A: You are correct; Marfan's syndrome (MFS) and Ehler-Danlos syndrome (EDS) have many similarities.
Like MFS, EDS is a disease of the connective tissues. As I noted in my column on MFS, connective tissues are responsible for holding the body together, as well as helping to supply nutrition and take away waste from the cells. Since MFS and EDS are both diseases of the connective tissues, it is not surprising that the clinical manifestations of these diseases have many overlapping characteristics.
Although I was taught that EDS is a very rare disease, with an incidence of only 1 in 400,000 people, the many different variants of EDS are very underdiagnosed, and the overall prevalence of EDS is probably closer to 1 in 5,000 people.
Like MFS, EDS is an inherited disease. There are many different possible gene mutations responsible for EDS, and there are at least 10 different subtypes of EDS that have been noted. EDS gene mutations are distinct from the gene mutations responsible for MFS, so EDS is a different disease than MFS. The specific differences in the gene mutations responsible for subtypes of EDS cause variations in their clinical manifestations as well as differences in their inheritance patterns, and this information is used to help identify which subtype a patient has.
As we saw for MFS, EDS is characterized by problems that arise from defects in the body's connective tissues. Common to patients with EDS are skin changes, with their skin usually being velvety soft and doughy white with the underlying blood vessels easily seen. The skin is usually very elastic, and can stretch quite a bit. Most EDS patients also have hyper-mobility of their joints, especially their fingers. The skin changes and the hyper-extensible joints are the common physical findings that suggest a diagnosis of EDS.
The most common subtype, type I, is a severe form of EDS with marked stretchability of the skin and pronounced hyper-mobility of the joints. This can cause the joints to dislocate very easily. As I noted above, EDS is an under-diagnosed condition, and type I may be diagnosed more often due to the pronounced clinical manifestations, so it may be that it is actually not the most common form.
Type IV EDS is also called the "arterial form" of EDS, due to the pronounced effects it has on the arteries. Patients with this subtype can have their arteries (including the aorta, as in MFS) spontaneously rupture. They can also have other internal organs spontaneously rupture, and either of these occurrences can be life-threatening, so it is not surprising that people with type IV EDS have a shortened life expectancy. Other subtypes of EDS affect other organ systems, including the eyes.
As noted above, the diagnosis of EDS is usually suspected on clinical grounds due to the patient's skin characteristics and their hyper-mobile joints. A skin biopsy to look at the chemical makeup of the connective tissue can sometimes help verify the diagnosis. The specific clinical manifestations and the inheritance pattern in a given patient can help identify which subtype they have. Although the genetics of EDS are better understood every day, there is no routine genetic test available yet to screen for this disease.
The treatment of EDS is aimed at avoiding complications of the disease and treating complications that do arise. The skin problems increase the risk of sunburns and other complications from the sun (including certain cancers), so avoiding the sun and using high-level sun block is key. Patients are also usually put on vitamin C, as this may benefit the connective tissues. Avoiding certain activities to prevent joint dislocations, and avoiding contact sports for EDS patients with certain subtypes (such as type IV), is part of a patient's preventative treatment. Although surgery may be required to prevent recurrent joint dislocations (and for other complications of EDS, including catastrophic artery or organ rupture), surgery is often riskier for the EDS patient since the skin problems can inhibit proper healing, increasing post-operative complications.
Patients with EDS should receive genetic counseling to understand the possibility that they will pass the disease on to their children, and they should be educated about possible complications of the subtype of disease they have to minimize potential problems.
More research is needed on this under-diagnosed disease. EDS is much more common than we used to think, and so increased public awareness of this disease is needed.
Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.
