Rare Disease Day will be commemorated on 28 February this year, as it has been every year since 2008. Coordinated by EURORDIS-Rare Diseases Europe, the day will bring together over 70 national groups across 106 countries in over 600 events to raise awareness and drive policy change for people living with these conditions.
Rare diseases are defined as those affecting fewer than one in 2,000 of the population in Europe and fewer than 200,000 in total in the US. About 85% of them impact fewer than one person in a million. Only around 1,200 out of all rare diseases have more than five documented cases published in scientific literature.1,2 This reflects the difficulty of identifying patients and the rarity of the disease itself.
Some rare diseases really are exceptionally uncommon. For instance, Ribose-5-Phosphate Isomerase (RPI) Deficiency, a metabolic disorder caused by the absence of a crucial enzyme, has been documented in only one diagnosed case, first identified in 1984. Field’s disease, a neuromuscular disorder that causes degeneration of muscles and weakening of the body, has only ever been known to affect two twin sisters.
However, the key message of Rare Disease Day is that, when considered together, rare diseases are not actually rare at all. Although estimates vary, there are somewhere between 6,000 and 10,000 rare conditions worldwide. According to Citeline (a Norstella company), some 300 million people worldwide live with a rare disease and about 5% of all people in the world will suffer from one at some point in their lives.2
Definition is difficult
Many of these conditions are very serious. They include cancers, rare infections, and immune deficiencies, among others with their cumulative impacts on sufferers, their carers, and the wider community are considerable. For a start, they disproportionately (75%) affect children when compared to the disease burden overall. In addition, 70% of rare diseases have their onset during childhood and 72% of them are of genetic origin.1
Rare diseases are characterized by a wide diversity of symptoms, many of them quite common, and these vary not just from disease to disease but also between patients suffering from the same condition. This can lead to serious delays in diagnosis and treatment.
Indeed, the average wait for a diagnosis is four to five years by different estimate and 70% of people with rare diseases wait more than a year to get a confirmed diagnosis after first seeking medical care.1,2 This is time many patients simply do not have, and this wait can mean the difference between life and death.
In part because these conditions are, by definition, rare, clinical knowledge and expertise remain limited, and 95% still do not have approved therapies. “Despite their great overall number, rare disease patients are the orphans of health systems, often denied diagnosis, treatment, and the benefits of research,” EUORDIS-Rare Diseases Europe says.1 Not surprisingly, rare disease patients suffer from depression at three times the rate of the general population.
Many of these diseases are chronic, progressive, and degenerative, leaving patients with debilitating loss of autonomy and life-long disabilities. This means disruption and financial difficulties for carers as well. EURORDIS-Rare Diseases Europe claims that 70% of people with rare diseases and their families reduce or completely stop professional activities as a direct result and a similar proportion of carers spend more than two hours each day on tasks related to the disease.1
Finding patients for trials
Research and development (R&D) into rare diseases is difficult, to say the least. The patients are few and geographically scattered, and it is consequently hard to recruit and retain them in sufficient numbers for clinical trials. Most of the conditions don’t have existing treatments and there is often no information or knowledge from previous studies to guide researchers.
“In many cases, few or no studies have ever been conducted in some of these conditions,” says Matt Holms, VP of sales – patient engagement & recruitment at Citeline. “Understanding where these potential patients exist, what sites to select, and ensuring enrolment are real challenges many sponsors are trying to solve for the first time within these rare diseases.”
In addition, there has been something of a shift in R&D focus towards large population chronic diseases, particularly following the success of GLP-1 agonists and expanding markets for cardiometabolic treatments, according to David Wild, pharma/biotech reporter for In Vivo. There is also uncertainty around such issues as federal funding and Medicare reimbursement for high-cost rare disease therapies
“In the EU, changes in the regulatory data protection for orphan drugs could be a challenge for developers of rare disease therapies over coming years,” adds Eliza Slawther, senior writer for Pink Sheet. “Meanwhile in the US, political changes also threaten to freeze funding for the development of medicines for rare diseases.”2
None of these problems will be easy to solve and the work to address them will continue for many years to come. There are probably many thousands of as yet unknown rare diseases to be discovered. Doubtless more will emerge as we cure certain common diseases, most obviously cancers, or simply manage them to prolong life for those affected by them.
Nonetheless, there are some promising trends. In 2024, 52% of the novel drugs approved by the US Food and Drug Administration (FDA) were for treating rare diseases. Citeline’s Pharma R&D Annual Review 2025 found that the number of rare diseases being targeted by pharma as a whole has risen each year to hit 786 and the industry has sponsored a total of 2,577 diseases in the field.3
A beacon of hope
On 28 February, individuals, organizations, and institutions are being asked to participate by raising awareness, engaging with communities, educating the general public, advocating for changes in policy to improve healthcare access and patient support, supporting research and care initiatives through more donations and more.
Part of Rare Diseases Day will be ‘Light Up for Rare’, where buildings are illuminated as a symbol of solidarity with people living with a rare disease. In Northern Ireland this year, for example, ten different buildings will be illuminated for the occasion, thanks to the work of the Northern Ireland Rare Disease Partnership (NIRDP) in building relationships with local authorities and raising awareness.4
Poignantly, on 21 February 2022, Rare Diseases Ukraine illuminated the Okhmatdyt Children’s Hospital in Kyiv. Russia invaded the following day. Since then, the hospital has been bombed and damaged but for three consecutive nights at the end of February 2024, it was illuminated again using large generators. “When we saw the light again, it was a signal of strength. We showed that we believe in our victory,” said Tetiana Kulesha, chairman of the Chairman of the Council for Rare Diseases of Ukraine.4
“Rare Disease Day is more than an awareness event,” the organisers say. “It is a movement toward a future where people with rare diseases receive equitable access to healthcare, research, and social support. Through global collaboration, advocacy, and action, we can create meaningful change for millions worldwide.”1
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References:
- https://www.eurordis.org/information-support/what-is-a-rare-disease/
- https://www.citeline.com/en/resources/rare-disease-r-and-d
- Pharma Projects 2025
- https://www.rarediseaseday.org/news/light-up-for-rare-global-initiative-impact/#:~:text=When%20we%20saw%20the%20light,Council%2C%20Rare%20Diseases%20of%20Ukraine4.