1. The D2 Receptor Gene in Gambling The study of Comings et al. (1996):Comings et al. (1996) GamblingGambling has been defined as an impulse control disorder (DSM-IV, 1994), and has many similarities with alcoholism and substance dependence.DSM-IV, 1994 Researchers have found a link between the D2A1 allele gene and drug addiction, some forms of severe alcoholism and other impulsive, addictive behaviors. A United States study examined whether a similar pattern was associated with pathological gambling. Contributor© POSbase 2005

2. The D2 Receptor Gene in Gambling Participants were 936 non-Hispanic Caucasians, including: © POSbase 2005  222 pathological gamblers diagnosed according to the DSM-IV (1994) criteria for pathological gamblingDSM-IV (1994) criteria for pathological gambling  714 controls screened to exclude drug and alcohol abuse.

3. The D2 Receptor Gene in Gambling Of the 222 pathological gamblers:  171 contributed blood samples.  102 contributed blood and completed a gambling questionnaire. Of the 714 controls:  484 of these were obtained from previously published studies.  The remaining 230 were newly tested for the current study. © POSbase 2005

4. The D2 Receptor Gene in Gambling The genotypes were read from blood samples by two blind readers. That is, they were blind as to whether the participant was a pathological gambler or a control. This eliminated a bias due to positive test strategy, that is a bias to incorrectly read the data in a manner that would support the hypotheses.positive test strategy © POSbase 2005

5. The D2 Receptor Gene in Gambling Dependent measures were: Prevalence of the D2A1 allele: The percentage of individuals carrying the D2A1/D2A1 or D2A1/D2A2 genotype. Frequency of the D2A1 allele: The total number of D2A1 alleles divided by the total number of haploid sets of chromosomes. © POSbase 2005

6. The D2 Receptor Gene in Gambling © POSbase 2005 NPrevalence of D 2 A1 Frequency of D 2 A1 Controls71426%0.15 Pathological Gamblers17151%0.27 Upper half of gambling score(44)41% Lower half of gambling score(58)64%

7. The D2 Receptor Gene in Gambling Both prevalence and frequency were higher in pathological gamblers than in controls. When the 102 pathological gamblers who had completed the gambling questionnaire were divided according to their gambling scores, those scoring in the upper half had higher prevalence than those scoring in the lower half. These results suggest that genetic defects in the dopamine receptor gene do play a role in the development of pathological gambling. © POSbase 2005