As we prepare for Rare Disease Day, it’s a good time to ask a simple question:
What does “rare” really mean?
In the U.S., a disease is considered rare if it affects fewer than 200,000 people, according to the National Organization for Rare Disorders (NORD). But for families living with Erdheim-Chester disease (ECD), “rare” often feels much more personal.
So just how rare is ECD in the United States?
A recent U.S.-based study led by Dr. Ronald Go on behalf of the Histio-Care Network helps put that into perspective. Using national cancer registry (SEER) data, the study reported an overall incidence rate of 1.3 new ECD cases per 10 million people in the U.S.
That number helps explain why ECD is so often misunderstood and why diagnosis can take so long.
At the ECD Global Alliance (ECDGA), we work every day to make sure that rarity does not mean isolation. By raising awareness, supporting research, and connecting patients and families worldwide, we help ensure that people living with ECD are recognized, diagnosed sooner, and supported every step of the way.
ECD may be rare — but this community is strong.
On Rare Disease Day and every day, thank you for being part of it.