Main

• • Looks at how a person's genes can impact their changes of having an autism spectrum disorder (ASD)
  • Genetics influence the way we behave
  • Genes are like building blocks made of DNA + they influence various aspects of a person's body, brain structure + development
• Twin studies

  • Bailey et al (1995) studied data from the British Twin study, focusing on twins where one individual in each pair had autism
  • They found that among identical twins (Mz), 60% both had autism, while it was 0% for non-identical (Dz)
  • The concordance rate for Mz twins was a striking 92% + 10% for Dz twins
• Twin studies 2

  • Twin early development study (TEDS) examined info from more than 3,000 sets of twins (Ronald et al 2006)
  • Discovered that social + communicative characteristics are strongly influenced by genetics. Concluded there is no single genetic cause for autism as a disorder
• Simplex and multiplex ASD

  • Researchers discovered on important difference among families affected by ASD
  • Simplex = one member of family with ASD
  • Multiplex = multiple members of family with ASD
  • Suggests different genetic causes for the condition
  • Multiplex = inherited
  • Simplex = 'de novs' - new genetic mutations that happen during the fertilisation of an egg by a sperm (CNVs) - more likely to occur when parents are older. The age of parents is a risk factor for simplex ASD
• Syndromic + Non-syndromic ASD

  • Non-syndromic = main diagnosed disorder without a clear genetic cause
  • Syndromic = Accompanies another primary condition with a known single-gene genetic cause
  • For example, Fragile X syndrome (FXS) caused by a mutation in the FMR1 gene on the X chromosome
  • Zingerwich et al (2009) about 60% of individuals with FXS also meet the diagnostic criteria for ASD - lead to a better understanding