Data on the numbers of undiagnosed diseases is not held centrally. The Department is committed to improving the diagnosis of rare diseases through the UK Strategy for Rare Diseases. This includes commitments to reduce times for diagnosis and to establish appropriate diagnostic pathways which are accessible to and understood by, healthcare professionals and patients.
The Department has commissioned research into the diagnostic odyssey for rare diseases to improve the measurement of rates of diagnosis. The Policy and Innovation Research Unit published the report Diagnostic Odyssey for Rare Diseases, Exploration of Potential Indicators in April 2015 (www.piru.ac.uk).
The Government is making substantial investment in infrastructure for research into rare diseases through the National Institute for Health Research. A total of over £800 million has been invested in Biomedical Research Centres and Units and a further £100 million in funding to support Clinical Research Facilities for experimental medicine. The Prime Minister’s 100,000 Genomes project is also focussing on rare diseases and has already led to a diagnosis for some patients who were unable to find a diagnosis through existing NHS tests.