Muscular Dystrophy

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which binds to merosin in muscle fiber basal laminae, as well as a number of other integral and cytoplasmic membrane proteins: [Alpha]-dystroglycan; [Alpha]-, [Beta]- and [Gamma]- sarcoglycans (see Figure 1). The DAGC provides a physical link and, potentially, a signaling pathway between the extracellular matrix and the internal scaffolding of the muscle cells. Mutations in the Duchenne gene result in dystrophin deficiency, which constitutes the pathogenic basis of DMD. Dystrophin is either absent or severely deficient in a person with DMD. When dystrophin is lost through gene mutation, the muscle falls apart under the tension generated when it contracts. Without dystrophin, the muscle fibers also lose their ability to regenerate and are eventually replaced with adipose tissue and fibrous connective tissue (see Fig. 2 and Fig. 3).
The Duchenne gene has been located on the short arm of the X chromosome. This means that Duchenne is inherited as an X-linked recessive ...

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on their toes. Affected boys are unable to keep up with normal children their age and are considered clumsy. By the age 3 to 5 years, generalized muscle weakness becomes more obvious. Weakness and wasting usually begins in the iliopsoas, quadriceps and gluteus muscles and soon spreads to involve the anterior tibial group. In upper limbs, the costal origin of pectoralis major, the latissimus dorsi, the biceps, triceps and brachioradialis muscle are the first involved. Calf muscles, and sometimes other muscles, are noticeably larger while other muscles are poorly developed. Parents may be falsely encouraged by a seeming improvement between the ages of 3 and 7, but this may only be due ...

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