Report Updates Number of Rare Diseases

There are more than 10,000 rare diseases, instead of the previous estimate of about 7,000, and about 33 million people live with a rare disease, according to a new report by the nonprofit organization RARE-X. The report uncovers rare diseases that were previously unrecognized. It includes insights from more than 20 organizations and people in the rare disease community.

Charlene Son Rigby

“Ensuring that the true magnitude of rare diseases is understood is critical,” Charlene Son Rigby, CEO of RARE-X, said in a press release. “If patient communities, researchers, drug developers, and policymakers are to address rare diseases, it’s essential to understand the magnitude of the problem.”

The authors used Orphanet and Online Mendelian Inheritance in Man (OMIM) as the two primary sources for disease entries, as well as DrugBank, the FDA’s Office of Orphan Drug website, and work included in Genome to Treatment (GTRx). Diseases were then characterized based on their available phenotypic description. The analysis showed that there are as many as 10,867 rare diseases, including genetic and non-genetic diseases.

The study authors organized rare diseases into four categories: conditions for which treatment is available, conditions that are considered diagnosable because there are genotypic and phenotypic descriptions (even if more research is needed), conditions that are poorly defined, and conditions that are not currently recognized in major databases.

Researchers identified just over 500 disorders, just 5% of all rare diseases, for which a treatment option is available. Additionally, 8,640 (80%) are theoretically diagnosable, and 2,227 (20%) are poorly defined and clinically actionable. About 87% of rare diseases are known or suspected genetic basis.

Half of all rare diseases affect infants and children, 30% of whom will die by the age of five.

In February 2022, the World Health Organization released the 11th edition of the International Classification of Diseases (ICD-11), which includes coding for almost 5,400 rare diseases. The ICD-11 used the diseases list in the Orphanet database and provides a unique code for each. Already, 35 countries are using the new coding, according to WHO.

Rare-X study authors said it’s important to have an accurate count of rare disease to help address the challenges patients and their caregivers face in the journey for a diagnosis. On average, it takes five to seven years to receive an accurate diagnosis.

“Our hope is that we will update this report periodically and will be able to report that more of those unknown conditions are now part of the medical knowledge bases, and diseases that are poorly defined become more fully understood,” the authors wrote. “Our approach is grounded in our desire to encourage disruptive thinking to advance research, further needed policies, and catalyze new care models. At the heart of everything lies the patient, who has more power to transform our understanding of rare disease than they may even know.”