As with other infectious diseases, most candidate gene studies for RSV infection and disease have focused on genes involved in immune pathways such as Toll-like receptor 4 (TLR4), cluster of differentiation 14 (CD14), surfactant proteins, cytokines, and chemokines (Awomoyi et al. 2007; Gentile et al. 2003; Paulus et al. 2007; Puthothu et al. 2006a, b, 2007a, b). Here, TLR4 is linked to infectious disease.