Genetics For AN Flashcards
What are genes?
A set of instructions and is a carrier for a set of instructions which are made up of DNA. Each person has 23 pairs of chromosomes, inherited from both parents (male and female) which make up all cells in the body which is known as the genome.
How are twin studies used to study genes?
Monozygote twins (MZ) should share 100% genes with each other as a single egg has fertilised their eggs therefore are identical. This means that if one twin has a gene for AN then the other twin will have that gene with 100% certainty. Concordance rate can be measured using this method to see if behaviour is genetic or not. Dizygotic twins therefore should share 50% of their genes.
If the behaviour is genetic what would we expect?
We’d expect the concordance rate to be higher in MZ twins than DZ as they are more genetically alike to each other.
What is concordance rate?
It tells us the percentage of cases where the behaviour occurs in both twins, rather than just one.
How are adoption studies used to study genes?
You look at the concordance rate between the child of the biological parent with the biological parent, and then the concordance rate between the biological child and the adopted parent. If AN is a biological cause then there should be an increase in concordance rate between the biological child and the biological parent as genetics suggest AN is inherited from the parent.
What is heritability estimate?
The percentage of estimate that are genetically inherited.
What are the 3 genes associated with AN?
- EPHX2
- TaqA1
- ITPR3
How does the EPHX2 gene cause AN?
It has links to anxiety and feeding problems, where parts of the brain for eating, such as the thalamus (which regulates the feeding of hunger) are all linked to this gene. Also there has been a link to metabolising cholesterol which has been linked to serotonin, which we know is associated to depression. If people are not getting serotonin from eating food, they are constantly feeling no pleasure therefore stop eating because they no longer feel pleasure.
What does the TaqA1 gene cause?
This gene is linked to addiction. This could cause obsessive weight loss symptoms or excessive need for excessive etc.
How is the ITPR3 gene said to cause AN?
It links to the taste of food, typically it makes food bitter or too sweet and therefore means people do not eat because they don’t like the taste of all foods. This links to motivation to eat food, if the food is not pleasurable to eat then the individual is not going to eat that food therefore is less motivated to eat.
