Such was the case with Tom Hopper. At Massachusetts General Hospital he underwent another round of extensive testing, but nothing proved definitive. Then one internist, Michael Barry, M.D., noticed that as soon as Hopper switched from a liquid diet to regular hospital food, he got sick. Barry spent an hour at Hopper's bedside, asking detailed questions about his extended family's medical history, including where his ancestors came from.
A DNA test confirmed Barry's suspicions: Hopper had a gene marker that made him especially susceptible to celiac disease, a fairly common autoimmune disorder characterized by an inability to process gluten — despite having had previous blood tests come back negative. It turns out that the blood test for celiac is negative in about 10 percent of those who have it. " By then I had seen dozens of doctors and six digestive specialists," recalls Hopper, " but none apparently understood the importance of looking at my diet."
Hopper is not the only patient to benefit from DNA testing. At the National Human Genome Research Institute, scientific director Daniel Kastner, M.D., Ph.D., and his team of researchers have increasingly used human-genome sequencing techniques to identify new diseases.
In 1999 Kastner and his team observed several families whose members suffered with similar symptoms of fevers, severe abdominal and chest pain, and skin rashes. Using a DNA analysis of their blood, the team identified mutations in one gene that caused a host of previously undiagnosed inflammatory diseases. "It wasn't even in medical textbooks and no one had a name for it," Kastner says today.
Since then, with further advances in human genetics as well as in cell and molecular biology, hardly a week goes by without the discovery of yet another disease-associated gene or mutation. "For a practicing physician who's already incredibly busy, keeping up with this deluge of new information is like trying to drink from a fire hose," says Kastner. "There's just so much of it to take in."
Next: What you can do. >>