Rare diseases are generally defined as affecting about 1 in 2,000 people.
Notes on verification
The 1-in-2,000 threshold is well-documented as the EU/EURORDIS definition of rare disease, confirmed by multiple reputable sources (EURORDIS, Rare Diseases International, EUPATI). However, this is not a universal standard—the US, Japan, and other jurisdictions use different definitional approaches (absolute counts or different ratios), so framing it as 'the' general definition slightly overstates its universality. [tier=bronze indep_score=0.525 clusters=4 claim_tier=notable | kind=interpretive eligibility=high (extractor: interpretive/medium)]
Sources
- This New Search Engine Helps Doctors Diagnose Rare, Obscure Diseases (seed:anatomy_and_medical_oddities)
- https://www.eurordis.org/information-support/what-is-a-rare-disease/ (corroboration)
- https://www.rarediseasesinternational.org/description-for-rd/ (corroboration)
- https://toolbox.eupati.eu/glossary/rare-disease/ (corroboration)
- https://www.disabled-world.com/definitions/lists/rare-disease.php (corroboration)