Classification and epidemiologic analysis of 86 diseases in <i>China's Second List of Rare Diseases </i>

Following the release of <i>China's First List of Rare Diseases</i> in May 2018, the Chinese government officially published <i>China's Second List of Rare Diseases</i> in September 2023. To date, there is no unified standard and international consensus for rare diseases, and epidemiologic data for most rare diseases in China are lacking. We investigated 86 rare diseases on the second list using Orphanet and other databases to clarify the classification, nomenclature, and epidemiologic data for these diseases, and we summarized the genotype and phenotype of hereditary diseases. The results showed that most of 86 rare diseases were coded in the database of Unified Medical Language System (UMLS), Orphanet, Medical Subject Headings (MeSH) and International Classification of Diseases, Eleventh Revision (ICD-11). Some rare diseases are composed by group of different disorders, in which multiple identifiers existed. Meanwhile, some rare diseases have different subtypes, which correspond to different identifiers. This increases the actual number of rare diseases in the second list. Over 50% of rare diseases are genetic rare diseases and they are mainly classified into neoplastic diseases, transplant-related disorders and neurological diseases. Epidemiologic data indicated that these rare diseases had a broad prevalence spectrum and over 20 rare diseases had a prevalence of over 1/10,000, these rare diseases in the <i>China's Second List of Rare Diseases</i> expanded the number and scope of rare diseases according to the China's official definition of rare diseases.