5.3.5 - Scott-Van Zeeland et al. (2013)

Question 1

AO1

X6

Answer 1

• The aim was to investigate genetic variants associated with the development of AN.
• DNA samples were taken from a group of 261 patients diagnosed with AN and 73 controls without the disorder, all of whom were female
• Another group of 500 DNA samples from AN patients and 500 DNA samples from non-sufferers were taken from the Price Foundation sample repository for further comparison
• To be used in the study the individual had to have a lifetime BMI of 15 or lower and have a history of being diagnosed with AN and the control group had BMIs of between 18-29
• Results found the EPHX2 gene is associated with the body metabolising cholesterol, and other research has found patients with AN show high levels of cholesterol despite being malnourished, supporting the concept of variants in this gene relating to AN
• They looked at brain regions that seemed to be relevant with regard to the sequencing they uncovered

Question 2

AO3

2S + 2W

Answer 2

• • Sample sizes were large throughout all stages of the study where DNA samples were taken from individuals who were all females and of European descent. Therefore there is a reasonable amount of validity in the conclusions as many factors such as gene varieties and gender which could affect the accuracy of how the EPHX2 gene influences the development of AN were controlled
• • This study has added to the developing body of research helping to understand the origins of AN, which found that variants in the EPHX2 gene may increase risk of developing anorexia. Therefore this added to the understanding of AN as an understudied disorder from a biological perspective and can take away blame and stigma from patients, encouraging more people to seek help
• • All of the patient samples come from females, and although most anorexics are female, and increasing number of males are being diagnosed. Therefore the study lacks population validity in relation to the entire target population and can’t be generalised to the 10% of males with AN
• • Very little is actually known about the actions of many genes and so, although a relationship has been seemingly uncovered, the explanation for how this gene is implicated in AN is still not understood. Therefore a lot of the explanation about the role of the EPHX2 gene, much gained from animal research, has little reliable evidence to support that the EPHX2 gene has variants increasing the risk of developing AN