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Collagen VI-related dystrophy
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Collagen VI-related dystrophy

Collagen VI-related dystrophy is a spectrum of disorders affecting muscles used for movement and connective tissue, ranging from mild to severe.

Overview

Collagen VI-related dystrophy is a group of disorders that affect muscles used for movement and connective tissue. Most affected individuals have muscle weakness and joint deformities called contractures that restrict movement and worsen over time. The spectrum includes Bethlem muscular dystrophy (mildest), an intermediate form, and Ullrich congenital muscular dystrophy (most severe).

Symptoms

  • Bethlem muscular dystrophy: Low muscle tone in infancy; slowly progressive muscle weakness appearing in childhood to early adulthood; contractures in fingers, elbows, shoulders, and ankles; potential respiratory muscle weakness in older individuals; skin abnormalities.
  • Intermediate form: Muscle weakness beginning in infancy; walking becomes increasingly difficult in early adulthood; contractures develop in childhood; potential need for mechanical ventilation.
  • Ullrich congenital muscular dystrophy: Severe muscle weakness from birth; many are unable to walk or lose the ability in early adolescence; contractures in shoulders, elbows, hips, and knees; joint laxity in fingers, wrists, toes, and ankles; requirement for mechanical ventilation.

Causes

Variants in the COL6A1, COL6A2, and COL6A3 genes cause these disorders. These genes provide instructions for making components of type VI collagen, which forms an extracellular matrix providing structural support to muscle cells and connective tissue. Variants result in a decrease, lack, or abnormality of type VI collagen, leading to an unstable extracellular matrix and progressive muscle weakness.

Inheritance

These conditions are often inherited in an autosomal dominant pattern, where one copy of the altered gene is sufficient to cause the disorder. Less commonly, they are inherited in an autosomal recessive pattern, requiring two copies of the variant gene.

Frequently Asked Questions

Yes, the inheritance pattern significantly impacts risk. In autosomal dominant cases, such as many forms of Bethlem dystrophy, an affected parent has a 50 percent chance of passing the variant to each child. In autosomal recessive cases, such as many forms of Ullrich dystrophy, both parents must be carriers, resulting in a 25 percent chance for each child to be affected. Genetic counseling is essential to determine the specific inheritance mode for a family, which guides reproductive planning and testing for partners.
Physical therapy is critical for maintaining range of motion and preventing the progression of contractures. Gentle, daily stretching exercises are recommended, focusing on the joints most prone to tightening based on the specific subtype. High-impact activities or exercises that cause significant muscle fatigue should generally be avoided, as overexertion can accelerate muscle damage and weakness. The therapy plan must be individualized to balance the need for mobility with the risk of injury to fragile muscles.
The key distinguishing feature is the pattern of joint involvement. Bethlem muscular dystrophy typically presents with contractures (tightening) in the fingers, elbows, shoulders, and ankles, while the hips and knees remain relatively flexible. In contrast, Ullrich congenital muscular dystrophy presents with severe contractures in the large joints such as the shoulders, elbows, hips, and knees, but paradoxically exhibits joint laxity (looseness) in the fingers, wrists, toes, and ankles. This specific distribution of tight versus loose joints is a hallmark diagnostic clue.
Respiratory muscle weakness is a significant risk, particularly in the intermediate and Ullrich forms, and can lead to hypoventilation and respiratory failure. Monitoring should begin in childhood for those with the intermediate form and in infancy for those with Ullrich congenital muscular dystrophy. Regular pulmonary function tests, including overnight oximetry, are necessary to detect early signs of respiratory compromise before overt symptoms like morning headaches or excessive daytime sleepiness appear.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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