What are Ehlers-Danlos Syndromes (EDS) and Hypermobility Spectrum Disorders?

Ehlers-Danlos syndromes are a group of connective tissue disorders that can be inherited and are varied both in how affect the body and in their genetic causes. They are generally characterized by joint hypermobility (joints that stretch further than normal), skin hyperextensibility (skin that can be stretched further than normal), and tissue fragility. (For information about the hypermobility spectrum disorders, please visit “About HSD”.)

The Ehlers-Danlos syndromes (EDS) are currently classified into thirteen subtypes. Each EDS subtype has a set of clinical criteria that help guide diagnosis; a patient’s physical signs and symptoms will be matched up to the major and minor criteria to identify the subtype that is the most complete fit. There is substantial symptom overlap between the EDS subtypes and the other connective tissue disorders including hypermobility spectrum disorders, as well as a lot of variability, so a definitive diagnosis for all the EDS subtypes when the gene mutation is known—all but hypermobile EDS (hEDS)—also calls for confirmation by testing to identify the responsible variant for the gene affected in each subtype.

For those who meet the minimal clinical requirements for an EDS subtype—but who have no access to molecular confirmation; or whose genetic testing shows one (or more) gene variants of uncertain significance in the genes identified for one of the EDS subtypes; or in whom no causative variants are identified in any of the EDS-subtype-specific genes—a “provisional clinical diagnosis” of an EDS subtype can be made. These patients should be followed clinically, but alternative diagnoses and expanded molecular testing should be considered. 

Please remember that an individual’s experience with an EDS is their own, and may not necessarily be the same as another person’s experience. Diagnostic criteria are meant solely to distinguish an EDS from other connective tissue disorders, and there are many more possible symptoms for each EDS than there are criteria.

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What are the symptoms of Ehlers-Danlos Syndrome?

Clinical manifestations of Ehlers-Danlos Syndrome are most often joint and skin related and may include:

Joints

Joint hypermobility; loose/unstable joints which are prone to frequent dislocations and/or subluxations; joint pain; hyperextensible joints (they move beyond the joint’s normal range); early onset of osteoarthritis.

Skin

Soft velvety-like skin; variable skin hyper-extensibility; fragile skin that tears or bruises easily (bruising may be severe); severe scarring; slow and poor wound healing; development of molluscoid pseudo tumors (fleshy lesions associated with scars over pressure areas).

Miscellaneous/Less Common

Chronic, early onset, debilitating musculoskeletal pain (usually associated with the Hypermobility Type); arterial/intestinal/uterine fragility or rupture (usually associated with the Vascular Type); scoliosis at birth and scleral fragility (associated with the Kyphoscoliosis Type); poor muscle tone (associated with the Arthrochalasia Type); mitral valve prolapse; and gum disease.

Each type of Ehlers-Danlos Syndrome is defined as a distinct problem in making or using one of the types of collagen. Collagen is what the body uses to provide strength and elasticity to tissue; normal collagen is a strong protein that allows tissue to be stretched but not beyond its limit, and then safely returns that tissue to normal. Collagen is found throughout the body, and Ehlers-Danlos Syndrome is a structural problem. An analogy: If one builds a house with bad materials, with cheap nails or only half the wood required, problems will arise. Some problems are more likely to show up than others, but because the bad or missing materials are everywhere and not necessarily visible, one can be surprised where some problems occur.

It is much the same thing with Ehlers-Danlos Syndrome and collagen. The collagen with which a person with Ehlers-Danlos Syndrome is built is not structured the way it should be, or only part of it is produced. With a badly built or processed collagen, the tissue that relies on it can be pulled beyond normal limits and thus be damaged. Collagen is the most abundant protein in the body and types of collagen can be found almost anywhere: in skin, muscles, tendons and ligaments, blood vessels, organs, gums, eyes, and so on.

The problems resulting from one’s body being built out of a protein that behaves unreliably can be widespread and in a wide range of severity. It shows up in places that seem unrelated until the underlying connection to Ehlers-Danlos Syndrome is recognized.

What are the types of Ehlers-Danlos Syndrome?

There are six defined types of Ehlers-Danlos Syndrome, as well as a number of mutations identified as Ehlers-Danlos Syndrome that fall outside the current system. The major types of Ehlers-Danlos Syndrome are classified according to the signs and symptoms that are manifested. Each type of Ehlers-Danlos Syndrome is a distinct disorder that “runs true” in a family. An individual with Vascular Type Ehlers-Danlos Syndrome will not have a child with Classical Type Ehlers-Danlos Syndrome. Learn more about the different types of Ehlers-Danlos Syndrome.

How is Ehlers-Danlos Syndrome diagnosed?

In 1997, a nosology was written at the Villefranche International Conference that refined the types of Ehlers-Danlos Syndrome into the current six major types. Each type has a set of major diagnostic criteria and of minor diagnostic criteria. Traditional diagnosis of Ehlers-Danlos Syndrome consists of family history and clinical evaluation to assess the diagnostic criteria. Genetic testing is available for most types of Ehlers-Danlos Syndrome, although not for the most common type, Hypermobility. The tests vary in accuracy; in most instances genetic testing should be used conservatively to confirm an Ehlers-Danlos Syndrome type diagnosis rather than to rule one out.

How prevalent is Ehlers-Danlos Syndrome?

At this time, research statistics of Ehlers-Danlos Syndrome show the prevalence as 1 in 2,500 to 1 in 5,000 people. Recent clinical experience suggests Ehlers-Danlos Syndrome is more common. The condition is known to affect both males and females of all racial and ethnic backgrounds.

How is Ehlers-Danlos Syndrome inherited?

The two known inheritance patterns for Ehlers-Danlos Syndrome include autosomal dominant and autosomal recessive Regardless of the inheritance pattern, we have no choice in which genes we pass on to our children.

What is the prognosis of someone with Ehlers-Danlos Syndrome?

The prognosis depends on the type of Ehlers-Danlos Syndrome and the individual. Life expectancy can be shortened for those with the Vascular Type of Ehlers-Danlos Syndrome due to the possibility of organ and vessel rupture. Life expectancy is usually not affected in the other types. There can be a wide or narrow range of severity within a family, but each person’s case of Ehlers-Danlos Syndrome will be unique. While there is no cure for Ehlers-Danlos Syndrome, there is treatment for symptoms, and there are preventative measures that are helpful for most.

What can I do now?

Ehlers-Danlos Society members are sharing information online and learning from each other in ways that were impossible not very long ago. Visit Ehlers-Danlos Society’s Facebook page, the Ehlers-Danlos Society Inspire Online Community, or look through the Resource Guides.