title: Muscle-bone characteristics in children with Prader-Willi syndrome.
abstract: BACKGROUND
  A decrease in muscle mass, low motor performance, and normal lumbar spine bone mineral density (BMD) have been reported in children with Prader-Willi syndrome (PWS). However, these data are limited by the fact that PWS children (who have short stature) were compared to age-matched healthy or obese individuals of normal height.
  
  
  OBJECTIVE
  The goal of the present study was to compare bone and muscle characteristics in PWS children to sex- and age- or height-matched healthy subjects.
  
  
  METHODS
  The study population included 17 PWS children (ages 6.2 to 17.5 yr; nine girls) who were not treated with GH. The axial skeleton was analyzed at the lumbar spine using dual-energy x-ray absorptiometry, and the appendicular skeleton (radius and tibia) was evaluated using peripheral quantitative computed tomography. Muscle parameters (mass, size, and functional parameters) were measured by dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and jumping mechanography, respectively.
  
  
  RESULTS
  Compared to height-matched controls, PWS patients had normal axial and appendicular BMD, as well as normal muscle size. Compared to age- or height-matched controls of normal weight, PWS patients had lower maximal muscle force and power relative to body mass during jumping. PWS patients had similar absolute maximal muscle force but lower absolute maximal power compared to age- or height-matched controls. Relationships between bone mass and muscle size and force were similar in PWS patients and in healthy subjects.
  
  
  CONCLUSIONS
  Relative to their height, PWS patients not treated with GH had normal axial and appendicular BMD, muscle size, and muscle-bone relationships.
authors.affiliation: Endocrinology Service, Department of Pediatrics, Sainte-Justine University Hospital, and Université de Montréal, Montreal, Quebec, Canada. edouard.t@chu-toulouse.fr
authors.forename: Thomas
authors.initials: T
authors.lastname: Edouard
authors.forename: Cheri
authors.initials: C
authors.lastname: Deal
authors.forename: Guy
authors.initials: G
authors.lastname: Van Vliet
authors.forename: Natacha
authors.initials: N
authors.lastname: Gaulin
authors.forename: Alain
authors.initials: A
authors.lastname: Moreau
authors.forename: Frank
authors.initials: F
authors.lastname: Rauch
authors.forename: Nathalie
authors.initials: N
authors.lastname: Alos
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001827:Body Height / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D016022:Case-Control Studies; D002648:Child; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000473:pathology*; D009929:Organ Size / Q000502:physiology; D011218:Prader-Willi Syndrome / Q000000981:diagnostic imaging / Q000473:pathology*