Interleukin-6 -174 G/C promoter gene polymorphism in nasal polyposis and asthma

Background: Interleukin-6 (IL-6) is an inflammatory mediator linked to nasal polyposis and asthma, with a single nucleotide poly- morphism -174 G/C that seems to promote an inflammatory status. We aimed to analyze the relationship between this poly-morhism and asthmatic nasal polyposis patients. Methodology: Cross-sectional study to investigate IL-6 - 174 G/C genotypes of 45 nasal polyposis with asthma patients, 63 nasal polyposis-only patients, 45 asthma-only patients and 81 subjects without both diseases. Aspirin intolerance and atopy were main exclusion criteria. IL-6 genotyping was performed using the PCR method with specific primers followed by restriction enzyme analysis, classifying patients in GG, GC or CC genotype. Results: The GG genotype was the most frequent in all inflammatory groups. Less than 40% of controls presented with the GG ge- notype. There were significant differences between inflammatory groups and control group. No significant differences were seen when comparing inflammatory groups to each other, other than between nasal polyposis-only group and asthma-only group. Conclusion: The IL-6 74 GG genotype was found more frequently in all inflammatory groups than in controls. This genotype could influence nasal polyposis and asthma, and seems to be more important in the latter.