Myopathy with lobulated fibers, cores, and rods caused by a mutation in collagen VI

Bethlem myopathy is a collagen VI–related muscle disorder that manifests with proximal muscle weakness and distal joint contractures. The autosomal dominantly inherited disease is caused by mutations in one of the 3 genes encoding the extracellular collagen VI chains ( COL6A1 , COL6A2 , COL6A3 ).1,2 Muscle biopsy usually reveals nonspecific changes. Here, we report on a patient with Bethlem myopathy caused by a COL6A3 mutation, presenting cores, nemaline rods, and lobulated fibers in the muscle biopsy. The authors thank the technical personnel of the Departments of Neuropathology, Neurology, and Radiology, RWTH University, Aachen, Germany, for technical assistance.