Biological Explanations: Genetic Factors

Question 1

One possible cause of schizophrenia may be

Answer 1

Heredity

Question 2

Schizophrenia runs in families

Answer 2

Risk of developing it is greater among individuals who have family members with the disorder

Question 3

There are a number of genes that each seem to increase the risk of schizophrenia

Answer 3

But only by a small amount on their own

Question 4

This suggests schizophrenia is polygenic

Answer 4

It requires a number of factors to work in combination

Question 5

Human genome studies by Ripke
Combined data from previous studies looking at the whole genetic makeup of 37k individuals with schizophrenia and compared to that of unaffected individuals

Answer 5

Found there were 108 separate genetic variations all associated with schizophrenia

Question 6

Family studies by Gottesman

Answer 6

Looked at the likelihood of developing schizophrenia depending on whether different biological relatives suffered from the disorder

Question 7

The risk of developing schizophrenia in the general population is 1% however

Answer 7

Individuals with a half sibling affected (with whom they shared 25% of genes) had a 6% risk of developing it themselves

Question 8

Risk of a person with a sibling affected by schiz (50% of genes) rises to 9%

Answer 8

Those with identical twin (100% shared genetic material) had a 48% risk of developing it themselves

Question 9

This shows the more genetic similarity to a schizophrenic individual

Answer 9

The greater the risk of developing the disorder

Question 10

Twin studies from Joseph

Answer 10

Pooled data for all studies prior to 2001 assessed the concordance rates between MZ and DZ
Overall MZ 40% DZ 7%