Yale Diagnostic Center of Excellence (YDCoE) for the Undiagnosed Diseases Network (UDN)

Being undiagnosed means living with ongoing or unexplained health problems that doctors have not been able to identify or name, even after extensive medical testing. This can happen when symptoms are rare, complex, or unrelated to known diseases.

Many undiagnosed individuals have already seen multiple specialists and undergone genetic testing, imaging scans, or lab work—yet still do not have clear answers. People may also remain undiagnosed because they have not had access to the right specialists, advanced diagnostic tools, or comprehensive medical care. People with undiagnosed diseases often face long and frustrating journeys in search of clarity regarding their health. Some may have extremely rare or not yet discovered conditions, while others may have unusual presentations of known diseases that complicate diagnosis.

This search can be financially draining, as repeated consultations, diagnostic tests, and treatments accumulate significant costs. The uncertainty can lead to feelings of isolation, confusion, and desperation as persistent symptoms affect their daily lives. The diagnostic process can be physically, emotionally, and economically exhausting.

If you or a loved one are experiencing ongoing medical symptoms without a precise diagnosis, we encourage you to explore the Undiagnosed Diseases Network (UDN) and see if you might be eligible to become a research participant. This initiative focuses on uncovering the causes of unexplained medical conditions and helps patients find answers to their health issues.

Many undiagnosed conditions may be caused by genetic problems that are not yet well understood.

Most UDN participants:

• Have had or will need genetic testing
• Have symptoms affecting multiple body systems (3 or more unexplained issues)
• May have unusual physical features (e.g., facial, skeletal differences) present since birth
• May have chronic conditions starting in childhood
• May have unusual responses to treatment, needing stronger, longer, or more frequent therapies
• May have a family history of similar undiagnosed health problems is another vital clue

1. Determine whether your patient is suitable for the UDN per the above criteria.
   If unsure, please get in touch with undiagnosed@yale.edu or the UDN Helpdesk for guidance.

2. Submit a case.
   Patients can submit their case themselves, or providers can submit on their behalf. All submissions must include a physician's letter (details below).

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