In a study by Buysschaert et al.[38] that involved 273 individuals with CRS and nasal polyps and 415 controls, genetic variation in IL-33 (SNP rs3939286) was significantly associated with CRS with nasal polyps in a two-stage discovery and replication analysis (OR = 1.53 [95%CI 1.21,1.96]; p = 0.00041). This evidence concerns the gene IL33 and nasal cavity polyp.