Urinary leukotriene and Bcl I polymorphism of glucocorticoid receptor gene in preschoolers with recurrent wheezing and high risk of asthma.

BACKGROUND Urinary leukotriene (LTE4) is an important marker of airway inflammation presence. A relationship between single nucleotide polymorphism in the glucocorticoid receptor (GCR) gene promoter (Bcl I polymorphism), development of asthma and sensitivity to glucocorticoids has been hypothesised. OBJECTIVE To explore the possible association between the Bcl I polymorphism and baseline levels of urinary LTE4 in preschoolers with recurrent wheezing episodes. We prospectively enrolled and classified 86 preschoolers based on the risk of developing asthma (by the Asthma Predictive Index [API]). METHODS At admission standardised questionnaires for demographics and respiratory illness characteristics were completed. The Bcl I polymorphism of the GCR was determined by a PCR-RFLP assay from blood samples, and urinary leukotriene was assessed from urine samples by an enzyme immunoassay. RESULTS We enrolled 86 preschoolers (46 with positive API and 40 with negative API). There were no statistical differences in demographic, respiratory illnesses and wheezing episodes characteristics between both groups. Also, the prevalence of Bcl I polymorphism was similar between positive vs. negative API groups (34.8% vs. 38.9% for homozygote GG, 56.5% vs. 52.8% for heterozygote GC, 8.7% vs. 8.3% for homozygote CC, respectively, p=0.94). However, urinary LTE4 (median [IQR]) was higher in preschoolers with positive than negative API (7.18 [5.57-8.96pg/ml] vs. 6.42 [3.96-8.07pg/ml], p=0.02, respectively). CONCLUSIONS In our population, wheezing preschoolers with positive API exhibit higher levels of urinary LTE4 than those with negative API; but there were no differences in Bcl I polymorphism of the GCR.