Ehlers-Danlos syndrome (EDS) is the name given to a group of related genetic disorders that affect the connective tissue. While the symptoms of the different EDS types overlap, classical EDS (cEDS) is characterized by skin hyperextensibility, atrophic or indented scars, and joint hypermobility.
It is thought to affect about 1 in 20,000 people, but those with milder forms of the disease may go undiagnosed.
What causes cEDS?
cEDS is usually caused by mutations in either the COL5A1 or COL5A2 genes. In rare cases, it may be due to mutations in the COL1A1 gene. These genes provide instructions, or blueprints for cells to make pieces of collagen type 5 and collagen type 1. Mutations in these genes mean that collagen type 1 and 5 are made incorrectly, or not at all.
Collagen is an important component of the connective tissue that gives shape to muscles and joints, holds organs together, and provides structure to the skin. In cEDS, the connective tissue is weak and easily damaged, causing the disease symptoms.
How is cEDS inherited?
In most people, cEDS is inherited from the parents. But some cases do occur due to new mutations in people with no family history of the disease.
When inherited from the parents, cEDS is passed on in an autosomal dominant manner, meaning that a mutation in one of the two copies of the disease-causing gene is sufficient to cause the disorder. So, if one parent has cEDS and the other does not, the child will have a 1-in-2 chance of developing cEDS. If both parents have cEDS — called an autosomal recessive inheritance pattern — their child will have a 3-in-4 chance of inheriting one or more copies of the mutation and developing cEDS.
What are the symptoms of cEDS?
People with cEDS have soft, velvety skin that is more elastic than normal. They bruise easily and their wounds do not heal properly, since their scar tissue is fragile and easily damaged.
Many patients with cEDS have hypermobile joints — meaning they can bend their joints further than normal. This may lead to frequent joint dislocations.
Muscle weakness (hypotonia) also may occur in people with cEDS, which can cause delayed motor development during childhood.
Some patients may have heart abnormalities caused by tissue weakness in the chambers, or valves of the heart. Spontaneous pneumothorax, or collapsed lung, also has been reported in some people with cEDS.
Pregnancy carries an increased risk for women with cEDS, as the fragile connective tissue may cause premature rupture of the amniotic sac that surrounds the fetus.
How is cEDS diagnosed?
cEDS is diagnosed with a physical examination that includes an assessment of hypermobility of the joints, using a system called Beighton scoring. The angle to which patients can bend their joints without pain is measured for each joint. Each joint that can be bent more than normal gives a certain score, and the combined score is used as a measure of hypermobility.
To confirm a diagnosis of cEDS, the physician will order a genetic test. For the test, a small sample of blood will be drawn from the patient. That sample will be sent to a laboratory to be examined any mutations in the genes associated with cEDS. Genetic test results may take four to six weeks to become available. Based on the results, the doctor may ask for additional tests to check for any complications that are common in cEDS, such as those affecting heart function, for example.
How is cEDS treated?
There currently is no cure for cEDS, though there are treatments for some of its symptoms.
Patients may need to undergo physiotherapy to strengthen their muscles and reduce the frequency of joint dislocations. Surgery may be needed for some people with cEDS to correct problems like hernias, prolapse, or dislocated joints.
It is advised that people with cEDS avoid sports that require joint strain, and medications that contain aspirin.
Last updated: Oct. 22, 2019
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