Rare diseases: Challenges and resources

Abstract

Together rare diseases affect millions of people, of all ages, around the world. However, there are countless others who are affected or at risk but remain undiagnosed and unaware of their disease. Rare diseases are frequently serious and life altering while many are life threatening or fatal. By definition rare diseases affect a relatively small population, making it a challenge to develop drugs and medical devices that prevent, diagnose, and treat these diseases. Scientists have found that rare diseases are usually genetic and chronic [1]. EURORDIS has estimated that at least 80% of rare diseases have genetic origins [2]. They go on to say “other rare diseases are the result of infections and allergies or due to degenerative and proliferative causes.” The prevalence of a rare disease is only an estimate and changes with location and time. For example, in Canada one in 12 Canadians has a rare disease; however, over 25 million Americans experience a rare disease [3]. In the United States a rare (or orphan) disease is generally considered to have a prevalence of fewer than 200,000 affected individuals. Certain diseases with more than 200,000 affected individuals may be included in this list of rare diseases if certain subpopulations of people who have the disease meet the criteria for prevalence standard for rare diseases [4]. It should be noted that there is not a uniform definition for rare diseases and each country establishes their own definition. In Japan, the legal definition of a rare disease is one that affects fewer than 50,000 patients residing in Japan, or about 1 in 2,500 people [5]. However, the European Commission on Public Health defines rare diseases as "life-threatening or chronically debilitating diseases which are of such low prevalence that special combined efforts are needed to address them"[6]. The term low prevalence is defined as fewer than 1 in 2,000 people. Diseases that are “statistically rare, but not life-threatening, chronically debilitating, or inadequately treated,” are not included in the definition [5].