Association of a regulatory polymorphism in the promoter region of the monoamine oxidase A gene with antisocial alcoholism.

We analyzed a novel functional 30-bp repeat polymorphism in the promoter region of the X-chromosomal monoamine oxidase A gene (MAOA) to test whether length variation of the repeat polymorphism contributes to variation in the individual vulnerability to antisocial behavior and liability to alcohol dependence. The repeat number (3-5) of the MAOA polymorphism was assessed in 488 male subjects of German descent, a sample comprising 185 psychiatrically screened control subjects and 303 alcohol-dependent subjects including 59 alcoholics with antisocial personality disorder. The frequency of the low-activity 3-repeat allele was significantly increased in 59 antisocial alcoholics compared to 185 control subjects (51 vs. 35%; P = 0.031) and to 244 alcoholics without antisocial personality disorder (51 vs. 32%; P = 0.008), respectively. We found no significant difference in the frequency of the 3-repeat allele between 244 alcoholics without an antisocial personality disorder and the control subjects. Our findings suggest that the low-activity 3-repeat allele of the MAOA promoter polymorphism confers increased susceptibility to antisocial behavior rather than alcohol dependence per se in alcohol-dependent males.