A dinucleotide repeat polymorphism at the gene for monoamine oxidase A and measures of aggressiveness.

The relationship between measures of aggressiveness (personality questionnaire scales, conduct disorder diagnosis, and symptom count) and a recently discovered dinucleotide repeat length polymorphism at the monoamine oxidase type A (MAOA) gene (MAOCA-1) as a candidate locus was examined in adolescents using polymerase chain reaction. No significant correlation between aggression scales and repeat length at the MAOCA-1 marker was found, whereas the categorical diagnosis of conduct disorder showed a nonsignificant trend for an association with the marker. Alternative explanations of this trend are discussed. The data obtained suggest that the polymorphism studied is not associated with the variation in aggressiveness.