Association of polymorphisms of NO synthases and arginase genes, clinical, laboratory and functional indicators with the level of nitrogen oxide in exhaled air in children with bronchial asthma

The article presents the results of a study of the associations of NO synthase and arginase genes in children with bronchial asthma with clinical, laboratory and functional parameters depending on the level of nitrogen oxide in exhaled air (FeNO). We examined 107 children with bronchial asthma, they were divided into 2 groups depending on the level of FeNO. We found a number of associations in the group of patients with an elevated level of FeNO (≥20 ppb): carriage of alleles and genotypes containing short tandem repeats of S (9–11) NOS1(AAT)n gene, with an early debut and severe course of the disease, an increased level of total IgE in blood serum; carriage of alleles and genotypes containing long tandem repeats L (12–16) of the NOS2A(CCTTT) n gene, with a moderate course of the disease, with an increased level of IgE; carriage of the allele *A of the ARGII gene (rs3742879) with a moderate course of the disease; carriage of the *G allele and heterozygous *AG genotype of the ARGII gene (rs3742879) with a decreased level of FEV1/FVC; carriage of L alleles and a combination of the SL and LL genotypes of the NOS1(AAT)n gene with elevated blood eosinophils (eosinophilia); a combination of S/L + L/L genotypes of the NOS1(AAT)n gene with fungal sensitization. The authors established the correlations between disease severity and NOS1(AAT)n; the age of the manifestation of the disease and NOS1(AAT)n; FEV1/FVC and ARGII (rs3742879); feedback between blood eosinophilia and NOS1(AAT)n. The authors also determined a number of associations in the group of patients with low level of FeNO (<20 ppb): carriage of alleles and genotypes containing short tandem repeats of S (9–11) gene NOS1(AAT)n, with fungal sensitization; carriage of alleles and genotypes containing long tandem repeats of L (12–16) gene NOS2A(CCTTT)n, with reduced FEV1 and FEV1/FVC; carriage of the homozygous genotype of *GG gene ARGII(rs3742879) with epidermal sensitization. With a reduced level of FeNO, the study determined a relationship between the severity of bronchial asthma and NOS1(AAT)n; degree of effectiveness of anti-inflammatory basic therapy and NOS1(AAT)n; fungal sensitization and NOS1(AAT)n; feedback between FEV1 and NOS2(CCTTT)n; FEV1/FVC and NOS2(CCTTT)n