In this review, we will summarize the current knowledge of genes implicated in the etiology of addictions. We will explore the future of genetic research in this field, and the challenges that need to be addressed, such as a lack of replication of association studies, the somewhat disappointing results from genome-wide association studies conducted so far, and the importance of identifying functional predictors to help make sense of the information gained. Furthermore, gene-environment interactions have not been studied extensively in addiction despite their potential importance. Several examples of genetic testing in medicine are well known; we will consider how genetic findings might be translated into clinical practice for the prevention and treatment of addictions. The need for and importance of pharmacogenetic studies of functional variants in the understanding of disease and therapeutics is discussed. The use of genetic information presents a variety of ethical and practical challenges, several of which are unique or more salient in drug addictions. A comprehensive list of relevant publications for the sections discussed can be found in a supplementary file (available at http://www.nature.com/clpt/index.html).
