In spite of the efforts made by geneticists to take into account the great variability of humans in their research, the reality is that the western population continues to be over-represented with respect to other more ethnically diverse populations that are hardly considered.
This lack of diversity in human genetic studies has serious consequences for science and medicine, according to the manifesto published today by a group of scientists in a special issue of Cell magazine. Data bias limits understanding of the genetic and environmental factors that influence health, as well as the ability to predict disease risk and the development of new treatments.
“Leaving entire populations out of human genetic studies is scientifically harmful and unfair,” says co-author Sarah Tishkoff, a geneticist at the University of Pennsylvania. “It’s important to study ethnically diverse populations because they may have differences in the genetic risk of getting diseases,” she told Sinc Tishkoff.
“We may lack genetic variants that play an important role in health and disease in ethnically diverse populations, which, in turn, can make it difficult to prevent and treat,” she adds.
The authors’ assessment refers primarily to so-called genetic association studies (GWAS). These trials are used to identify the mutation or ‘responsible’ person in the DNA of a disease and often have implications for clinical practice and health policy.
Alessia Ranciano, member of Sarah A. Tishkoff’s team, collects samples from a Nilo-Saharan participant. (Photo: Tishkoff Lab)
In 2018 the ancestry of individuals included in GWAS studies was 78 % European, 10 % Asian, 2 % African, 1 % Hispanic and less than 1 % of all other ethnic groups.
The fact that people of European descent continue to be over-represented in research, while other populations are largely excluded from analysis, has serious consequences for both science and medicine, according to the authors.
This lack of ethnic diversity offers a partial view of the human genome with incomplete or even misleading information that puts public health at risk and reinforces health disparities between different communities.
GWAS studies look for small variations in the genome that occur more frequently in people with a particular disease than in people without it. In this way, this small variation provides keys to creating more effective treatments.
According to Scott M. Williams, also co-author and researcher at Case Western Reserve University, “approaches are being developed to predict a person’s risk of diseases such as Alzheimer’s, heart disease or diabetes based on their multi-gene status.
However, “the lack of diversity in human genomic studies can exacerbate health inequalities,” says Williams, because data bias limits understanding of factors that influence health.
To begin with, “such calculations cannot be applied to people of other ethnic backgrounds,” he adds, “because risk prediction would be imprecise; and genetic variation among populations can affect the efficacy of a drug or the likelihood that it will cause adverse events.
“There are diseases such as oculocutaneous albinism that are rare in Europe but relatively frequent in some African regions,” says the third author, Giorgio Sirujo, a researcher at the University of Pennsylvania.
The three researchers agree on the need to take into account the complete landscape of human variation in this type of studies, warning of the danger of focusing on populations of limited diversity as before.
A complete understanding of human genetics and its relationship to disease requires studies in people representing the entire “landscape of human variation,” as patterns of genetic variation affect both disease risk and the efficacy and safety of treatment.
Therefore, “priority should be given to biobanks that include individuals of diverse ethnicities to calculate the genetic risk of disease, which translates into better health care for all populations,” Sirugo says.
“These initiatives will require the political will to improve funding and infrastructure to study genomic and phenotypic diversity in global populations. The success of the future of genomic and precision medicine depends on it,” the researcher concludes.