Genetic explanation for mental illness (Topic2)

Question 1

The genetic explanation

Answer 1

There is some evidence certain disorders are passed from one parent to child through genetic transference.
e.g children may inherit eye colour- they could inherit either a disorder or a disposition towards a disorder.
Would be no guarantee they would have that disorder e.g depression- but if environmental factors sufficient, person may be more likely to have disorder.
Due to the nature of genetics: only half genes come from each parent, is possible for one child to show tendency and sibling does not.
Study on twins with identical genetic makeup (monozygotic- one egg) and non-identical (dizygotic- two eggs) helps see impact of genes & environment.
Adoption studies also show how children with biological parents with mental illness and adopted by parents without, such illness are impacted by their environment & influence of genes.

Question 2

Genetic vulnerability to schizophrenia

Answer 2

Schizophrenia is caused by high levels of dopamine. Anti-psychotic medicine lowers dopamine levels.
Schizophrenia is inherited from parents through genes, runs in families.
Schizophrenics often have deficit in PPP3CC gene.
Closer person is genetically to someone with schizophrenia- more likely to develop.
18 x more likely to develop if person has close relative with schizophrenia than a person without relative with it.
Adoption studies comparing biological and adoptive families also suggest schizophrenia is genetic.

Question 3

Concordance rate for identical twins (monozygotic-one egg)

Answer 3

48%
Rate still high even when twins brought up separately.

Question 4

Concordance rate for non identical twins (dizygotic- two eggs)

Answer 4

17%

Question 5

Concordance rate for cousins

Answer 5

2%