Genetic SZ Theory

Question 1

how many genes involved in SZ

Answer 1

• 700 genes linked to SZ.

Question 2

DG syndrome

Answer 2

• Genes could mutate, 25% people with DiGeorge syndrome get SZ.

Question 3

COMT

Answer 3

COMT gene and DiGeorge linked to SZ as DG deletes it, then there is no gene to instruct an enzyme to break down dopamine in prefrontal cortex, results in SZ symptoms.

Question 4

DISC1

Answer 4

• DISC1 gene abnormality are 1.4x more likely to develop SZ (kim et al). This creates codes for GABA which regulates dopamine and glutamate in limbic system.

Question 5

Diathesis-stress model

Answer 5

• genes create a vulnerability for SZ than cause it. Could possess SZ genes but biological or env factors trigger it. Genes are the required element.

Question 6

Genetic Evidence for SZ

Answer 6

Gottesman 1991:
- Positive relationship between increasing genetic similarity of family members and their increased risk of developing schizophrenia.

Question 7

Genetic - Concordance rate for Gottesman

Answer 7

MZ twins: 48%
DZ twins: 17%
Siblings: 9%
Parents: 6%

Question 8

Genetic - MZ twins and Environmental factors

Answer 8

MZ Twins share 100% of genes, although this suggests a strong basis and the existence of candidate genes for schizophrenia. There are no 100% concordance rates, demonstrating there are environmental influences acting on the development of SZ.

Question 9

Genetic SZ Evaluation

Answer 9

• Failed to isolate single gene that causes SZ.

+ Tienari found that 7% of adoptees with SZ had bio mothers with SZ.

• Harrison and Owen (2003) report up to 6 genes involved in susceptibility to disorder.
• Concordance rate not 100%, there could be other factors.