Alcohol dependence and polymorphisms of serotonin-related genes: Association studies

Variations in 5HT-related genes contribute to the alterations of serotonergic neurotransmission, which is implicated in the etiopathology of alcoholism. In this preliminary study we have tested polymorphisms of genes involved in 5HT transport and turnover for their association with alcohol dependence. A case group of males with type 2 alcoholism (N=59) and a control group of healthy males (N=282), both of Croatian origin, were analyzed for the frequency distribution of polymorphisms in 5HT transporter (5HTT-VNTR2, 5HTT-LPR), monoamine oxidase A (MAOA-uVNTR) and B (MAOB-A/G) and tryptophan hydroxylase 1 (TPH1 A218C) and 2 (TPH2 G-703T) genes. An increase in the frequencies of 10-repeat allele (p = 0.010; OR = 1.73; 95% CI = 1.14-2.60) and 10/10 genotype (p = 0.006; OR = 2.57; 95% CI = 1.32-5.00) of the 5HTT-VNTR2 polymorphism was found in alcoholic patients. No differences between case and control groups were observed for the other tested polymorphisms. Present results support earlier studies implicating the role of 5HTT gene in alcoholism. The increase of sample size (in progress) is expected to enable search of more subtle differences, as well as re-evaluation of these preliminary findings.