Myofibrillar Myopathies and the Z-Disk Associated Proteins

Myofibrillar myopathies (MFMs) are typically autosomal dominant myopathies with late onset progressive muscle weakness and symptoms initially evident in the distal muscle groups. However, there is a significant variability in the presentation of these diseases, with the age of onset ranging from infantile to late seventies; the involvement of the heart, respiratory muscles, distal or proximal muscle groups; and severity covering the full spectrum from mild muscle weakness to premature lethality. Several myopathies were identified with symptoms within this broad spectrum and the recognition of a common pathology allowed the grouping of these diseases under a single term, MFM [1]. Problems in the classification of these disorders still exist, partially due to the wide spectrum of clinical presentation and the lack of detailed analysis of biopsy samples to identify the defining features of MFM.