Ehlers-Danlos syndrome (EDS) refers to a group of related genetic diseases that affect connective tissues. Its symptoms vary depending on the type and severity of the disease, ranging from very mild to life-threatening. Most EDS patients have joint hypermobility, meaning they can easily be dislocated.
What is disease prevalence?
Disease prevalence is an estimate of the frequency of cases recorded in a given population. This estimate is affected by the disease in question. For example, some genetic diseases only occur in small populations within a particular country or region. Some might be so rare that they may only be seen in a single family.
While the number of cases for every 1 million people are often reported worldwide, it would be disingenuous to do so for rare diseases.
How prevalent is EDS?
The prevalence of EDS differs by type of disease.
Hypermobile EDS is thought to affect between 1 in 5,000 and 1 in 20,000 individuals. The classical type is more rare, thought to affect between 1 in 20,000 and 1 in 40,000 individuals. Classical-like EDS is difficult to distinguish in medical literature reporting from the classical type, and so may also occur in roughly 1 in 20,000 to 1 in 40,000 people.
Other types of EDS are very rare, with only a few cases reported worldwide. Dermatosparaxis EDS is an example of an extremely rare type of EDS, with only a few cases recorded in medical literature. Vascular EDS is reported to have a prevalence of 1 in 100,000 individuals, and cardiac-valvular EDS a prevalence of less than 1 in a million people.
Kyphoscoliotic EDS has primarily been reported in areas of Greece, Turkey, and the Middle East. The precise prevalence of this type of EDS is not known, but the frequency of carriers (people who have one copy of a disease-causing mutation, but show no symptoms) is estimated to be 1 in 150 people in this study, last revised in 2018.
Brittle cornea syndrome also seems to be especially prevalent in the Middle East, with a small number of families being affected. The worldwide prevalence of this type is not known.
Musculocontractural EDS is also very rare and is thought to affect less than 1 in a million people worldwide, as is myopathic EDS.
Spondylodysplastic EDS has an unknown prevalence.
The combined prevalence of the different types of EDS is thought to be around 1 in 5,000 people worldwide.
New studies on prevalence
A study published in the British Medical Journal in 2019 examined the number of reported hypermobile EDS cases in Wales.
The study searched medical records for diagnoses, and found 1 in 500 medical cases between June 1990 and July 2017 with either hypermobile EDS or another type of EDS. The researchers concluded that hypermobile EDS is more common than has been previously reported, and in fact, may not be a rare disease at all.
The study also noted more patients being diagnosed in the most recent years examined, indicating that physicians are getting better at detecting EDS, especially its milder forms, which in previous decades might have gone undiagnosed. However, the Ehlers-Danlos Society, in response to the study, cautioned that its finding may not be predictive of how common EDS is worldwide.
Both groups suggest that more in-depth studies be performed, allowing for a better estimate of the worldwide prevalence of EDS.
Last updated: Feb. 13, 2020
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