New research from the United States indicates that the racial and ethnic identities individuals claim may not accurately reflect their genetic heritage or ancestry.
The study’s researchers emphasize that recognizing this discrepancy between self-identified categories and genetic data is crucial for scientists aiming to effectively treat diverse populations.
“This paper is critically significant as it clarifies the link between genomic diversity and racial/ethnic classifications in the US,” stated the co-authors. Eduardo Tarazona Santos, a Population Genetics Professor at the Federal University of Minas Gerais in Brazil, commented.
He further noted that the findings are “essential for the advancement of precision medicine tailored to everyone’s needs,” in an email to Live Science. This approach considers individual genetic, environmental, and lifestyle aspects.
Medicines for All
The research was published on June 5th. In the American Journal of Human Genetics, Tarazona Santos and collaborators examined DNA samples from over 230,000 individuals who contributed to the All of Us Research Program funded by the National Institutes of Health, which focuses on enhancing precision medicine through the inclusion of diverse and underrepresented groups.
Traditionally, most large genetic studies have predominantly involved individuals of European ancestry. The push towards more inclusive research aims to mitigate health disparities. However, the initiative has faced significant funding cuts in recent months, which hinder progress.
Related: What is the difference between race and ethnicity?
Utilizing principal component analysis, the team examined genetic resemblances and differences within the database. They referred to genetic catalogs with DNA samples from around the globe, including the 1000 Genomes Project, to compare self-identified racial (white, black or African-American, Asian-American) and ethnic categories (Hispanic/Latinx, etc.) with the data collected in surveys.
The researchers discovered that individuals identifying with the same racial or ethnic group exhibited considerable genetic differences. In fact, “most genetic variance lies within races and ethnic groups, not between them,” according to the study’s findings.
The analysis revealed that genetic variation among individuals across different races and ethnicities forms a “gradation,” as opposed to clear divisions into “clusters” based on racial or ethnic lines. “We found a gradient of genetic variation across these categories,” the authors noted.
These findings are also discussed in an upcoming Nature study set to release in 2024. At that time, the project faced critiques from some experts who claimed that the methodologies for analyzing race and ethnicity could be misinterpreted to propagate the misconception that humans can be categorically divided into distinct races. However, subsequent studies using alternative analytical methods presented contradictory results.
US Interstate Variation
The study also identified genetic diversity among individuals within the same ethnic and racial categories across various states in the US. This variability could reflect “the historical effects of US colonization, the transatlantic slave trade, and recent migrations,” according to the author.
A notable instance occurred among Hispanic or Latino participants residing in California, Texas, and Arizona, where a significant proportion have mixed Indigenous and European ancestry.
In contrast, those identified as Hispanic or Latino in New York exhibited the highest percentage of African ancestry, which aligns with recent migration trends from the Caribbean to New York.
The authors highlight that their results indicate the genetic background of Americans is intricate, emphasizing that “racial and ethnic social composition does not accurately mirror the actual genetic ancestry.” Consequently, they advise against using race and ethnicity as proxies for ancestral backgrounds in genetic research.
Tesfaye Mersha, a professor of pediatrics and human genetics at Cincinnati Children’s Hospital Medical Center and the University of Cincinnati, concurs that self-reported categories should be excluded from genetic studies. Instead, these classifications may be more appropriate for social research “where they are known to have significant impacts,” he mentioned in an email to Live Science.
Nonetheless, Mersha cautioned against over-interpreting the findings of genetic variation at local and state levels. “In some states, participant numbers were quite low, which can distort local estimates and restrict broader generalizations,” he added. “Additionally, high population mobility across states blurs geographic boundaries, particularly when multi-generational ancestry data is lacking,” he explained. Therefore, understanding family history within specific regions is vital to draw accurate conclusions.
Source: www.livescience.com