Progressive proximal weakness with contractures and respiratory failure: an unusual presentation of Bethlem myopathy.

Bethlem myopathy is a rare collagen VI-related muscle disorder characterised by slowly progressive proximal weakness and joint contractures. Walking is usually preserved into adulthood and respiratory involvement is relatively mild. A 53-year-old woman had longstanding proximal limb weakness, early contractures and respiratory insufficiency. Despite an apparent clinical improvement on follow-up, initially attributed to immunotherapy, genetic testing ultimately identified a pathogenic COL6A1 mutation. This case highlights diagnostic challenges in late-presenting myopathies and emphasises the importance of genetic testing in atypical cases.