What is the appropriate approach to testing for Ehlers‑Danlos syndrome?

Testing for Ehlers-Danlos Syndrome

Diagnosis of hypermobile Ehlers-Danlos syndrome (hEDS) is primarily clinical using the 2017 international consensus criteria, which requires three mandatory components: (1) generalized joint hypermobility assessed by the Beighton score, (2) systemic manifestations of connective tissue disorder, and (3) exclusion of alternative diagnoses—with genetic testing playing a critical role in this exclusion process. 1

Diagnostic Approach for hEDS

Step 1: Assess Joint Hypermobility Using the Beighton Score

The Beighton scoring system is the standardized tool for assessing generalized joint hypermobility 1:

Required thresholds:

• ≥6/9 points in children before puberty
• ≥5/9 points from puberty to age 50
• ≥4/9 points for those ≥50 years old

The 9-point assessment includes:

• Passive dorsiflexion of 5th fingers beyond 90° (1 point each side)
• Passive apposition of thumbs to forearm (1 point each side)
• Elbow hyperextension >10° (1 point each side)
• Knee hyperextension >10° (1 point each side)
• Forward flexion with palms flat on floor with knees straight (1 point)

Step 2: Identify Systemic Manifestations

Look for at least 2 of the following features 1:

• Soft, velvety, or hyperextensible skin
• Atrophic scarring or poor wound healing
• Easy bruising
• Tissue fragility
• Musculoskeletal pain (chronic, often widespread)
• Family history of similar features

Step 3: Exclude Alternative Diagnoses Through Genetic Testing

This is where genetic testing becomes essential. Recent evidence demonstrates that genetic testing identifies alternative or additional diagnoses in 26.4% of patients who initially met clinical criteria for hEDS 2. This finding fundamentally challenges the notion that hEDS diagnosis is purely clinical.

Recommended genetic testing approach:

• EDS gene panel testing should be performed to exclude other EDS subtypes and overlapping connective tissue disorders 2, 3
• In children presenting with EDS features, an EDS panel confirmed molecular diagnosis in 75% of those meeting clinical criteria and 28% of those who didn't fully meet criteria 3
• Testing is particularly important because hypermobility may represent a shared phenotype across inflammatory diseases, monogenic syndromes, and chromosomal abnormalities 2

Clinical correlates that increase likelihood of positive molecular diagnosis 3:

• Generalized joint hypermobility
• Poor wound healing
• Easy bruising
• Atrophic scars
• Skin hyperextensibility
• Developmental dysplasia of the hip

Special Considerations for Vascular EDS (vEDS)

For vascular EDS, genetic confirmation with COL3A1 testing is mandatory because clinical criteria alone are insufficient and misdiagnosis has life-threatening implications 4, 5.

Red flags requiring COL3A1 genetic testing:

• Arterial rupture or dissection at young age
• Spontaneous pneumothorax/hemothorax
• Intestinal perforation
• Thin, translucent skin
• Easy bruising
• Family history of sudden death or vascular events

The Villefranche criteria for vEDS have 79% sensitivity but limited specificity (60%), meaning clinical diagnosis alone misses cases and overdiagnoses others 4. Molecular confirmation is essential because not all COL3A1 variants are pathogenic, requiring expert interpretation 5.

Testing for Associated Conditions

When to Test for POTS and MCAS

Do not perform universal screening for POTS or MCAS in all hEDS patients 1. Instead, test only when clinical manifestations suggest these conditions:

Test for POTS when patients report:

• Orthostatic intolerance symptoms
• Lightheadedness upon standing
• Tachycardia with position changes
• Diagnostic criteria: Heart rate increase ≥30 bpm within 10 minutes of standing (≥40 bpm in adolescents 12-19 years) without orthostatic hypotension 1

Test for MCAS when patients have 1:

• Episodic symptoms across ≥2 organ systems (GI, skin, cardiac, respiratory)
• Symptoms triggered by foods, heat, emotion, mechanical stimuli
• Testing approach: Serum tryptase at baseline and 1-4 hours after symptom flares
• Positive result: Increase of 20% above baseline plus 2 ng/mL 1

Additional GI Testing in hEDS Patients

For patients with chronic upper GI symptoms and comorbid POTS 1:

• Gastric emptying studies (abnormal gastric emptying is more common than general population)
• Anorectal manometry and balloon expulsion testing for lower GI symptoms (high prevalence of pelvic floor dysfunction and rectal hyposensitivity)

Consider earlier celiac disease testing in hEDS patients with varied GI symptoms, not just diarrhea 1.

Common Pitfalls to Avoid

1. Assuming hEDS diagnosis is purely clinical without genetic exclusion - 26.4% will have alternative diagnoses on genetic testing 2

2. Relying on clinical criteria alone for vEDS - This leads to both missed diagnoses and overdiagnosis with serious management implications 4, 5

3. Universal screening for POTS/MCAS - Only test when clinical manifestations are present 1

4. Misinterpreting genetic variants - Not all COL3A1 or other gene variants are pathogenic; expert interpretation is essential 5

5. Overlooking that hypermobility can be a shared phenotype across multiple conditions including inflammatory diseases and chromosomal abnormalities 2

Practical Algorithm

1. Calculate Beighton score - If meets age-appropriate threshold, proceed
2. Document systemic manifestations - Need ≥2 features
3. Order EDS gene panel - Essential for excluding alternative diagnoses
4. If vascular features present - COL3A1 testing is mandatory
5. Test for POTS/MCAS only if symptomatic - Not routine screening
6. Refer for expert interpretation - Especially for variant assessment and complex cases

The key paradigm shift: While hEDS has no identified genetic cause, genetic testing remains critical to exclude the 26.4% of patients who actually have alternative diagnoses requiring different management strategies 2.