Relationships between TLR4 pathway Single Nucleotide Polymorphisms, Distance to Roadway, and Asthma Diagnosis and Severity
We obtained individual-level data from the Environmental Polymorphisms Registry, including SNP data, residential address, and asthma diagnosis and symptoms. Subjects (n=1,823) were divided into three “responder type” groups based on genetic profiles: (1) hyper-responders (carriers of CD14 and TNFa and wild-type TLR4 and TIRAP); (2) hypo-responders (carriers of TLR4 and/or TIRAP and wild-type CD14 and TNFa); and (3) others. We geocoded addresses and calculated the distance between each subject’s residence and nearest road, considering highways, major roads, and secondary/connecting roads. We classified each subject’s proximity to the nearest road as either <250m or >250m; in a sensitivity analysis, we used this distance classification but only considered proximity to highways and major roads (i.e., excluding secondary/connecting roads). Asthma outcomes were examined separately using a logistic regression model (asthma diagnosis) and cumulative logit model (asthma-related sleeplessness, activity limitations, emergency room [ER] visits). Covariates included sex, smoking status, race, and home environmental tobacco smoke.
Over half of the subjects (n=1,016, 55.7%) lived >250m from the nearest road; 807 subjects (44.3%) lived <250m from the nearest road. Whites were more likely than blacks/African Americans to report asthma diagnosis (OR=1.33, CI: 1.07, 1.65), and men were less likely to report asthma diagnosis (OR=0.53, CI: 0.43, 0.64) and symptoms. Individuals closer to roads (<250m) were more likely to report asthma diagnosis (OR=1.25, CI: 1.03, 1.52). Hypo responders were less likely than hyper responders to report asthma-related activity limitations (OR=0.58, CI: 0.36, 0.98). Sensitivity analysis results were consistent with the main analysis findings; additionally, for subjects <250 from a road, regular responders were less likely than hyper responders to report more severe asthma, as indicated by asthma-related ER visits (OR=0.37, CI: 0.14, 0.97).
Learning Areas:Chronic disease management and prevention
Environmental health sciences
Evaluate possible gene-environment interactions in asthma incidence and severity by examining SNP combinations, residential distance to roadway as a proxy for traffic-related air pollution exposure, and asthma outcomes
Keyword(s): Asthma, Genetics
Qualified on the content I am responsible for because: I received my Ph.D. in Environmental Epidemiology in 2014 and have completed coursework on epidemiology, statistical analysis, and study design. Further, I have published in peer reviewed journals on these topics. My co-authors on this analysis and presentation are experienced researchers and physicians.
Any relevant financial relationships? No
I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.