A survey on Prader-Willi syndrome in the Italian population: prevalence of historical and clinical signs.

Clinical criteria for the diagnosis of Prader-Willi Syndrome (PWS) were established by consensus in 1993 (Holm et al.). Specific molecular testing is now available and the purpose of diagnostic criteria has shifted to identify individuals to test, thus avoiding the expense of unnecessary analysis. The aim of this study was to find clinical indicators to select patients with suspected PWS for laboratory testing. We analyzed the prevalence of clinical signs and symptoms in 147 genetically diagnosed Italian patients with PWS (67 males and 80 females), aged from 9 months to 34.6 years (13.6 +/- 8.3 years), using the consensus diagnostic criteria, and according to age, sex and type of genetic abnormality. The prevalence of several clinical features changed significantly with age, but very few with sex. According to genetic subtypes (deletion vs UPD), only hypopigmentation and acromicria were more frequent in patients with deletion. Some criteria considered as minor or supportive by Holm et al. have higher prevalence than some major criteria. In conclusion, in order to identify patients with suspected PWS to submit to laboratory testing, we recommend a classification of clinical criteria according to age, giving more attention to those so-called minor or supportive criteria.