Role of Genotype in the Cycle of Violence in
Ian W. Craig,1
We studied a large sample of male children from birth to
adulthood to determine why some children who are maltreated
grow up to develop antisocial behavior, whereas others do
not. A functional polymorphism in the gene encoding the
neurotransmitter-metabolizing enzyme monoamine oxidase A
(MAOA) was found to moderate the effect of
maltreatment. Maltreated children with a genotype conferring
high levels of MAOA expression were less likely to
develop antisocial problems. These findings may partly
explain why not all victims of maltreatment grow up to
victimize others, and they provide epidemiological
evidence that genotypes can moderate children's
sensitivity to environmental insults.
1 Medical Research
Council Social, Genetic, and Developmental Psychiatry Research
Centre, Institute of Psychiatry, King's College, London SE5 8AF, UK.
2 Department of
Psychology, University of Wisconsin, Madison, WI 53706, USA.
3 Dunedin School of
Medicine, Box 913, University of Otago, New Zealand.
whom correspondence should be addressed. E-mail: firstname.lastname@example.org