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

Oxytocin's Regulation of Thermogenesis May Be the Link to Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is a genetic neurodevelopmental disorder that is caused by either the deletion of the paternal allele of 15q11-q13, maternal uniparental disomy of chromosome 15 or defects in the chromosome 15 imprinting centre and is characterized by cognitive impairment, hyperphagia and low metabolic rate with significant risk of obesity, as well as a variety of other maladaptive behaviours and autistic spectrum disorder (ASD). Many of the features seen in PWS are thought to be due to hypothalamic dysfunction resulting in hormonal abnormalities and impaired social functioning. The preponderance of evidence indicates that the Oxytocin system is dysregulated in PWS individuals and that this neuropeptide pathways may provide promising targets for therapeutic intervention although the process by which this dysregulation occurs in PWS awaits mechanistic investigation. PWS individuals present abnormalities in thermoregulation an impaired detection for temperature change and altered perception of pain indicating an altered autonomic nervous system. Recent studies indicate that Oxytocin is involved in thermoregulation and pain perception. This review will describe the update on PWS and the recent discoveries on Oxytocin regulation of thermogenesis together with the potential link between Oxytocin regulation of thermogenesis and PWS to create a new groundwork for the treatment of this condition.

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.

Obesity in Prader-Willi syndrome: physiopathological mechanisms, nutritional and pharmacological approaches

Prader-Willi syndrome (PWS) is a genetic disorder caused by the lack of expression of genes on the paternally inherited chromosome 15q11.2-q13 region. The three main genetic subtypes are represented by paternal 15q11-q13 deletion, maternal uniparental disomy 15, and imprinting defect. Clinical picture of PWS changes across life stages. The main clinical characteristics are represented by short stature, developmental delay, cognitive disability and behavioral diseases. Hypotonia and poor suck resulting in failure to thrive are typical of infancy. As the subjects with PWS age, clinical manifestations such as hyperphagia, temperature instability, high pain threshold, hypersomnia and multiple endocrine abnormalities including growth hormone and thyroid-stimulating hormone deficiencies, hypogonadism and central adrenal insufficiency due to hypothalamic dysfunction occur. Obesity and its complications are the most common causes of morbidity and mortality in PWS. Several mechanisms for the aetiology of obesity in PWS have been hypothesized, which include aberration in hypothalamic pathways of satiety control resulting in hyperphagia, disruption in hormones regulating appetite and satiety and reduced energy expenditure. However, despite the advancement in the research field of the genetic basis of obesity in PWS, there are contradictory data on the management. Although it is mandatory to adopt obesity strategy prevention from infancy, there is promising evidence regarding the management of obesity in adulthood with current obesity drugs along with lifestyle interventions, although the data are limited. Therefore, the current manuscript provides a review of the current evidence on obesity and PWS, covering physiopathological aspects, obesity-related complications and conservative management.

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.

Hypogonadism in the Prader-Willi syndrome from birth to adulthood: a 28-year experience in a single centre

BACKGROUND

Hypogonadism is a key feature of Prader-Willi syndrome (PWS) but clear strategies for hormone replacement are lacking.

OBJECTIVE

To evaluate gonadal status and outcome in patients attending a Scottish PWS clinic from 1991-2019.

METHODS

In 93 (35F:56M) patients, median follow-up 11.2 years, gonadal and pubertal status were assessed clinically. Pelvic ultrasound findings and basal/stimulated gonadotrophins were compared with age-matched controls.

RESULTS

Females: Of 22 patients aged >11, 9 had reached B4-5, while 5 were still at B2-3, and 6 remained prepubertal. Eight patients experienced menarche aged 9.8-21.4 years, none with a normal cycle. Uterine length and ovarian volumes were normal but uterine configuration remained immature, with low follicular counts. Gonadotrophins were unremarkable, serum estradiol 129 (70 - 520) pmol/L. Only 5 patients received oestrogen replacement. Males: Fifty-four (96%) patients were cryptorchid (9 unilateral). Weekly hCG injections resulted in unilateral/bilateral descent in 2/1 of 25 patients. Of 37 boys aged >11, 14 (9 with failed/untreated bilateral cryptorchidism) failed to progress beyond G1, 15 arrested at G2-3 (testes 3-10 ml), and 8 reached G4-5. Gonadotrophins were unremarkable except in boys at G2-5 in whom FSH was elevated: 12.3/27.3 vs 3.25/6.26 U/L in controls (p<0.001). In males aged >13, testosterone was 3.1 (0.5-8.4) nmol/L. Androgen therapy, given from 13.5-29.2 years, was stopped in 4/24 patients owing to behavioural problems.

