GENETICS Flashcards
1
Q
GENETICALLY DETERMINED
A
- suggests a single schizo gene or number of genes can be passed down
- risk of having schizophrenia is 1%
- rosenthal studied quadruplets in which 4 girls were all identical to each other all developed schizophrenia although differed in age of onset and precise symptoms known as genian quadruplets
- probability of all 4 developing by chance is 0.00001%
2
Q
TWIN STUDIES
A
- Gottesman found concordance rate for MZ twins was 48% and only 17% for DZ twins
- as both share the same environment the highlighter concordance rate for MZ may be to do with shared genes
- Gottesman and shields found that heritability of schizophrenia varied depending on severity of symptoms with severer cases having higher concordance rates
3
Q
ADOPTION STUDIES
A
- tiernari et al studied 164 adoptees whose bio mums had schizophrenia and found 6.7% also received diagnosis compared to 2% of the control group with non mothers
- also found those with a high genetic risk to better in a supportive environment better than those who don’t have a high risk but brought up in poor environments
4
Q
WHICH GENES
A
- studies point towards some genetic influence and also highlight importance of environment
- unlikely the illness is attributed to a single gene more likely it is polygenic
- o Donovan et al 108 specific locations linked with schizophrenia 83 had never been reported before
- the genes identified were those involving brain tissue but also genes in the immune system however it has not been found how these genes cause the illness
5
Q
EPIGENETICS
A
- issue with genetic theory is the not 100% concordance rate so there must be something else happening for there to be a low concordance rate
- epigenetics could explain this while MZ twins have 100% identical genes expression of these genes can be affected by the environment
- eg if one had a stressful experience or illness the other didn’t this could cause the expression of their gene to change explaining concordance rate
6
Q
DIATHESIS STRESS MODEL
A
- another factor is the diathesis stress model which may explain concordance rates
- suggests cause of illness is both genetic and environment
- individual may inherit predisposition (diathesis) but not develop illness unless of an environmental trigger (stress) eg family upbringing or even living in the city
- therefore individual carrying genetic predisposition may not develop it unless they have an environmental trigger
