Metabolic syndrome in children with Prader-Willi syndrome: the effect of obesity.

BACKGROUND AND AIMS: Prader-Willi syndrome (PWS), the most frequent syndromic obesity, is associated with elevated morbidity and mortality in pediatric and adult ages. In PWS, the presence of metabolic syndrome (MS) has not yet been established. The aim of the study was to estimate the frequency of MS and its components in pediatric subjects according to obesity status.METHODS AND RESULTS: A cross-sectional study was performed in 109 PWS children aged 2-18 years (50 obese and 59 non-obese) and in 96 simple obese controls matched for age, gender, and also for BMI with obese PWS. Obesity was defined when SDS-BMI was >2. Non-obese PWS showed significantly lower frequency of hypertension (12%) than obese PWS (32%) and obese controls (35%)(p=0.003). The same was observed for low HDL-cholesterol (3% vs 18% and 24%, p=0.001) and high triglycerides (7% vs 23% and 16%, p=0.026). Frequency of altered glucose metabolism was not different among groups (2% vs 10% and 5%), but type 2 diabetes (four cases) was present only in obese PWS. Non-obese PWS showed lower insulin and HOMA-index respect to obese PWS and obese controls (p ≤ 0.017). Overall MS frequency in PWS was 7.3%. None of the non-obese PWS showed MS compared with 16% of obese PWS and controls (p<0.001). When obesity was excluded from the analysis, a significantly lower frequency for clustering of ≥ 2 factors was still found in non-obese PWS (p=0.035).CONCLUSION: Non-obese PWS showed low frequency of MS and its components, while that observed in obese PWS was very close to those of obese controls, suggesting the crucial role of obesity status. Prevention of obesity onset remains the most important goal of PWS treatment. Early identification of MS could be helpful to improve morbidity and mortality in such patients.