What is EDS?

Ehlers-Danlos Syndrome (EDS) is not one condition — it is a group of thirteen heritable connective tissue disorders, all of which share a common thread: something has gone wrong with collagen. Collagen is the structural protein that holds the body together. It is found in skin, joints, ligaments, tendons, blood vessel walls, and organs. When collagen is faulty — either because of how it is produced, processed, or what type is made — the structures it supports become fragile, stretchy, or unstable in ways that cause real, often severe, and frequently invisible suffering.

The thirteen subtypes of EDS are each distinct conditions with different genetic causes, different clinical presentations, and different implications. Classical EDS (cEDS) is caused by mutations in COL5A1 or COL5A2 genes and produces fragile, stretchy skin and significant joint hypermobility. Vascular EDS (vEDS) is caused by mutations in COL3A1 and is the most life-threatening subtype — arterial and organ rupture are genuine risks, and many patients do not survive past middle age. Kyphoscoliotic EDS (kEDS), Dermatosparaxis EDS (dEDS), and others each have known genetic markers that can be confirmed by targeted testing.

The most common subtype — hypermobile EDS (hEDS) — affects the majority of EDS patients and is, paradoxically, the only subtype without a confirmed genetic marker as of 2024. This is not because the genetic cause does not exist; researchers believe it does. It is because the genetics of hEDS are almost certainly polygenic and complex, and the research required to characterise it fully has been chronically underfunded. The diagnostic criteria for hEDS were revised in 2017 specifically to improve accuracy and reduce over-diagnosis, and they rely on clinical assessment of joint hypermobility, skin findings, family history, and the exclusion of other diagnoses.

EDS is estimated to affect between 1 in 2,500 and 1 in 5,000 people for the rarer subtypes, while hEDS may affect as many as 1 in 500. It is not rare in the way some conditions are rare — it is underdiagnosed, and for reasons we will explore in the next lesson, that underdiagnosis can span years or even decades. EDS affects all sexes, all ethnicities, and all ages. It is not a childhood condition that resolves — it is a lifelong condition that requires lifelong management.

One important point about EDS and the broader community: many people with EDS also meet criteria for hypermobile spectrum disorder (HSD), a related but distinct diagnosis for those who have symptomatic hypermobility without meeting the full hEDS criteria. HSD is not a lesser diagnosis — its impact on quality of life is comparable, and both conditions benefit from the same management approaches.