[Myofibrillar myopathies]

The aim of this study is to analyse the different types of myopathies that are included under the name of filament pathologies and to review both their clinical, pathological and genetic aspects.

The term filament pathologies embraces a heterogeneous group of diseases caused by mutations in the genes that code for the intermediate filaments. Myofibrillar myopathies or myopathies with desmin accumulation belong to the group of filament pathologies. Myofibrillar myopathies are clinically and genetically heterogeneous diseases, with common myopathological bases, which translate a process of myofibril degradation. One characteristic of these diseases is the presence of desmin immunoreactive inclusions in the cytoplasm of the muscle fibres. Approximately a third of the cases are due to mutations in the desmin gene, although to date mutations in the alpha-B-crystallin gene have been reported in two families. In the other patients the gene responsible for the disease remains unknown.

The complexity of the so-called 'filament pathologies' calls for a multidisciplinary approach to the patient so that the myopathy can be correctly classified. This should consist in a clinical and neurophysiological examination, an immunohistochemical and electron microscope study of the muscle biopsy, and a genetic analysis to check for mutations in the desmin and the alpha-B-crystallin gene.