TLR4 and asthma: Based on their importance in the immune response to microbial exposure we aimed to investigated the gene-environmental interaction between ten SNPs in the TLR2 (rs4696480, rs1898830, rs3804100), TLR4 (rs1927911, rs46986790), TLR6 (rs1039559, rs5743810) and CD14 (rs2915863, rs5744455, rs2569190) genes and exposure to childhood farm exposure or childhood rural environment on the risk of early-onset asthma or late-onset asthma.