Sz: Genetics

Question 1

A01

Answer 1

Chance of getting sz 0.3-0.7%
Chance increases when related to sz
Child- 13%
DZ twin- 17%
MZ twin- 48%
Deletion of COMT gene (dopamine levels are not controlled effectively in frontal lobe) results in loss of reality + hallucinations
Specific genes trigger symptoms 
Deletion of chromosome 22 (containing 30-40 genes)- causes syndrome DiGeorge where 1 in 4 have sz 

C4-A is specific gene accelerates pruning (Higher risk of developing sz)

Differences suggest to cause:

1) critical pathways damaged
2) adaptive creative ways- evolutionary link
3) sensitivity to chemicals (e.g. Harrison and Weinberger, 2004 highlighted that it may alter the functions of the synapse)

Question 2

AO1- Kendler et al (1985)

Answer 2

found that 1st degree relatives of those with schizophrenia are 18 times more at risk than the general Population. Children with both parents who suffer from schizophrenia have a CONCORDANCE RATE OF 48%

Question 3

AO1- Sherrington (1988)

Answer 3

a gene located on chromosome 5 has been linked to schizophrenia

Question 4

AO1- Miyakawa (2003)

Answer 4

schizophrenics have a defective version of a gene called PPP3CC

Question 5

+AO3- Tienari et al (2000)

Answer 5

adoption study controlled for environmental influence and found that almost 7% of adoptees had a biological mother with the same disorder, compared to only 2% of Schizophrenic children with non-SZ biological parents

Question 6

+AO3- Gottesman & Shields

Answer 6

gathered 62 twin pairs, Zygosity was decided, gathered hospital notes, interviews with twin and parents. 42% MZ, 9% DZ

Question 7

+AO3- Kety

Answer 7

DZ twin – 17%

MZ twin – 48%

Question 8

+AO3- NT theory

Answer 8

Can be used in unison with Neurotransmitter theory (the genes cause the change in NT)

Question 9

+AO3- useful

Answer 9

Explains the trends of how it runs in families making it a credible and useful theory

Question 10

-AO3- Tamminga and Schulz (1991)

Answer 10

have suggested research has failed to isolate a single recessive or dominant gene which causes the illness

Question 11

-AO3- Reductionist

Answer 11

The disorder may be more complicated than that and may be the expression of many genes which cause it

ignores cognitive explanations

Question 12

-AO3- Harrison and Owen (2006)

Answer 12

has suggested up to 6 different genes may be involved in susceptibility

Question 13

-AO3- Environmental factors

Answer 13

Concordance not 100% therefore showing that the environment plays a role not just genetics

twin studies- environments aren’t really equal, sample issues etc