Abstract. – OBJECTIVE: Fibromyalgia syn- drome (FMS) is a pain syndrome in which com- mon pain in muscle-skeletal system, sleeping disorder and fatigue symptoms coexist. The aim of the present study was to determine SOD and GPX enzyme levels in FMS as well as to investi- gate possible associations between FMS and Ala9Val polymorphism of MnSOD2 and Pro198Leu polymorphism of GPX1. PATIENTS AND METHODS: The study includ- ed 127 women FMS patients and 56 healthy sub- jects. Total SOD and total GPX enzyme activities were determined in patient and control groups. In addition, frequencies of Ala9Val polymor- phism of MnSOD2 and Pro198Leu polymor- phism of GPX1 were also detected. RESULTS: SOD enzyme activity was higher in FMS group compared to control (p < 0.001). GPX enzyme activity, on the other hand, was not dif- ferent between FMS and control groups. No sig- nificant differences were found between geno- type and allele frequencies of GPX1 and Mn- SOD2 polymorphisms. CONCLUSIONS: Elevated total SOD and un- changing total GPX1 activities in FMS patients could be the reason for increased oxidative stress and lipid peroxidation in FMS. Genotype and allele frequencies of Ala9Val polymorphism of MnSOD2 and Pro198Leu polymorphism of GPX1 in FMS have been studied first time in the present study, and no associations were found between them and FMS. Key Words: Fibromyalgia, SOD, GPX, Oxidative stress, Polymor- phism. Introduction Fibromyalgia syndrome (FMS) is a chronic pain syndrome accompanied by extensive pain in European Review for Medical and Pharmacological Sciences Evaluation of some antioxidant enzyme activities (SOD and GPX) and their polymorphisms (MnSOD2 Ala9Val, GPX1 Pro198Leu) in fibromyalgia A. AKBAS 1 , A. INANIR 2 , I. BENLI 1 , Y. ONDER 3 , L. AYDOGAN 1 1 Department of Biochemistry, Gaziosmanpasa University Medical Faculty, Tokat, Turkey 2 Department of Department of Physical Therapy and Rehabilitation, Gaziosmanpasa University Medical Faculty, Tokat, Turkey 3 Department of Department of Public Health, Gaziosmanpasa University Medical Faculty, Tokat, Turkey Corresponding Author: Ali Akbas, MD; e-mail: draliakbas@hotmail.com 1199 body, rigidity in muscles, fatigue, poor sleep qual- ity and cognitive difficulties as well as by syn- dromes such as anxiety, depression and impair- ment in conducting the daily activities 1,2 . FMS in- cidence is higher in women than in men 3 . FMS etiopathogenesis have not been fully revealed yet, but central and autonomous nervous system, neu- rotransmitters, hormones, immune system, exter- nal stress factors and psychiatric conditions seem to be involved 4 . Recent studies have shown an as- sociation between FMS and oxidative stress 5 . Oxidative stress is the breakdown of the bal- ance between reactive oxygen species (ROS) and antioxidant defense system. Since ROS such as superoxide anions, hydrogen peroxide and hy- droxyl radical have unpaired electrons, they are quite reactive molecules. Therefore, they dam- age biomolecules such as proteins, lipids and nu- cleic acids, resulting in various diseases 6 . An- tioxidant defense system enzymes such as super- oxide dismutase (SOD) and glutathione peroxi- dase (GPX) prevents oxidative stress through in- activation of ROS. SOD enzyme eliminates damaging effects of free radicals by converting superoxide radical into oxygen and hydrogen peroxide and GPX enzyme by converting hydro- gen peroxide into water 7,8 . Polymorphisms observed in genes encoding SOD and GPX enzymes result in decreases of ac- tivities of these enzymes. One of these polymor- phisms, MnSOD2 Ala9Val, causes changes in signal sequence of the mitochondrial MnSOD en- zyme and affects the transport of enzyme to mito- chondria, which results in changes in function and localization of the enzyme. Pro198Leu polymor- phism of GPX1 enzyme, on the other hand, caus- es proline to leucine change in codon 198 of GPX1 enzyme. Leucine affects the binding of se- 2014; 18: 1199-1203