The National Institutes of Health undiagnosed diseases program

PURPOSE OF REVIEW: To review the approach to undiagnosed patients and results of the National Institutes of Health (NIH) undiagnosed diseases program (UDP), and discuss its benefits to patients, academic medical centers, and the greater scientific community. RECENT FINDINGS: The NIH UDP provides comprehensive and collaborative evaluations for patients with objective findings of disease whose diagnoses have long eluded the medical community. Intensive review of patient records, careful phenotyping, and new genomic technologies have resulted in the diagnosis of new and extremely rare conditions, expanded the phenotypes of rare disorders, and determined that symptoms are caused by more than one disorder in a family. SUMMARY: Many children and adults with complex phenotypes remain undiagnosed despite years of searching. The most common undiagnosed disorders involve a neurologic phenotype. Comprehensive phenotyping and genomic analysis utilizing nuclear families can provide a diagnosis in some cases and provide good 'lead' candidate genes for others. A UDP can be important for patients, academic medical centers, the scientific community, and society.