Tobacco smoking is associated with many diseases causing 5 million deaths per year worldwide and is regarded as one of the leading causes of death. Addiction is of the most notorious tobacco-related syndrome and is mainly attributed to nicotine. The causes of tobacco smoking addiction were intensively investigated with several components. Epidemiologic, pharmacologic, neurobiological and genetic studies were main study topics. Genetic studies of smoking and nicotine dependence has been studied for 50 years. Twin, family and adoption studies show evidence for genetic effects on smoking and nicotine dependence. Molecular genetic analyses have identified genes associated with the amount smoked and nicotine dependence. The high heritability of addiction has stimulated much work aimed at identifying susceptibility genes using positional genetics. Candidate gene approaches are also being used for the genetic dissection of smoking addiction. These two approaches had a major impact on our understanding of disease pathophysiology in last 2 decades. Recent work indicates that epigenetic mechanisms or the chemical markings of the DNA and the surrounding histone proteins remain labile through the lifespan and can be altered by environmental factors. Thus, epigenetic mechanisms are an attractive molecular hypothesis for environmental contributions to tobacco smoking addiction. Genome wide association and copy number variation studies are new genetic techniques and they would probably provide us important information in the near future. In this report we aimed to review progress of genetic studies in smoking addiction from classical genetic studies to new epigenetic approaches.
Smoking, addiction, genetics, epigenetics