SAN FRANCISCO, May 12 (UPI) -- Genetic risk factors for asthma identified in recent years may not apply to black children, or other minorities, due to studies including only white asthma patients, researchers say.
A new study conducted by the University of California San Francisco found nearly all known genetic risk factors for asthma could not be replicated with black patients, finding instead other genetic markers that may increase risk for the condition.
Asthma is the most common chronic medical condition in children of all racial and ethnic groups. In the United States, prevalence is highest among Puerto Ricans, at 18.4 percent, followed by 14.6 percent of African-Americans, 8.2 percent of whites and 4.8 percent of Mexicans. Among these groups, Puerto Rican and black children's asthma is more severe and more difficult to control with medications, according to researchers.
Despite one-third of all children with asthma being black or Puerto Rican, less than five percent of all federally funded lung disease research has included racial or ethnic minorities, according to a separate study UCSF researchers published last year in PLOS Medicine.
"This paper shows that understanding that people are different -- not better or worse, equal or unequal, but different at a genetic level -- can be important and should be looked at to improve health," Oona Risse-Adams, a sophomore at Lowell High School in San Francisco and co-lead author of the new study, said in a press release.
For the study, published in the journal Immunogenetics, researchers analyzed data on 1,227 black children, 812 with asthma and 415 healthy, who participated in the Study of African Americans, Asthma, Genes and Environments.
The researchers were surprised to find that 95 percent of known genetic risk factors for asthma couldn't be replicated with the study group.
They did, however, find a variant in the PTCHD3 gene was a significant risk factor among children in the study, and report the top three genes they linked to asthma have also been associated with obesity and inflammation.
Although obesity increases risk for asthma, because of increases in inflammation -- which plays a major role in asthma attacks and the chronic condition itself -- the researchers suggest the genes may separately have an effect on obesity and asthma, which may be the focus of future studies.
"Almost all the genetic studies of asthma have been done using white patients only, but you can't assume these results will apply to other ethnic groups," said Dr. Esteban Burchard, a professor at the University of California San Francisco and director of the UCSF Asthma Collaboratory lab. "This paper is an important first step towards truly understanding the biology of asthma in African-Americans."