title: Autism spectrum disorders and epigenetics.
abstract: OBJECTIVE
  Current research suggests that the causes of autism spectrum disorders (ASD) are multifactorial and include both genetic and environmental factors. Several lines of evidence suggest that epigenetics also plays an important role in ASD etiology and that it might, in fact, integrate genetic and environmental influences to dysregulate neurodevelopmental processes. The objective of this review is to illustrate how epigenetic modifications that are known to alter gene expression without changing primary DNA sequence may play a role in the etiology of ASD.
  
  
  METHODS
  In this review, we summarize current knowledge about epigenetic modifications to genes and genomic regions possibly involved in the etiology of ASD.
  
  
  RESULTS
  Several genetic syndromes comorbid with ASD, which include Rett, Fragile X, Prader-Willi, Angelman, and CHARGE (Coloboma of the eye, Heart defects, Atresia of the nasal choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness), all demonstrate dysregulation of epigenetic marks or epigenetic mechanisms. We report also on genes or genomic regions exhibiting abnormal epigenetic regulation in association with either syndromic (15q11-13 maternal duplication) or nonsyndromic forms of ASD. Finally, we discuss the state of current knowledge regarding the etiologic role of environmental factors linked to both the development of ASD and epigenetic dysregulation.
  
  
  CONCLUSIONS
  Data reviewed in this article highlight a variety of situations in which epigenetic dysregulation is associated with the development of ASD, thereby supporting a role for epigenetics in the multifactorial etiologies of ASD.
authors.affiliation: Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Daria
authors.initials: D
authors.lastname: Grafodatskaya
authors.forename: Brian
authors.initials: B
authors.lastname: Chung
authors.forename: Peter
authors.initials: P
authors.lastname: Szatmari
authors.forename: Rosanna
authors.initials: R
authors.lastname: Weksberg
mesh_terms: D000293:Adolescent; D017204:Angelman Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D058747:CHARGE Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics; D015897:Comorbidity; D044127:Epigenesis, Genetic / Q000235:genetics*; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics / Q000523:psychology; D006801:Humans; D058627:Megalencephaly / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D011218:Prader-Willi Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D015518:Rett Syndrome / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D012307:Risk Factors; D012931:Social Environment; D014424:Turner Syndrome / Q000175:diagnosis / Q000235:genetics