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Am J Respir Crit Care Med. 2011 Feb 15;183(4):449-54. doi: 10.1164/rccm.201005-0758OC. Epub 2010 Sep 17.

Regulatory haplotypes in ARG1 are associated with altered bronchodilator response.

Author information

  • 1Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. reqdu@channing.harvard.edu

Abstract

RATIONALE:

β₂-agonists, the most common treatment for asthma, have a wide interindividual variability in response, which is partially attributed to genetic factors. We previously identified single nucleotide polymorphisms in the arginase 1 (ARG1) gene, which are associated with β₂-agonist bronchodilator response (BDR).

OBJECTIVES:

To identify cis-acting haplotypes in the ARG1 locus that are associated with BDR in patients with asthma and regulate gene expression in vitro.

METHODS:

We resequenced ARG1 in 96 individuals and identified three common, 5' haplotypes (denoted 1, 2, and 3). A haplotype-based association analysis of BDR was performed in three independent, adult asthma drug trial populations. Next, each haplotype was cloned into vectors containing a luciferase reporter gene and transfected into human airway epithelial cells (BEAS-2B) to ascertain its effect on gene expression.

MEASUREMENTS AND MAIN RESULTS:

BDR varied by haplotype in each of the three populations with asthma. Individuals with haplotype 1 were more likely to have higher BDR, compared to those with haplotypes 2 and 3, which is supported by odds ratios of 1.25 (95% confidence interval, 1.03-1.71) and 2.18 (95% confidence interval, 1.34-2.52), respectively. Luciferase expression was 50% greater in cells transfected with haplotype 1 compared to haplotypes 2 and 3.

CONCLUSIONS:

The identified ARG1 haplotypes seem to alter BDR and differentially regulate gene expression with a concordance of decreased BDR and reporter activity from haplotypes 2 and 3. These findings may facilitate pharmacogenetic tests to predict individuals who may benefit from other therapeutic agents in addition to β(2)-agonists for optimal asthma management. Clinical trial registered with www.clinicaltrials.gov (NCT00156819, NCT00046644, and NCT00073840).

PMID:
20851928
[PubMed - indexed for MEDLINE]
PMCID:
PMC3056223
Free PMC Article
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