A haplotype analysis is consistent with the role of functional HTR1B variants in alcohol dependence

Background: Animal and human studies have suggested that the serotonergic system plays an important role in alcohol consumption and abuse, mainly due to the serotonin receptor 1B (5-HT1B) function in the mesolimbic reward pathway. Association studies between the HTR1B gene variants and alcoholism have found significant results. There is also evidence for a complex balancing regulation of the gene by two functional variants in the promoter region (rs11568817 and rs130058), which are in linkage disequilibrium. Methods: The aim of this study is to investigate the role of the most relevant variants (rs11568817, rs130058, rs6296 and rs13212041) of the HTR1B gene in the susceptibility to alcohol dependence. The sample comprised 136 Brazilian alcoholics of European descendent and 237 controls. Results: The results suggest an association between a functional variant of the gene (rs11568817) and alcohol dependence (p = 0.001). In addition, this association could also be confirmed in an independent sample using imputed data from a GWAS, where marginal significant association (p = 0.03, one-tailed) with the same allele was obtained. The pattern of distribution of haplotypes was significantly different between patients and controls (p < 0.0001), which is consistent with the role of the two functional variants of the promoter region. Conclusion: In conclusion, our findings point to an association between functional variants in the promoter region of the HTR1B gene and alcohol dependence, supporting previous neurobiological evidences of the involvement of HTR1B variations in alcohol-related phenotypes. (C) 2011 Published by Elsevier Ireland Ltd.