title: Visual capacity and Prader-Willi syndrome.
abstract: OBJECTIVE
  Prader-Willi syndrome (PWS) refers to a genetic disorder induced by an anomaly on chromosome 15 occurring with a frequency of one in 10,000 to 20,000. It is characterized by a unique set of features including infantile hypotonia, obesity in childhood, small hands and feet, hypogonadism, and mental retardation. Reported here are the results of ophthalmic examinations of persons with PWS, together with results from controls comparable in age, percentage of body fat, and intelligence. These data bear on the hypothesis that the ocular anomalies in PWS are unique to this syndrome.
  
  
  METHODS
  A comprehensive investigation of PWS brought children and adults to Vanderbilt University for extended testing, which included an ophthalmic examination. Genetic analysis determined unequivocally the PWS diagnosis and identified subgroups-deletion and maternal disomy. A group of persons without PWS but generally comparable in age, body composition, and intelligence served as controls.
  
  
  RESULTS
  Significant differences between the deletion and disomy subgroups were not found for the clinical ophthalmic measures. The incidence of anomalies in the combined PWS was similar to those reported in previous studies. A similar pattern was present in the control group except for myopia and stereopsis. An effect of genetic subgroup, however, was observed for random element stereopsis with the maternal disomy group having a greater degree of impairment.
  
  
  CONCLUSIONS
  The overall similarity between the PWS and control groups on all measures except myopia and stereopsis suggest that many of the anomalies in PWS found in prior studies are due to factors inherent in a general dysfunctional population, rather than reflective of an ocular signature unique to PWS.
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: R
authors.initials: R
authors.lastname: Fox
authors.forename: R B
authors.initials: RB
authors.lastname: Sinatra
authors.forename: M A
authors.initials: MA
authors.lastname: Mooney
authors.forename: I D
authors.initials: ID
authors.lastname: Feurer
authors.forename: M G
authors.initials: MG
authors.lastname: Butler
mesh_terms: D000328:Adult; D003867:Depth Perception / Q000502:physiology; D005124:Eye Abnormalities / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D009216:Myopia / Q000235:genetics / Q000503:physiopathology; D010468:Perceptual Disorders / Q000235:genetics / Q000503:physiopathology*; D011218:Prader-Willi Syndrome / Q000235:genetics / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology*