Heritable factors account for approximately 40-60% of the total variance of 
liability to alcohol dependence. The present study tested whether a novel 
functional polymorphism in the promotor region of the X-chromosomal monoamine 
oxidase A gene (MAOA) was related to antisocial and anxious-depressive traits in 
alcoholics. Due to the X-chromosomal localization of the MAOA gene, 
psychobiological traits were compared separately for both genders of 298 male 
and 66 female alcoholics. In males, 30 of 59 alcoholics with antisocial 
personality disorder carried the low-activity 3-repeat allele in contrast to 
only 7 of 31 anxious-depressive alcoholics (51% vs. 23%; p = 0.02). Likewise, 
female anxious-depressive alcoholics showed a trend towards a low frequency of 
genotypes with the 3 repeat allele compared to female alcoholics without these 
symptoms (29% vs. 53%; p = 0.09). Taken together, these findings suggest that 
the 3-repeat allele of the MAOA polymorphism contributes modestly to the 
dimension of overand underreactive behaviors as possible antecedents of 
alcoholism.