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There are more than 6,000 known rare diseases with many more that are yet to be discovered. While each of these conditions is rare, combined, these diseases affect an estimated 25 million Americans. Arriving at a diagnosis for a rare or unknown condition can be a long and frustrating process for patients, often involving several years of testing and multiple doctors. And even with a diagnosis, nothing may be known about the mechanisms underlying the disease and therefore effective treatments may not exist. The Undiagnosed Diseases Network (UDN) is actively working to address both of these issues. First, by bringing a nationwide network of top clinicians and laboratory researchers together, the UDN is able come up with diagnoses for some of the most complex medical cases. Also, by promoting research into the biological mechanisms of these rare conditions, the likelihood of designing treatments and hopefully cures for these diseases will be increased. Participants accepted into the UDN undergo an extensive one week clinical evaluation, often involving state of the art diagnostic techniques such as genetic sequencing. The information obtained from clinical testing are then brought to the laboratory setting for in depth biological testing. The UDN began accepting participants in September 2015, and as of January 2019 has already accepted 1221 applicants with undiagnosed conditions and made 260 diagnoses. Profiles of some of these participants can be found on the UDN’s Participant Pages. Common Fund support for the UDN has been approved through 2022 with the goal of creating a sustainable national resource for patients struggling to find a diagnosis.

Check out this video for an example of the types of collaborations the UDN uses to find diagnoses


An audio described version of this video is also available on YouTube.

This page last reviewed on September 13, 2023