Mutations in 19 different genes are known to cause Ehler-Danlos syndrome (EDS), a group of disorders that affect the body’s connective tissue. To confirm a diagnosis of EDS, physicians can conduct a physical examination, skin biopsies, imaging tests, and genetic testing.
There are many different types of EDS, each having several distinctive physical features. Overall, EDS is characterized by hypermobility — an unusually large range of joint movement — hypotonia, or weak muscles, and dislocation of joints.
Clinicians often will use more than one of these methods to diagnose EDS:
Physical examination involves assessing the hypermobility of joints based on a nine-point scale called the Beighton scoring system. A score of 5 or more on the Beighton scale indicates joint hypermobility. The 2017 International Diagnostic Criteria lays down several physical criteria that characterize each of the 13 types of EDS.
Skin biopsies may help clinicians properly identify the EDS subtype that a patient has. Skin biopsies can be used for histological studies, electron microscopy examination, or fibroblast culture for genetic testing.
Genetic testing is performed to identify mutations and confirm a diagnosis. The subtypes of EDS for which the affected genes are known include classical, vascular, kyphoscoliotic, arthrochalasia, and dermatosparactic. Genetic testing is performed using techniques such as next-generation sequencing (NGS) and copy number variant (CNV) detection strategies.
According to the Villefranche classification of EDS, the following genes are screened for mutations to confirm the diagnosis of common EDS subtypes:
- Classical EDS — COL5A1, COL5A2; rarely COL1A1
- Vascular EDS — COL3A1
- Kyphoscoliotic EDS — PLOD1, FKBP14
- Arthrochalasic EDS — COL1A1, COL1A2
- Dermatosparactic EDS — ADAMTS2
The family history of the patient also plays an important role in diagnosis. If EDS is confirmed, it is important that all immediate family members also undergo genetic testing.
Conditions such as osteogenesis imperfecta (brittle bone disease), Ullrich congenital muscular dystrophy, Bethlem myopathy, and skeletal dysplasias often have symptoms similar to those of EDS, which can result in misdiagnosis.
Last updated: Oct. 15, 2019
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