Genetics of Substance Use, Abuse, Cessation, and Addiction. Novel Data Implicate Copy Number Variants.

Abundant evidence from family, adoption, and twin studies point to large genetic contributions to individual differences in vulnerability to develop dependence on addictive substances. Twin data suggest that much of this genetic vulnerability is shared by individuals who are dependent on a variety of addictive substances, though some are likely to be substance-specific. Twin data for abilities to quit smoking provide some of the best evidence for genetic influences on abilities to achieve and maintain abstinence from use of an addictive substance.Here, we approach genetic contributions to addiction vulnerability and ability to quit from the bottom-up. We describe a series of working hypotheses concerning the genetic architecture of addiction that are supported by evidence of differing strengths. These data, overall, provide a substrate to improve understanding of substance dependence and the ability to quit smoking. With better understanding of genetic influences on these phenotypes, we will be better positioned to improve understanding of the large environmental influences on these phenotypes, to personalize treatments, and to personalize prevention strategies for individuals at especial risk.