Background: Nitric Oxide (NO) has been proposed as an important signaling molecule. NO produced by the inducible NO synthase enzyme NOS2A is generated at high levels in certain types of inflammation. A pentanucleotide polypyrimidine microsatellite CCTTT has been identified in the promoter region of the NOS2A gene.

Objective: The aim of this study was to analyze the (CCTTT)n polymorphism in patients with asthma and nasal polyposis.

Material and methods: The study included 292 white individuals (194 patients and 98 controls). Asthma was diagnosed according to American Thoracic Society criteria and classified in accordance with the guidelines of the Global Initiative for Asthma. Skin prick tests were performed in all individuals. The polymorphism was analyzed by an electrophoretic method and by direct sequencing.

Results: A significant association was detected for a 15-repeat cutoff in nasal polyposis (Fisher P value = .0001, Monte Carlo P value [after 104 simulations] = .002). Multivariate analysis adjusted for age and sex confi rmed this association with an increased risk of nasal polyposis (odds ratio, 14.39; 95% confidence interval, 3.02 - 68.60; P = .001).

Conclusion: The number of CCTTT repeats in the promoter region of NOS2A could be associated with the inflammatory process of nasal polyposis in our population. Modifi cations of NOS2A transcription levels could be involved in this association.

Key words: Asthma. Gene. Nasal polyposis. NOS2A. Polymorphism. Promoter.