COMT and Addictive alcohol use: Of note, various genetic mutations and polymorphisms that play a role in DAergic neurotransmission have been suggested to contribute to increased vulnerability to alcohol addiction, including the DA receptor D2 Taq1A polymorphism [113,114,115], the DA transporter gene Slc6a3 polymorphism [113,116], and the missense mutation within the catechol-O-methyltransferase (Comt) gene [112,117,118,119].