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Pharmacol Ther. 2013 Dec;140(3):267-79. doi: 10.1016/j.pharmthera.2013.07.006. Epub 2013 Jul 18.

Implications of genome wide association studies for addiction: are our a priori assumptions all wrong?

Author information

1
Molecular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD 21224, United States. Electronic address: shall@intra.nida.nih.gov.

Abstract

Substantial genetic contributions to addiction vulnerability are supported by data from twin studies, linkage studies, candidate gene association studies and, more recently, Genome Wide Association Studies (GWAS). Parallel to this work, animal studies have attempted to identify the genes that may contribute to responses to addictive drugs and addiction liability, initially focusing upon genes for the targets of the major drugs of abuse. These studies identified genes/proteins that affect responses to drugs of abuse; however, this does not necessarily mean that variation in these genes contributes to the genetic component of addiction liability. One of the major problems with initial linkage and candidate gene studies was an a priori focus on the genes thought to be involved in addiction based upon the known contributions of those proteins to drug actions, making the identification of novel genes unlikely. The GWAS approach is systematic and agnostic to such a priori assumptions. From the numerous GWAS now completed several conclusions may be drawn: (1) addiction is highly polygenic; each allelic variant contributing in a small, additive fashion to addiction vulnerability; (2) unexpected, compared to our a priori assumptions, classes of genes are most important in explaining addiction vulnerability; (3) although substantial genetic heterogeneity exists, there is substantial convergence of GWAS signals on particular genes. This review traces the history of this research; from initial transgenic mouse models based upon candidate gene and linkage studies, through the progression of GWAS for addiction and nicotine cessation, to the current human and transgenic mouse studies post-GWAS.

KEYWORDS:

Addiction; CI; DAT; DRD2; DRD3; DRD4; DZ; Drug abuse; GABA receptor subunit gene α3; GABRA3; GWAS; Genetics; Genome-wide association study; KO; Knockout; Linkage; MDMA; METH; MNB; MOR; MZ; Molecular Neurobiology Branch; NET; SERT; Transgenic; VMAT2; WT; cocaine insensitive; dizygotic; dopamine D(2) receptor; dopamine D(3) receptor; dopamine D(4) receptor; dopamine transporter; genome wide association studies; knockout; methamphetamine; methylenedioxymethamphetamine; monozygotic; norepinephrine transporter; serotonin transporter; vesicular monoamine transporter 2; wildtype; μ opioid receptor

PMID:
23872493
PMCID:
PMC3797854
DOI:
10.1016/j.pharmthera.2013.07.006
[Indexed for MEDLINE]
Free PMC Article

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