It’s not actually that rare to have a rare disease

Dr. Ana Rath

Director of Orphanet – INSERM US14

Rare diseases currently affect at least 3.5%, but maybe as much as 5.9%, of the worldwide population. That’s equivalent to around 300 million people worldwide.

For the first time, the number of people living with a rare disease in the world can be estimated. According to a paper published in September 2019 by the European Journal of Human Genetics, based on publicly-available epidemiological data in the Orphanet database, the number of people living with a rare disease is estimated at 300 million worldwide.

The Orphanet database collects and curates data on rare diseases and orphan drugs, and is coordinated at the French Institute of Health and Medical Research (INSERM) by Dr. Ana Rath. Rare diseases are defined in the Orphanet database according to the European Union definition of not more than one in 2,000 persons in the European population. The study was conducted with EURORDIS, Rare Diseases Europe, and Orphanet-Ireland.

According to the research presented, rare diseases affect, at any point in time, 3.5% – 5.9% of the worldwide population. This is equivalent to a conservative estimate of around 300 million people worldwide, or 4% of the world’s population. The analysis shows that there are over 6,000 clinically defined rare diseases, 72% are genetic, and 70% of rare diseases start in childhood.

The figures presented in the paper are derived from data from 67.6% of the prevalent rare diseases. As this analysis does not take into account rare cancers, nor rare diseases caused by rare infectious diseases and poisonings, the number of people affected by rare diseases is likely to be considerably higher.

Robust data for policy development

The study shows that 149 of the rare diseases analysed affect around 80% of the rare disease population. These most prevalent diseases each affect 100 – 500 people per one million. The next most prevalent 241 rare diseases analysed affect 10 – 100 people per one million people. Collectively, these nearly 400 diseases affect at least 98% of the rare disease population with a prevalence of 10 – 500 people per one million people. The remaining diseases analysed are the less prevalent diseases as they affect less than 10 people per one million people. This data can help inform health, social care and research planning to best serve patients and assure a maximal coverage of rare diseases.

Better data ahead

“Even if these are the best figures we can obtain today, they likely underestimate the number of rare disease patients still not visible in healthcare and social care systems,” stated Ana Rath (Orphanet). “Having a specific codification system for them in national systems, such as the Orphanet nomenclature of rare diseases (ORPHA codes),will help obtain definitive figures and, more importantly, produce data needed to adapt healthcare systems for the most vulnerable people.”

A public health priority

The research presented using Orphanet data show that collectively, rare diseases are not rare, and supports over two decades of efforts from the rare disease community to advocate for rare diseases as a public health priority that affects millions of people around the world, and not the few.

This public health priority, supported for many years at the European level, has been championed at the global level at the United Nations and has recently been integrated as a priority within the drive for Universal Health Coverage. The 300 million rare disease patients worldwide are sure to benefit from this new political dynamic that seeks to assure that no-one, no matter their rarity, is left behind.