AN Contemporary study - Scott Van Zeeland Flashcards
What is the aim of the Scott Van Zeeland contemporary study?
To study a number of gene variants which might play a role in anorexia using a candidate gene approach (the 152 genes are candidates for contributing to disease risk)
What is the IV and DV of the Scott Van Zeeland contemporary study?
IV: The genotype (DNA sample) from the AN and control participants
DV: Total cholesterol levels and BMI of AN and control participants
What is the sample of the Scott Van Zeeland contemporary study? (4 points)
All participants were European women
Experimental group:
+ 1,205 anorexics (the cases)
+ Started experiencing symptoms at age 14
+ Lifetime BMI of 15 or less
Control group:
+ 1,948 people without the condition
+ No history of AN
+ BMI: 18-29
Cohorts:
Discovery Cohort:
262 participants (early onset severe AN cases)
80 controls (not underweight)
DNA Pooling Cohort:
500 AN cases and 500 controls
All anorexic participants self-reported to be ‘restrictive type AN’ where a person limits their calorie intake with or without purging
What was the procedure of the Scott Van Zeeland contemporary study? (3 steps)
- DNA samples were collected and sequenced using solution-based hybridization technology
+ Quality control of DNA samples was ensured by excluding participants with more than 10% of their genome missing - Comparisons of allele frequencies between the pools of DNA were made
- Allen Brain Atlas was used to explore the expression patterns of genes in specific brain regions
What were the results of the Scott Van Zeeland contemporary study? (4 points)
Two gene variants of ESR2 (Estrogen Receptor Beta gene) showed the strongest association with anorexia
This supports previous studies suggesting that oestrogen receptors might play a role in anorexia
A new association found between abnormal gene expression of EPHX2 in the corpus callosum and hippocampus
This indicates a sex-specific effect of EPHX2, impacting cholesterol levels, weight gain and overall BMI
What was the conclusion of the Scott Van Zeeland contemporary study? (2 points)
New association between EPHX2 gene variants and anorexia susceptibility identified
Provided a new foundation for future study of the condition
How generalisable is the Scott Van Zeeland contemporary study? (4 points)
Low generalisability of the sample population used for DNA analysis
Only participants with a genome of European descent were included in the sequencing analysis - 1 participant was even excluded because of a genome mixture with Hispanic descent
Gynocentric and ethnocentric despite using a large DNA sample of over 3000 participants
The findings are only relevant to a specific target population of female AN sufferers of European descent - not to males or other ethnic groups
How reliable is the Scott Van Zeeland contemporary study? (4 points)
Used highly scientific genetic variant analysis and self-report scales like the State-Trait Anxiety Inventory and Beck Depression Inventory
These could be repeated by others to test for inter-rater reliability
Data was compared with other studies to see how these fit with the gene variants - similar conclusions were drawn
Suggests that the study has been reported in sufficient detail for independent researchers to repeat, increasing the reliability
How applicable is the Scott Van Zeeland contemporary study to real life? (4 points)
Findings have strong application findings for anorexic patients
One of the findings was a new association of 14 gene variants of EPHX2 to anorexia increasing susceptibility
Such conclusions provide a new foundation for future study of AN:
+ They lead to a more scientific approach using a biological basis
+ They challenge older assumptions that it is a purely sociocultural disorder
Findings provide new insights which could lead to new therapeutic treatments or drug targets for AN patients
How is the Scott Van Zeeland contemporary study internally valid? (2 points)
High internal validity - control group of non-AN patients was used as a baseline measurement to compare the results
Use of matched-pairs design for age, gender, and ethnicity between the experimental and control group ensured extraneous variables were accounted for
How is the Scott Van Zeeland contemporary study not internally valid? (2 points)
Biologically reductionist - focuses primarily on EPHX2 and ignores environmental and learning behaviours
Causation cannot be inferred - not apparent how these gene variants are implicated in anorexia despite the semblance of a relationship
How ethical is the Scott Van Zeeland contemporary study? (2 points)
All participants:
+ Were screened using psychometric scales like the Beck Depression Inventory and State-Trait Anxiety Inventory
+ Gave informed consent for the use of their DNA samples for sequencing and genetic analysis
