Effect of Smoking Habit in the Serotonin Level and 5-HTTLPR Gene Polymorphism

  • Mona N. Al-Terehi College of Science, University of Babylon, Hillah, Iraq
  • Usama S. Altimari Al-Nisour University College, Baghdad, Iraq
  • Ola K. A. Alkadir Al-Nisour University College, Baghdad, Iraq
Keywords: 5-HTTLPR gene polymorphism, Serotonin level, Smoking habit.


This study deals with the effect of smoking in the serotonin level and 5-HTTLPR gene polymorphism. It included smoker and nonsmoker individuals, and blood samples were collected to an estimated serotonin level and DNA isolation for genotyping detection. The results reveal that smoking causes non-significant decreased in serotonin level (p less than 0.605), and non-significant differences were observed with age and BMI. Among three genotypes LL, SS and LS, the LS were more observed in the non-smoker group while SS is more frequent in smoker group in non-significant differences (p less than 0.764, 0.453), respectively. LL was a lower percentage in both groups. The allele frequency was detected by Hardy-Weinberg equation, where S allele was more observed in smoker (0.66) and non-smoker (0.58), respectively in non-significant differences (p less than 0.2445). The serotonin level was decreased in LS and LL, respectively with significant changes in the smoker group (p less than 0.032) while non-significant in non-smoker group (p less than 0.466). Conclusions: the present study concluded that the smoker may affect in the 5-HTTLRP gene polymorphism that leads to changes in serotonin level.