What Is Ehlers-Danlos Syndrome?

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Reference Article: Facts about Ehlers-Danlos syndrome.

A woman with Ehlers-Danlos syndrome has the palms of her hands touching and pointed up, behind her back, between her shoulder blades.
People with Ehlers-Danlos syndrome may have increased joint mobility as one of their symptoms. (Image credit: Shutterstock)

Ehlers-Danlos syndrome (EDS) is a rare condition that appears in at least 1 in 5,000 people worldwide, according to the National Institutes of Health (NIH) Genetics Home Reference. More people became aware of the syndrome in October 2019 when famous singer-songwriter Sia revealed in a series of tweets that she has EDS. Others with EDS responded in droves online, often referring to those in their community as "zebras." 

According to the international Ehlers-Danlos Society, the reference to zebras is borrowed from a common expression heard in medicine: "When you hear hoofbeats behind you, don't expect to see a zebra." In other words, medical professionals are typically taught to look out for more-common ailments rather than testing for ultrarare diagnoses. Due to this approach, people with EDS and related disorders can sometimes be left in the lurch, hunting for explanations about their health that few doctors can readily provide. 

The EDS community adopted the zebra as its mascot because "sometimes when you hear hoofbeats, it really is a zebra." In this spirit, The Ehlers-Danlos Society includes patients, caregivers, health care professionals and supporters working "towards a time when a medical professional immediately recognizes someone with an Ehlers-Danlos syndrome." 

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What causes Ehlers-Danlos syndrome?

EDS disrupts the integrity of connective tissues in the body that normally support the skin, bones and blood vessels, as well as many muscles, according to the NIH. The condition may range from mildly bothersome to potentially life-threatening. Although the syndrome manifests differently in different people, many patients with EDS display a large range of joint movement, known as hypermobility; poor muscle tone; and loose, velvety skin prone to bruising and scarring. 

These symptoms are not universal. As of 2017, a diagnostic manual titled "The International Classification for the Ehlers-Danlos Syndromes" characterized 13 distinct forms of EDS, each with its own array of defining features and underlying causes, according to the National Organization for Rare Disorders (NORD). Many of these forms share characteristics, such as unstable joints or fragile heart valves and blood vessels, but specific traits may be unique to particular subtypes, according to the Hypermobility Syndromes Association. 

Despite their wide variation, most forms of EDS appear to stem from related genetic mutations, according to NORD. Some of the affected genes contain instructions for building collagen, a fibrous protein that strengthens connective tissues throughout the body and comes in a variety of subtypes. Other genes help determine how the body processes collagen and how other structures interact with the protein, and these genes may also have functions beyond those related to connective tissue, according to the NIH. 

Mutations related to EDS can be passed from parent to child either as a dominant trait, meaning the child needs to inherit only one copy of the mutated gene to develop the syndrome, or as a recessive trait, which means one mutated gene must be inherited from each parent. Occasionally, the mutation may not be picked up from either parent but instead occurs spontaneously in an egg or sperm cell. According to NORD, specific genetic tests can help families determine how the syndrome manifests among their relatives. 

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In all, 19 genes appear to be associated with 12 different forms of the syndrome. The only subtype without a gene mutation associated with it yet is the hypermobile EDS subtype, also known as hEDS, according to the Hypermobility Syndromes Association. 

Diagnosis and treatment 

Physicians typically diagnose EDS based on patient history, clinical examinations and genetic testing, according to NORD. 

Doctors can evaluate how extensible the skin is by gently pulling at it, and they may determine how mobile a patient's joints are based on a measure called the Beighton scale. Imaging tests, including CT, MRI and X-ray scans, can help doctors spot structural abnormalities in heart valves, blood vessels, bones and other tissues. Doctors may also take tissue samples to examine collagen structure more closely. Genetic tests help doctors to determine which specific subtype of EDS a patient may have. The Ehlers-Danlos Society has a free, handy checklist of criteria to review for an EDS diagnosis. 

Related: 7 Diseases You Can Learn About from a Genetic Test

Although there is no cure for EDS, doctors often prescribe medications to help patients cope with troublesome symptoms, according to the Mayo Clinic. Depending on the subtype, these drugs may include those for pain relief or blood-pressure control. Physical therapy may be recommended to help strengthen muscles and stabilize joints that may otherwise dislocate. EDS patients sometimes need surgery to repair joints that dislocate repeatedly, as well as ruptured blood vessels and organs in certain subtypes. Screening for hypertension and arterial disease should be done regularly after diagnosis, adds NORD. 

Physicians recommend that patients with EDS avoid contact sports, weightlifting and other physical activities that could place those individuals at risk of injury, particularly to the joints, according to the Mayo Clinic. Exercises like walking, swimming, doing tai chi and using a stationary bike are good options for staying active while minimizing stress on the body. Depending on symptom severity, doctors may recommend that patients stay away from difficult-to-chew foods, as these may injure the jaw, and playing musical instruments that may put strain on the lungs, such as reeded wind or brass instruments. 

EDS patients, particularly children, can greatly benefit from a supportive network of family and friends who understand their condition, the Mayo Clinic adds. Emotional support, advice and educational materials can also be found in online communities, as summarized by The Ehlers-Danlos Society.

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Nicoletta Lanese
Nicoletta Lanese
Channel Editor, Health

Nicoletta Lanese is the health channel editor at Live Science and was previously a news editor and staff writer at the site. She holds a graduate certificate in science communication from UC Santa Cruz and degrees in neuroscience and dance from the University of Florida. Her work has appeared in The Scientist, Science News, the Mercury News, Mongabay and Stanford Medicine Magazine, among other outlets. Based in NYC, she also remains heavily involved in dance and performs in local choreographers' work.