Genetic Profile and Proximity to Roadways Affect Asthma Symptoms, Study Finds

Patients with asthma with certain genotype combinations demonstrate more intense symptoms when combined with a close proximity to roadways, suggesting that traffic-related air pollution exposure may affect the likelihood of asthma diagnosis and exacerbations, according to a recent study published by Scientific Reports.

The researchers examined the associations between single nucleotide polymorphisms (SNPs) and the combinations of SNPs in the toll-like receptor 4 (TLR) pathway, residential distance to roadway as a proxy for traffic-related air pollution exposure, and asthma diagnosis and exacerbations.

The study considered individual data on genotype, residential address, asthma diagnosis, and exacerbations from the Environmental Polymorphisms Registry. Patients were divided into 3 groups—hyper-responders, hypo-responders, and neither—and they measured the participants' distance between their residence and nearest major road.

Patients with certain genetic profiles had exhibited more intense symptoms following exposure to traffic pollution. Furthermore, patients with asthma who lacked this genetic profile did not have the same sensitivity to traffic pollution and do not experience worse asthma symptoms.

The authors emphasized that the results are based on genetic variation and in order to further understand this concept, people should think of human genes as written instructions for making proteins, according to a press release.

"All humans have the same genes, in other words the same basic instructions, but in some people one DNA base pair has been changed," co-lead author Shepherd Schurman, MD, associate medical director of the National Institute of Environmental Health Sciences (NIEHS) Clinical Research Unit, said in a statement. "This common type of genetic variation is called a single nucleotide polymorphism or SNP, and it can alter the way proteins are made and make individuals more or less prone to illness."

Patients who were hyper-responders and lived close to heavily travelled roads were found to have the worst asthma symptoms, such as difficulty breathing, chest pain, cough, and wheezing. Patients with asthma who were hypo-responders and lived further from busy roads had milder symptoms.

"This research is a great example of how we can approach disease prevention on a personal level, and tailor our treatments to suit individual patients," she said. "That way we can be more efficient with our treatments and preventative measures, while at the same time cutting health care costs,” Janet Hall, MD, clinical director of NIEHS, said.

The researchers suggested that hyper-responders who are exposed to traffic pollution should receive air purification intervention, such as HEPA (high-efficiency particulate air) filters in their homes. Therefore, this study could enhance the quality of life for people with asthma in the future, according to the authors.

Reference

Schurman SH, Bravo MA, Innes CL. Toll-like receptor 4 pathway polymorphisms interact with pollution to influence asthma diagnosis and severity. Sci Rep. 2018;8(1):12713. doi: 10.1038/s41598-018-30865-0.