gentics explanation for schiz Flashcards
is it bio or social?
bio
what have scientist long known?
that schizophrenia runs in the family
what % of general population have schizophrenia?
1%
what % of people with first degree relative?
10%
what % of people with second degree relative?
2-6%
what & of people with MZ twin?
40-60%
what researchers provided evidence for MZ twins?
Gottesman, found concordance of disorder in MZ twins to be 48%
what do they high figures (percentages) suggest about schiz?
that genetics is the largest explanation
what fraction of people with schiz have a family history?
less than a third
has there been a single gene that causes schiz?
no
how can schiz occur if there is no family history?
mutations
what are mutations?
changes in genes, copying errors, radiation, poison or viruses
what are the genes involved in the theory?
- disc 1
- 2q11
- xq23
- c4
what is 2q11 depletion?
a section of the gene 2q11 missing
what happens when someone has 2q11 depletion?
show psychotic symptoms similar to schizophrenia
what is the frequency of those with symptoms in 2q11?
18%
what has disc 1 got to do with schizophrenia?
has been implicated in the of psychiatric disorders (including schizophrenia) although there is no clear chromosomal abnormality relating it directly to schiz
what else can be looked at if it isn’t one individual genes?
a gene variant that occurs in a groupings of genes
what is the example of a gene variant?
rare gen variant xq23
how has q23 been linked to schiz?
kirov et al found that 52% of cases of schizophrenia had this gene variant
what does synapse pruning got to do with schiz?
loss of healthy brain synapses due to increases c4 gene activity, leads to cognitive symptoms found in schizophrenia
what does an increase of c4 gene activity head to?
excessive gene pruning
how many weaknesses is there for genes as theory?
5
what is a criticism of the theory?
it is reductionist in the fact it only focuses on genes, does not focus as a whole (social)
is the study applicable to those who have no family history at all?
not, not able to explain, in complete
how does the theory have high reliability?
there are many different methods that can be used to study effects of genes such as family and twin study swell as dna pooling
what did xu et al di and was he a strength or weakness?
strength
examined genetic makeup of 1077 people including 152 schiz and their parents. found that 10% of schiz patients had a mutation that distinguished dna from parents compared to 2%. shows that schiz can be explained through mutations
what did gottesman and shields find?
compared mz and dz twins, identified them through blood tests and fingerprints. gathered medical info, questionnaires and interviews with them and parents. found that the concordance rate of schiz for mz was 42% and dz was 9%
why can gottesman and shields be a weakness?
they did not find 100% so there must be environmental factors
why is the explanation reductionist?
does not look at a whole, consider environmental factors
why are there no reliable findings?
the area of genes is too complex for findings ro be similar, there has not been an explanation of one gene yet
what did tiwari say?
other factors in scgiz come from environment and there is a need to study this is order to fully understand
