Researchers analyzed DNA from nearly 50,000 people of non-European decent and found 27 new genetic variants associated with chronic diseases, including high blood pressure, type 2 diabetes and kidney disease. They also looked at genetic associations with behavior, finding variants associated with daily smoking and coffee drinking habits. The goal of the study was to understand how disease risk is influenced by genomic variants in different ethnic groups.
“This paper gives us a glimpse of how ethnic diversity can be harnessed to better understand disease biology and clinical implications,” said Lucia Hindorff, Ph.D., program director in the Division of Genomic Medicine at National Human Genome Research Institute (NHGRI)and a co-author of the paper. “This paper represents an important comprehensive effort to incorporate diversity into large-scale studies, from study design to data analysis.”The work was funded by the NHGRI and the National Institute on Minority Health and Health Disparities, both parts of the National Institutes of Health.
In the current study, researchers conducted genome wide association study (GWAS), searching the genomes of 49,839 individuals for small variations, called single nucleotide polymorphisms (SNPs) that occur more frequently in people with a particular disease or behavior than in people without them. The individuals were of African-American, Hispanic/Latino, Asian, Native Hawaiian and Native American ancestry.
The data was part of the Population Architecture using Genomics and Epidemiology (PAGE) study. The researchers used strategies tailored for analysis of multi-ethnic and admixed populations, describing a framework that can be used for future studies of diverse populations. In additions to the 27 new variants, they looked at 8,979 established genomic variants in European ancestry populations andfound 38 to also be common in the multiethnic groups.
The researchers also found that the frequency of genomic variants associated with certain diseases can differ from one group to another. For example, a strong association was found between a new genomic variant and smokers and their daily cigarette usage in Native Hawaiian participants. However, this association was absent or rare in most other populations, showing that findings from one population cannot always be generalized to others.
They also found that a variant in the hemoglobin gene, which is known for its role in sickle cell anemia, is associated with greater amount of blood glucose attached to hemoglobin in African-Americans. The study is also the first to confirm this variant within Hispanic/Latinos, who have shared ancestry that is mixed with European, African and Native American ancestry.
Despite the promise of the Human Genome Project, most GWASs to date have not included diverse populations. In fact, a 2016 paper also published in Natureby University of Washington scientists study showed that only 19 percent of the data from used in these studies was from non-white individuals. This means that current health disparities in the U.S. could only get worse if future treatments are based almost exclusively on populations of European decent, the authors of the current study wrote.
“In the United States—where minority populations have a disproportionately higher burden of chronic conditions—the lack of representation of diverse populations in genetic research will result in inequitable access to precision medicine for those with the highest burden of disease. We strongly advocate for continued, large genome-wide efforts in diverse populations to maximize genetic discovery and reduce health disparities,” they wrote.