Ehlers-Danlos Syndrome
Medical Author: William C. Shiel Jr., MD, FACP, FACR
Medical Editor: Melissa Conrad Stöppler, MD
What is Ehlers-Danlos syndrome?
Ehlers-Danlos syndromes are a group of disorders which share common
features including easy bruising, joint hypermobility (loose joints),
skin that stretches easily (skin hyperelasticity or laxity), and weakness of tissues.
The Ehlers-Danlos syndromes are inherited in the genes that are passed from parents to offspring. They are
categorized according to the form of genetic transmission into different types with many
features differing between patients in any given type. The fragile skin and loose joints is often a result of abnormal genes that produce abnormal proteins that
confer an inherited frailty of collagen (the normal protein "glue" of our tissues).
In 2001, researchers discovered a new form of Ehlers-Danlos syndrome that is caused by an inherited abnormality in a protein other than collagen that also normally
plays a role in binding together the cells of our tissues (including the skin, tendons, muscle, and blood vessels). Abnormalities in this protein, called tenascin, also lead to a form of Ehlers-Danlos syndrome. Researchers suspect that tenascin could play a role in regulating the normal distribution of collagen in the connective tissues of the body.
What are the types of Ehlers-Danlos syndromes?
Classical type
(formerly types I & II)
Marked joint hypermobility, skin
hyperextensibility (laxity), and fragility are characteristic of the classic type of Ehlers-Danlos syndrome. The smooth, velvety skin is fragile and tears or bruises easily with minor trauma. Joint dislocations and
scoliosis are common. Joint instability can lead to sprains and strains. This classical type is inherited as an autosomal dominant genetic trait (directly passed on from one parent to child).
Hypermobility type
(formerly type III)
Joint hypermobility is the major manifestation of this form of Ehlers-Danlos syndrome. Any joint can be affected, and dislocations are frequent.
This type is also inherited as an autosomal dominant genetic trait.
Vascular type
(formerly type IV, the arterial form)
In this form of Ehlers-Danlos syndrome, spontaneous rupture of arteries and bowel is a serious manifestation that can lead to death. Clubfoot can be present at birth. Skin laxity is of varying degrees. Veins can be very visible through the skin. It is primarily inherited as an autosomal dominant (directly passed on from one parent to child) genetic trait, but recessive (not seen in family members or only in one generation of members of the same family,
meaning that an individual must inherit two copies of the mutation, one from
each parent) trait inheritance has been described.
Kyphoscoliosis type
(formerly type VI)
Fragile globe of the eyes,
significant skin and joint laxity, and severe curvature of the spine
(scoliosis) are typical features. Its inheritance pattern is autosomal
recessive.
Arthrochalsia type
(formerly type VIIB, arthrochalasis multiplex congenita)
Patients are short in
height and severely affected by joint laxity and dislocations. Skin
involvement is variable. Both utosomal dominant and recessive inheritance
is possible. A skin biopsy can be used to diagnose this disorder.
Dermatosparaxis type
(formerly type VIIC)
Patients have severely fragile skin that is soft and doughy with sagging and folding. This rare form of Ehlers-Danlos syndrome can be diagnosed with a skin biopsy.
Tenascin-X deficient type
Joint hypermobility, hyperelastic skin, and fragile tissue are seen. Patients
with this type lack the multiple shrinking (atrophied) scars in the skin that
are often seen in classic Ehlers-Danlos. It is inherited as an autosomal
recessive genetic trait.
Other rare variant types have been reported in single families.
Next: How is Ehlers-Danlos diagnosed? »
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