Article: Ehlers-Danlos syndrome, arthrochalasia type

What is Ehlers-Danlos syndrome, arthrochalasia type?

Ehlers-Danlos syndrome is a group of inherited disorders that affect connective tissue, the tissue that binds and supports the body's muscles, ligaments, organs, and skin. The arthrochalasia type is characterized by very loose joints and dislocations involving both hips. This type of Ehlers-Danlos syndrome combines the types formerly called VIIA and VIIB.

Ehlers-Danlos syndrome, arthrochalasia type is a subtype of Ehlers-Danlos syndrome.

This form of Ehlers-Danlos syndrome mainly affects the joints and skin. Infants are born with dislocations of both hips and an unusually large range of joint movement (called hypermobility). Hypermobility causes both large and small joints to be unstable and to dislocate frequently. Infants with hypermobile joints often appear to have weak muscle tone, which can make them seem "floppy." Hypermobile joints can delay the development of motor skills such as standing and walking. People with the disorder have soft, velvety skin that is moderately stretchy, fragile, and prone to bruising but does not usually scar abnormally. Other symptoms include early-onset arthritis and an increased risk of bone loss and fracture.

How common is Ehlers-Danlos syndrome, arthrochalasia type?

This condition is very rare; about 30 cases have been reported worldwide.

What genes are related to Ehlers-Danlos syndrome, arthrochalasia type?

Mutations in the COL1A1 and COL1A2 genes cause Ehlers-Danlos syndrome, arthrochalasia type.

The proteins made by these genes are used to assemble larger molecules called type I collagens. Collagens provide structure and strength to connective tissue throughout the body. A mutation in the COL1A1 or COL1A2 gene alters the structure and processing of type I collagen. As a result, collagen fibrils cannot be assembled properly. This defect weakens connective tissue in the skin, bones, and other tissues, resulting in the signs and symptoms of the condition.

How do people inherit Ehlers-Danlos syndrome, arthrochalasia type?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder. Most cases occur in people with no history of the disorder in their family. These sporadic cases appear to be caused by new mutations in the COL1A1 or COL1A2 gene. A few cases are inherited from a parent who has the condition.


Source: Genetics Home Reference
Cache Date: April 13, 2005

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