Chunk #18 — Identifying Specific Genes Related to AOD Dependence — Genes Encoding Proteins Involved in Neurotransmission — Genes Encoding the GABAA Receptor
Interest in the GABAA receptor genes on chromosome 4 grew when this region consistently was identified in genome-wide scans looking for linkage with alcohol dependence (Long et al. 1998; Williams et al. 1999). Subsequently, COGA investigators systematically evaluated short DNA segments of known location (i.e., genetic markers) that were situated in the GABAA receptor gene cluster on chromosome 4. These studies found that a significant association existed between multiple SNPs in the GABRA2 gene and alcohol dependence (Edenberg et al. 2004). This association has been replicated in multiple independent samples (Covault et al. 2004; Fehr et al. 2006; Lappalainen et al. 2005; Soyka 2007). In addition, the same SNPs in the GABRA2 gene have been shown to be associated with drug dependence in both adults and adolescents (Dick et al. 2006a), as well as with the use of multiple drugs in another independent sample (Drgon et al. 2006).
