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Serving the Undiagnosed

Publication date: 24 Aug 2019

Obtaining an accurate diagnosis is key to getting appropriate medical treatment. Many patients with rare disorders confront chronic illness, going from doctor to doctor, with no clear answers. Advances in diagnostic technology, including the ability to sequence genomes, has opened the door to matching patients with known rare diseases as well as discovering new ones. Bringing such technologies to patients is a focus of various rare disease organizations and advocacy groups, including the Rare Genomics Institute. The U.S. National Institutes of Health has joined the effort in recent years with the establishment of the Undiagnosed Diseases Network (UDN). The UDN consists of more than a dozen medical and research institutions located throughout the U.S. that seek to find diagnoses for patients who have unidentified chronic conditions. Patients apply to the main UDN website and can be matched to a center nearest their home. 

One UDN site is the Stanford Center for Undiagnosed Diseases in Palo Alto, California. Patients who have an objectively defined abnormal condition that has come up negative through extensive conventional testing can access the service by applying online. They will fill out a brief application, including demographic information and details about their undiagnosed condition, and attach a recommendation letter from their physician. Once an application is received, a research coordinator will follow-up to obtain relevant medical records. The application is reviewed by the site’s clinical team and a decision is made on acceptance. 

After patients are accepted for the Stanford UDN, they will travel to Palo Alto for an evaluation, which includes seeing a UDN physician, a blood draw and any other testing that is recommended (such as X-ray, MRI or skin biopsy). The patient may also see consulting physicians who may offer expert opinions on the undiagnosed condition. After testing and consultation, the patient returns home and the UDN begins working on their case by running tests and holding round table meetings with physician teams, genetic counselors, and expert scientists. The analysis may take anywhere from several months to years. Participants may be reimbursed for travel and lodging expenses. Research testing and visits are covered by UDN, but standard clinical testing may be billed through insurance. 

The multiple UDN clinical sites share resources and information. There is one biorepository, one coordinating center, one metabolomics (analysis of chemical fingerprints from cellular processes) core, one sequencing core and two model organism cores. The patient’s information and test results can be analyzed at various sites, focusing on science and collaboration. One UDN site may have experts that can benefit undiagnosed patients at another location. 

Below are figures for numbers of applicants, acceptances and diagnoses achieved numbers as of June 2019 for the Stanford UDN and the UDN nationwide.








Stanford UDN




UDN as a whole  






While these numbers show that many patients in the program may not succeed in obtaining a diagnosis, their participation may help lay the groundwork for future success.  Rare diseases, are by definition infrequent, and understanding of specific disorders necessarily comes from aggregate data from similarly affected individuals. Cumulative data collected over long periods of time may be needed to determine causes and effects.  The UDN therefore continues to follow patients who remain undiagnosed and will reanalyze their data or seek new testing if beneficial.

On the other hand, diagnosed patients can benefit in many ways.  There may be changes in medical treatment and therapeutic approach based on the newfound understanding.  Patients can seek out others with the same diagnosis, join advocacy groups and participate in drug discovery efforts.  Online communities such as RareShare can facilitate connecting with others to exchange information and coping strategies.  By doing so, patients will recognize that they are not alone.   

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