title: Longitudinal follow-up of autism spectrum features and sensory behaviors in Angelman syndrome by deletion class.
abstract: BACKGROUND
  Angelman syndrome (AS) is a neurogenetic disorder characterized by severe intellectual disability, lack of speech, and low threshold for laughter; it is considered a 'syndromic' form of autism spectrum disorder (ASD). Previous studies have indicated overlap of ASD and AS, primarily in individuals with larger (∼6 Mb) Class I deletions of chromosome 15q11-13. Questions remain regarding whether intellectual disability solely contributes to ASD features in AS and how ASD features in AS change over time. In this study, we used a dimensional approach to examine ASD symptom severity in individuals with AS Class I versus Class II deletions within the context of cognitive development over time.
  
  
  METHODS
  A total of 17 participants with a larger, Class I deletion and 25 participants with a smaller Class II deletion (∼5 Mb) were enrolled (age range = 2-25 years; 5 years 5 months). Standardized measures of cognition, language, motor skills, adaptive skills, maladaptive behavior, autism, and sensory-seeking behaviors/aversions were given at baseline and after 12 months.
  
  
  RESULTS
  Despite equivalent cognition and adaptive behavior, the results of repeated measures analyses of variance indicate that participants with Class I deletions have greater impairment in social affect (F = 8.65; p = .006) and more repetitive behaviors (F = 7.92; p = .008) compared to participants with Class II deletions. Although both groups improve in cognition over time, differences in ASD behaviors persist.
  
  
  CONCLUSIONS
  Despite a lack of differences in cognition or adaptive behavior, individuals with Class I deletions have greater severity in ASD features and sensory aversions that remain over time. There are four genes (NIPA 1, NIPA 2, CYFIP1, and GCP5) missing in Class I and present in Class Il deletions, one or more of which may have a role in modifying the severity of social affect impairment, and level of restricted/repetitive behaviors in AS. Our results also suggest the utility of a dimensional, longitudinal approach to the assessment of ASD features in populations of individuals who are low functioning.
authors.affiliation: Departments of Pediatrics Psychiatry, Vanderbilt University, Nashville, TN, USA. sarika.u.peters@vanderbilt.edu
authors.forename: Sarika U
authors.initials: SU
authors.lastname: Peters
authors.forename: Lucia
authors.initials: L
authors.lastname: Horowitz
authors.forename: Rene
authors.initials: R
authors.lastname: Barbieri-Welge
authors.forename: Julie Lounds
authors.initials: JL
authors.lastname: Taylor
authors.forename: Rachel J
authors.initials: RJ
authors.lastname: Hundley
mesh_terms: D000293:Adolescent; D000328:Adult; D017204:Angelman Syndrome / Q000145:classification* / Q000235:genetics* / Q000503:physiopathology; D002648:Child; D002652:Child Behavior / Q000523:psychology*; D002659:Child Development Disorders, Pervasive / Q000235:genetics* / Q000503:physiopathology; D002675:Child, Preschool; D002872:Chromosome Deletion; D002884:Chromosomes, Human, Pair 15 / Q000145:classification / Q000235:genetics; D003072:Cognition Disorders / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D015894:Genome, Human; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D009483:Neuropsychological Tests; D012678:Sensation Disorders / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D012920:Social Behavior Disorders / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D055815:Young Adult