NOS1 and respiratory syncytial virus bronchiolitis: However, we identified four nonsynonymous variants that were significantly associated with increased risk of asthma following severe RSV bronchiolitis in infancy, including one in African Americans in NOS1 (Bonferroni threshold: α78 = 6.4x10-4) and three in European Americans in FLG, ADRB2, and NCAM1 (α49 = 1.0x10-3) (Table 4).