To win a battle, soldiers must have a good sense of their adversary. But for people with mysterious diseases that defy diagnosis, the enemy remains unknown. To address this challenge, the US National Institutes of Health (NIH) plans to launch a center that brings together a team of 25 NIH multidisciplinary experts to evaluate and treat patients at its Clinical Center.

The new Undiagnosed Diseases Program, announced on 19 May, will bring together specialists from the NIH Clinical Center as well as the country's National Human Genome Research Institute (NHGRI) and the Office of Rare Diseases. Until now, people with rare, undiagnosed diseases had no central site at the NIH to turn to for diagnosis and treatment.

Excluding cases of undiagnosed illnesses, more than 6,000 known rare medical conditions affect a total of 25 million people in the United States alone. Many individuals with such ailments show a baffling collection of symptoms involving multiple organ systems or have rare, unknown subtypes of known diseases, says NIH director Elias Zerhouni.

“These are abandoned disorders, about which the medical profession has given up,” says NHGRI clinical director William Gahl. “By default, many are considered psychiatric disorders when there might in fact be an underlying, undiagnosed physical disorder.”

Take, for example, the case of 26-year-old Amanda Young, whose rare genetic immune disorder took longer than a decade to diagnose, during which time she suffered many life-threatening infections, surgeries and a leg amputation. When she first began developing symptoms as a child—frequent, intractable infections—this pathway and the mutation was unknown, Gahl explains. NIH scientists have since pinned her weakened immune system on a mutation in the IRAK4 gene and hope that such discoveries will help bring them closer to providing effective treatment.

With only $280,000 of funding annually for three paid staff members (two nurse practitioners and a scheduling assistant), the program will draw on the expertise of NIH scientists, who will, as a team, review an estimated two cases a week. As well as treatment, the program's other goal is to develop new diagnostic algorithms and, ultimately, new diagnostics.

“We are encouraged and excited by this first step toward coordinated care for patients who may never receive a diagnosis,” says Mary Dunkle of the National Organization of Rare Diseases, a patient advocacy group based in Danbury, Connecticut. “This gives us a place to start—a place to send patients who call us for help.”