Article: Ehlers-Danlos syndrome

What is Ehlers-Danlos syndrome?

Ehlers-Danlos syndrome is a group of disorders that affect connective tissue, the tissue that supports skin, bones, tendons, ligaments, blood vessels, and other organs. Defects in connective tissue cause the signs and symptoms of Ehlers-Danlos syndrome, which vary from mildly loose joints to life-threatening complications.

Genetic changes are related to the following types of Ehlers-Danlos syndrome.

• Ehlers-Danlos syndrome, arthrochalasia type
• Ehlers-Danlos syndrome, classical type
• Ehlers-Danlos syndrome, dermatosparaxis type
• Ehlers-Danlos syndrome, hypermobility type
• Ehlers-Danlos syndrome, kyphoscoliosis type
• Ehlers-Danlos syndrome, vascular type

In the past, there were more than 10 recognized types of Ehlers-Danlos syndrome. In 1997, researchers proposed a simpler classification that reduced the number of major types to six and gave them descriptive names. These six major types are listed above. Other types of the condition may exist, but they have been reported only in single families or are not well characterized.

Although all types of Ehlers-Danlos syndrome affect the joints and many also affect the skin, features vary by type. An unusually large range of joint movement, called hypermobility, is characteristic of several forms of Ehlers-Danlos syndrome, particularly the hypermobility type. Joints are unstable and prone to dislocation, chronic pain, and early-onset arthritis. Many people with Ehlers-Danlos syndrome also have soft, velvety skin that is highly elastic (stretchy) and fragile. Some forms of Ehlers-Danlos syndrome, notably the vascular type, can involve serious and potentially life-threatening complications. Blood vessels and organs can tear (rupture) unpredictably, causing acute pain, internal bleeding, and shock.

How common is Ehlers-Danlos syndrome?

The overall prevalence of all types of Ehlers-Danlos syndrome may be about 1 in 5,000 births worldwide. The prevalence of the six types differs dramatically. The most common are the hypermobile forms (the classical and hypermobility types). Other forms are very rare. For example, fewer than 10 infants and children with the dermatosparaxis type have been described worldwide.

What genes are related to Ehlers-Danlos syndrome?

Mutations in the ADAMTS2, COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, PLOD1, and TNXB genes cause Ehlers-Danlos syndrome.

Mutations in these genes usually alter the structure, production, or processing of collagen or proteins that interact with collagen. Collagen provides structure and strength to connective tissue throughout the body. A defect in collagen can weaken connective tissue in the skin, bones, blood vessels, and organs, resulting in the features of the disorder.

How do people inherit Ehlers-Danlos syndrome?

Inheritance patterns depend on the type of Ehlers-Danlos syndrome. Some forms of the condition are inherited in an autosomal dominant pattern, which means only one of the two copies of the gene in question must be altered to cause the disorder. Other types are inherited in an autosomal recessive pattern, which means both copies of the gene must be altered for a person to be affected by the condition. Please refer to the summary for each type of Ehlers-Danlos syndrome for a discussion of its inheritance pattern.