Genetic makeup doesn't always correspond with a person's claimed racial or ethnic identity.
Gittin' down to the nitty-gritty of genetics, a fresh study recently dropped in The American Journal of Human Genetics. This research delves into the complicated relationship existing between self-reported racial and ethnic identities in the U.S., and a person's genetic background or ancestral roots.
It's crucial to never brush off this gap between a person's self-proclaimed identity and their genetic makeup, as those in science world are keen on developing targeted treatments for patients, the smart researchers behind the study insist.
"This research packs a punch because it elucidates the interlink between genomic diversity and racial and ethnic categories within the U.S. in an unprecedented manner," said Eduardo Tarazona-Santos, a professor of genetic population at the Federal University of Minas Gerais in Brazil and co-author to the study.
They say this clarity is crucial in developing appropriate precision medicine treatments, the kind that's tailored to each individual – taking into account their genes, environment, and lifestyle.
Precision Medicine for the Masses
The study, published on June 5th, had Tarazona-Santos and his gang peeping at 230,000 people's DNA. These folks lent their genetic data to the All of Us research database, a trove collected through a National Institutes of Health program striving to advance precision medicine.
Historically, large-scale genetic studies predominantly included people of European descent. Efforts like the All of Us project, however, slice up medical inequity by corralling folks from varied and underrepresented populations. Lately, the program's faced quite the financial hurdles that've vexingly slowed down recruitment and progress.
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The researchers applied a method called principal component analysis to identify genetic similarities and dissimilarities among those in the database. They also contemplated genetic catalogs, such as the 1000 Genomes Project, to ascertain how people's genetic lineage matched up with the racial (white, Black or African American, Asian American) and ethnicity (Hispanic/Latino or not) categories employed in the All of Us questionnaire.
Surprisingly, individuals deemed to be from the same racial and ethnic groups showed various genetic differences, suggestive of the fact that "most genetic variance is within race and ethnicity groups rather than between groups," the study authors penned in the report.
In essence, the examinations found that people segmented into racial and ethnic clusters are more like gradients of genetic variation as opposed to distinct groups. "We noticed gradients of genetic variation that transcended those categories," the authors wrote.
The study's findings buck a controversial paper published in 2024 in Nature that utilized All of Us participants' genomic data. This previous paper was met with myriad criticisms from experts, naysayers asserting that the technique employed to analyze race and ethnicity data could be twisted to make the case for an ill-informed notion that humans can be neatly categorized into race-defined groups. Interestingly, the new study, employing an alternate data-crunching technique, reached an opposing conclusion.
Genes Vary Across U.S. States
The research also illuminated that even within the same racial and ethnic group, people in the U.S. display genetic variation among different states. This may be a consequence of U.S. colonization, the transatlantic slave trade, and recent migrations, the authors suggested.
A classic example of this phenomenon was observed among Hispanic or Latino individuals residing in California, Texas, and Arizona, who came up with a high proportion of Native American ancestry, as opposed to those living elsewhere in the U.S. Such findings can be attributed to the ancient connection between these regions and Mexico, boasting an expansive Indigenous-European mixed population.
In contrast, Hispanic or Latino individuals inhabiting New York were observed to possess the highest proportion of African ancestry, which is entirely consistent with recent migrations from the Caribbean to New York.
The authors summarize that the genetic backgrounds in the U.S. are exceptionally intricate, and racial and ethnic constructs hardly represent underlying ancestry in genetic research. To that end, the researchers counsel against employing race and ethnicity as proxies for ancestry in such studies.
Tesfaye Mersha, a professor of pediatrics and human genetics researcher at Cincinnati Children's Hospital Medical Center and the University of Cincinnati, seconds that thought. He believes these self-reported categories shouldn't be integrated into genetic studies. Instead, these categories should be reserved for social studies, where they'll indeed matter a whole lot, he adds.
However, Mersha also emphasizes caution when inferring conclusions concerning regional and state-level genetic variation. He points out that certain states had low numbers of participants, which may affect regional estimates and restrict the generalizability of the findings. Moreover, the high population mobility across states blurs geographical boundaries, particularly in the absence of multigenerational ancestry data, Mersha notes. In simpler terms, due to people frequently shuffling around, it's challenging to make assumptions without a good sense of how long their families have been living in a particular state.
- The findings of the study, published in The American Journal of Human Genetics, highlight the importance of understanding the interlink between genomic diversity and racial and ethnic categories within the U.S., as it is crucial for developing targeted health-and-wellness treatments that consider each individual's unique genetic makeup and medical-conditions.
- The research reveals that individuals deemed to be from the same racial and ethnic groups often show various genetic differences, suggesting that the conceptualization of people as distinct racial or ethnic groups might not accurately represent their underlying genetic ancestry in health-and-wellness and science studies.
