SLC6A3 and alcohol dependence: For example, polymorphisms in the serotonin 2A receptor gene, dopamine transporter, μ-opioid, or GABA A receptor genes have been associated with alcohol dependence (Oslin et al., 2003; Edenberg and Kranzler, 2005; Ramchandani et al., 2011; Bhaskar et al., 2012; Wrzosek et al., 2012).