Hypermobile Ehlers-Danlos syndrome (hEDS) is the most common type of EDS affecting around one in 5,000 to one in 20,000 individuals worldwide. It is characterized by symptoms such as soft, smooth, and fragile skin, hypermobile joints, frequent joint dislocations, scoliosis (abnormal curvature of the spine), and osteoarthritis (inflammation of the bones).

What causes hEDS?

Genetic mutations have not been identified in most cases of hEDS. However, in a few cases, hEDS is caused by mutations in the TNXB gene, which encodes for a protein called tenascin-X. This protein associates with collagen protein in the connective tissues and its absence reduces the strength of the connective tissue in the skin, cartilage, joints, bones, and blood vessels, resulting in the characteristic symptoms of hEDS.

How is hEDS inherited?

The hEDS is inherited in an autosomal dominant pattern. This means that a mutation in one of the two copies of the causative gene is sufficient for the disease to develop. The mutated gene may be inherited from either the father or the mother. If parents do not have the disease, a child might in some cases get hEDS because of mutations during fetal development.

What are the symptoms of hEDS?

Patients with hEDS show characteristic symptoms such as:

  • joint hypermobility in elbows, knees, fingers, and toes.
  • frequent joint dislocations and subluxations (partial dislocation) of the shoulder, kneecap, and temporomandibular joint (the joint that connects the lower jaw to the skull).
  • soft, smooth skin that is highly elastic and bruises easily.
  • chronic muscle and bone pain.
  • early-onset osteoarthritis (bone inflammation), osteoporosis (low bone density), and osteopenia (low bone mineralization).
  • gastrointestinal problems that include bloating, nausea, vomiting, heartburn, constipation, or hiatal hernia that causes heartburn or gastroesophageal reflux disease (GERD).
  • dysfunction of the autonomic nervous system causing issues such as fatigue, dizziness, fainting, memory changes, poor concentration, reduced sweat production, changes in gut movement, bladder dysfunction, among others.
  • problems in the mouth such as fragile gums that bleed easily, gum recession, gum disease, pointed and deep teeth, shortened roots, abnormal enamel, tooth fractures, and other dental issues.
  • heart valve problems such as mitral valve prolapse.
  • blood vessel problems such as aortic root dilatation (enlargement of the blood vessel that distributes blood from the heart to the rest of the body).
  • increased risk of pelvic prolapse, and painful menstruation and intercourse in women.
  • increased risk of pregnancy complications such as premature rupture of membranes or rapid labor and delivery.

How is hEDS diagnosed?

The clinical diagnosis of hEDS requires the presence of three criteria:

Criterion 1: Positive diagnosis of joint hypermobility based on the Beighton scoring system as recommended by the 2017 international classification of EDS, which includes:

  • the ability to bend the pinky or fifth finger backward at an angle greater than 90 degrees towards the wrist (one point for each hand).
  • the ability to push the thumb to the wrist (one point for each thumb).
  • hyperextension of each elbow greater than 10 degrees (one point for each elbow).
  • hyperextension of each knee greater than 10 degrees (one point for each knee).
  • the ability to place the palms on the floor while standing with the knees fully extended (one point).

To confirm generalized joint hypermobility, the Beighton score must be equal to or greater than 6 for children before puberty, equal to or greater than 5 for adolescents and adults younger than 50, and equal to or greater than 4 for adults older than 50.

Criterion 2: Features characteristic of hEDS such as chronic muscle and joint pain, and a positive family history with at least one immediate relative who meets the hEDS diagnostic criteria. Genetic testing is available for known TNXB gene mutations and is done if family history suggests EDS.

Criterion 3: Exclusion of other disorders whose symptoms overlap with hEDS.

How is hEDS treated?

Treatment for hEDS is symptom-based and varies from patient to patient. Some of the options include:

Assistive devices such as braces to improve joint stability and protective taping of joints can also help. Some patients may need wheelchairs or scooters to reduce the stress on joints in their lower extremities.

 

Last updated: Oct. 22, 2019

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Ehlers-Danlos News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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Özge has a MSc. in Molecular Genetics from the University of Leicester and a PhD in Developmental Biology from Queen Mary University of London. She worked as a Post-doctoral Research Associate at the University of Leicester for six years in the field of Behavioural Neurology before moving into science communication. She worked as the Research Communication Officer at a London based charity for almost two years.