[Diagnostic methodology in muscular pathologies]

To analyse the different methodologies and their technical approaches, and compare the value and specificity of each of them in the diagnostic interpretation of muscular biopsies.

Since the first descriptions by Duchenne in the 19th century, a series of stages for interpreting muscular biopsies crucial to the methodological approach were developed. The largest groups of muscular diseases (neurogenic atrophy, dystrophy and others), which were established on the basis of purely morphological studies, were later examined using histochemical techniques that allowed some diseases to be considered on an individual basis. One decisive factor in interpreting muscular biopsies and in diagnostic accuracy was the application of immunohistochemical techniques. The discovery of the gene responsible for Duchenne and Becker muscular dystrophies, and the later identification of dystrophin using reverse genetics, triggered off a series of events which led to the identification of various genes and proteins responsible for a number of muscular diseases. From that moment onwards it became possible to distinguish between previously undefined muscular dystrophies, e.g. different types of limb girdle dystrophy, to subclassify allelic diseases, such as Becker muscular dystrophy, and to identify carriers of X-linked diseases, for example. Ultrastructural examinations have also proved to be very useful.

At present, the degree of diagnostic accuracy achieved in muscular pathologies is remarkable and the discoveries that have gradually been made have marked a series of stages, none of which has excluded the one preceding it and all of which are of great importance when it comes to interpreting a muscular biopsy.