Update on Phenotypes of Hereditary Myopathies and Indication for a Muscle Biopsy

The classic presentation of a myopathic syndrome is a symmetrical proximal weakness and atrophy of limb muscles. Over the past 100 years many familial myopathic syndromes have been described. By the use of molecular genetics many of these syndromes are now classified and gene products are characterised. Today at least 2 X-chromosomal, 7 dominant, 15 recessive limb girdle muscular dystrophies (LGMDs), 8 myofibrillar myopathies, and 4 repeat associated myopathies are genetically classified. Beyond this, congenital myopathies, hereditary inclusion body myopathies, hereditary metabolic myopathies, and mitochondrial myopathies can be genetically distinguished. For future therapy and better understanding of the basic molecular mechanisms, a definite genetic diagnosis is nowadays important. In the absence of the,,diagnostic gene chip", the indication for an open incision muscle biopsy is still obligate for making the diagnosis in recessive LGMDs, metabolic myopathies, and acquired myopathies, like inflammatory myopathies. In contrast, in dominant transmitted myopathic disorders a direct gene analysis is recommended. This survey focuses on myopathic syndromes and the indication for a diagnostic muscle biopsy.