Inquire at the office, social service or charity work management department. Rare diseases refer to those diseases with extremely low incidence. Rare disease, also known as "orphan disease", has no clear definition in China. According to the definition of the World Health Organization, rare diseases are diseases with a total population of 0.65 ‰ ~/kloc-0 ‰. Inquiries can be made in hospital offices, social work services or charity work management departments.