Substance dependence, such as heroin addiction, can have a devastating impact on the lives of the affected individuals, their families and the wider society. According to the World Health Organization (UNODC, World Drug Report 2012; www.who.int), heroin use has increased two to three fold since the 1980s and the ensuing health concerns are severe; the risk of death in drug users is 20 to 30 times greater than in non-drug users, mostly from overdose or acquired infections. Heroin produces strong euphoric effects and addiction can develop rapidly in vulnerable individuals. Dependence on the drug represents a chronic and relapsing condition, characterized by compulsive consumption, craving, tolerance, withdrawal symptoms and negative behavioral effects. Although dependency is frequently a culmination of complex interactions between behavioral, cognitive, and physiological factors, genetic factors can contribute 30–80% of the liability to risk [1,2]. The combination of findings from genetic studies, model organisms and molecular studies in humans has led to the hypothesis of a biological underpinning to heroin dependence, with particular emphasis on the role of the central nervous system [3]. This has inevitably led
