Myofibrillar myopathy: No evidence of apoptosis by TUNEL

The pathogenesis of myofibrillar myopathy (MFM) is not known. Muscle biopsy specimens demonstrate increased expression of cell cycle regulatory protei ns as well as the ectopic expression of lamin B and nuclear matrix protein in the cytoplasm, suggesting the possibility of apoptosis. The authors inve stigated for apoptosis using the TUNEL method in six muscle biopsy specimen s from patients with MFM. There was no evidence of apoptotic myonuclei in a ny of the MFM muscle biopsies. Further studies regarding the pathogenesis o f MFM and the possible role of mitotic catastrophe are needed.