There is emerging evidence showing that the immunopathogenesis of dry eye is complicated and multifactoral, involving chronic inflammatory infiltration of lacrimal and salivary glands, as well as other ocular surface tissues, interruption of neuronal stimulation for tear secretion, defects of transmembrane and secretory mucin expression, as well as meibomian gland dysfunction, topical drugs preservatives, etc. Unfortunately, the precise mechanisms of dry eye syndrome were not fully understood [3]. The gene discussed is MUC5AC; the disease is dry eye syndrome.