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 proteins as well as the ectopic expression of lamin B and nuclear matrix protein in the cytoplasm, suggesting the possibility of apoptosis. The authors investigated for apoptosis using the TUNEL method in six muscle biopsy specimens from patients with MFM. There was no evidence of apoptotic myonuclei in any of the MFM muscle biopsies. Further studies regarding the pathogenesis of MFM and the possible role of mitotic catastrophe are needed.