TNF‐α was shown to significantly increase the levels of MUC5AC and human chloride channel calcium‐activated 1 (hCLCA1) protein in primary epithelial cells derived from sinus mucosa, and MUC5AC expression was inhibited by chlorine channel blockers, indicating that TNF‐α can increase the expression of mucin in CRS by directly up‐regulating hCLCA1.46, 47, 48. The gene discussed is CLCA1; the disease is congenital rubella syndrome.