For decades, genetic research on schizophrenia has disproportionately centered on European-descent populations. In fact, people with African ancestry make up about 2% of all genome-wide association study subjects. This underrepresentation has created major gaps in scientists’ understanding of how genetic risk for schizophrenia manifests across all of humanity.

To address this, researchers from the Icahn School of Medicine at Mount Sinai, SUNY Downstate Health Sciences University, and the Department of Veterans Affairs have expanded the study populations included in schizophrenia genetic research. These scientists have conducted one of the largest genome-wide association studies of schizophrenia in diverse ancestral populations to date, uncovering a multitude of new genetic landmarks that previous studies had missed. Out of around 100,000 electronic health records concerning people of African ancestry, 13,528 individuals were found to have schizophrenia, while 65,232 remained unaffected. This information was then combined with data from individuals of European and East Asian ancestry comparison, allowing researchers to compare genetic patterns across populations.

Using this more inclusive sample, 100 new regions in the human genome were discovered to be associated with schizophrenia. These regions can be associated with 708 specific genetic changes that may contribute to schizophrenia risk. Many of these genetic changes were identified in those with African ancestry, displaying that the study’s genetic diversity aided researchers in reaching this conclusion.

It is important to note that the human genome is more similar than it is different from person to person. These researchers have not found completely different genetic causes of schizophrenia among different populations. Instead, small differences in the same shared DNA occur at different frequencies depending on population. This distinction continues to be critical outside of the laboratory. For example, Black Americans have historically been diagnosed with schizophrenia three to four times more than the average white American. This disparity may reflect differences in how schizophrenia is recognized and further diagnosed in clinical settings, as well as broad social factors. Studying these minor variations in DNA allows scientists to see how the same disorder can develop through different genetic paths, while involving the same biological processes.

The relevance of this research goes beyond simply adding numbers to a genetic database. “You really have to sample a broad population to understand the pathophysiologic basis of these complex mental health conditions and better tailor treatments for the amazing and diverse people we serve,” says Dr. Eric Achtyes, a psychiatrist at Western Michigan University School of Medicine and a co-author of the study. Representation in medical research allows for a more complete understanding of disease and the biological differences that exist between individuals and populations. With a more complete picture of a disorder like schizophrenia, researchers can better understand genetic risks, and identify new potential therapies. Continuing to include more diverse populations in the conversation can ensure that future discoveries and treatments are relevant to as many people as possible.

Though these researchers have uncovered a multitude of clues associated with how schizophrenia relates to the human genome, they have not found a single explanation for its occurrence. Schizophrenia is an extremely complex illness, involving both biological and environmental factors. The value of the study, however, primarily lies in how it impacts scientists’ understanding of the disorder. By expanding representation in genetic research, scientists may continue to find that the importance of genetic research depends not only on what they study, but also on who is represented in their research.