[A genetic view of addiction].

The genetic analyses of addictions recently converted to genome-wide association studies (GWAS) and thanks to national and international consortia, allowed to recruit large cohorts of patients. This approach allowed the identification of the first susceptibility gene in addiction (tobacco), with genes CHRNA5, CHRNA3 and CHRNB4 encoding the α5, α3 and b4 subunits involved in the formation of nicotinic receptors, explaining 14% of the attributable risk for tobacco dependence. Variants of ADH1B and ADH1C genes encoding alcohol dehydrogenases enzymes have also been consistently associated, this time with alcohol dependence (AD). Finally, DRD2 and ANKK1 genes, involved in the dopaminergic pathway, and which were initially associated with AD, are now considered to be involved in a broader phenotype (addiction to psychoactive substances) including opiates. Future directions in molecular study of addiction are gene x environment interactions though the epigenetic approach. Numerous studies already investigated the methylome in addiction, including histone and microRNA modifications.