What is Ehlers-Danlos Syndrome Type 5?
Ehlers-Danlos syndrome (EDS) type 5 is an outdated classification term that is no longer used in current medical practice. The modern 2017 International Classification recognizes 13 distinct EDS subtypes based on genetic and clinical criteria, and the historical "type 5" designation does not correspond to any of these current subtypes 1.
Historical Context and Modern Classification
The Villefranche Nosology, published in 1998, delineated six EDS subtypes and was the standard classification system for two decades 1. However, this system has been superseded by the 2017 International Classification, which expanded recognition to 13 subtypes based on advances in molecular genetics and clinical understanding 1.
- The old numerical classification system (types 1-11) has been replaced with descriptive names based on clinical and genetic features 1, 2
- 19 different causative genes have now been identified across the EDS spectrum, mostly related to collagen synthesis and extracellular matrix components 3, 4
- The current classification groups subtypes by pathogenetic mechanisms rather than arbitrary numbers 1
Current EDS Subtypes You Should Know
The hypermobile type is the most common, accounting for 80-90% of all EDS cases 3, 5. Key features include:
- Joint hypermobility confirmed by Beighton scale scores: ≥6/9 points for prepubertal children, ≥5/9 for adults under 50, and ≥4/9 for adults over 50 5
- Soft or velvety skin with normal or slightly increased extensibility 6
- Chronic joint or limb pain, recurrent dislocations, and easy bruising 6
- Aortic root dilation occurs in one-quarter to one-third of cases, though dissection risk without significant dilation is not thought to be elevated 6
The vascular type (formerly type IV) poses the greatest mortality risk due to spontaneous arterial and organ ruptures 3. This is the most critical subtype to identify for prognostic purposes.
Clinical Hallmarks Across All EDS Types
The defining triad includes 7:
- Joint hypermobility with recurrent dislocations or subluxations
- Skin hyperextensibility and tissue fragility (severity varies by subtype)
- Tissue fragility affecting blood vessels, organs, and wound healing
Diagnostic Approach
Diagnosis of all EDS subtypes except hypermobile type requires molecular confirmation with identification of causative genetic variants 1. For hypermobile EDS, diagnosis remains clinical based on revised criteria that distinguish it from other joint hypermobility disorders 1.
- Physical examination focusing on Beighton scale assessment, skin texture, and tissue fragility 6
- Echocardiogram to evaluate for aortic root dilation (present in 25-33% of hypermobile and classic types) 6
- Dilated eye exam to exclude Marfan syndrome 6
- Genetic testing for suspected subtypes other than hypermobile type 1
Common Pitfall to Avoid
Do not use outdated numerical classifications when communicating about EDS. Using terms like "type 5" creates confusion and may lead to inappropriate management, as the historical numbering system does not align with current genetic and clinical understanding 1, 2. Always refer to EDS subtypes by their descriptive names (hypermobile, classical, vascular, etc.) based on the 2017 International Classification.