There are six types of Ehlers-Danlos syndrome (EDS): three major types and three rarer ones. Hypermobility, classical, and vascular are the most common, while kyphoscoliosis, arthrochalasis, and dermatosparaxis are so rare that less than 100 cases of each have been reported. Originally, researchers recognized 10 types of Ehlers-Danlos syndrome, but the simpler classification of six was introduced in 1997. It is possible that more than the six recognized types of Ehlers-Danlos syndrome exist, but these types have been found in specific families only and are not well defined or understood.
The most common of the six types of Ehlers-Danlos syndrome is hypermobility, formerly type III. Approximately one in 10,000 to 15,000 people are affected by this type of EDS. Typical symptoms include loose and unstable joints, muscle fatigue, and easy bruising. Joint instability causes frequent dislocation that can lead to chronic degenerative joint disease and premature osteoarthritis. Being double-jointed is not necessarily the same as having this type of EDS.
The classical type of EDS was formerly classified as types I and II and affects around one in 10,000 to 20,000 people. Loose joints and muscle fatigue are also found in these patients, but the distinguishing symptoms are related to skin. The skin is extremely elastic and fragile. The patient will bruise and scar easily, heal slowly from wounds, and have extra folds of skin in areas like the eyelids. Fatty deposits are common on the forearms and shins, while elbows and knees will develop fibrous growths.
The least common of the major types of Ehlers-Danlos syndrome is the vascular type, formerly type IV. Although it is rare, affecting about one in 100,000 to 200,000 people, it is one of the most serious types because it impacts blood vessels and organs. Blood vessels and organs are fragile and rupture easily. The skin is almost translucent, and the face typically has a characteristic appearance of protruding eyes, sunken cheeks, and a thin nose and lips. Many of these patients may develop a collapsed lung and heart valve problems.
The three remaining types of Ehlers-Danlos syndrome are extremely rare, affecting less than 100 people each. Kyphoscoliosis is characterized by severe scoliosis and fragile ocular globes. Arthrochalsia patients will be short and severely restricted by loose joints and resulting dislocations. Signs of dermatosparaxis are very fragile and sagging skin. Additional possible types have primarily been found in individual families and have yet to be fully defined.
Although the six types of Ehlers-Danlos syndrome are well defined, individual cases frequently defy categorization. There can be an overlap of certain symptoms that leads to a delay in diagnosis or to misdiagnosis. Treatment is largely limited to relief of symptoms, because as of 2011 there is no cure for this syndrome. Individuals with EDS who plan on having children should consult with a genetic counselor prior to conceiving.
The type of EDS can determine a patient’s prognosis and outlook. The severity of symptoms varies significantly across types of Ehlers-Danlos syndrome. Although the majority of patients can expect to live a normal lifespan, some will have mild symptoms while others will be severely restricted. EDS is a lifelong problem, but the fear of pain and degeneration can be as great or greater a burden than the physical symptoms.