February 28th is International Rare Disease Day, an event that aims to raise awareness of rare diseases and the pressing need for more research.
Rare Diseases By The Numbers
Rare diseases might be rare, but the patients and families affected by them are numerous. Here are some statistics courtesy of the National Organization for Rare Disorders (NORD), which sponsors Rare Disease Day.
In the United States, a disease is considered rare if it affects fewer than 200,000 individuals at one time. In general (and outside the US), a rare disease affects fewer than 1 in 2,000 individuals. However, there are almost 7,000 rare diseases identified so far. Collectively, they affect about one in ten individuals. That’s 30 million people in the US alone, and more than half of them are children.
Let’s not forget the emperor of all maladies. There are at least 100 different types and 400 subtypes of cancer. In 2017, an estimated 1.7 million people were diagnosed with one of them. Rare cancers (brain, pancreatic, ovarian, thyroid, stomach, leukemia, lymphoma, or pediatric cancers) account for around 50% of all cancer patients.
The Need for Research
The OMIM database of genetic disorders lists 6,773 unique disease phenotypes, including 5,188 (77%) for which the molecular basis is known. And yet, the typical diagnostic rates for clinical exome sequencing (that’s when a laboratory sequences all genes in a patient) is around 35%. In other words, the majority of rare disease patients fail to achieve a molecular diagnosis from sequencing. Their odyssey to find one can last years, involving hundreds of additional tests and medical procedures.
Even for patients who carry a molecular diagnosis, the outlook is often grim. Less than 5% of rare diseases have an FDA-approved therapy. This leaves hospitals and healthcare providers to treat such patients with off-label medications, if they can offer any treatment at all.
Drugs that treat rare diseases are often called orphan drugs because pharmaceutical companies are reluctant to develop them under usual marketing conditions. That’s because the process of bringing a new drug to market takes 10 years and costs millions of dollars. When fewer than 200,000 patients have a disease, it’s unlikely that those costs can be recouped.
The governments of the US, Japan, Australia, and the EU have passed legislation to incentivize orphan drug development. However, a great deal of basic research is still required to understand the molecular bases of rare diseases and identify potential therapeutic targets.
Advocate for Rare Disease Research
Patients and families are the most important advocates for rare disease research. Some of the things they can do are:
- Participate in Rare Disease Day events to boost awareness.
- Encourage lawmakers to increase research funding.
- Join genetics advocacy groups like the Genetic Alliance
- Connect with other families affected by rare diseases.
For more ways to get involved, visit the Rare Disease Day page for the US.