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For 14 years, researchers have known that a causal variant for early-onset asthma resides on chromosome 17. This chromosome holds one of the most highly replicated and significant genetic associations with asthma. The team noted that they wouldn’t have identified it in this study without a diverse population that included African Americans, many from the metro Detroit area.
Researchers examined 5,630 African American participants with and without asthma from Henry Ford Health System, University of California San Francisco (UCSF), and Children’s Hospital of Philadelphia (CHOP).
Participants from Henry Ford were part of the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-Ethnicity (SAPPHIRE).
Researchers identified a variant that resides in a gene called gasdermin-B (GSDMB). The team found that the protective variant caused alternative splicing or editing of the final gene, resulting in a messenger RNA sequence missing exons six and seven.
The group expects that this finding will help researchers understand how this particular gene affects a child’s risk of developing asthma.
“This study is one of the best examples that demonstrates diversity matters in genetic research,” said L. Keoki Williams, MD, MPH, the study’s senior author and co-director of Henry Ford’s Center for Individualized and Genomic Medicine Research.
“African Americans have greater variation in their genome due to their African ancestry and this allowed us to pin-point a variant on chromosome 17 which has eluded asthma researchers for over a decade.”
The results also demonstrate the importance of including diverse populations in research studies. As genetic data and personalized medicine become more commonplace in healthcare, investigators will need to have data from a broader range of patients to ensure they understand disease risks and development in different races and ethnicities.
“African Americans have been represented in less than 3 percent of these types of studies, yet make up 13 percent of the US population,” said Hongsheng Gui, PhD, a Henry Ford researcher and study co-author.
“Another reason to have diverse study populations is that many of the genetic risk markers found in one population group don’t replicate in other population groups. However, the variant that we found appears to confer the same magnitude of asthma risk in both African Americans and non-Hispanic white Americans.”
Researchers have increasingly made an effort to broaden the diversity of data in genomic studies. Recently, a team from UC San Diego identified genetic markers for prostate cancer that may be specifically useful in men of African ancestry. The addition of these biomarkers to an existing genetic risk score led to improved performance in identifying men of African ancestry at highest risk of prostate cancer.
“Genetic tools to predict a man's lifetime risk of prostate cancer might allow us to target cancer screening efforts to the men who are most likely to need it,” said principal investigator Tyler Seibert, MD, PhD, assistant professor at UC San Diego School of Medicine and radiation oncologist at Moores Cancer Center at UC San Diego Health.
“We are addressing a major public health problem and simultaneously addressing a concern that genomics and genetic tests may exacerbate health disparities because people of non-European ancestry are severely under-represented in most studies.”
By Jessica Kent