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 < .05) with elevated 4-year IgE level; each was also associated with increased severe exacerbations. Final multivariable models demonstrated associations between T2206C and severe exacerbations in both white and African American children (hazard ratio, 3.95; 95% CI, 1.64-9.51; and hazard ratio, 3.08; 95% CI, 1.00-9.47), despite ICS use. Interaction models supported a true gene-environment effect in white subjects (interaction P = .004). T2206C was also associated with decreased FCER2 expression (P = .02).


CONCLUSIONS
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.


CONCLUSIONS
Genetic variation in FCER2 may help form a prognostic model for ICS response in asthma.
Tantisira
Kelan G
KG
Channing Laboratory, Brigham and Women's Hospital, Boston, MA 02115, USA. kelan.tantisira@channing.harvard.edu
Silverman
Eric S
ES
Mariani
Thomas J
TJ
Xu
Jingsong
J
Richter
Brent G
BG
Klanderman
Barbara J
BJ
Litonjua
Augusto A
AA
Lazarus
Ross
R
Rosenwasser
Lanny J
LJ
Fuhlbrigge
Anne L
AL
Weiss
Scott T
ST
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy* / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D019819:Budesonide / Q000008:administration & dosage / Q000627:therapeutic use; D002648:Child; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D020641:Polymorphism, Single Nucleotide; D017455:Receptors, IgE / Q000097:blood / Q000235:genetics* / Q000502:physiology; D012720:Severity of Illness Index
D000305:Adrenal Cortex Hormones; D017455:Receptors, IgE; D007073:Immunoglobulin E; D019819:Budesonide