Mytonic Muscular Dystrophy

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Myotonic Muscular Dystrophy (MMD) is a disease genetically based and inherited from one generation to the next. Such disease is also known as dystrophia mytonica and Steinert¡¦s disease. This genetic defect was an unusual one that ascended from the unknown and shook the scientific community in the early 1990s. Unlike other types of dystrophy, MMD often doesn¡¦t appear to be a problem until adulthood and is characterized by myotonia, a delayed relaxation of the muscles after contraction. It is a form of dystrophy that affects the muscle and numerous organs in our body, while the symptoms widely vary from one person to next. Overall, MMD is a rare disease found in 1 of 8,000 in which ultimately affects 40,000 people throughout the United States.

Myotonic Dystrophy is a multisystem disorder that affects skeletal muscle, smooth muscle, eyes, heart, endocrine system, and central nervous system. It can be classified into two types: DM1 and DM2, also known as Proximal Myotonic Myopathia (PROMM). DM1 is caused by a continuous repeat of CTG located on chromosome 19, while DM2 is caused by the expanded quadruplet of CCTG on chromosome 3. They are both inherited as autosomal dominant trait, differing only by the characteristic of DM2 that contains one or more ion-channel defects. The second type of myotonic dystrophy is rarely found; therefore I will focus my research mainly on type 1. Here, clinical findings have been categorized into three phenotypes: congenital, classical, and mild. In congenital MMD, onset occurs in infancy or early childhood of less then 10 years of age. During infancy, the disease may be characterized by hyponia with sucking and swallowing, and severe generalized weakness at birth, often with respiratory deficiency and early death. Myotonia most often begins in early childhood generally between the ages of five and ten years of age. Muscle weakness, wasting of the face, and distal limbs are the common characteristics; while absence of tendon...
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