The United States’ most famous epidemiological study, the Framingham Heart Study, is about to take a medically promising step that could help in the effort to discover genes responsible for common diseases. But the move is also likely to raise questions about the commercial exploitation of patients’ medical records.

Since the Framingham study began in 1948, some 10,000 residents of Framingham, Mass., have been poked, prodded and measured every two years in a massive effort to uncover risk factors for heart disease. The study has been extraordinarily successful, turning up, among other things, the link between cholesterol and clogged arteries. Now, officials at Boston University, which administers the study on behalf of the National Heart, Lung, and Blood Institute, have formed a company to mine the data for genes that contribute to diseases such as dementia, arthritis and the onset of deafness in adults.

Framingham Genomic Medicine plans to spend millions over the next several years to organize the information and begin large-scale DNA testing. “The amount of data ready to be culled out of this study is limitless,” says chief scientific officer Fred Ledley.

The demand for so-called “phenotype” data (measurements of an individual’s actual physical characteristics) from well-studied populations like Framingham is rising dramatically thanks to rapid advances in genetic technology. “Genetic analysis can be done with an arbitrarily great degree of precision. But you are limited by patient data,” says Ledley. “This is the missing link.”

In fact, genomic researchers expect they will eventually need medical data on hundreds of thousands, even millions, of people. For that reason, some European governments with centralized health care systems are now casting hungry eyes on their citizenry’s medical records. The U.K. Medical Research Council, for instance, is planning a massive study involving more than 500,000 volunteers, and scientists have lobbied the U.K.’s National Health Service to create a genetic database encompassing the entire British population. Similar national databases are under consideration in Italy and Estonia.

So far, however, private companies have taken the lead in creating phenotype databases-a move that’s proved both lucrative and controversial. In Iceland, Reykjavik-based deCode Genetics, which got government approval to create a database based on the medical records of that nation’s 275,000 citizens, has been accused of violating patient privacy and plundering Iceland’s genetic heritage. Despite the criticism, the company has signed a research alliance worth up to $200 million with Hoffman-La Roche, which hopes to use the data as a starting point for new medicines.

The question of who should benefit from a patient’s medical records is also at issue in the Framingham study. “We are trying to be very open and proactive with the Framingham population, to get their buy-in and support for what we are doing,” says Art Klausner, a partner with Domain Associates in Princeton, N.J., part of a financial consortium that’s planning to invest $22 million in Framingham Genomic Medicine. The company plans to donate some of its profits to the Framingham community.

While experts in biomedical ethics say that’s a good start, exploiting phenotype databases for commercial purposes remains problematic. For instance, do the consent forms patients sign to participate in such studies include adequate disclosures of how their DNA and tissues will be used in the future? “Privacy drives the concern about these databases. People are fearful that information about genetics could be used against them,” says Arthur Caplan, director of the University of Pennsylvania Center for Bioethics. Entire ethnic groups may also be at risk, since genetic research could lead to findings, such as vulnerability to a specific disease, that could stigmatize them. “The very things that make a population good to study also make it tricky,” says Caplan.