Schizophrenia: Genetic Factors

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  • Created by: Olivia
  • Created on: 06-03-13 20:46
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  • Schizophrenia: Genetic Factors
    • Appaears to run in families
      • Proportional to the amount of genes which are shared
      • MZ twins: Risk = 48%
        • However, vhance of developing is below 100% = other factors play a part
      • DZ twins + children with one effected parent: 17%
      • Grandchildren = 5%
      • General population = 1%
    • Twin Studies
      • Asuumption = MZ twins will have a greater concordance rate
      • MZ twins are genetically identical. Dz twins only share around 50% of genes
      • CARDNO ET AL (2002): Used strict diagnostic criteria - showed concrodance rate of MZ twins to be 26.% and 0% for DZ
        • Provides strong evidence for a genetic component
          • MZ twins relatively rare in population and only 1% expected to have schz. = sample sizes small
          • Twin studies dont all use same diagnostic criteria = comparisons can not always be made
            • Different defintions produce different concordance rates - MCGUFFIN ET AL (1984)
          • Concorndance rates can also be calculated in different ways + vary depending on method used
    • Adoption studies
      • Allows you to look at people with a mother with the disorder, but adoptive parents with no history of it
        • KETY (1994): high rates of schiz. in individuals whose parents had the disorder, but not adoptive parents
      • TIENARI (1991): Identified 155 adopted children whose biological mothers had schiz. Comapred with adopted children with no family history = 10% of group 1 developed it whereas 1% in group 2
        • Strong evidence for genetic component in schiz.
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