Genetic explanations (biological)

Question 1

What is the genetic explanation?

Answer 1

when faulty genes lead to the disorder
chances of developing SZ increases if a close relative has the disorder

Question 2

What did Gottesman (1991) find?

Answer 2

family study
when one Mz twin had Sz there was a 48% chance of the other developing it
this dropped to 9% if it was a sibling or Dz twin
falls to 2% if it’s an aunt
this indicates a positive correlation as the number of genes shared with a relative who has sz, increases our chances of developing it

Question 3

Explain candidate genes

Answer 3

a number of genes have been linked to Sz= polygenetic
this leads to biological changes that are responsible for the symptoms
genome= looking at all genetic material rather than just one gene

Question 4

What was the procedure of Ripke’s study?

Answer 4

He combined all previous data from genome wide studies of Sz
Compared the genetic makeup of 37,000 people with a diagnosis of Sz and a control group of 113,000

Question 5

What are the findings of Ripke’s study?

Answer 5

found that 108 separate genetic variations were associated with a slightly increased risk of Sz
Different studies identified different candidate genes; it’s likely Sz is aetiologically heterogeneous
this means there are a combination of factors including genetic variation that can lead to the condition

Question 6

What is the role of mutation?

Answer 6

Sz can have a genetic origin in the absence of family history of the disorder
an explanation for these mutations in parental DNA can be caused by radiation, poison or viral infection
Brown et al: evidence for mutation comes from positive correlations between paternal age (associated with sperm mutation) and risk of Sz
increases from around 0.7% with fathers under 25 to over 2% with fathers over 50

Question 7

Support for the genetic explanation

Answer 7

Adoption studies like Tienari (2004) showed that biological children of parents with Sz are at a heightened risk even if they grow up in an adopted family
Ripke (2018) showed a concordance rate of 33% for Mz twin and 7% for Dz twins
Support as it shows that Sz is mostly caused by biological factors

Question 8

Limitation for the genetic explanation

Answer 8

Ignores psychological factors
Biological risks include birth complications and smoking
Psychological risk factors include childhood trauma which leaves people more vulnerable

Question 9

what did Morkvet (2017) find? (limitation for genetics)

Answer 9

67% of people who had Sz and related psychotic disorders all reported to have at least one childhood trauma
As opposed to 38% of a matched group with a non-psychotic mental health issues