ABSTRACT
BACKGROUND: A recent family-based genomewide screen revealed linkage between the 5q31 region and the diagnosis of asthma, but only in those exposed to environmental tobacco smoke (ETS). Among the candidate genes in this region is CD14. METHODS: To determine whether polymorphisms in the CD14 gene are related to this gene-by-environment interaction in Latinos, we used both family-based and cross-sectional cohort analysis to test for interactions between CD14 genotypes/haplotypes, exposure to ETS, and asthma-related phenotypes in 659 Mexican and Puerto Rican families. RESULTS: We identified 21 single nucleotide polymorphisms (SNPs) in the CD14 gene by sequencing 72 Puerto Ricans, Mexicans, and African Americans with asthma. Three SNPs, -810, -159, and +1437, were further genotyped in families with asthma. Among all subjects with asthma exposed to ETS, without regard to ethnicity, CD14 +1437 genotypes were associated with asthma severity. SNP +1437 GG or GC genotypes were significantly associated with lower baseline FEV1 using both family-based (p = 0.0009) and cross-sectional cohort (p = 0.03) analyses. Subjects with asthma with the GG or GC genotypes who were exposed to ETS had mean baseline FEV1 (% predicted) values 8.6% lower than subjects not exposed to ETS (p = 0.03). As previously observed in whites, we found an interaction between plasma IgE levels, SNP -159 genotypes, and ETS exposure (p = 0.0002). The lowest IgE levels were in those subjects with the TT genotype and who were exposed to ETS regardless of ethnicity. CONCLUSIONS: Our data suggest a gene-by-environment interaction between CD14 genotypes and ETS, which affects pulmonary function and IgE levels among Latinos with asthma.
Subject(s)
Asthma/physiopathology , Hispanic or Latino , Immunoglobulin E/blood , Lipopolysaccharide Receptors/genetics , Polymorphism, Single Nucleotide , Tobacco Smoke Pollution/adverse effects , Adolescent , Asthma/drug therapy , Asthma/ethnology , Asthma/genetics , Bronchodilator Agents/therapeutic use , Child , Female , Gene Frequency , Genotype , Humans , Linkage Disequilibrium , Lung/physiopathology , Male , Severity of Illness IndexABSTRACT
BACKGROUND: In the United States, Puerto Ricans and Mexicans have the highest and lowest asthma prevalence, morbidity, and mortality, respectively. Ethnic-specific differences in the response to drug treatment may contribute to differences in disease outcomes. Genetic variants at the beta(2)-adrenergic receptor (beta(2)AR) may modify asthma severity and albuterol responsiveness. We tested the association of beta(2)AR genotypes with asthma severity and bronchodilator response to albuterol in Puerto Ricans and Mexicans with asthma. METHODS: We used both family-based and cross-sectional tests of association with 8 beta(2)AR single nucleotide polymorphisms in 684 Puerto Rican and Mexican families. Regression analyses were used to determine the interaction between genotype, asthma severity, and bronchodilator drug responsiveness. RESULTS: Among Puerto Ricans with asthma, the arginine (Arg) 16 allele was associated with greater bronchodilator response using both family-based and cross-sectional tests (p = 0.00001-0.01). We found a strong interaction of baseline FEV(1) with the Arg16Glycine (Gly) polymorphism in predicting bronchodilator response. Among Puerto Ricans with asthma with baseline FEV(1) < 80% of predicted, but not in those with FEV(1) > 80%, there was a very strong association between the Arg16 genotype and greater bronchodilator responsiveness. No association was observed between Arg16Gly genotypes and drug responsiveness among Mexicans with asthma. CONCLUSIONS: Ethnic-specific pharmacogenetic differences exist between Arg16Gly genotypes, asthma severity, and bronchodilator response in Puerto Ricans and Mexicans with asthma. These findings underscore the need for additional research on racial/ethnic differences in asthma morbidity and drug responsiveness.
Subject(s)
Albuterol/therapeutic use , Asthma/drug therapy , Bronchodilator Agents/therapeutic use , Hispanic or Latino/genetics , Mexican Americans/genetics , Adolescent , Albuterol/pharmacokinetics , Alleles , Asthma/genetics , Bronchodilator Agents/pharmacokinetics , Child , Female , Gene Frequency , Genotype , Haplotypes , Humans , Male , Mexico , Polymorphism, Single Nucleotide , Puerto Rico/ethnology , Receptors, Adrenergic, beta-2/genetics , Receptors, Adrenergic, beta-2/metabolism , Regression Analysis , Respiratory Function Tests , United StatesABSTRACT
In the United States, Puerto Ricans and Mexicans have the highest and lowest asthma prevalence, morbidity, and mortality, respectively. To determine whether ethnicity-specific differences in therapeutic response, clinical response, and/or genetic factors contribute to differences in asthma outcomes, we compared asthma-related clinical characteristics among 684 Mexican and Puerto Rican individuals with asthma recruited from San Francisco, New York City, Puerto Rico, and Mexico City. Puerto Ricans with asthma had reduced lung function, greater morbidity, and longer asthma duration than did Mexicans with asthma. Bronchodilator responsiveness, measured as percentage change from baseline FEV1, was significantly lower among Puerto Ricans with asthma than among Mexicans with asthma. Puerto Ricans with asthma had on average 7.3% (95% confidence interval [CI], 4.6 to 9.9; p < 0.001) lower bronchodilator reversibility in FEV1, higher risk of an emergency department visit in the previous year (odds ratio, 2.63; 95% CI, 1.6 to 4.3; p < 0.001), and of previous hospitalization for asthma (odds ratio, 1.94; 95% CI, 1.2 to 3.2; p = 0.009) than Mexicans. Subgroup analysis corroborated that Puerto Ricans with asthma had more severe disease than did Mexicans on the basis of lung function measurements, responsiveness to beta2-adrenergic agonists, and health care use. We conclude that Puerto Ricans with asthma respond less to albuterol than do Mexicans with asthma. These findings underscore the need for additional research on racial/ethnic differences in asthma morbidity and response to therapy.
