoclonal antibody targeting an epitope in the loop connecting helix 1 and 2 of GH, which is missing in 20 kDa-GH; the 20 kDa-GH was measured using a time resolved fluorescence assay based on two monoclonal antibodies with no cross-reactivity to 22-kDa GH. GHRH plus ARG significantly stimulated the secretions of 22 kDa- and 20 kDa-GH in nonobese (at 30, 45, 60 and 90 min and at 45, 60, 90 and 120 min vs. 0 min, p<0.05, with GH peaks of 15.8±10.3 ng/ml and 2.7±1.2 ng/ml, respectively) and in nonGHD PWS (at 30, 45 and 60 min and at 45, 60 and 90 min vs 0 min, p<0.05, with GH peaks of 12.5±9.0 ng/ml and 2.0±1.8 ng/ml, respectively). No significant GHRH plus ARG-induced changes in 22 kDa- and 20 kDa-GH were observed in obese or GHD PWS patients, the only exception being the increase of 22 kDa-GH (p<0.05) 60 min after the stimulus administration in GHD group (with GH peaks of 6.9±4.7 ng/ml and 0.8±0.6 ng/ml in obese subjects and 8.5±6.0 ng/ml and 1.2±1.0 ng/ml in GHD subjects for 22 kDa- and 20 kDa-GH, respectively). The GH responses for both isoforms were significantly higher in nonobese than in obese PWS patients (at 45 and 60 min for 22 kDa-GH and at 45, 60, 90 and 120 min for 20 kDa-GH, p<0.05), while no differences were detected between GHD vs. nonGHD groups. As previously reported in healthy subjects, the ratios of circulating levels of 22 kDa- to 20 kDa-GH remained constant after GHRH plus ARG both in obese/non-obese and GHD/non-GHD groups, thus suggesting the preservation of a normal balance in GH isoforms in PWS.

Postprandial metabolism in adults with Prader-Willi syndrome

OBJECTIVE

Individuals with Prader-Willi syndrome (PWS) are commonly restricted to 60-75% of height-appropriate calorie intake because they rapidly become obese on a normal diet. This study measured changes in energy expenditure, glucose and lipid homeostasis, and metabolic flexibility in response to a meal in PWS adults.

METHODS

11 adults with PWS were compared with 12 adiposity-matched and 10 lean subjects. Indirect calorimetry was conducted at baseline and 210 min after a standardized 600 kCal breakfast to assess energy expenditure and substrate utilization. Circulating glucose, insulin, C-peptide, glucagon, nonesterified fatty acids, and triglycerides were measured up to 240 min. Insulin sensitivity and insulin secretion rate were assessed by HOMA-IR and C-peptide deconvolution, respectively. Body composition was determined by dual-energy X-ray absorptiometry.

RESULTS

The PWS group had lower lean mass than the obesity control group. Corrected for lean mass, there were no differences between the PWS and obesity groups in resting metabolic rate or metabolic flexibility. Total and abdominal fat mass, insulin sensitivity, and insulin secretion rate were also similar between these groups.

CONCLUSIONS

This study did not detect an intrinsic metabolic defect in individuals with PWS. Rather, lower lean mass, combined with lower physical activity, may contribute to weight gain on an apparent weight-maintenance diet.

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.

Growth hormone treatment of Prader-Willi syndrome has long-term, positive effects on body composition

AIM

Growth hormone (GH) treatment is a relatively new concept in adults, and the knowledge of its long-term effects is limited. We studied ten men with Prader-Willi Syndrome (PWS) after more than 5 years of GH treatment.

METHODS

Study participants underwent a detailed physical examination, including blood tests. Five had received GH as childhood and five had started GH as adults.

RESULTS

The total duration of GH treatment was 16 ± 4 years in the childhood PWS group and 15 ± 1 years in the adulthood PWS group. Their respective mean ages were 27 ± 4 years and 44 ± 4 years, mean heights were 178 ± 11 cm and 156 ± 5 cm, and mean body mass indexes were 32.4 ± 10.3 kg/m(2) and 28.9 ± 4.6 kg/m(2) . There were no differences in body composition between the groups and all lipids and insulin-like growth factor 1 were normal or close to normal. Four had well-controlled type 2 diabetes. The GH doses in the childhood and adulthood groups were 0.4 mg and 0.3 mg, respectively.

CONCLUSION

Men with PWS who received GH treatment displayed positive effects on body composition independent of when the GH treatment had started. Only patients who gained weight developed diabetes. The duration of GH treatment should balance the benefits and observed side effects.

Review of growth hormone therapy in adolescents and young adults with Prader-Willi syndrome

Consensus guidelines from the Growth Hormone Research Society Workshop recommend growth hormone therapy in all children with genetically confirmed Prader-Willi syndrome (PWS) in combination with dietary, lifestyle and environmental interventions. As yet, however, there are limited published data regarding the use of growth hormone therapy in adolescents and young adults with PWS. This review focuses on the advantages and disadvantages of growth hormone therapy in this particular group. The risk of complications, challenges with consent for therapy, the need for contraception in females with PWS and the appropriate monitoring required are all factors which must be carefully considered in this challenging patient group. Transition from paediatric to adult services can be difficult for most adolescents, but especially so for PWS adolescents and should be undertaken under the care of experienced paediatric and adult endocrinologists and a multidisciplinary team approach. Further research is, however, still required in the management of PWS patients during adolescence.

Dual-energy X-ray absorptiometry is a valid method to estimate visceral adipose tissue in adult patients with Prader-Willi syndrome during treatment with growth hormone

CONTEXT

Visceral adipose tissue (VAT) is established as a risk factor for type 2 diabetes and cardiovascular disease, but the radiation exposure and cost of computed tomography (CT) measurements limits its daily clinical use.

OBJECTIVE

The main objective of this study was to compare the degree of agreement between VAT measurements by a new dual-energy X-ray absorptiometry (DXA) application and one of the standard methods, CT, in a population of patients with Prader-Willi syndrome (PWS) before and after GH treatment. Furthermore, we tested whether VAT estimations by these two methods are equivalent in assessing the metabolic risk in this population.

DESIGN AND PATIENTS

Data from the Norwegian population of a multicenter study in adults with genetically proven PWS were used. Subjects with complete anthropometry, biochemical, and imagistic measurements at all study visits (baseline and after 12 and 24 months of GH treatment) (n = 14, six men) were included. VAT was quantified both using CT scans (GE Lightspeed 16 Pro) of the abdomen at L2-L3 level and a total body DXA scan (GE Healthcare Lunar Prodigy).

RESULTS

VAT DXA was strongly associated with VAT CT at baseline (r = 0.97) and after 12 (r = 0.90) and 24 months (r = 0.89) of GH treatment (all P < .001). We found moderate to strong positive correlations between VAT by both methods, and blood pressure, weight, body mass index, waist circumference, glucose metabolism, and other fat depots (arms, legs, android, trunk, total body) but no association with age, gender, blood lipids, and IGF-I. Adiponectin was negatively associated with the amount of VAT. At baseline, the highest correlation with homeostasis model assessment of insulin resistance (HOMA-IR) was found for VAT DXA (r = 0.76, P = .001) and VAT CT (r = 0.75, P = .002), respectively.

CONCLUSION

VAT can be accurately estimated by DXA, in patients with PWS, and might contribute to the assessment of the metabolic risk.