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.