genetics

• schizophrenia is hereditary
• twin studies have found concordance rates of about 48%. between parents and children its between 46 - 13% depending on if its one parent or both
• specific candidate genes have been identified that appear to increase the risk of developing schizophrenia.
• specific candidate genes have been identified that appear to increase the risk of developing schizophrenia.
• schizophrenia appears to be polygenic because multiple genes have been identified in schizophrenia
• research has found 128 genetic variations at 108 locations on the human chromosomes that contribute most to developing schizophrenia. many of the genes are linked to the brain and to the immune system
• Kety et al

  studied 207 children whose mothers had schizophrenia

  the results were compared to 104 normal children

  children were aged 10 - 18 years old

  16.2% in the high risk group developed schizophrenia

  1.9% in the low risk group developed schizophrenia
• Gottesman

  concluded that if both your parents suffer from schizophrenia, you had a 46% chance of developing it.

  a 13% chancw if one parent had it

  a 9% chance if a sibling had it
• Kendler

  18 times more likely to get schizophrenia if a member of family has it. the more genetically similar relatives are, the more concordance is found
• Gottesman and Shields

  studied 40 sets of twins

  concordance for MZ twins: 58%

  concordance for DZ twins: 17%

  anallysed 5 existing twin studies and found concordance of 75 - 91% for MZ twins, showing a strong genetic link
• Tienari

  Studied 164 adopted children whose biological mothers had schizophrenia and a control group of 197 adopted children from mothers without schizophrenia

  all were adopted by 4 years old

  concordancw of 6.7% in schizophrenic group compared to 2% in the control group

  strong evidence for genetics, even without the environment
• evaluation

  although schizophrenia runs in families, they also usually share the same environment, so cannot conclusively point to genes as the only cause. family explanations may be useful
• evaluation

  it is most likely a combination of genetics creating a vulnerability to developing the illness, and then environmental / social factors triggering the illness [the stress - diathesis model]
• evaluation

  concordance is not 100%, meaning there must be other causes of schizophrenia outside of genetics
• evaluation

  twin studies often ignore the influences of social class and other socio - psychological factors
• evaluation

  twin studies do not all use the same diagnostic criteria therefore different diagnoses will produce different concordance rates
• evaluation

  concordance rates can also be calculated differently depending on the method used - therefore, puts doubt over the reliability of such studies