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Abstract
Muscle fibre is the structural building unit of skeletal muscle. Each muscle fbre is made up of smaller subunits as any other cell in the body, for example: (the nucleus, cell membrane,……etc.), yet the structure of muscle fibres enables it to perform its contractile function.
The cell membrane proteins play a crucial role in the pathogenesis of muscular disorders; and in the last few years there has been a great advance in discovering these proteins and their genetic precursors.
Myopathies are muscle diseases unrelated to any disorder in innervation or neuromuscular junction. There has been many trials to classify muscular disorders; one of the best accepted trials is the one based on whether it is an inherited or acquired disorder.
Muscular dystrophies are one of the inherited myopathies. The first historical account of muscular dystrophies was in the nineteenth century, but the breakthrough advance was made in the year 1987, when the dystrophin protein and its precursor gene were discovered. After that many subtypes of muscular dystrophy were discovered with the causative gene and the cell membrane protein defect.
Many classifications were introduced to classify muscular dystrophies in a simplified way that would help physicians to identify all types in clinical practice. At the beginning, it was based on the distribution of the weakness and the affected muscles. With the enormous advance in molecular genetics, new classifications were introduced based on the affected cell membrane protein and the equivalent gene defect.
Congenital muscular dystrophies (CMD) are a type of muscular dystrophies that has an early onset of symptom appearance, as it usually starts at birth or within the first few months of life.
It is classified into two main types: CMD with central nervous system (CNS) involvement (Fukuyama congenital muscular dys¬trophy, Walker-Warburg syndrome, and muscle-eye-brain disease) and CMD without CNS involvement (Merosin negative and Merosin positive subtypes).
Each subtype of CMD has its characteristic clinical and histopathological features.
Limb girdle muscular dystrophies (LGMD) are another type of muscular dystrophies that is characterized by preservation of facial and extraocular muscles.
It is classified into autosomal recessive and auto-somal dominant groups. There are eleven autosomal recessive and seven autosomal dominant subtypes that have been described until now.
For many years there have been no definitive treatment for CMD or LGMD. All the available measures were non specific and non curable; these measure were concerned with the promotion of life style of the diseased cases, such as a well balanced diet, preservation of respiratory functions and prevention of bone deformities.
Now, with the great scientific advance, there are many new lines of management for such cases. One of these lines depends on early detection and prevention of occurrence of these disorders, depending on family and genetic counseling. Another line of management tries to stop the progress of the disease and to treat the cause, important examples of these new lines are gene therapy, myoblast transplantation and myostatin therapy.
Also surgical management has a very important role in improving the burden caused by these disorders, owing to the great advance in this field in the last few years.
The idea that muscular dystrophies are non evitable inherited disorders is widely challenged nowadays. This is due to the great progress in the possible ways of management, the progress that carries a lot more in the near future.