Background and aims:The primary aim of the present review was to summarize the findings of genetic studies conducted on problem and pathological gambling. Method: Literature searches were conducted using PubMed, Medline and the HuGE Navigator databases using the keywords 'gambling' and 'genetic*'. Results: The literature searches identified 21 empirical studies that had analyzed data from eight independent samples. Empirical research utilizing twin data accounted for eight of the studies, while gene association data were presented in 13 studies (including one genome wide-association study [GWAS] study). Twin studies emphasized the significant role of genetic and individual environmental factors in problem and pathological gambling. Gene association studies primarily reported the involvement of the dopaminergic and serotonergic systems. Discussion: Despite the relatively low number of genetic studies, the data clearly indicated the genetic vulnerability of problem and pathological gambling. Studies to date have mainly investigated and verified the role of factors reported to be important in other types of addiction, and it is suggested that pathological gambling should be included as a subtype of 'Reward Deficiency Syndrome' (RDS). It is concluded that future research should attempt to identify possible gambling specific susceptibility factors.Keywords: Problem/pathological gambling, gambling addiction, behavioral addiction, systematic review, twin studies, genetic association studies, reward deficiency syndrome.
INTRODUCTIONPathological gambling is a chronic, progressive disorder that is often associated with serious financial consequences, loss of employment, substance use, health problems, relationship problems, and criminalization [1,2]. Although pathological gambling is still classified among impulse control disorders, it has now been classified as an addiction disorder in the new DSM-V. With this change, gambling disorder is the first behavioral addiction [3,4] to be officially considered an addictive disorder. As with all addictions, pathological gambling disorder is a multi-causal behavior. In addition to the relatively widely researched social and psychological etiological factors, more recent research has emphasized the importance of neurobiological factors. Despite the increase in neurobiological research, the number of studies examining the genetic aspects of pathological gambling is low compared to chemical addictions [5].There are now well-defined methods available for the analysis of genetic factors. Both twin and adoption studies enable the analysis of the individual and epistatic effects of genetic factors and their interactions with environmental factors. Furthermore, molecular genetic studies do not typically allow for the estimation of the genetic effect in general, but for the identification of one or more specific genetic factors. The aim of the present paper is to provide a systematic review and summary of all the empirical research concerning the genetic background of problem and...