[Molecular pathogenesis of muscular diseases]

Recent advances in the field of molecular myology have provided significant insight into the pathological mechanisms underlying a variety of neuromuscular disorders. Genetic abnormalities can now be linked to primary and secondary pathophysiological changes in muscle fibres which compromise structural, metabolic, regulatory or contractile mechanisms. Ion channel myopathies such as paramyotonia congenita, hyper- and hypokalaemic periodic paralysis, myotonia congenita, episodic ataxia and malignant hyperthermia were established as linked to mutations in genes encoding the sodium channel, dihydropyridine receptor, chloride channel, potassium channel and the ryanodine receptor calcium release channel, respectively. Metabolic disorders affecting skeletal muscle were found to be due to deficiencies in a variety of enzymes. Identification of defects in components belonging to the gigantic dystrophin-glycoprotein complex led to the discovery of the molecular pathogenesis of Duchenne muscular dystrophy and related disorders. Based on these molecular findings, it is now feasible to design and evaluate new techniques such as gene and myoblast transfer therapy in order to replace defective components in diseased muscle fibres.