Genome-wide association study identifies ALLC polymorphisms correlated with FEV₁ change by corticosteroid.

OBJECTIVES: Asthma can be suppressed by inhaled corticosteroids (ICS). However, response to ICS shows marked inter-individual variability. This study is aimed to identify the genetic variants associated with the change in the percentage of forced expiratory volume in 1second (%ΔFEV1) following ICS treatment.

METHODS: A genome-wide association study was performed in a Korean asthmatic cohort. To further investigate these genetic associations, 11 additional single-nucleotide polymorphisms (SNPs) on the allantoicase (ALLC) gene were selected from the HapMap database and genotyped in the same asthmatic patients in the follow-up study.

RESULTS: In a genome-wide study, we identified the lowest P-value in ALLC, but none of the SNPs met the genome-wide association criteria (P<1.0×10(-8)). However, among 25 SNPs on ALLC in the follow-up study, 6 variants showed significant associations with the mean %ΔFEV1 in the study subjects (P<3.73×10(-6)).

CONCLUSIONS: Although the associated signals could not overcome the genome-wide multiple correction due to small sample size (n=189), our results suggest that associated SNPs of ALLC might be genetic predictors of response to ICS, at least with respect to ΔFEV1 in Korean asthmatics.