RHINOLOGY Genetic polymorphism of antioxidant enzymes in eosinophilic and non-eosinophilic nasal polyposis Abdulvahap Akyigit 1,6 • Erol Keles 2 • Ebru Onalan Etem 3 • Ibrahim Ozercan 4 • Hatice Akyol 5 • Oner Sakallioglu 1 • Turgut Karlidag 2 • Cahit Polat 1 • Irfan Kaygusuz 2 • Sinasi Yalcin 2 Received: 18 January 2016 / Accepted: 9 August 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the para- nasal sinuses, and its pathophysiology is not yet precisely known. It is suggested that oxygen free radicals play an important role in the pathogenesis of nasal polyposis. This study aimed to identify genetic polymorphisms of super- oxide dismutase (SOD 2), catalase (CAT), and inducible nitric oxide synthase (iNOS) enzymes in eosinophilic CRSwNP and non-eosinophilic CRSwNP patients; the study also aimed to evaluate the effect of genetic poly- morphism of antioxidant enzymes on CRSwNP etiopathogenesis. One hundred thirty patients, who received endoscopic sinus surgery due to CRSwNP, and 188 control individuals were included in this study. Nasal polyp tissues were divided into two groups histopatholog- ically as eosinophilic CRSwNP and non-eosinophilic CRSwNP. Venous blood samples were taken from the patient and control groups. Polymorphisms in the Ala16Va1 gene, which is the most common variation of SOD-2 gene, and 21 A/T polymorphisms in catalase gene were evaluated with the restriction fragment length poly- morphism method and -277 C/T polymorphism in the iNOS gene was evaluated with the DNA sequencing method. The GG genotype distribution for the (-277) A/G polymorphism in the iNOS gene was a statistically sig- nificant difference between eosinophilic CRSwNP and control groups (p \ 0.05). The CC genotype distribution for the SOD2 A16V (C/T) polymorphism was not statisti- cally significant in all groups (p [ 0.05). The TT genotype distribution for the A/T polymorphism in catalase gene at position -21 was statistically significant differences in eosinophilic CRSwNP and control groups (p \ 0.05). Increased free oxygen radical levels, which are considered effective factors in the pathogenesis of CRSwNP, can occur due to genetic polymorphism of enzymes in the antioxidant system and genetic polymorphism of antioxi- dant enzymes in eosinophilic CRSwNP patients might contribute to the pathophysiology. Keywords Chronic rhinosinusitis with nasal polyps  Inducible nitric oxide synthase  Superoxide dismutase  Catalase  Genetic polymorphism Introduction Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the paranasal sinuses and although many studies were conducted, its pathophysiol- ogy is not yet precisely known. It was shown that edema and inflammation are closely related to inflammatory cell infiltration [1–4]. Free radicals, which are produced during phagocytosis of inflammatory cells, are the main source of biological & Abdulvahap Akyigit cerrah23@gmail.com 1 Department of ENT, Elazig Education and Research Hospital, Elazig, Turkey 2 Department of ENT, Firat University Faculty of Medicine, Elazig, Turkey 3 Department of Medical Biology, Firat University Faculty of Medicine, Elazig, Turkey 4 Department of Pathology, Firat University Faculty of Medicine, Elazig, Turkey 5 Department of Pathology, Elazig Education and Research Hospital, Elazig, Turkey 6 Department of Otorhinolaryngology, Elazig Training and Research Hospital, 23119 Elazig, Turkey 123 Eur Arch Otorhinolaryngol DOI 10.1007/s00405-016-4259-z