Polymorphisms in the IL4, IL4RA, and FCERIB genes and asthma severity

Background: Genetic polymorphisms have been associated with asthma and asth ma severity. Objective: We sought to determine whether 3 polymorphisms were associated w ith severe asthma indicated either by the occurrence of a fatal (or near-fa tal) asthma attack or by severe airflow obstruction. Methods: We obtained DNA and clinical data from asthmatic subjects who eith er died or nearly died during an asthma attack and from a group of subjects with mild-to-moderate asthma who had never experienced a fatal or near-fat al asthma episode. These groups were compared with a group of nonatopic non asthmatic control subjects. The level of airflow obstruction (FEV1 percent predicted) in the subjects with mild-to-moderate asthma was used as an addi tional measure of disease severity, The subjects were genotyped for the IL4 *C-589T promoter polymorphism and the IL4RA*Q576R and the FCERIB*E237G amin o acid substitutions. Results: The results showed that the FCERIB*E237G and IL4RA*Q576R polymorph isms were not associated with fatal or near-fatal asthma. However, the IL4* -589T allele was significantly increased in the subjects with fatal or near -fatal asthma compared with nonasthmatic subjects (odds ratio [OR], 1.8; P = .02) and subjects with mild-to-moderate asthma (OR, 1.9; P = .02). There was no interaction between the IL4*-589T and IL4RA*576R alleles. Of the 3 p olymorphisms, only the IL4R4*576R allele was associated with severe airflow obstruction (OR, 8.2; P = .01). Conclusion: These data suggest that the ILA4*-589T allele is a risk factor for life-threatening asthma and that the IL4RA*576R allele is a risk factor for a low level of lung function in asthmatic subjects.