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.