Forms of Ehlers-Danlos Syndrome

What is Ehlers-Danlos syndrome?

Ehlers-Danlos syndrome is a group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Defects in connective tissues cause the signs and symptoms of these conditions, which range from mildly loose joints to life-threatening complications.

The various forms of Ehlers-Danlos syndrome have been classified in several different ways. Originally, 11 forms of Ehlers-Danlos syndrome were named using Roman numerals to indicate the types (type I, type II, and so on). In 1997, researchers proposed a simpler classification (the Villefranche nomenclature) that reduced the number of types to six and gave them descriptive names based on their major features. In 2017, the classification was updated to include rare forms of Ehlers-Danlos syndrome that were discovered more recently. The 2017 classification describes 13 types of Ehlers-Danlos syndrome.

What are overall symptoms of EDS?

An unusually large range of joint movement (hypermobility) occurs in most forms of Ehlers-Danlos syndrome, and it is a hallmark feature of the hypermobile type. Infants and children with hypermobility often have weak muscle tone (hypotonia), which can delay the development of motor skills such as sitting, standing, and walking. The loose joints are unstable and prone to dislocation and chronic pain. In the arthrochalasia type of Ehlers-Danlos syndrome, infants have hypermobility and dislocations of both hips at birth.

 

Many people with the Ehlers-Danlos syndromes have soft, velvety skin that is highly stretchy (elastic) and fragile. Affected individuals tend to bruise easily, and some types of the condition also cause abnormal scarring. People with the classical form of Ehlers-Danlos syndrome experience wounds that split open with little bleeding and leave scars that widen over time to create characteristic "cigarette paper" scars. The dermatosparaxis type of the disorder is characterized by loose skin that sags and wrinkles, and extra (redundant) folds of skin may be present.

Some forms of Ehlers-Danlos syndrome, notably the vascular type and to a lesser extent the kyphoscoliotic, classical, and classical-like types, can cause unpredictable tearing (rupture) of blood vessels, leading to internal bleeding and other potentially life-threatening complications. The vascular type of Ehlers-Danlos syndrome is also associated with an increased risk of organ rupture, including tearing of the intestine and rupture of the uterus during pregnancy.

Other types of Ehlers-Danlos syndrome have additional signs and symptoms. The cardiac-valvular type causes severe problems with the valves that control the movement of blood through the heart. People with the kyphoscoliotic type experience severe curvature of the spine that worsens over time and can interfere with breathing by restricting lung expansion. A type of Ehlers-Danlos syndrome called brittle cornea syndrome is characterized by thinness of the clear covering of the eye (the cornea) and other eye abnormalities. The spondylodysplastic type features short stature and skeletal abnormalities such as abnormally curved (bowed) limbs. Abnormalities of muscles, including hypotonia and permanently bent joints (contractures), are among the characteristic signs of the musculocontractural and myopathic forms of Ehlers-Danlos syndrome. The periodontal type causes abnormalities of the teeth and gums.

What is the overall frequency of EDS?

The combined prevalence of all types of Ehlers-Danlos syndrome appears to be at least 1 in 5,000 individuals worldwide. The hypermobile and classical forms are most common; the hypermobile type may affect as many as 1 in 5,000 to 20,000 people, while the classical type probably occurs in 1 in 20,000 to 40,000 people. Other forms of Ehlers-Danlos syndrome are rare, often with only a few cases or affected families described in the medical literature.

Sources

1. NIH: U.S. National Library of Medicine

  • The above information is from the National Institute of Health.  Click on the link above to be taken to the source.

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