U. PITTSBURGH (US) — Puerto Rican children who have asthma are more likely to have been exposed to violence and to have changes in a gene that is associated with stress, new research shows.
Asthma rates are known to be higher among Puerto Rican children, whether they live in the island or in the continental US, according to the study, which is the first to examine the links between asthma, stress, and gene variation.
Researchers have been studying these high-risk children to better understand their elevated asthma rates. In a previous project with Puerto Ricans, psychosocial stress in a parent was found to be linked to increased asthma symptoms in their children.
“Recently, there was a University of California study that showed traumatic life experiences affect a certain gene product involved in cellular stress responses in adults and was linked to a higher risk of post-traumatic stress disorder or PTSD,” says Juan C. Celedón, chief of Pediatric Pulmonology, Allergy, and Immunology at the University of Pittsburgh.
“We wanted to see whether similar gene alterations could be found among Puerto Rican children with asthma.”
For the study, published in the American Journal of Respiratory and Critical Care Medicine, Celedón and colleagues recruited children ages 6 to 14 years who had four Puerto Rican grandparents from randomly selected San Juan households. Of the group, 271 had physician-diagnosed asthma and wheeze in the prior year and 266 did not have asthma or a history of wheezing.
Blood samples were drawn for DNA analysis, all parents completed a questionnaire, and children 9 years and older answered another standard questionnaire about exposure to violence.
Researchers looked for evidence of a biochemical process called methylation of the promoter, or “on-off” switch, of a gene called ADCYAP1R1, which the California study linked to PTSD. They found that increased methylation was associated with higher odds of having asthma and with exposure to violence, and that increasing exposure to violence was linked with a greater risk of asthma.
They showed that a certain variation, or polymorphism, in the ADCYAP1R1 gene in study participants was also associated with asthma, but not with methylation.
“It appears there is a subgroup of people who may be more susceptible to asthma because of exposure to violence, and we need to understand how that happens,” Celedón says.”Most asthma studies have focused on environmental factors such as air pollution. This is one of the first to look at the impact of stress on epigenetics, which can cause differences in gene expression.”
Co-authors of the paper include researchers from the University of Puerto Rico and Harvard School of Public Health. The study was funded in part by National Institutes of Health.
Source: University of Pittsburgh