Esma Ulusoy1, Mehtap Çevik2, Belgin Süsleyici2

1Department of Molecular Biology and Genetics, Yıldız Technical University, Istanbul, Turkey
2Department of Molecular Biology, Marmara University, Istanbul, Turkey

Keywords: Dopamine, DRD2 gene, polymorphism, TaqIA, tobacco addiction.


Objectives: In this study, the relationship between tobacco addiction levels, early smoking, and DRD2 TaqIA polymorphism was investigated.

Materials and methods: The present study included 36 smokers and 12 non-smoking voluntary controls. Study groups were established as the non-smoking control group and addicted (less than 1 pack, between 1-2 packs, more than 2 packs per day) groups. Genotypes of the dopamine type-2 receptor (DRD2) gene TaqIA polymorphic region from genomic DNA isolated from oral swab samples were determined by PCR followed by Restriction Fragment Length Polymorphism (RFLP) analysis.

Results: Presence of the DRD2 TaqIA homozygous polymorphic genotype in addicted individuals who smoked two or more packs per day and the absence of non-smoker control individuals may indicate that the polymorphic TaqIA allele of the DRD2 gene is associated with smoking. It was found that individuals carrying the polymorphic TaqIA allele in homozygous (~13 years) and heterozygous forms (~16.3 years) had a lower age of starting smoking compared to homozygous wild types (~18.6 years). Mean BMI (body mass index) of the study participants was 24.66 kg/m2 (normal weight), waist/hip ratio 0.82 (no abdominal obesity).

Conclusion: The results of our study suggest that the TaqIA variant allele is related to early smoking condition. In addition, it was determined that there was a higher tendency of smoking addiction among children of addicted parents.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.


All demographic data of the study groups were collected by Didem Duman and Aye Sena Demircio¤lu.