Rare diseases are a particular group of complex, chronic and progressive conditions. They are also heterogeneous conditions that can affect practically every system and organ of the body, requiring coordinated multidisciplinary care.
According to the definition established by the European Union, the clinical conditions that affect 5 or less in every 10,000 citizens are considered rare. There are more than 7000 different rare diseases or syndromes, currently recorded in the Orphanet portal for Rare Diseases and Orphan Drugs (Weinreich et al., 2008).
The majority of rare diseases are genetic or even hereditary, while many may be due to a combination with environmental factors that take place during pregnancy or shortly after birth. Often, and especially if they are not timely diagnosed to pursue treatment, rare diseases can cause irreversible, visible or invisible, disabilities and even premature death.
People diagnosed with a rare disease face a deterioration in their quality of life. They may be(come) unable to learn and do professional work, which has destructive consequences for their financial situation and everyday living.
Many authors and scientific groups have stressed how rare diseases, affecting 30 million people in Europe, 25 million people in the USA and 300 million people worldwide, are and should be regarded as a public health priority in need of a comprehensive plan of action to accommodate their devastating social and financial consequences on the person, the family, the society and the State itself (Valdez et al., 2016; Nguengang et al., 2019: Eurordis, 2022).
Challenges in rare disease diagnosis and therapies
Given the rarity and variability of rare diseases, clinical expertise in diagnosis and management is often limited and scattered across countries with large populations, which have been able to accumulate expertise in rare disease diagnosis and management over the years, based on large cohorts of patients.
At the same time, the symptoms of a rare disease may resemble those of common conditions only to further complicate or delay diagnosis.
Rare disease therapies are known as “orphan” therapies or “orphan” drugs. It is estimated that at least one approved treatment is available for only 5% or fewer of rare diseases. The cost of these therapies is extremely high for patients who often find themselves in unbearable financial strains (Willmer, 2022).
Eurordis (2022) Another Step Closer: Why Europe should keep striving toward an Action Plan for Rare
Diseases. Available at https://www.eurordis.org/europe-striving-toward-an-action-plan-for-rarediseases/.
Nguengang Wakap, S., Lambert, D. M., Olry, A., Rodwell, C., Gueydan, C., Lanneau, V., ... & Rath, A. (2020). Estimating cumulative point prevalence of rare diseases: analysis of the Orphanet database. European Journal of Human Genetics, 28(2), 165-173. Available at https://www.nature.com/articles/s41431-019-0508-0
Weinreich SS, Mangon R, Sikkens JJ, Teeuw ME, Cornel MC. [Orphanet: a European database for rare diseases]. Nederlands Tijdschrift Voor Geneeskunde. 2008 Mar;152(9):518-519. PMID: 18389888.
Valdez, R., Ouyang, L., & Bolen, J. (2016). Public Health and Rare Diseases: Oxymoron No More. Preventing chronic disease, 13, E05. https://doi.org/10.5888/pcd13.150491