“Higher order” addiction molecular genetics: Convergent data from genome-wide association in humans and mice

Abstract

Family, adoption and twin data each support substantial heritability for addictions. Most of this heritable influence is not substance-specific. The overlapping genetic vulnerability for developing dependence on a variety of addictive substances suggests large roles for "higher order" pharamacogenomics in addiction molecular genetics. We and others have now completed genomewide association (GWA) studies of DNAs from individuals with dependence on a variety of addictive substances vs appropriate controls. Recently reported replicated GWA observations identify a number of genes based on comparisons between controls and European-American and African-American polysubstance abusers. Here we review the convergence between these results and data that compares control samples and a) alcohol dependent European Americans, b) methamphetamine dependent Asians and c) nicotine dependent samples from European backgrounds. We also compare these human data to quantitative trait locus (QTL) results from studies of addiction-related phenotypes in mice that focus on alcohol, methamphetamine and barbiturates. These comparisons support a genetic architecture built from largely-polygenic contributions of common allelic variants to dependence on a variety of legal and illegal substances. Many of the gene variants identified in this way are likely to alter specification and maintenance of neuronal connections. KeywordsAssociation genome scanning; substance dependence; microarray; pooled; neuronal connections * To whom correspondence should be addressed at: Molecular Neurobiology, Box 5180, Baltimore, MD 21224 phone: (410) 550-2843 x 146, fax: (410) 550-1535, guhl@intra.nida.nih.gov. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access A. Studies of human addiction vulnerabilitiesVulnerability to addictions is a complex trait with strong genetic influences that are largely shared by abusers of different legal and illegal addictive substances [1][2][3][4]. This conclusion comes from family, adoption and twin studies. Family studies clearly document that first degree relative (eg sibs) of addicts display greater risk for developing substance dependence than more distant relatives [1,5]. Adoption studies consistently find greater similarities between substance abuse phenotypes with biological relatives than with adoptive family members [1]. In twin studies, differences in concordance between genetically identical and fraternal twins also support heritability for vulnerability to addictions [3,[6][7][8][9][10][11][12]. Twin data allows quantitation of the amount, about 50%, of ad...

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