(CCTTT)n polymorphism of NOS2A in nasal polyposis and asthma: a case-control study.

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 10(4) simulations] = .002). Multivariate analysis adjusted for age and sex confirmed 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. Modifications of NOS2A transcription levels could be involved in this association.