Journal of Intellectual Disability Research doi: 10.1111/j.1365-2788.2005.00770.x     pp     ©  Blackwell Publishing Ltd 69 Blackwell Science, LtdOxford, UKJIRJournal of Intellectual Disability Research -Blackwell Publishing Ltd, 16978Original ArticlePrader–Willi syndrome in Western AustraliaA. K. Thomson et al. Correspondence: Allyson K. Thomson, Centre for Human Genetics, Edith Cowan University,  Joondalup Drive, Perth, WA , Australia (e-mail: a.thomson@ecu.edu.au). A long-term population-based clinical and morbidity review of Prader–Willi syndrome in Western Australia A. K. Thomson, 1 E. J. Glasson 1,2 & A. H. Bittles 1 1 Centre for Human Genetics, Edith Cowan University, Perth, Australia 2 School of Population Health and Centre for Child Health Research, University of Western Australia, Perth, Australia Abstract Background An investigation of the clinical morbid- ity and genetic profiles of individuals with Prader– Willi syndrome (PWS) in Western Australia (WA) was undertaken as part of a wider study into the effects of intellectual disability (ID) on the life course of individuals. Methods All persons with a diagnosis of PWS were identified from the records of the Disability Services Commission of WA (DSC). The DSC client files formed the main data source, and were supple- mented by information from other state health data sets. The analysis was retrospective and quantitative in nature. Results A total of  individuals were identified,  of whom exhibited normal methylation patterns and so were analysed separately (PWS-like). The ages of the PWS group ranged from . to  . years, with six persons deceased. Most people with PWS (  %) had mild or moderate ID, and  % lived in their family home. The birth prevalence of the disorder was in   births. Respiratory disorders, dentistry and gastrointestinal disorders were common reasons for hospital admission, with epilepsy or convulsions also reported at moderate frequency. The PWS-like group shared many clinical features in common with PWS patients, the principal exceptions being hypo- tonia and feeding difficulties in infancy. Conclusions The estimated birth prevalence of PWS was lower than expected; however, the case ascertain- ment method may have excluded some individuals. Older people with PWS were generally living in shel- tered accommodation. As the cohort ages, demand for places in similar accommodation will increase, adding to the existing burden on service providers. Substantial future increases in the use of medical services and hospital-based care also are predicted with the onset of age-associated disorders. Keywords ageing, genomic imprinting, intellectual disability, morbidity, Prader–Willi syndrome Introduction Prader–Willi syndrome (PWS) is a chromosomal dis- order caused by absence of the paternal imprint from the chr  q  –q  region. The syndrome has an esti- mated prevalence rate of per     births (Stromme  ; Whittington et al.  ; Smith et al.  ), and was first described by Prader et al. (  ). Symptoms common to most patients are intellectual