Genetic Factors in Aggression: MAOA gene

Question 1

what is the MAOA gene?

Answer 1

controls the production of an enzyme called monoamine oxidase A (MAO-A)
- gene = MAOA
- enzyme = MAO-A

Question 2

what does MAO-A do?

Answer 2

regulates the neurotransmitter serotonin

Question 3

what is the role of serotonin?

Answer 3

plays an important role in impulsive aggression

Question 4

what are the variants of genes?

Answer 4

• low-activity variant
• high-activity variant

Question 5

what does the MAOA gene come in?

Answer 5

low variant
- MAOA-L

Question 6

what does low activity variant MAOA gene cause?

Answer 6

MAOA-L results in low activity of the MAO-A enzyme = MAO-A deficiency
- this variant is linked to high level of aggressive behaviour

Question 7

what is the MAOA gene nicknamed as?

Answer 7

warrior gene

Question 8

who are the researchers involved with nicknaming of MAOA gene as warrior gene?

Answer 8

Lea and Chambers

Question 9

what did Lea and Chambers find?

Answer 9

• MAOA-L variant was possessed by 56% of New Zealand Maori men, compared to 34% Caucasians
• historically, Maori people had a reputation for being ferocious warriors

Question 10

who is the researcher involved in linking MAOA-L and aggression?

Answer 10

Brunner et al

Question 11

what did Brunner et al do?

Answer 11

• studied 28 men from a large Dutch family who were repeatedly involved in impulsively aggressive violent criminal behaviours (e.g. rape, attempted murder and physical assault)

Question 12

what did Brunner et al find?

Answer 12

• the dutch men had abnormally low levels of the enzyme MAO-A as well as the MAOA-L gene variant = Brunner syndrome