Dr. Friend had worked in academia — M.I.T. and Harvard — then founded a biotechnology company, Rosetta Inpharmatics, and later helped run the cancer drug discovery effort at Merck. He began each new position feeling optimistic. More and more was being discovered about disease-causing genes. “I thought we should be able to develop drugs,” he said.

But all too often disease-causing mutations destroy or disable genes, and drugs would have to restore what was lost, which can be difficult.

So Dr. Friend and Dr. Schadt decided to flip it around and search for a good gene mutation that counteracts the bad and — in an easier process — mimic that with a drug.

They gave their plan a name, The Resilience Project, and decided to search databases that held genetic and clinical information, looking for healthy people with mutations for fatal diseases that strike early in life. If the people had lived far past the age when the disease should have appeared, they assumed they might have a lucky good gene mutation that blocked the bad.

Now, a year later, “we are in this interesting place between excited and frustrated,” Dr. Friend says. They analyzed data from over 500,000 people and found 20 who seem to be protected from a fatal disease. But because of privacy issues there were no names attached to the data.

Four of the subjects are in China. Dr. Schadt and Dr. Friend are trying to find a way to contact them, but “it is very difficult,” Dr. Schadt said.

Dr. Friend and Dr. Schadt are now looking at other databases that might make it easier to contact subjects, but also decided they need to try different approaches. One will be to simply ask healthy people to let them sequence their DNA, putting out the word that they are looking for volunteers, perhaps hundreds of thousands of them. People who agreed would be contacted only if they appeared to be protected from a fatal disease.