Ehlers-Danlos syndrome is far more common than the medical community once believed. For decades, textbooks cited a prevalence of 1 in 5,000, but that figure turns out to have originated as an unreferenced “reasonable estimate” in a single textbook. Newer research using actual health records suggests the true number is closer to 1 in 500 when EDS and the related hypermobility spectrum disorders are counted together.
The Old Estimate vs. New Evidence
The 1 in 5,000 figure still appears across medical websites and patient handouts, but a large national study published in BMJ Open challenged it significantly. Researchers analyzed electronic health records covering the entire population of Wales and identified 6,021 people with a diagnosis of EDS or joint hypermobility syndrome (now classified under EDS or hypermobility spectrum disorder). That translated to a diagnosed prevalence of about 194 per 100,000 people, or roughly 1 in 500.
That number represents only people who already had a formal diagnosis in their medical records. Since EDS is widely recognized as underdiagnosed, the actual prevalence could be higher still. The study’s authors concluded that EDS and hypermobility spectrum disorders “have historically been considered rare diseases” and that “this assertion should be reconsidered.”
Prevalence by Type
There are 13 recognized subtypes of EDS, and they vary enormously in how common they are. The hypermobile type (hEDS) accounts for the vast majority of cases. Demographic data for hEDS patients remain limited, partly because the diagnostic criteria were only formalized in 2017, and many people with the condition are grouped with the broader category of hypermobility spectrum disorders.
The rarer subtypes have much more clearly defined prevalence figures:
- Classical EDS: approximately 1 in 20,000 to 40,000 people
- Vascular EDS: approximately 1 in 100,000 to 200,000 people
Vascular EDS is the most medically serious subtype because it affects blood vessels and organs, but it is also among the least common. The other rare subtypes, including kyphoscoliotic, dermatosparaxis, and arthrochalasia EDS, are rarer still, with only a few hundred cases reported worldwide for some of them.
Why Women Are Diagnosed Far More Often
About 70% of the diagnosed cases in the Welsh study were women. For hypermobile EDS specifically, the gap is even more dramatic. Although hEDS is an autosomal dominant genetic condition, meaning it should theoretically affect men and women equally, studies have found a ratio as high as 9 women diagnosed for every 1 man.
Researchers at the Mayo Clinic are actively investigating whether biological sex differences in immune function and cellular energy production help explain why women appear to develop more severe or recognizable symptoms. But diagnostic bias likely plays a role too. Men with joint hypermobility may be less likely to seek care for pain, or their symptoms may be attributed to other causes. The true sex ratio remains an open question.
A Decade to Get Diagnosed
One reason EDS appears rarer than it actually is: many people who have it spend years without a correct diagnosis. The median time from first symptoms to a confirmed diagnosis of hypermobile EDS is about 10 years, and patients typically see more than 10 different clinicians before someone identifies the condition.
This delay happens for several reasons. EDS symptoms overlap with dozens of other conditions. Joint pain, fatigue, digestive problems, and frequent injuries are common complaints that rarely prompt a doctor to think about a connective tissue disorder. Many physicians received little or no training on EDS in medical school, particularly the hypermobile type, which doesn’t show up on standard blood tests or imaging. Without a reliable biomarker, diagnosis relies on clinical evaluation of joint mobility, skin elasticity, family history, and a checklist of associated features.
The long diagnostic journey means that prevalence data based on medical records almost certainly undercount the real number of affected people. Someone who has been told they have fibromyalgia, chronic fatigue syndrome, or “just” flexible joints may actually meet the criteria for hEDS or a hypermobility spectrum disorder.
EDS vs. Hypermobility Spectrum Disorders
Since 2017, the international classification system draws a line between hypermobile EDS and hypermobility spectrum disorders. Both involve joints that move beyond the normal range and both can cause chronic pain, but hEDS requires meeting a stricter set of diagnostic criteria, including specific patterns of systemic involvement like unusually stretchy skin, easy bruising, or problems with the cardiovascular system.
People who have symptomatic hypermobility but don’t meet every hEDS criterion are classified under hypermobility spectrum disorder. In practice, the two conditions share many of the same symptoms and challenges, and the Welsh prevalence figure of 1 in 500 combines both groups. From a patient’s perspective, the distinction matters less than getting appropriate care, since the management strategies overlap substantially.
Is EDS Still Considered Rare?
Technically, most individual subtypes of EDS meet the definition of a rare disease (fewer than 200,000 affected people in the United States, or roughly 1 in 1,500). Classical EDS and vascular EDS are unquestionably rare. But when hypermobile EDS and hypermobility spectrum disorders are considered as a group, the numbers tell a different story. A prevalence of 1 in 500 would mean roughly 660,000 people in the U.S. alone, well above the rare disease threshold.
The “rare” label has real consequences. It affects research funding, physician awareness, insurance coverage, and how seriously patients are taken when they describe their symptoms. As diagnostic awareness improves and more population-level studies are conducted, the gap between the old 1-in-5,000 estimate and the actual number of affected people will likely continue to narrow.