What is Ehlers-Danlos Syndrome?

EDS is a heterogenous group of genetic disorders that cause defects in one or more gene that code(s) for different types of collagen proteins. Collagen is responsible for providing strength and adhesion to the body's tissues. Some types of EDS are inherited in an autosomal dominant manner. In these cases, each child of one affected parent has a 50% chance of inheriting EDS. Other types of EDS are inherited in an autosomal recessive manner, where a child has a chance of being affected only if both parents are either affected themselves or are carriers. On rare occasions, spontaneous mutations due occur, where neither parent is affected or a carrier.

EDS is a group of connective tissue disorders, each type of EDS has its own estimated prevalence. The prevalence of the entire group of EDS is currently estimated to be 1 in 5,000 births, with no racial nor sexual predisposition. The most prevalent type of EDS is suspected to be Type 3, also known as the Hypermobility Type.  The lack of awareness and knowledge by the medical community is contributing to misdiagnosis. Due to the lack of invested research, testing for EDS is limited; although, some types can be tested for via blood work. Others (like EDS Type 3) require a clinical diagnosis, confirmed by a knowledgable geneticist. 

Terms:

EDS: stands for Ehlers-Danlos Syndrome

EDSer: term used to describe an individual diagnosed with EDS

Zebra: the zebra represents ALL RARE CONDITIONS as a result of the overuse of the medical zebra aphorism. In order to distinguish EDS from other rare conditions, the EDS community has adopted the Turquoise Zebra to represent EDS. 

Collagen: main component of connective tissues and the most abundant protein in our bodies.

Click Here to learn more about collagen. 

Connective Tissues: the structural portions of our body that essentially hold the cells of the body together. These tissues form a framework, or matrix, for the body. The connective tissues are composed of two major structural protein molecules, collagen and elastin. There are many different types of collagen protein that vary in amount in each of the body's tissues. Elastin has the capability of stretching and returning to its original length, like a spring or rubber band. Elastin is the major component of ligaments (tissues that attach bone to bone) and skin. In patients with connective tissue diseases, it is common for collagen and elastin to become injured by inflammation. Diseases in which inflammation of collagen tends to occur are also referred to as collagen diseases. 

Connective Tissue Disorders: connective tissue makes up a variety of physical structures including tendons and the connective framework of fibers in muscles, capsules and ligaments around joints, cartilage bone, adipose tissue, blood and lymphatic tissue. Connective tissues are composed of two major structural protein molecules: collagen and elastin. There are many different types of collagen proteins in each of the body's tissues. In some patients with connective tissue disorders, the collagen proteins have acquired mutations within its genetic make-up, resulting in collagen proteins that do not function properly. Due to the vast variety of collagen proteins throughout the body, connective tissue disorders affect individuals differently. Some affected sites specific to EDS include: joints, heart valves, organ walls, arterial walls, skin and the lungs.

How is EDS classified?

Up to 1967, the classification of EDS only covered those symptoms dealing with fragile skin, but by 1986 it had been divided into 11 distinct types covering a wide range of varying symptoms. Later, in 1997, these were further simplified into 6 major types. These types include: Classical, Hypermobility, Vascular, Kyphoscioliosis, Arthrochalasia, and Dermatosparaxis. 

Note: the severity of symptoms varies enormously amongst those afflicted.

The classic type of EDS has the hallmark skin hyperextensibility, joint hypermobility, and easy bruisability, along with fragile and velvety soft skin and delayed wound healing with exaggerated scar formation. This latter feature can be especially problematic after surgery, when skin cannot adequately hold stitches.

Hypermobility typeEDS is so called because of the extreme joint hypermobility it causes; skin manifestations tend to be less severe. Joint instability and chronic musculokeletal pain has been reported to be more prominent in this type however. 

Vascular type EDS is the only type that has been reported to reduce lifespan. Joint hypermobility and skin hyperextensibility are unusual, but bruise-ability is striking. This type also has the very dangerous tendency for the bowel and large arteries to spontaneously rupture. This can be particularly problematic during pregnancy, when the uterus can rupture as well. Roughly one quarter of people with vascular type EDS have a serious medical complication by the time they are twenty, and 80% of them have a problem by the time they hit forty. These complications usually include the rupture of an artery of organ or spontaneous bowel perforation.

Kyphoscoliosis type EDS yields a curved spine and extremely weak muscle tone.

Arthrochalasia typeEDS causes severely loose joint culminating in the dislocation of both hips; and Dermatosparaxis type EDS is characterized by very saggy and fragile skin. These types are exceedingly more rare than the other types of EDS.

Note: Infants with EDS often appear to have weak muscle tone, which can delay the development of motor skills such as sitting, standing, and walking. The loose joints are unstable and prone to dislocation, chronic pain, and early-onset arthritis. Dislocations involving both hips are a characteristic finding in infants with the arthrochalasia type of EDS