Genetics of addiction in legal medicine and forensic investigation: SNPs variations associated with nicotine and cannabis dependence

Substance addiction is a complex chronic brain disorder, characterized by neurobiological changes leading to compulsive drug seeking and taking. Although environmental factors contribute to drug addiction, evidence showed that genetic factors with multiple genes also play a significant role. Cannabis and tobacco result as the most common widely abused substances. Epidemiological studies have strongly implicated genetics in nicotine and marijuana consuming and vulnerability to subsequent dependence, estimating the range of heritability from 34% to 78% for cannabis and approximately from 50% to 70% for nicotine. Furthermore, varying aspects of impulsive personality and principal psychiatric disorders co-occur with tobacco and cannabis dependence status. We evaluate the possibility of identifying an individual's risk probability to become an addict, based on a genotype analysis and the different possible applications in legal medicine and forensic genetics.