Genetic cause of AN Flashcards
AN genetic
intro
genes are sets of instructions that carry information,
they’re made out of DNA which is responsible for protein synthesis which is important and development
the genome is all the genes in that cell
chromosomes contain genes contain millions of combinations of the four bases in pairs of DNA
humans have 23 pairs of chomozones
23 from mother and 23 from the father
this is why the traits are shared between family members
genes are responsible for a trait due to having pairs of chromosomes you have two
there are either dominant or recessive
the dominant Gene always takes prevalence over the recessive one and you will always have the trait of the dominant Gene
if genetics is the cause of anorexia there are two ways it could be shown
AN genetic
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Kipman 1999
and famiky studies
According to kipman 1999 if anorexia was explained by genes
then we would expect the frequency of anorexia in relatives of someone with anorexia would be higher than a general population
there is one way that we can study for this
By using family studies to look at the first degree relative which is siblings, parents and children
of people with and without a diagnosed eating disordered
to establish the hereditability estimate
which is currently at 70% for anorexia
(which is defined as the percentage difference between family members or twins due to genetics)
The closer to 100% the family is the higher the risk of anorexia
the low percentage equals the more likely that it is due to environmental factors
AN genetic
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twin studies
The other way genes can be shown to be cause of schizophrenia is that if anorexia is experienced by twins then identical MZ twins would have a higher concordance rate
( the proportion to which they share the same attribute(AN) the other twin has)
MZ twin had anorexia it is likely the other MZ twin would also develop this
There is one way that we can study for this
Twin cities has MZ twins share 100% DNA
so if there is a high concordance rate between them higher than DZ twins then it is highlight with those a genetic link to the development of AN
but if there is a higher concordance rate in DZ twins but it is likely to have an environmental link to the development of AN
AN genetic
Pg3
EPHX2
No one gene can explain all an symptoms as it is a polygenetic disorder but there are 3 genes that are linked to it one of which is ephx2
This Gene codes the enzyme epoxide hydrolase which regulates cholesterol metabolism
which is linked with serotonin which has links that are associated with feeding anxiety such as being anxious about eating around others which is a symptom of an
This gene is also linked to parts of the brain such as the hypothalamus which regulates and feeding
as well as the amygdala which regulates fear response such as the fear of gaining weight
AN genetic
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ITPR3
Another Gene but is linked to am is i t p r 3
Codes for protein that detects the taste of food if this Gene is faults me in anorexia nervation they will be unable to use taste as a motivator to eat more food
which is therefore a left of a reason for them to do so
leading to eating disorder developing
AN genetic
PG5
DAT1 +alt/cred
A final Gene that is linked anorexia is dat1 which codes for protein regulator transport of dopamine
it could mean dope activity is distrupted
leading to a lack of motivation and satisfaction after eating that’s others may normally get out of this
meaning anorexic person there is less than a reason to eat
This may have an alternative slash credibility point as this could mean that anorexic could be caused by neurotransmitters not genes
AN genetic
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Grice et al 2002 + Social cause oppose gene-
Grice 2002
Does a study w/ 192 families where two or more of the members had anorexia
There was no significant evidence of genetics until a focused on a subgroup of 37 families with two plus members with restrictive anorexia
and it showed strong evidence for a subset ability Gene on chromosome one as it is similar between groups in each family
Therefore this is good evidence support for genetic explanation for restrictive anorexia
ALT:
Wade 2007
found that when studying anorexia participants
their childhood often consisted of family members making consistent comments about their weight
therefore they would have a pressure to be thin
and develop anorexia eating disorder therefore there could be a social cause rather than a genetic cause
meaning this is evidence opposing genetic explanation
AN genetic
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Fairburn and Harrison 2003 + concordence rate is never 100%-
Fairburn and Harrison 2003
Find concordance rates of 55% in NZ twins the 5% of DZ twins for anorexia
showing more concordance rate in MZ than DZ twins for anorexia ..
showing a strong genetic component it’s cause and
therefore supporting the genetic explanation
only 55% of the MZ twins this means that genetics is a factor however there are also must be other factors that’s combine to form the cause of anorexia
Demonstrates them must be some other environmental social factors as well as biological and genetics in anorexia as the concordance rate is not 100%
AN genetic
PG3
REDUCTIONIST + CULTURAL NASSER 1986-
By simplifying anorexia down to a singular cause of genetics
it can be more scientifically measured and studies
via methods such as genetic markers and genetic variants being identified by DNA sampling
which are both scientific and objective measurements that are internaly valid
as cause and effect can be accurately established without misinterpretation
Therefore this case being reductionist is a positive for the theory
nasser 1986
Found 12% of Egyptian women studying at the university in London developed anorexia
compared to none of 16 Egyptian studdingly Cairo
supporting the idea that cultural factors influenced the development of anorexia
this study opposes views as an explanation of anorexia
AN genetic
PG4
Scott van zeeland ‘13 + neg implication -
Scott van zeeland 2013
Conducted a genome wide associations to the gwas to identify genes related to anorexia
262 female anorexia diagnosed patients we used
along with 80 control who were matched on age and ethnicity
500 DNA samples were gathered from each group
and there was no significant variants associated with anorexia
but they did identify SETS of variants that were significantly Association of anorexia 35 variants of itpr3 and 14 variants in ephx2
Of those 14 variants there was one set that was significantly associated with anorexia nervosa
They ID sets of variant of genes that were associated with anorexia novosa and therefore supporting the genetic explanation of anorexia
A bad implication of if genes caused anorexia such as dat1 or ephx2
then the implication in extreme cases
could lead to a eugenics movement of sterilizing those with the faulty anorexia genes to stop them reproducing and passing on his genes and anorexia
this is an incredibly unethical implication of this that’s is unlikely to happen unless in extreme cases
An example of eugenics is a Nazi Germany when they did it to schizophrenics
AN genetic
PG5
SLT as an alt, drug treatment and diathesis
An alternative explanation could be social learning theory due to vicarious learning
an patient could see a thin person being praised then deem them as a role model
and then become thin themselves to get praised further and then this will continue until they lose a lot of weight and they become obsessed with it and then anorexia will develop
This is an alternative to the genetic explanation
It is also incorporated in the diabetes stress model which indicates that both genetic and other biological explanations
as well as social or learning or cultural explorations should all be combined into One explanation to look at the cause of a disorder such as anorexia overall instead of in a reductionist lens
An application of the genetic explanation is that because it is biological there could be drugs used to dampen the effects of anorexia
One such drug is the second generation anti-sychotic olanzapine
Which has been used to take treat anorexia
due to its side effects of gaining weight and appetite and reducing the extreme beliefs about Body Image and related eating thoughts
it also reduces progression when confronted by people about their weight
Therefore due to the genetic explanation showing how the cause of anorexia is partially biological and to do with the dat1 gene
that codes for the the regulation of the transport of dopamine
shows us how and why olanzapine has been used to treat anorexia’s side effects effectively
