Association of STin2 VNTR Polymorphism in the SLC6A4 Gene with Increased Risk of MS Disease

Background: Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) that is characterized by inflammation, demyelination and axonal injury. Although the etiology of MS disease is still unknown, many studies suggest that immune system dysfunction plays an important role in the pathogenesis of this disease. The serotonin serves as a mediator between CNS and the immune system and is involved in modulating the interactions between the nervous and immune system. Therefore, it seems that modulation of serotonin function play a potential role in autoimmune process and MS disease. Serotonin transporter determines duration of serotonin action and its effect on nerve receptors by regulation of serotonin concentration in synapses. One of common polymorphisms of serotonin transporter gene (SLC6A4) is variable number of tandem repeats of 17 bp in intron 2 (STin2 VNTR). Different repeat number within the VNTR plays an important role in regulating transcription of the SLC6A4 gene and activity of serotonin. Methods: In this study, STin2 VNTR polymorphism of SLC6A4 gene was assessed in 100 patients with MS and 100 healthy volunteers, using the PCR technique. Results: The results showed that STin2.10/10 genotype compared with the STin2.12/12 genotype (P= 0/04) increased risk of MS disease and STin2.12 allele acts as adominant allele. Conclusion: The results of this study, is hypothesized that the STin2. 10/10 genotype by modulating the transcription of serotonin transporter and function of serotonin may participate in the pathophysiology of MS disease.