Ehlers-Danlos Syndrome Type 7: Symptoms, Diagnosis, and Management

What are the Symptoms of Ehlers-Danlos Syndrome Type 7?

Ehlers-Danlos Syndrome (EDS) Type 7, specifically Arthrochalasia Type (formerly Type VIIA and VIIB), is a rare genetic connective tissue disorder primarily characterized by severe generalized joint hypermobility, recurrent joint dislocations, and distinctive skeletal abnormalities due to defects in collagen processing.

Understanding Ehlers-Danlos Syndromes

Ehlers-Danlos Syndromes (EDS) are a group of heritable connective tissue disorders affecting collagen, the most abundant protein in the human body. Collagen provides strength and elasticity to tissues such as skin, joints, blood vessels, and organs. Defects in collagen synthesis, processing, or structure lead to a wide spectrum of symptoms, primarily affecting the musculoskeletal and integumentary (skin) systems. There are currently 13 recognized types of EDS, each with distinct genetic causes and clinical manifestations.

Ehlers-Danlos Syndrome Type 7 (Arthrochalasia Type)

EDS Type 7, now known as Arthrochalasia Type (a-EDS), is caused by mutations in the COL1A1 or COL1A2 genes, which encode the alpha-1 and alpha-2 chains of Type I collagen, respectively. These mutations typically lead to a deficiency in the processing of procollagen to collagen, specifically impacting the cleavage of the N-terminal propeptide. This processing error results in abnormally structured collagen molecules that cannot properly assemble into strong, stable fibrils, leading to the characteristic tissue fragility and laxity observed in affected individuals.

Key Symptoms of EDS Type 7 (Arthrochalasia Type)

The clinical presentation of EDS Type 7 is characterized by a distinctive set of symptoms, primarily affecting the joints and skeletal system, but also involving the skin.

Severe Generalized Joint Hypermobility and Dislocation

This is the most prominent and defining feature of EDS Type 7.

• Congenital Bilateral Hip Dislocation: A hallmark symptom, often present at birth or detected shortly thereafter. This is a crucial diagnostic indicator.
• Recurrent Dislocation of Other Major Joints: Individuals frequently experience subluxations (partial dislocations) and full dislocations of various joints, including:
  • Shoulders
  • Knees (patellar dislocation)
  • Elbows
  • Fingers and toes
• Extreme Joint Range of Motion: Due to the laxity of ligaments and joint capsules, joints can move far beyond their normal physiological limits, leading to instability and chronic pain.
• Early Onset Osteoarthritis: The chronic joint instability and repeated dislocations can lead to premature degeneration of joint cartilage, resulting in early-onset osteoarthritis and associated pain and stiffness.

Skeletal Abnormalities

Beyond joint instability, EDS Type 7 can manifest with specific skeletal issues:

• Muscle Hypotonia: Reduced muscle tone, which can contribute to joint instability and developmental motor delays in infancy.
• Scoliosis: Curvature of the spine is common, ranging from mild to severe, and can progress over time.
• Osteopenia/Osteoporosis: Reduced bone mineral density, leading to an increased risk of fractures, even with minimal trauma.
• Short Stature: Some individuals may exhibit slightly reduced adult height.

Skin Manifestations

While not as severe as in some other EDS types, skin issues are present:

• Mild to Moderate Skin Hyperextensibility: The skin can be stretched more than normal, though it usually recoils well.
• Easy Bruising: Capillary fragility can lead to easy bruising and purpura (purple spots on the skin).
• Delayed Wound Healing and Atrophic Scars: Wounds may heal slowly, and scars can be thin, widened, or "cigarette paper-like" in appearance.

Other Potential Symptoms

Less common but reported symptoms can include:

• Mild Facial Dysmorphism: Subtle facial features such as a broad nasal bridge or epicanthal folds.
• Dental Anomalies: Crowding or other dental issues.

Diagnosis of EDS Type 7

Diagnosis of EDS Type 7 is primarily based on clinical criteria, particularly the presence of congenital bilateral hip dislocation combined with severe generalized joint hypermobility. Confirmation is typically achieved through genetic testing, which identifies pathogenic variants in the COL1A1 or COL1A2 genes. Biochemical testing of collagen can also show the retention of the N-terminal propeptide in type I collagen.

Management and Prognosis

There is no cure for EDS Type 7. Management focuses on symptom relief, preventing complications, and improving quality of life. This often involves:

• Physical Therapy: To strengthen muscles around joints and improve stability, while carefully avoiding activities that exacerbate instability.
• Orthopedic Interventions: Surgical correction for hip dislocations and other joint issues may be necessary.
• Pain Management: To address chronic joint pain.
• Regular Monitoring: For scoliosis, bone density, and other potential complications.

The prognosis varies depending on the severity of symptoms and the effectiveness of management strategies. While individuals with EDS Type 7 face significant physical challenges, early diagnosis and comprehensive multidisciplinary care can help manage symptoms and improve functional outcomes.

Important Considerations

It is crucial for individuals experiencing these symptoms to seek evaluation from a medical geneticist or a physician specializing in connective tissue disorders. Self-diagnosis or attempting to manage such a complex condition without expert medical guidance can lead to further complications. This information is for educational purposes only and should not be considered medical advice.