Aerial view of a giant illuminated decoration of the Aztec sun stone and the Zocalo main square, Mexico City.

Mexico City’s people have trusted researchers with their medical histories.Credit: Cristopher Rogel Blanquet/Getty

Two decades ago, scientists asked more than 150,000 people living in Mexico City to provide medical data for research. Each participant gave time, blood and details of their medical history. For the researchers, who were based at the National Autonomous University of Mexico in Mexico City and the University of Oxford, UK, this was an opportunity to study a Latin American population for clues about factors contributing to disease and health. For the participants, it was a chance to contribute to science so that future generations might one day benefit from access to improved health care. Ultimately, the Mexico City Prospective Study was an exercise in trust — scientists were trusted with some of people’s most private information because they promised to use it responsibly.

Over the years, the researchers have repaid the communities through studies investigating the effects of tobacco and other risk factors on participants’ health1. They have used the data to learn about the impact of diabetes on mortality rates2, and they have found that rare forms of a gene called GPR75 lower the risk of obesity3. And on 11 October, researchers added to the body of knowledge on the population’s ancestry4.

But this project also has broader relevance — it can be seen as a model of trust and of how the power structures of science can be changed to benefit the communities closest to it.

Mexico’s population is genetically wealthy. With a complex history of migration and mixing of several populations, the country’s diverse genetic resources are valuable to the study of the genetic roots of diseases. Most genetic databases are stocked with data from people with European ancestry. If genomics is to genuinely benefit the global community — and especially under-represented groups — appropriately diverse data sets are needed. These will improve the accuracy of genetic tests, such as those for disease risk, and will make it easier to unearth potential drug targets by finding new genetic links to medical conditions.

At the same time, wealthy nations have, for centuries, been extracting natural resources from low- and middle-income countries and pocketing the proceeds. Scientific data, unfortunately, have been among those resources. Even well-intentioned programmes that emphasize — or require — investigators to share the data from their published studies with the communities from which the information was gathered can reinforce this power structure. Researchers in wealthy nations can access databases more quickly and easily using powerful tools than can those in resource-poor areas; and participating scientists in poorer countries are often not given the credit they are due.

Moreover, if the analyses are designed without the input from the communities from which the data originated, they are less likely to be relevant to that population. This could mean that the promise of serving future generations of Mexicans might go unmet, engendering distrust in scientists and their research aims in the process.

To counter this history, researchers associated with the Mexico City Prospective Study came up with a data-sharing proposal that was expressly designed to benefit scientists in Mexico who want to use the study’s data for their own research. The data will be made freely available to researchers in Mexico for up to two years before those in other countries can access them. The authors have also arranged to provide free computing services to those researchers who might want access but who lack the infrastructure to perform analyses on such a massive data set.

There are conditions. Those who wish to benefit will need to ensure that the data are kept securely, and they are not allowed to try to identify the participants. They will also need to seek approval from the original consortium members. Researchers in Mexico who are granted early access to the data can still collaborate with others around the world. It is an important step towards addressing inequities in data sharing that have persisted despite efforts to ensure that the information is shared openly. The study’s data-sharing policy builds on previous agreements in which scientists from wealthy countries worked with genomic data from participants in low-income nations.

The solution reached by the Mexico City Prospective Study is not perfect. Two years of advance access to the data is hardly enough to level the playing field between researchers in Mexico and those in wealthier nations, says Phaik Yeong Cheah, a bioethicist at the Mahidol Oxford Tropical Medicine Research Unit based in Bangkok. To generate genomic data and perform the analyses, the research team partnered with the Regeneron Genetics Center in Tarrytown, New York — an industry-sponsored initiative — and with other pharmaceutical companies. Under the terms of agreement, the initiative will have access to the data from the project alongside scientists in Mexico.

But the spirit of the effort — to specifically consider the ability of researchers to access and analyse the data collected from their communities — is one that more projects could adopt, as they explore ways to counteract the power hierarchies rooted in history that are perpetuated today.

That does not apply only to genetics research. Many fields — including ecology, epidemiology and geology — rely on communities around the world to supply crucial data. It is essential that we explore ways to ensure that those data are used to benefit those who shared them in the first place.