Although the role of TLR4 in asthma is still controversial, it is becoming clear that several factors should be considered in the TLR4-mediated development of allergen-induced Th2 responses, including polymorphism of CD14, the cell type in which TLR4 is engaged, the dose of stimuli, and the timing of exposure (5). The gene discussed is TLR4; the disease is asthma.