ArticlesThe D2 Dopamine Receptor Gene: A Review of Association Studies in Alcoholism and Phenotypes
Section snippets
The drd2 gene: alcoholism and other substance use disorders
Eight months after our first study (13) appeared in press, a group at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) published a report (17) that, while finding a higher prevalence of the A1 allele in alcoholics compared to their controls, claimed a lack of significant involvement of the DRD2 gene in alcoholism. However, it should be noted that there were important differences between our study and theirs. In our study, the prevalence of the DRD2 A1 allele was compared between
Phenotypic expression of drd2 genotypes
If the described mutations in the DRD2 gene associate with alcoholism and other substance use disorders, then such mutations should have neural correlates. In the absence of such correlates, it may be reasonably assumed that the said mutations have no functional significance. However, besides the differentiation of the clinical severity of alcohol and other drug use disorders, based on A1+ (A1/A1 and A1/A2 genotypes) and A1− (A2/A2 genotype only) allelic classification, a growing number of
Comments
The DRD2 has been one of the most intensively studied genes in alcoholism and other substance use disorders. The initial controversy surrounding the DRD2 association with alcoholism appears to be resolving as a large number of studies are beginning to address and to clarify the various issues raised about the nature of this association.
Conclusions
- 1.
Combined analysis of Caucasian studies reveals an association of the DRD2 A1 allele with alcoholism. This association is most robust when more severe alcoholics are compared with assessed controls. However, no association is found when less severe alcoholics are compared with unassessed controls. These findings suggest that two factors are critical in this association: the type of alcoholics and the nature of controls used.
- 2.
Considering that the present analysis consisted of a large number of
Acknowledgements
The author thanks Adele C. Smithers and The Christopher D. Smithers Foundation for their generous financial support and is grateful for the dedicated involvement of many scientific colleagues.
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