Objective: It is considered that genetic factors may play a role in the development of MS, which is caused by demyelination and axonal damage in central nervous system. Several studies, showing that NOS has a neuroprotective activism, have been conducted. It is known that, contrary to NOS1 ve 2, gene expression of NOS3 from NOS family does not show neurotoxic effect, but has a protective activism. Therefore, this study aimed to investigate the relationship of NOS3 gene expression levels with MS disease.

Material and Method: 93 MS patients between the ages of 17-65 were examined in the study at Gaziantep University school of medicine, Sahinbey Research and Application Hospital Neurology Department. The control group consisted of 93 healthy volunteers. It was found that the mean age of patients with MS was 35.60 and in the control group was 33.80. The study was conducted with RT-PCR method.

Results: The gene expression in alleles of NOS3*2, NOS3*3, and NOS3*4 in NOS3 patient/control groups were observed to decrease significantly, and the differences between groups with the Mann-Whitney method within 95% confidence interval (p <0.05) were analyzed.

Conclusion: A result of the reduced gene expression of NO, it might be considered that its protective effects on neuronal cells may be inadequate. NO and NOS3 genes might be expected to be a promising approach at diagnosis and the development of new treatment strategies. However; gene expression level of NOS3 gene may seem statistically different between patients and controls, since it shows a lot of variability in each group, in order to be able to claim that it is associated with the formation of MS, studies with larger patient groups are needed. This is the first study designed for that purpose.