Regularly, I am asked what is an orphan disease? what is the difference between “rare” and “orphan disease”? And some believe that orphan disease is only a disease for which there is no diagnostic or name. I will answer those questions.
First, what is a rare disease?
A rare disease is a disease that has a prevalence (frequency) low in the population. The most common definition of a rare disease is as follows: a disease that affects less than 1 in 2000 people in a population (the United States, a disease for which there are fewer than 200,000 people in the population is said) . Examples of rare diseases: cystic fibrosis, Duchenne muscular dystrophy, Huntington’s disease, myasthenia gravis, Angelman syndrome, etc.. About 7,000 rare diseases have been identified worldwide.
Finally, a rare disease is a disease that has no name. Indeed, an individual may suffer from a disease that doctors are unable to identify. In general, an undiagnosed disease is a rare disease. These diseases are unknown because much of rare diseases.
Quebec’s population is about 7.8 million in 2010, so this means that according to the definition above, a particular rare disease is a disease that affects fewer than 3,900 people in the Quebec population. This number (3,900) is the maximum, because the vast majority of rare diseases have a frequency of less than 1/100, 000 person with the population (fewer than 78 individuals in Quebec).
What is an orphan disease?
The term “orphan” appeared in the early 1980s in the United States in connection with the treatment of rare diseases. Thus, they said that was an orphan disease if there was no treatment for this disease other than treating the symptoms. Companies and researchers were reluctant to develop a drug for a rare disease, because it is not economically profitable. The United States, Europe and some other countries have laws or regulations that allow companies to obtain tax and other advantages to develop a treatment for a rare disease. The experimental drug then obtained the designation of “orphan”.
Rare disease vs. orphan disease
The term “orphan disease” was widespread and often we confuse “rare” and “orphan disease” because the vast majority of rare diseases are neglected in many ways: lack of information about the disease, delay in diagnosis, little information on the medical care, little or no research and no treatment (there are approximately 350 orphan drugs for rare diseases around 7000).
There are rare orphan diseases that are less than others, for example, cystic fibrosis or certain muscle diseases. Either they are the most common or rare, for some reason, they were more “adopted” as other diseases (eg, cystic fibrosis is one of the first major hereditary diseases for which we found the causative gene in the 1980s and which is relatively more research on other rare diseases). But cystic fibrosis is still an orphan treatment that would cure this disease.
Conversely, there are some common diseases that can be considered “orphan”, such as celiac disease, which affects about 1 in 133 people in Canada, but that is still little known and long time to diagnose. Other common orphan diseases are infectious tropical diseases that are more prevalent in developing countries (eg parasites such as roundworms, Chagas disease, leishmaniasis on, etc..). These diseases called “neglected diseases”.
A rare disease is generally defined as a disease with a frequency of less than 1 in 2000 people in the population. An orphan disease is not only an undiagnosed or unknown, but a disease that has a name disease. In general, we can say that “rare disease” equals “orphan disease” because due to their rarity, rare diseases are not adopted by researchers and the pharmaceutical industry and little known in the field of health and population in general. Hoping that one day we no longer rare diseases called orphan diseases