Abstract
Introduction: Prader-Willi syndrome (PWS) is a complex hypothalamic disorder, combining hypotonia, intellectual disability (ID), pituitary hormone deficiencies and hyperphagia. In PWS, up to 3% of patients die every year. In half of the patients, the cause of death is obesity related and / or of cardiovascular (CV) origin.
Obesity is caused by hyperphagia combined with a low energy expenditure. Untreated hormone deficiencies like hypogonadism and hypothyroidism can cause low muscle mass and low basal rest metabolism (BRM) leading to this low energy expenditure. Patients with PWS should exercise one hour daily to compensate for their low BRM. However, hormone deficiencies usually cause fatigue, leading to exercise intolerance. Musculoskeletal and / or behavioral problems can also cause reduced physical activity. The subsequent sedentary lifestyle can induce CV risk factors like hypertension, hypercholesterolemia and diabetes mellitus (DM).
Another risk factor often present in PWS is sleep apnea, which can be central (CSA), obstructive (OSA) or both. Both CSA and OSA can lead to pulmonary hypertension and a further increase in obesity.
The above mentioned health problems often remain unnoticed and untreated, which is partly due to the behavioral phenotype of PWS (patients seldomly report pain and hardly ever complain about physical problems). However, if left untreated, these risk factors can cause CV complications leading to hospital admission or even death. To reveal yet undiagnosed health problems, we performed a systematic health screening among adults with PWS.
Methods: We systematically screened 115 adults with PWS (mean age 31.4 ± 12.1 y, mean BMI 31.8 ± 9,5 kg/m2) for the presence of undiagnosed health problems and cardiovascular risk factors. Based on a medical questionnaire, medical file search, extensive interview, thorough physical examination and biochemical measurements we made an overview of the undiagnosed health problems in adults with PWS. If possible, we performed polygraphy to test for sleep apnea.
Results: Undiagnosed health problems (hypertension, DM, hypercholesterolemia, sleep apnea, hypothyroidism and hypogonadism) were present in 50% of the patients. 10% had multiple undiagnosed health problems simultaneously. All males and 94% of females had hypogonadism and 15% had hypothyroidism. Hypertension and / or hypercholesterolemia were present in 20% and DM was present in 16%. One third of patients was not on a diet and 22% exercised less than 30 minutes a day. Sleep apnea was present in 17 of 26 patients tested.
Conclusion: We detected a striking number of undiagnosed health problems among adults with PWS which, if left untreated, can pose a serious health threat. Systematic screening is needed to detect these problems in an early phase. This will prevent burdensome and expensive complications and might even reduce mortality in this vulnerable patient population.
Simulating Metabolic Flexibility in Low Energy Expenditure Conditions Using Genome-Scale Metabolic Models
