What diseases are associated with muscular and joint hypermobility?

Diseases Associated with Muscular and Joint Hypermobility

Joint hypermobility is a defining feature of multiple disease categories: hereditary connective tissue disorders (particularly Ehlers-Danlos syndromes), congenital and adult-onset myopathies, neurodevelopmental disorders, and autonomic/immune dysfunction syndromes.

Primary Connective Tissue Disorders

Ehlers-Danlos Syndromes (EDS)

• Hypermobile EDS (hEDS) represents 80-90% of all EDS cases and is diagnosed clinically using the 2017 criteria, requiring a Beighton score ≥5/9 in adults under 50 years, ≥4/9 for those over 50, and ≥6/9 for prepubertal children 1, 2, 3
• Vascular EDS (Type IV) is caused by COL3A1 mutations and carries the highest mortality risk, with median survival of 48 years due to arterial rupture and organ perforation 4
• Classical EDS (Types I and II) results from COL5A1 or COL5A2 mutations and presents with joint hypermobility, skin hyperextensibility, and atrophic scarring 4
• The 2017 EDS Classification now recognizes 13 distinct subtypes caused by mutations in 19 different genes 5

Other Connective Tissue Disorders

• Marfan syndrome features joint hypermobility alongside aortic root dilation, lens dislocation, and skeletal abnormalities 6, 7
• Loeys-Dietz syndrome presents with arterial tortuosity, aneurysms, and joint hypermobility 6

Hypermobility Spectrum Disorders (HSD)

• HSD is diagnosed when joint hypermobility occurs with musculoskeletal pain but does not meet criteria for hEDS or another systemic disorder 8, 5
• This diagnostic category fills the gap between asymptomatic joint hypermobility and hypermobile EDS 5

Congenital and Adult-Onset Myopathies

Muscle Extracellular Matrix Disorders

• Ullrich congenital muscular dystrophy and Bethlem myopathy are caused by collagen VI defects and present with joint hypermobility, muscle weakness, and contractures 6, 7
• Congenital muscular dystrophy with joint hyperlaxity features prominent hypermobility alongside progressive muscle weakness 7
• FKBP14-related kyphoscoliotic EDS represents an overlap between myopathy and connective tissue disorder 6

Core Myopathies

• Multi-minicore disease and central core disease (RYR1-related) present with joint hypermobility, mild-to-moderate muscle weakness, and distinctive muscle biopsy findings 6, 7
• SEPN1-related myopathy features prominent joint hypermobility with early spinal rigidity 6
• Limb girdle muscular dystrophy 2E presents with both joint hyperlaxity and contractures 7

Autonomic Dysfunction Syndromes

Postural Orthostatic Tachycardia Syndrome (POTS)

• POTS affects 31-39% of patients with hEDS, characterized by heart rate increase ≥30 beats/min in adults (≥40 beats/min in adolescents 12-19 years) within 10 minutes of standing without orthostatic hypotension 1, 3, 4
• The association is attributed to vascular laxity from abnormal collagen, peripheral neuropathy, and emerging autoimmune mechanisms 4
• Up to 40% of POTS patients report a viral infection as the precipitating event 3

Immune and Mast Cell Disorders

Mast Cell Activation Syndrome (MCAS)

• MCAS occurs in 23.7% of patients with hEDS, presenting with flushing, urticaria, wheezing, and multisystem symptoms triggered by foods, temperature changes, and medications 1, 3, 4
• Diagnosis requires baseline serum tryptase elevation of 20% above baseline plus 2 ng/mL during symptomatic flares 4
• Mechanical stimuli such as surgery can trigger mast cell degranulation in hEDS patients 4

Gastrointestinal Manifestations

• Up to 98% of hEDS patients experience gastrointestinal symptoms, including nausea, abdominal pain, severe constipation, bloating, early satiety, gastroesophageal reflux, and dysmotility 1, 3, 4
• Pelvic floor dysfunction is highly prevalent and contributes to lower GI symptoms 4
• Irritable bowel syndrome (IBS) is diagnosed in one-third of POTS patients and is more common in those with concomitant hEDS 1

Cardiovascular Complications

• Aortic root dilation occurs in 25-33% of hypermobile and classical EDS cases, requiring echocardiographic surveillance 2, 3, 4
• Surveillance intervals: annually if aortic root <4.5 cm with growth <0.5 cm/year; every 6 months if diameter >4.5 cm or growth >0.5 cm/year 4

Neurodevelopmental Disorders

• Joint hypermobility accompanies various congenital neuromuscular disorders and monogenic multiple malformation/intellectual disability syndromes 9
• Developmental coordination disorders show strong association with joint hypermobility, though the mechanistic nature of this relationship requires further investigation 9

Critical Diagnostic Pitfalls to Avoid

• Do not perform universal POTS/MCAS testing in all hEDS patients; testing should be targeted to those presenting with specific clinical manifestations of these conditions 1
• Avoid invasive vascular procedures in suspected vascular EDS, as fatal complications from arterial rupture have been reported 4
• Do not delay COL3A1 genetic testing when vascular EDS is suspected, as this represents a medical emergency with life-threatening implications 4
• Recognize that asymptomatic hypermobility can become symptomatic over time; preventive strengthening is essential even when current symptoms are mild 2
• Do not attribute all symptoms to post-infectious syndrome when the patient displays a classic hEDS phenotype with multisystem involvement 4