muscular dystrophy

muscular dystrophy n any of a group of hereditary diseases characterized by progressive wasting of muscles called also progressive muscular dystrophy see BECKER MUSCULAR DYSTROPHY, DUCHENNE MUSCULAR DYSTROPHY

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a group of muscle diseases, marked by weakness and wasting of selected muscles, in which there is a recognizable pattern of inheritance. The affected muscle fibres degenerate and are replaced by fatty tissue. The muscular dystrophies are classified according to the patient's age at onset, distribution of the weakness, the progression of the disease, and the mode of inheritance. Isolated cases may occur as a result of gene mutation. Confirmation of the diagnosis is based upon electromyography and muscle biopsy.

One common form is Duchenne's muscular dystrophy, which is inherited as a sex-linked recessive character and is nearly always restricted to boys. It usually begins before the age of four, with selective weakness and wasting of the muscles of the pelvic girdle and back. The child has a waddling gait and lordosis of the lumbar spine. The calf muscles - and later the shoulders and upper limbs - often become firm and bulky. Although the disease cannot be cured, physiotherapy and orthopaedic measures can relieve the disability. The identification of the gene abnormality raises the possibility of gene therapy in the future. See also Becker muscular dystrophy, dystrophia myotonica.

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a group of genetic degenerative myopathies characterized by weakness and atrophy of muscle without involvement of the nervous system. The three main types are called pseudohypertrophic, facioscapulohumeral, and limb-girdle.