In a study performed in 2006, the levels of ADCAP1, BPIFA1, and SOD proteins were found to be differentially expressed in NPs of Chinese patients with CRSwNP and refractory CRSwNP, suggesting that the reduced expression levels of their genes may be related to the pathogenesis of CRSwNP [105]. This evidence concerns the gene SOD1 and chronic rhinosinusitis with nasal polyps.