One of the February events I forgot to mention earlier this month is the Rare Diseases Day which falls on February 28. You might have stumbled across these terms before: rare diseases, orphan diseases. Let’s see whether we can clarify these terms.
Rare diseases, also known as orphan diseases are diseases with very low prevalence. In the US, a disease is considered rare when prevalence in a population is fewer than 200,000 affected individuals. In Europe, rare diseases are those that affect five out of every 10,000 people. There are hundreds, even thousands of diseases and conditions considered “rare” but we seldom hear about them except perhaps when watching episodes of Dr. House.
Here’s some info from the Rare Diseases Day campaign:
Rare diseases are life-threatening or chronically debilitating diseases with a low prevalence and a high level of complexity. 6000 to 8000 rare diseases have been identified, affecting 30 million European citizens. Patients with very rare diseases and their families are particularly isolated and vulnerable. The life expectancy of rare disease patients is significantly reduced and many have disabilities that become a source of discrimination and reduce or destroy educational, professional or social opportunities.
Some of the more “well-known” rare diseases are the Guillain-Barre Syndrome (supposedly linked to certain vaccines), Huntington Disease (this is what Dr Remy Hadley – played by Olivia Wilde – has), and Reye Syndrome (associated with aspirin use in children). A comprehensive (though not complete) list of rare diseases can be found here.
Rare disease should not be confused with the term neglected diseases. Neglected diseases are not necessary rare, they just don’t get all the attention they deserve because most of these are tropical diseases highly prevalent in low-income countries of Asia, Africa, and Latin America. Even though they are prevalent, they, like rare diseases, are not considered worthy enough of the time, not the mention the financial investment, needed to develop vaccines and treatments. Example of neglected diseases are schistosomiasis, African Sleeping Sickness (African trypanosomiasis), and dengue fever.
Back to rare diseases, February 28 is chosen to mark Rare Diseases Day and this year’s theme is “Bridging Patients and Researchers.”
So why are rare diseases also called orphan diseases?
“The rare disease patient is the orphan of health systems, often without diagnosis, without treatment, without research, therefore without reason to hope.”
If there are orphan diseases, there are also orphan drugs. Drugs for [rare] diseases and conditions are commonly referred to as “orphan drugs”.
According to the US Orphan Drug Act:
- “…because so few individuals are affected by any one rare disease or condition, a pharmaceutical company which develops an orphan drug may reasonably expect the drug to generate relatively small sales in comparison to the cost of developing the drug and consequently to incur a financial loss;
- there is reason to believe that some promising orphan drugs will not be developed unless changes are made in the applicable Federal laws to reduce the costs of developing such drugs and to provide financial incentives to develop such drugs;…”
Thus the Orphan Drug Act is aimed to provide incentives to pharmaceutical companies to develop orphan drugs for rare diseases. Incentives include tax advantages, less strict regulations (e.g. fewer clinical trials since there isn’t often enough patients to test), and special considerations in patenting and licensing. Because of such incentives, orphan drug applications for approval have doubled in the last decade. According to the Tufts Center for the Study of Drug Development, the US FDA has granted orphan drug status to 425 experimental drugs between 2006 and 2008. From 2000 and 2002, it was only 208.
However, there are still many rare diseases without any cure. Thus, Rare Diseases Day aims to increase awareness about this issue. The main messages of the Rare Diseases Day campaign are:
- Rare Disease Research is an important area of research
- Rare Disease Research needs to be better funded
- Patients and Researchers win by working together