NOS2 and asthma: In children without asthma [25], significant associations have been evidenced between FeNO levels and genetic variants of NOS2 promoter region (including rs1889022 and rs10853181, two SNPs in LD with rs6505510 (D′ = 1, r2 = 0.4) associated with FeNO levels in adults without asthma in our study).