FCER2: A pharmacogenetic basis for severe exacerbations in children with asthma

Background Although inhaled corticosteroids (ICSs) generally protect against severe exacerbations in asthma, they may result in elevated IgE levels, which are associated with exacerbations. Objective To determine whether variation in the low-affinity IgE receptor gene, FCER2 , is associated with severe exacerbations defined as emergency department visits and/or hospitalizations in patients with asthma on ICSs. Methods We resequenced, then genotyped 10 FCER2 single nucleotide polymorphisms (SNPs) in 311 children randomized to inhaled budesonide as part of the Childhood Asthma Management Program. We evaluated the association of FCER2 variants with IgE levels and presence or absence of severe exacerbations over the 4-year clinical trial. We also evaluated differences in cellular expression of the novel FCER2 SNP, T2206C. Results In white subjects, 3 FCER2 SNPs were significantly associated ( P P = .004). T2206C was also associated with decreased FCER2 expression ( P = .02). Conclusion FCER2 predicts the likelihood of treatment protocol success in asthma. The associations of T2206C with IgE level, severe exacerbations, and FCER2 expression may provide a mechanistic basis for the observed findings. Clinical implications Genetic variation in FCER2 may help form a prognostic model for ICS response in asthma.