The evidence for association among these genes and AUD is mixed, with the exception of ALDH2’s well-replicated association [58]. A meta-analysis indicates an association between variation in the 5-HTTLPR polymorphism and AUD; however, there is some indication that this reflects publication bias [59]. A meta-analysis of the commonly studied OPRM1 Asn40Asp (A118G) polymorphism indicated no association with substance dependence (opioid, alcohol, nicotine, or cocaine) [60]. There is some evidence for association among variants in the nicotinic receptor gene cluster on chromosome 15 and AUD [61]; however, other studies have reported null effects [62].
