anorexia - genetics explanation

Question 1

Kipman et al - twin study

Answer 1

compared 106MZ and 56 DZ twins
MZ concordance rate - 4%
DZ concordance rate - 7%

Question 2

criticisms of Kipman et al

Answer 2

for anorexia to be completely genetic, 100% of MZ twins should have anorexia

twins are likely to have grown up in the same environment - environmental factors could be responsible

Question 3

what are family studies used for

Answer 3

to see if anorexia is passed down genetically

Question 4

Woodside et al. - Family study

Answer 4

first degree relatives are more likely to have anorexia than third degree relatives

as first degree relatives share more genes than third degree relatives, this is evidence for genetics as an explanation

Question 5

criticism of Woodside et al.

Answer 5

first degree relatives are more likely to have shared the same environment compared to their third degree relatives, which suggests that the environment could be a factor

Question 6

what are the three specific genes that can be linked to anorexia

Answer 6

EPHX2

ITPR3

DAT1

Question 7

ITPR-3 gene

Answer 7

codes for a protein involved in detecting the taste of food - such as bitter and sweet

people with AN are unable to use taste as a motivator to eat if this gene is faulty

Question 8

DAT1 gene

Answer 8

linked to the function of dopamine on the reward system

if this gene mutates, dopamine activity is disrupted, resulting in a lack of motivation and satisfaction that others would get from eating

Question 9

EPHX2 gene

Answer 9

produces an enzyme that helps regulate cholesterol metabolism

cholesterol metabolisms is connected to serotonin, which is a chemical linked to anxiety and depression

gene influences part of the brain involved in eating and hunger (hypothalamus) and the fear response (amygdala)

problems with this genes expression may cause fear and low mood around food due to its impact on both hunger regulation and the fear response

Question 10

Scott-van-Zeeland et al (2013) - aim

Answer 10

to identify genes associated with anorexia

Question 11

Scott-van-Zeeland et al (2013) - research method

Answer 11

a genome wide association study (GWAS) that identified genetic markers that are more frequent in people with anorexia

Question 12

Scott-van-Zeeland et al (2013) - participant

Answer 12

262 females with AN
80 controls
DNA samples taken from both
ppts matched on age and ethnicity

Question 13

Scott-van-Zeeland et al (2013) - procedure

Answer 13

ppts DNA was compared against 500 DNA samples from individuals with AN and 500 samples from ppts without AN

samples taken from the Price Foundation Sample Repository

Question 14

Scott-Van-Zeeland et al (2013) - results

Answer 14

no single genetic variant associated with AN

a combination of variants showed a significant genetic difference between the AN ppts and the controls

variants in the ITPR3 gene and the EPHX2 gene could be associated with the disorder