What is Ehlers‑Danlos syndrome?

What is Ehlers-Danlos Syndrome?

Ehlers-Danlos syndrome (EDS) is a heterogeneous group of hereditary connective tissue disorders characterized by three hallmark features: joint hypermobility, skin hyperextensibility, and tissue fragility. 1, 2

Disease Classification and Subtypes

EDS encompasses 14 distinct subtypes, with 13 having identified molecular causes involving mutations in 20 different genes—primarily those encoding fibrillar collagens (types I, III, and V), their modifying enzymes, and proteoglycan-related enzymes 2. The subtypes vary dramatically in severity and clinical manifestations:

Hypermobile Type (hEDS)

• Most common subtype, accounting for 80-90% of all EDS cases 3, 4
• Molecular basis remains unknown—no genetic test available 2, 4
• Diagnosis is purely clinical, requiring all three criteria: (1) generalized joint hypermobility (Beighton score ≥5/9), (2) musculoskeletal and systemic manifestations consistent with connective tissue disorder, and (3) exclusion of alternative diagnoses 5, 6
• Features include joint laxity, easy bruising, functional bowel disorders, osteoporosis, and chronic pain 5
• Mild aortic root dilation occurs in one-quarter to one-third of patients, but dissection risk is not significant without substantial dilation 5

Vascular Type (vEDS or Type IV)

• Most severe and life-threatening form 7, 8
• Caused by mutations in COL3A1 gene affecting type III collagen 7, 8
• Prevalence: 1/50,000 to 1/200,000 8
• Characterized by easy bruising, thin translucent skin with visible veins, characteristic facial features, and spontaneous rupture of arteries, uterus, or intestines 7
• Median survival only 48-51 years due to arterial dissections/ruptures 7, 8
• Arterial ruptures often occur without preceding aneurysm formation 7
• Aortic dissection occurs in up to 10% of patients 8

Clinical Manifestations

The clinical presentation varies by subtype but commonly includes:

• Musculoskeletal: Recurrent joint dislocations/subluxations, chronic joint and limb pain, scoliosis 5, 9
• Dermatologic: Soft, velvety, or hyperextensible skin; abnormal wound healing; easy bruising 5, 2
• Cardiovascular: Aortic root dilation, arterial aneurysms and dissections, arterial tortuosity 5, 7
• Gastrointestinal: Functional bowel disorders (98% of hEDS patients meet DGBI criteria), organ rupture in vEDS 7, 3
• Autonomic: Neurally mediated hypotension, postural orthostatic tachycardia syndrome (POTS) 5, 3

Diagnostic Approach

For Hypermobile Type

The Beighton scale (9-point system) assesses joint hypermobility 5:

• Passive dorsiflexion of fifth fingers >90° (2 points)
• Passive thumb apposition to forearm (2 points)
• Elbow hyperextension >10° (2 points)
• Knee hyperextension >10° (2 points)
• Forward flexion with palms flat on floor (1 point)

Score ≥5 required, plus soft/velvety skin without fragility, and absence of features suggesting other EDS subtypes 5.

For Vascular Type

Diagnosis requires DNA or protein studies confirming COL3A1 gene defect 7. Clinical suspicion based on characteristic features should prompt immediate genetic testing.

Critical Management Considerations

Cardiovascular Surveillance

• hEDS with normal aortic root: Echocardiogram every 2-3 years until adult height, then only if symptomatic 5
• hEDS with aortic dilation: Echocardiogram every 6 months if diameter >4.5 cm or growth >0.5 cm/year 5
• vEDS: Annual vascular surveillance from cerebrovascular circulation to pelvis using duplex ultrasound, low-radiation CT, or CMR 8

Medical Treatment

• vEDS: Celiprolol (beta-blocker with vasodilatory properties) reduces vascular morbidity; start after age 10 years 8
• Aggressive blood pressure control is essential 8
• hEDS: Physical therapy is the only proven efficacious treatment for reducing joint instability and pain 10

Surgical Considerations

• vEDS: Surgery only for life-threatening ruptures due to tissue fragility, hemorrhage tendency, and poor wound healing 7
• Use pledgeted sutures and careful tissue handling 7
• Avoid invasive imaging in vEDS—fatal complications reported 7

Pregnancy Risks

• vEDS has extremely poor pregnancy outcomes: Risk of gravid uterus rupture and vessel rupture at delivery or postpartum 7
• hEDS: Individualized multidisciplinary approach addressing tissue fragility, joint hypermobility, pain, and comorbidities 11

Prognosis

Life expectancy varies dramatically by subtype:

• hEDS: Normal life expectancy with appropriate management 10
• vEDS: Average survival 51 years, with recurrence rate of 1.6 vascular events per 5-year period 8

The key clinical pitfall is failing to distinguish between hEDS and vEDS—the former requires supportive care and surveillance, while the latter demands aggressive medical management and has life-threatening implications requiring immediate genetic confirmation and specialized vascular monitoring 7, 8.