CONCLUSION

Despite invariable hypogonadism, few females and only half the males with PWS in this study received hormone replacement. Double-blind placebo-controlled crossover trials of sex steroids are required to address unproven behavioural concerns.

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.

Stimulated GH levels during the transition phase in Prader-Willi syndrome

PURPOSE

Early institution of GH therapy in children with Prader-Willi syndrome (PWS) yields beneficial effects on their phenotype and is associated with a persistent improvement of body composition, both in the transition age and in adulthood. Reports from GH stimulation testing in PWS adults, however, suggest that GH deficiency (GHD) is not a universal feature of the syndrome, and the current Consensus Guidelines suggest to perform a reassessment of persistent GHD so as to continue GH therapy after reaching adult height. Few data about GH responsiveness to stimulation testing throughout the transitional period in PWS are available to date. Thus, we investigated the prevalence of GHD in a large cohort of patients with PWS during the transition phase.

PATIENTS AND METHODS

One hundred forty-one PWS patients, 72 females and 69 males, aged 15.4-24.9 years, were evaluated by dynamic testing with growth hormone-releasing hormone (GHRH) plus arginine (GHRH + ARG). To define GHD, both BMI-dependent and BMI-independent diagnostic cut-off limits were considered.

RESULTS

According to BMI-dependent criteria, 10.7% of normal weight (NW), 18.5% of overweight and 22.1% of obese PWS maintained a status of GHD. Similar results were obtained by adopting a cut-off limit specific for the adult age (26.2%), as well as criteria for the transition phase in NW subjects (25%).

CONCLUSION

Our study shows that about 20% of patients with PWS fulfilled the criteria for GHD during the transitional age, suggesting the need of an integrated analysis of GH/IGF-I axis, in the context of the general clinical picture and other endocrine abnormalities, in all subjects after attainment of final stature.

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.

Body fat distribution and circulating adipsin are related to metabolic risks in adult patients with newly diagnosed growth hormone deficiency and improve after treatment

OBJECTIVE

The relationships between body fat distribution, the adipokine adipsin and metabolic risks were assessed in patients with adult growth hormone deficiency (AGHD) before and after growth hormone (GH) treatment.

METHODS

Sixty newly diagnosed AGHD patients were included in our study, 24 of whom were evaluated after at least one year of GH treatment. Anthropometric parameters, glucolipid metabolism and the adipokine adipsin were measured. Visceral adipose tissue (VAT) and body composition were evaluated using a dual-energy X-ray-absorptiometry (DXA) scanner.

RESULTS

At baseline, the higher VAT group had worse glucolipid metabolism parameters. Basal GH was negatively associated with VAT (r=-0.277, p = 0.045), while minimal correlations were found with fat mass depots, such as limbs and trunk fat (all p > 0.05). Adipsin was correlated with total body fat (r = 0.543, p < 0.001), VAT (r = 0.563, p < 0.001) and insulin resistance (r = 0.353, p = 0.006). The effect of GH administration on fat distribution was mainly reflected in the reduction in VAT. Partial improvements were found in lipid profiles, including increased high-density lipoprotein (HDL) and decreases in triglycerides (TGs) and lipoprotein(a), while glucose metabolism showed little change. The adipsin level also decreased significantly. The best predictors of VAT at baseline were trunk fat and IGF-I, and after treatment, VAT was predicted by decreased adipsin and an increase in lean mass.

CONCLUSIONS

(1) VAT is an important metabolic risk factor for AGHD patients. (2) GH treatment decreased body fat predominantly in the visceral and central fat depots. (3) The lipid profiles partially improved after treatment, while glucose metabolism showed little change.

Dietary Management for Adolescents with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a complex, multisystem neurodevelopmental disorder affecting approximately 1 in 25,000 live births. PWS is caused by absence of expression of paternally inherited imprinted genes on chromosome 15q11-q13. The syndrome typically occurs due to one of three genetic mechanisms: paternal deletion of involved genes, maternal uniparental disomy, or imprinting center defects. These genetic anomalies lead to well-described clinical phenotype that includes hypotonia, hypothalamic dysfunction, social and behavioral issues, life-threatening hyperphagia, and elevated probability of obesity. Adolescents with PWS are at the highest risk for development of life-threatening obesity due to increased access to food, decreased physical activity, and hyperphagia. Currently, the only treatment for the hyperphagia is environmental control, including locked kitchens and continuous supervision of the affected individual. Caloric intake must be restricted to prevent obesity, which subsequently increases the hunger drive even more. Research and clinical practice have demonstrated that increasing physical activity along with insuring a well-balanced, nutritionally dense diet can improve overall weight control in adolescents with PWS.