Abstract
Muscle hypotonia and failure to thrive are key symptoms of Prader–Willi syndrome (PWS) allowing diagnosis during infancy already. Improved general care as well as Coenzyme Q~10~ (CoQ~10~) and growth hormone (GH) are administered to improve PWS children's outcome. This study aims to investigate psychomotor development of young PWS children in relation to body weight and body composition at baseline as well as to the effects of GH or CoQ~10~ therapy. Twenty‐six young children (age 1.0 ± 0.1 years, mean ± SEM) with PWS genetically proven at age 0.1 ± 0.1 years (17 deletions, 8 maternal disomy) were divided into three groups: Group 1 on GH therapy (started in 1994–1996, 6 mg/kg/week) tolerating low body weight (<50th centile), group 2 on GH (1997–2000) and group 3 on CoQ~10~ (2001–2002, 2.5 mg/kg/day orally), both combined with active early weight management to achieve weight >50th centile. Anthropometry, body composition and Griffith's developmental scores (DQs) were assessed before therapy and after 12 months. DQs were not related to infants' weight, lean mass or genetic background. DQs improved significantly with chronological age and were best in the most recently diagnosed group. Improved psychomotor development, mainly due to progress in locomotor development, did not differ between GH and CoQ~10~ treated groups. In conclusion, while only GH has significant effects on growth and body composition, GH and CoQ~10~ therapy act equally on psychomotor development of PWS infants. However, improving psychomotor development may merely reflect an age‐related phenomenon additionally depending on early diagnosis and introduction of appropriate care. © 2008 Wiley‐Liss, Inc.