Assesment of the effect of serotonin transporter gene polymorphisms on tinnitus parameters in patient with tinnitus

The underlying mechanism associated with occurence of tinnitus is unknown. Previous studies revealed a relationship between tinnitus and depression. Potentially, the most substantial similarity in between might stem from serotonin. Disruption in the serotonergic mechanisms may lead to tinnitus. However, association of serotonergic mechanisms with tinnitus has not been investigated properly. The objective of this study was to assess asociation of tinnitus parameters with serotonin transporter gene polymorphism.Fifty-four patients with subjective tinnitus and 174 healthy controls were included in this study. All patients filled a questionare form (demographic and clinical information, TEQ, BDQ), had odyologic evaluation and measurement of tinnitus parameters (frequency, loudness, minimal masking level, residual inhibition). DNA was isolated from the leukocytes obtained from venous blood for genetic analysis. VNTR and promoter polymorphisms of the serotonin transporter gene were assessed.There was no significant differene between the polymorphism results of the patients and controls (p>0.05). There was no association between tinnitus parameters and polymorphisms (p>0.05). There was a relationship between VAS scores of the patients and promoter polymorphism (p<0.05). It was found that patients with L/L genotype had higher VAS scores (p<0.05).There is no relationship between VNTR and promoter polymorphisms of the serotonin transporter gene and objective-measurable psychoacoustic parameters of tinnitus. There is a relation between serotonin transporter gene polymophism and VAS scores of tinnitus patients. In the light of these findings, serotonin transporter gene polymorphism, and in turn serotonin, does not play a role in occurence and determination of psychoacoustic parameters of tinnitus. However, promoter polymorphism is associated with limbic system interactions as well as emotional response occuring in tinnitus patients. Since presence of L/L variant of promoter polymorphism leads to serotonin depletion through reuptake of serotonin in the synaptic region, limbic system symptoms of the patients with this genotype are more prominant. That is, instead of occurence of tinnitus, serotonergic mechanisms are associated with emotional effects that tinnitus cause in patients through limbic system.Key Words: Tinnitus, Serotonin, Serotonin transporter gene, polymorphisms