In combing the genome, scientists can use genetic clues to determine a person’s risk for psychiatric disease and even identify new drug targets. But the benefits of these discoveries will be limited to people of European descent.
Nearly 90% of participants in genome-wide association studies (GWASs), which search for gene variants linked to disease, are of European ancestry. This Eurocentric focus threatens to widen existing disparities in racial and ethnic mental health.
“If you develop certain interventions based on only a single population profile, then you’ll be leaving out the rest of the populations in the world,” says Solomon Teferra, MD, PhD, associate professor of psychiatry at Addis Ababa University, Ethiopia. In a growing trend, psychiatric researchers are diverging from the field’s European bias and are working to correct the imbalance in DNA databases.
The significant downsides of genomics’ one-track mind
One obstacle hindering therapeutic advances in psychiatry is a shallow understanding of the mechanisms of disorders. “The biggest problem in terms of advancing research for mental health conditions is that we don’t understand the underlying biology,” says Laramie Duncan, PhD, assistant professor of psychiatry and behavioral sciences at Stanford (Calif.) University. “Genetics is one of the best ways to systematically look for new clues about the underlying biology.”
At the advent of genomic research, scientists thought it best to study DNA from people of a single ancestry from one continent. “Researchers for a long time held the idea that it was going to be too complicated to include multiple ancestries in the first rounds of genetic analyses,” says Dr. Duncan.
Studying DNA from someone with ancestors from multiple parts of the world wasn’t compatible with methods used in the early days of GWASs. “Individual parts of a person’s DNA can be linked back to one region of the world or another, and most of our methods essentially assume that all of a person’s DNA came from one region of the world,” says Dr. Duncan.
Because many genes are usually involved in psychiatric disorders, scientists need large numbers of participants to detect uncommon, influential variants. Early research was concentrated in North America and Europe so that scientists could readily collect samples from people of European ancestry.
“It then went out of hand because it became routine practice to use only this one group, essentially White, European ancestry people,” says Karoline Kuchenbaecker, PhD, associate professor of psychiatry at University College London.
Yet findings from one population won’t necessarily translate to others. “And that’s exactly what has been shown,” says Dr. Teferra. Polygenic risk scores developed for schizophrenia from European samples, for example, perform poorly among people of African ancestry, although among Europeans, they are strongly effective at differentiating European individuals with and those without schizophrenia. Moreover, drugs that target a gene identified from studies in European populations may be harmful to other groups.
Studies drawn from a diverse pool of participants would benefit a wider swath of humanity. They would also allow scientists to discover small areas of overlap in genomes of different populations, which would help them close in on the true biology of diseases and ensure that “we’re all benefiting from more diverse data in genetics and psychiatric genetics,” says Dr. Kuchenbaecker.