Charlotte Höybye (IPWSO Clinical Scientific Advisory Board member)
Department of Endocrinology, Metabolism and Diabetology
Karolinska University Hospital
It is well known that health improves with less obesity and increased physical fitness. However, in PWS much is unknown and there are many ongoing studies on these topics providing new and updated information.
In the following I have summarized some of the presentations that I found useful for clinical practice and for future studies.
A detailed knowledge of body composition in children with PWS is scarce. Camila E. Orsso and colleagues from USA carefully examined body composition in 17 children with PWS compared to 16 obese controls. They showed that PWS children have similar amounts of fat in the abdomen, but reduced quantity of skeletal muscle mass compared to healthy, obese children. These findings might be some of the explanation for the difficulties with coordination, balance and posture observed in PWS.
All studies on growth hormone treatment in adults with PWS have uniformly shown improvement in body composition. Graziano Grugni and colleagues from Italy studied the effect of a mean of 7.5 years of growth hormone treatment in 21 adults with PWS compared to 20 adults with PWS without growth hormone treatment. Improvements were observed in body composition, total cholesterol levels, IGF-I levels, liver morphology, and pulmonary function, in the absence of negative effects on carbohydrate metabolism and cardiac function. The present study adds to previous studies all showing beneficial effects of GH therapy in adults with PWS. This treatment is however not a registered treatment for adults with PWS in any country as yet.
The presence of latent central adrenal insufficiency (CAI) in PWS remains unclear as well as whether PWS individuals have an alternation of the HPA (Hypothalamus-Pituitary-Adrenal; HPA) axis or not. Yuji Oto and colleagues from Japan evaluated the HPA axis in 36 children and adults with PWS using the insulin tolerance test. All 36 participants had normal baseline levels of ACTH and cortisol as well as a normal response to the test, however, in 25 peak cortisol was delayed. The clinical consequences of these findings are unclear and further studies are needed.
Jorgelina Stegmann and colleagues from Argentina presented data regarding gallstones in PWS. They had examined 19 individuals with PWS and found that 36.84% had gallstones, as compared to approximately 15% in the general population. Similar risk factors for gall stones as for general population were noted, being obesity, sudden weight loss and family history of gallstones. Gallstones might result in abdominal pain and discomfort and it is important in the clinical evaluation of patients with PWS to be aware of the high reported frequency of gall stones.
Ann M. Manzardo and colleagues from USA presented data on the frequency of blood clots obtained from a 66 item survey distributed electronically to active members of the Prader-Willi Association (USA). Interim results from 539 responders identified 22 (4%) with a history of clots. The preliminary results suggest an increased risk of blood clots in PWS with increased age, obesity, leg edema, vasculitis, and family history of clots whereas individuals with clots were less likely to have received growth hormone. Further studies are needed to evaluate the effectiveness of interventions such as weight loss, anticoagulation, risks associated with genetic predisposition and PWS subtype and potential benefits of growth hormone therapy on the causation and development of blood clots in PWS.
P Lemoine and colleagues from France retrospectively collected deaths certificates from 2004 to 2012. They documented younger age at death in PWS 31 years vs. 73 years in the general population. The first cause of death was respiratory failures representing 48.2% (33% in children and 50.6% in adults) in PWS vs. 6% in the general population. The second cause of death was sudden death 17.7% (25% in children and 16.4% in adults) and the third cause cardiac disease 11.7% (8.3% in children and 12.3% in adults). Prospective studies are required in different countries in order to describe more precisely the causes of deaths and for implementation of specific prevention strategies.
In this context systematic recording is important to get information on health and function of individuals with PWS. Jessica Bohonowych and colleagues from USA presented The Global Prader-Willi Syndrome registry, which is managed and funded by the Foundation for Prader-Willi Research, is hosted by the National Organization of Rare Disorders (NORD), and is a participant in the NIH-supported Global Rare Disease Registry. The Global PWS Registry was launched in May 2015 and has ~800 participants as of early 2016. It is comprised of a series of 37 web-based surveys covering natural history. Data is self-reported by a parent or guardian of individuals with PWS. Future plans for the registry is to continue enrollment, promote survey completion, and begin leveraging de-identified data through collaborations with researchers, companies, and other parties involved in advancing solutions for PWS.