title: Appetite hormones and the transition to hyperphagia in children with Prader-Willi syndrome.
abstract: OBJECTIVE
  Prader-Willi syndrome (PWS) is a genetic neurodevelopmental disorder with several nutritional phases during childhood proceeding from poor feeding, through normal eating without and with obesity, to hyperphagia and life-threatening obesity, with variable ages of onset. We investigated whether differences in appetite hormones may explain the development of abnormal eating behaviour in young children with PWS.
  
  
  METHODS
  In this cross-sectional study, children with PWS (n=42) and controls (n=9) aged 7 months-5 years were recruited. Mothers were interviewed regarding eating behaviour, and body mass index (BMI) was calculated. Fasting plasma samples were assayed for insulin, leptin, glucose, peptide YY (PYY), ghrelin and pancreatic polypeptide (PP).
  
  
  RESULTS
  There was no significant relationship between eating behaviour in PWS subjects and the levels of any hormones or insulin resistance, independent of age. Fasting plasma leptin levels were significantly higher (mean ± s.d.: 22.6 ± 12.5 vs 1.97 ± 0.79 ng ml(-1), P=0.005), and PP levels were significantly lower (22.6 ± 12.5 vs 69.8 ± 43.8 pmol l(-1), P<0.001) in the PWS group compared with the controls, and this was independent of age, BMI, insulin resistance or IGF-1 levels. However, there was no significant difference in plasma insulin, insulin resistance or ghrelin levels between groups, though PYY declined more rapidly with age but not BMI in PWS subjects.
  
  
  CONCLUSIONS
  Even under the age of 5 years, PWS is associated with low levels of anorexigenic PP, as in older children and adults. Hyperghrelinaemia or hypoinsulinaemia was not seen in these young children with PWS. Change in these appetite hormones was not associated with the timing of the transition to the characteristic hyperphagic phase. However, abnormal and/or delayed development or sensitivity of the effector pathways of these appetitive hormones (for example, parasympathetic and central nervous system) may interact with low PP levels, and later hyperghrelinaemia or hypoinsulinaemia, to contribute to hyperphagia in PWS.
authors.affiliation: Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, London, UK. tony.goldstone@imperial.ac.uk
authors.forename: A P
authors.initials: AP
authors.lastname: Goldstone
authors.forename: A J
authors.initials: AJ
authors.lastname: Holland
authors.forename: J V
authors.initials: JV
authors.lastname: Butler
authors.forename: J E
authors.initials: JE
authors.lastname: Whittington
mesh_terms: D015992:Body Mass Index; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005215:Fasting / Q000097:blood; D005247:Feeding Behavior; D005260:Female; D054439:Ghrelin / Q000097:blood*; D006801:Humans; D006963:Hyperphagia / Q000378:metabolism* / Q000503:physiopathology; D007223:Infant; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D020738:Leptin / Q000097:blood*; D008297:Male; D019894:Peptide YY / Q000097:blood*; D010641:Phenotype; D011218:Prader-Willi Syndrome / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D054439:Ghrelin; D020738:Leptin; D019894:Peptide YY; D007334:Insulin-Like Growth Factor I