Mitochondrial abnormalities in the myofibrillar myopathies

Myofibrillar myopathies are a genetically diverse group of skeletal muscle disorders, with distinctive muscle histopathology. Causative mutations have been identified in the genes MYOT , LDB3 , DES , CRYAB , FLNC , BAG 3 , DNAJB 6 , FHL 1 , PLEC and TTN , which encode proteins which either reside in the Z‐disc or associate with the Z‐disc. Mitochondrial abnormalities have been described in muscle from patients with a myofibrillar myopathy. We reviewed the literature to determine the extent of mitochondrial dysfunction in each of the myofibrillar myopathy subtypes. Abnormal mitochondrial distribution is a frequent finding in each of the subtypes, but a high frequency of COX ‐negative or ragged red fibres, a characteristic finding in some of the conventional mitochondrial myopathies, is a rare finding. Few in vitro studies of mitochondrial function have been performed in affected patients.