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Serotonin transporter promoter polymorphism (5-HTTLPR) genotype was previously found associated with substance use disorders, particularly in the subjects with comorbid antisocial behavior, and with temperament and personality traits at risk for substance abuse. Aim of the present study was to evaluate the possible association between 5-HTTLPR genotype and the availability to experiment illegal drugs among adolescents, in relationship with psychological characteristics. 216 caucasian high school students (aged 14–19 ys), 125 abstinent subjects, who have never experimented psychotropic drugs, and 91 experimenters of illegal drugs have been genotyped. Aggressiveness levels and temperamental traits were measured in both abstinent subjects and experimenters utilizing respectively Buss-Durkee-Hostility-Inventory (BDHI) and Cloninger Three-dimensional Personality Questionnaire (TPQ). Data about school performance have been also collected. The short-short (SS) genotype frequency was significantly higher among experimenters compared with abstinent subjects (p = 0.001). The odds ratio for the SS genotype vs the long-long (LL) genotype frequency was 4.67, 95% Cl (1.97–11.04), when experimenters were compared with abstinent students. The SS genotype frequency was significantly higher among aggressive/novelty seeker (NS) experimenters with poor school achievements, compared with drugs experimenters without aggressiveness and school failure (p = 0.02). When evaluated on the entire sample, BDHI mean total scores, NS scores at TPQ and school failure frequency were significantly higher in SS individuals, in comparison with LL subjects. Our data suggest that a decreased expression of the gene encoding the 5-HTT transporter, due to “S” promoter polymorphism, may be associated with an increased availability to experiment illegal drugs among adolescents, particularly in the subjects with more consistent aggressiveness, NS temperament and learning disabilities. [ABSTRACT FROM AUTHOR]

Summary. The promoter of the monoamine oxidase A (MAO-A) gene was analysed to test whether length variation of the repeat polymorphism contributes to variation in individual vulnerability to aggressive-criminal behaviour, and liability to heroin dependence. The repeat number of the MAO-A polymorphism was assessed in 199 male subjects of Italian descent, a sample comprising 95 healthy subjects and 104 heroin-dependent subjects including 52 addicted individuals with violent behaviour and antisocial personality disorder. The frequency of the low-activity 3-repeat allele was significantly higher in violent offenders among heroin addicts, compared to addicted individuals without antisocial behaviour (34.6 vs. 15.4%; p<0.03) and controls (18.9%; p<0.05). No significant difference was evidenced in the frequencies of the MAO-A alleles between heroin-dependent subjects in general and control subjects. High activity 4-repeat allele frequency was significantly higher in addicted individuals without antisocial behavior compared to antisocial-aggressive heroin-dependent subjects (76.9 vs. 55.8%; p<0.02). Buss Durkee Hostility Inventory (BDHI) mean total scores were significantly higher in heroin addicts than in controls (p<0.001), and in antisocial-violent heroin addicts in comparison with addicted individuals without antisocial behaviour (p<0.005). Among heroin addicts BDHI irritability, suspiciousness and resentment subscales scores were found significantly higher in low activity 3-repeat allele subjects than in high activity alleles subjects (p<0.001; p<0.05; p<0.05, respectively). No association was found between MAO-A polymorphism and suicide history. Our findings suggest that the low-activity 3-repeat allele of the MAO-A promoter polymorphism confers increased susceptibility to antisocial-violent behavior and aggressiveness, rather than drug dependence per se, in heroin-dependent males. [ABSTRACT FROM AUTHOR]