Rare diseases are commonly defined as conditions affecting about one in 2,000 people.
Notes on verification
The 1-in-2,000 threshold is the widely cited EU/WHO-region definition and matches the original source framing, but is not universal—US, Japan, and other countries use different thresholds (e.g., US defines by absolute population count, ~1 in 1,500-1,650).
Sources
- This New Search Engine Helps Doctors Diagnose Rare, Obscure Diseases (smithsonianmag.com)
- https://www.eurordis.org/information-support/what-is-a-rare-disease/ (eurordis.org)
- https://www.rarediseasesinternational.org/description-for-rd/ (rarediseasesinternational.org)
- https://www.technologyreview.com/2013/03/18/179360/the-rare-disease-search-engine-that-outperforms-google/ (technologyreview.com)
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11300358/figure/F1 (pmc.ncbi.nlm.nih.gov)
- https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/rare-disease (sciencedirect.com)