What is Ehlers-Danlos syndrome (EDS)?
Ehlers-Danlos syndrome (EDS) is a group of genetic disorders that affect the body’s connective tissues, which are proteins that support the blood vessels, skin, bones, and other organs in the body. Connective tissues also provide elasticity and strength to the body's underlying structures.
Individuals with Ehlers-Danlos syndrome often have fragile, stretchy skin and hypermobile (extremely flexible) joints. A form of Ehlers-Danlos syndrome called vascular EDS is generally regarded as the most severe form of EDS. Vascular EDS cause the walls of the blood vessels, uterus, or intestines to break. Couples who are planning to start a family may want to consult a genetic counselor since vascular EDS can cause dangerous complications in pregnancy.
There are 13 subtypes of Ehlers-Danlos syndrome (EDS) with a set of diagnostic criteria for each subtype. Ehlers-Danlos syndromes were initially named using Roman numerals according to their designated types--e.g., type I, II, III, and so on. In 1997, the Villefranche nomenclature was proposed by researchers to reduce the number of EDS to six types. Descriptive names were also given according to the major features of each type of EDS. However, the classification of EDS was updated in 2017 to include recently discovered and rare forms of EDS. This updated classification describes 13 forms of Ehlers-Danlos syndrome.
Although each EDS subtype affects different regions of the body, all types of EDS have one thing in common, and that is hypermobility or overly flexible joints. EDS affects 1 out of 5,000 people around the world according to the U.S. National Library of Medicine's Genetics Home Reference. The most common types of EDS are hypermobility and the classic type. A rare type of EDS called dermatosparaxis only affects around 12 children worldwide.
Signs and Symptoms
Ehlers-Danlos syndromes usually affect the skin and joints, which may include:
- Hypotonia (weak muscle tone)
- Muscle pain
- Fragile skin that is soft, velvety, and highly elastic or stretchy
- Easy bruising
- Abnormal scarring
- Delicate blood vessels
- Poor wound healing
There are also specific symptoms for each type of EDS according to the National Organization for Rare Disorders (NORD). They include:
- Arthrochalasia - Delayed motor movement, hypotonia (low muscle tone), and hip dislocation at birth.
- Brittle Cornea - Severe ocular (eye or vision) problems such as corneal rupture after minor trauma, keratoconus (corneal degeneration), keratoglobus (protrusion and thinning of the cornea), and blue sclera (bluish tint or discoloration in the white parts of the eye).
- Cardiac-Valvular - Minor EDS symptoms, but may require surgery in people with severe heart defects.
- Classical - Symptoms include loose joints, stretchy skin, delicate blood vessels, and thin, discolored scars. Other symptoms may include heart valve problems and small lumps under the skin. Heart valve problems may lead to poor blood circulation and heart failure over time. A life-threatening heart condition called aortic dissection may occur in such cases.
- Classical-Like - Classical-like and classical EDS have the same signs and symptoms, but with different genetic causes.
- Dermatosparaxis - Signs and symptoms include short fingers, short height, small jaw, loose facial skin, bluish discoloration of the sclera, hernia, slow healing of wounds, increased risk of diaphragm or bladder rupture.
- Hypermobility - Chronic pain, frequent joint dislocation, bowel disorders, lightheadedness, degenerative joint disease and emotional problems.
- Kyphoscoliotic - Worsening scoliosis (spine problem) that may affect breathing and eye problems, such as loss of vision, glaucoma, nearsightedness, retinal detachment, including an increased risk of eyeball rupture.
- Musculocontractural - Eye problems, club foot, low muscle tone and strength, scoliosis, developmental delay, restricted movement of fingers, and skull or facial deformities.
- Myopathic - Loss of hearing, scoliosis, decreased muscle function and low muscle tone from birth.
- Periodontal - Early tooth loss due to teeth problems and gum disease.
- Spondylodysplastic - Short stature, developmental delay, bulging eyes with a bluish tint, tapered fingers, weak thumb muscles, and wrinkled palms.
- Vascular - This type of EDS is detected at birth because of physical deformities, such as hip dislocation and club foot. Other physical features include prominent eyes, thin lips and nose, sunken cheeks, varicose veins, and old-looking hands. People with vascular EDS also have an increased risk of headches, aneurisms, stroke, seizures, and complications in wound healing after surgery. Other potential risks are bleeding of major blood vessels and organs, such as the aorta, intestines, and the uterus.
Causes and Risk Factors
Since Ehlers-Danlos syndromes are inherited disorders, they are caused by genetic mutations. Although other types of EDS have unknown genetic causes, many EDS subtypes have genes, which can be identified through a blood test. In most cases, EDS gene mutations tend to change how collagen is used or produced in the human body.
Some EDS subtypes have a dominant pattern of inheritance, which means that a child only gets the syndrome from one parent who has the mutated gene (50-50 percent chance). The risk of having the syndrome also depends on the subtype that runs in the family.
Other types are also recessive, which means that a child needs to get a mutated gene from both parents. In this case, a child from parents with the mutated gene has a 1 in 4 chance of having EDS. There are no other known risk factors other than having a family history of EDS. EDS equally affects men and women including every race and ethnicity.
- Genetic Testing: Involves blood tests to check for any genetic mutations.
- Echocardiogram (Cardiac Ultrasound): A diagnostic test that can help doctors identify heart abnormalities.
- Skin Biopsy: Involves the collection of a skin sample to check for any abnormalities in the production of collagen.
- DNA Testing with IVF (In Vitro Fertilization): This test can help confirm if an embryo has a defective gene. It is usually done when the eggs are fertilized outside a woman's body.
However, even if EDS genes are found in a person's blood, a diagnosis can also be made based on the person's clinical signs and symptoms. An example would be the type of EDS called hypermobile EDS (hEDS), which has a genetic cause but without a specific gene identified yet. This type of EDS is usually diagnosed using a person's signs and symptoms and family history.
Ehlers-Danlos syndrome has no cure. However, treatments can help relieve its symptoms, which may also vary from one person to another. Treatments may include:
- Blood pressure medications
- Over-the-counter pain relievers (as needed)
- Prescription pain medications
- Physical therapy to rehabilitate joint and muscle instability
- Surgery or stitches to repair damaged organs, blood vessels, or joints