Muscular Dystrophy(MD) is a rare inherited disease of the nerves and muscles that occurs mostly in males. The most common type of muscular dystrophy causes rapid muscle wasting and progressive weakness early in life, usually between the ages of 2 and 5.Muscle wasting begins in the shoulder and pelvic areas. Fat and connective tissue may grow into muscles and cause abnormal elargement (hypertrophy), especially in the calf muscles of the legs. Within several years muscular dystrophy affects the muscles of the upper body and arms. Eventually all the major muscles are affected.
MD can occur at different ages of a person's life, ranging from infancy to middle age or later. The type of the disease is based in part on when in a person's life MD appears, as well as the severity of the muscle weakness, which muscles are affected, the rate of symptom progression, and the way the disease arises. Some forms affect only males; others affect both males and females. Some sufferers still enjoy a normal life span with mild symptoms that progress very slowly, while others experience fast and severe muscle weakness and wasting, dying in their late teens to early 20s.
There are nine major forms of muscular dystrophy:
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Myotonic (also called MMD or Steinert's disease). The most common form of muscular dystrophy in adults, myotonic muscular dystrophy affects both men and women, and it usually appears any time from early childhood to adulthood. In rare cases, it appears in newborns (congenital MMD). The name refers to a symptom, myotonia -- prolonged spasm or stiffening of muscles after use. This symptom is usually worse in cold temperatures. The disease causes muscle weakness and also affects the central nervous system, heart, gastrointestinal tract, eyes and hormone-producing glands. In most cases, daily living isn't restricted for many years. Sufferers have a decreased life expectancy.
- Myotonic
- Duchenne
- Becker
- Limb-Girdle
- Faciscapulohumeral
- Congenital
- Oculopharyngeal
- Distal
- Emery-Dreifuss
Duchenne. The most common form of muscular dystrophy in children, Duchenne muscular dystrophy affects only males. It appears between the ages of 2 and 6. The muscles decrease in size and grow weaker over time yet may appear larger. Disease progression varies, but many sufferers need a wheelchair by the age of 12. In most cases, the arms, legs and spine become progressively deformed. Some sufferers are mildly retarded. Severe breathing and heart problems mark the later stages of the disease. Sufferers usually die in their late teens or early 20s.
Becker. This form is similar to Duchenne muscular dystrophy, but the disease is much milder: symptoms appear later and progress more slowly. It usually appears between the ages of 2 and 16 but can appear as late as age 25. Like Duchenne muscular dystrophy, it affects only males and causes heart problems. Disease severity varies. Sufferers can usually walk into their 30s and live further into adulthood.
Limb-Girdle. This appears in the teens to early adulthood and affects males and females. In its most common form, it causes progressive weakness that begins in the hips and moves to the shoulders, arms and legs. Within 20 years, walking becomes difficult or impossible. Sufferers typically live to mid to late adulthood.
Facioscapulohumeral. Facioscapulohumeral refers to the muscles that move the face, shoulder blade and upper arm bone. This form of muscular dystrophy appears in the teens to early adulthood and affects males and females. It progresses slowly, with short periods of rapid muscle deterioration and weakness. Severity ranges from very mild to completely disabling. Walking, chewing, swallowing and speaking problems can occur. About 50% of sufferers can walk throughout their lives. Sufferers usually live a normal life span.
Congenital. Congenital means present at birth. Congenital muscular dystrophies progress slowly and affect males and females. The two forms that have been identified -- Fukuyama and congenital muscular dystrophy with myosin deficiency -- cause muscle weakness at birth or in the first few months of life, along with severe and early contractures (shortening or shrinking of muscles that causes joint problems). Fukuyama congenital muscular dystrophy causes abnormalities in the brain and often seizures.
Oculopharyngeal. Oculopharyngeal means eye and throat. This form of muscular dystrophy appears in men and women in their 40s, 50s, and 60s. It progresses slowly, causing weakness in the eye and face muscles, which may lead to difficulty swallowing. Weakness in pelvic and shoulder muscles may occur later. Choking and recurrent pneumonia may occur.
Distal. This group of rare diseases affects adult men and women. It causes weakness and wasting of the distal muscles (those farthest from the center) of the forearms, hands, lower legs, and feet. It is generally less severe, progresses more slowly and affects fewer muscles than other forms of muscular dystrophy.
Emery-Dreifuss. This rare form of muscular dystrophy appears from childhood to the early teens and affects only males. It causes muscle weakness and wasting in the shoulders, upper arms and lower legs. Life-threatening heart problems are common and can also affect carriers -- those who have the genetic information for the disease but do not develop the full-blown version (including mothers and sisters of sufferers). Contractures, or muscle shortening, occur early in the disease. Weakness can spread to chest and pelvic muscles. The disease progresses slowly and causes less severe muscle weakness than some other forms of muscular dystrophy.
Who is Affected by MD?
MD is not contagious. MD happens because of a problem with a person's genes.
A diagnosis will inevitably affect everyone who is close to the child: parents, grandparents, extended family members and friends. Keep in mind that reactions will vary. Ways of coping with such serious news differ from person to person. For many, anger, shock and sadness are the prevailing feelings. Sometimes these feelings are directed at the doctor who gave the diagnosis, sometimes parents blame themselves for passing on the mutated gene that causes MD, or one parent may blame the other. Often people blame God. It will take time to come to terms with the diagnosis. Keeping a solid support system in place and facing fears with courage and optimism can often reduce the anxiety and stress associated with these feelings.
What Causes MD?
The type of MD is determined by which gene is defective. Most of the muscular dystrophies are a form of inherited disease called X-lnked disorders or genetic diseases that mothers can transmit to their sons even though th mothers themselves are unaffected by the disease.
Men carry one X chromosome and one chromosome. Females carry two X chromosomes. Thus, in order for a girl to become affected by muscular dystrophy, both of her X chromosomes would have to carry the defective gene. A few muscular dystrophies aren't inherited at all and occur bucause of a new gene abnormality or mutation.
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