Possible association between -954G/C iNOS polymorphism in nasal polyposis. A case-control study in a population group of Northern Romania

BACKGROUND. Polymorphisms for genes encoding chemosensitive signalling proteins like NOS2 might contribute to the variability in individual susceptibility to nasal polyposis. NO produced by the inducible NO synthase enzyme NOS2A is generated at high levels in certain types of inflammation, so that the role of NOS2 might also be important in nasal polyposis etiopathogeny.

MATERIAL AND METHODS. This is a cross-sectional, randomized, case-control study for the evaluation of the frequency of -954G/C NOS2A2 alleles among patients with nasal polyposis. The study included 91 cases of nasal polyposis diagnosed patients (nasal endoscopy and CT scan examination), and 117 healthy unrelated controls. NOS2 genotyping was carried out using PCR amplification of relevant gene fragment and it was followed by restriction enzyme digestion. Detection of the variant alleles was determined through analysis of resulting restriction fragment length polymorphism (RFLP) followed by gel electrophoresis.

RESULTS. Molecular analysis revealed an increased frequency of NOS2 variant allele in the study group compared to the control group (p=0.019, OR=1.991, CI=1.08-3.67). A statistically significant finding was highlighted among allergic and nonallergic patients with nasal polyposis (p=0.046, OR=0.449. CI=0.208-0.969) and a relationship between nasal polyposis patients with asthma and non-asthmatic patients (p=0.119, OR=1.825, CI=0.875-3.80).

CONCLUSION. The main finding of our study is that -954G/C polymorphism of NOS gene seems to be associated with an increased risk for nasal polyposis.