12698 IUPAC Gold Book - orphan disease 10.1351/goldbook.12698 12698 current 1 Disease for which drug research, development, and marketing is economically unfavourable. The poor commercial environment could be due to a lack of economic incentives or a lack of understanding of the diseases or a combination of both. Sometimes the term "rare disease" is used synonymously with orphan disease, although there is a slight difference. For example, a rare disease is so uncommon that there is no drug development effort. Which diseases are classified as orphan depends strongly on the country that classifies it. In the United States, for example, any disease affecting less than \(\pu{200000}\) people is considered an orphan or rare disease. Europe and countries such as Japan, Australia, and Singapore have a different definition. neglected disease https://goldbook.iupac.org//terms/view/12690 orphan drug https://goldbook.iupac.org//terms/view/12699 PAC, 2013, 85, 1725. 'Glossary of terms used in medicinal chemistry. Part II (IUPAC Recommendations 2013)' on page 1744 (https://doi.org/10.1351/PAC-REC-12-11-23) https://goldbook.iupac.org/terms/view/12698/html https://goldbook.iupac.org/terms/view/12698/json https://goldbook.iupac.org/terms/view/12698/plain Citation: 'orphan disease' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.12698 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-05-28T07:18:17+00:00