What is the definition of a rare disease?

Generally speaking, rare diseases refer to conditions with extremely low incidence rates. According to the World Health Organization (WHO), a rare disease is defined as one affecting 0.65‰ to 1‰ of the total population. A more detailed analysis is as follows:

Rare diseases can be classified into more than ten major categories based on symptoms and pathogenesis, encompassing approximately 7,000 different types. Most rare diseases are congenital and lack specific treatments, making them difficult to cure and often life-threatening. According to the WHO definition, rare diseases affect between 0.65% and 1% of the population. Common examples of rare diseases include albinism, acromegaly, and idiopathic pulmonary arterial hypertension. Due to their low occurrence rates, many rare diseases have few documented cases, making research particularly challenging.

Since rare diseases are typically congenital, pregnant women are advised to undergo regular prenatal checkups to help prevent or reduce the risks of inherited rare diseases causing disability or death.