The increased risk of LRTIs, especially bronchiolitis, in infants with the AG + GG genotype of GSTP1 (rs1695) or the GSTT1-null genotype after exposure to high levels of perinatal anxiety may be explained by the reduced enzymatic activity in the AG + GG genotype of GSTP1 (rs1695) and by the loss of enzymatic activity in the GSTT1-null genotype [27, 28]. This evidence concerns the gene GSTP1 and bronchiolitis.