Desmin myopathy: Distinct filamentopathy caused by mutations in the desmin gene
Dalakas MC., Vasconcelos OM., Kaminska A., Kwiesciski H., Hilton-Jones D., Squier W., Goldfarb LG.
Intermediate filaments are 10 nm structures that interact with actin and microtubules to form the cytoskeletal scaffolding of the cells. They share a common structure of a dimer with 2 alpha helical chains intertwined in a coiled-coil highly conserved rod structure. In the muscle, intermediate filaments constitute 1% of the total proteins and include lamin A/C, emerin, desmin, paranemin, nestin, vimentin, peripherin and possibly syncoilin. Together with various proteins associated with them, such as plectin and αB crystalline, the intermediate filaments play a fundamental role in the structural resilience of the myofibres. A group of neuromuscular diseases that selectively affect intermediate filaments, has now emerged that can be collectively called "filamentopathy". The prototypic filamentopathy causing myopathy is the one due to mutations in the desmin gene (desmin myopathy); others may be due to defects in nuclear intermediate filaments such as lamin A/C and emerin, causing dilated cardiomyopathy or Emery-Dreifuss muscular dystrophy; and still others due to mutations in plectin or αB crystallin causing myofibrillar myopathy, as discussed later. The prototypic filamentopathy affecting nerves is the one due to mutations in gigaxonin that results in an axonal neuropathy; the prototypic filamentopathy affecting skin is caused by mutations in the keratin gene. Finally, mutations in neurofilament subunits may lead to motor neuron cell death.