Ehlers-Danlos syndrome comprises a heterogeneous group of collagen disorders (hereditary connective tissue disease).
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Epidemiology
The combined prevalence for all types of Ehlers-Danlos syndrome is estimated to be at least 1 of every 5000 individuals. There is no significant gender predominance.
Clinical presentation
Ehlers-Danlos syndrome clinically manifests with
- skin hyperelasticity and fragility
- joint hypermobility
- blood vessel fragility with bleeding diathesis 1
- poor tissue healing with delayed healing with tissue paper-like scarring 1
Subtypes
There are at least ten subtypes with variable inheritance patterns. The majority are autosomal dominant:
- types I and II (also called classic Ehlers-Danlos syndrome) are autosomal dominant and result from mutations in COL5A1 and COL5A2 9.
- type III (also called hypermobility Ehlers-Danlos syndrome) is autosomal dominant with an unknown biochemical origin 9.
- type IV (also called vascular Ehlers-Danlos syndrome 4) is autosomal dominant and involves the arteries, GI tract, uterus and skin; COL3A1 mutation result in type III collagen production
- type VI (also called kyphoscoliosis Ehlers-Danlos syndrome 9) is recessively inherited. It results from a mutation in the gene that encodes lysyl hydroxylase
- type VII is is subclassified into arthrochalasia (type VIIa/b - autosomal dominant) and dermatosparaxis (type VIIc - autosomal recessive) which result from mutations in COL1A1/COL1A2 and procollagen N-peptidase respectively. COL1A1/COL1A2 mutations result in defective conversion of procollagen to collagen 9.
- types V, VIII, IX and X are very rare and their features have not been fully described 1
The 2017 Ehlers-Danlos classification lists 13 subtypes, including several newly-identified rare forms of the disease 7,8.
Radiographic features
The imaging findings of Ehlers-Danlos syndrome are best discussed according to system.
Soft tissue
- multiple ovoid calcifications (<1 cm) in the subcutaneous tissue
- ectopic ossification 2
Skeletal
- hemarthrosis (especially knees)
- recurrent dislocation: including spontaneous dislocation of the temporomandibular joint 3
- precocious osteoarthritis
- kyphoscoliosis
- spondylolisthesis
- arachnodactyly
Vascular
- fragile blood vessels
- arterial aneurysm formation
- increased occurrence of arterial dissection: aortography contraindicated 2
- dolichoectasia
Thoracic
Gastrointestinal
- ectasias of the gastrointestinal tract