A genetic association study involving 470 children hospitalized for RSV-induced bronchiolitis, their parents, and 1008 randomly selected population controls showed that single-nucleotide polymorphisms (SNPs) of VDR (vitamin D receptor), JUN, IFNA5, NOS2A, and FCER1A were significantly associated with severe RSV-induced bronchiolitis at both the allele and genotype levels (Janssen et al., 2007). This evidence concerns the gene IFNA5 and bronchiolitis.