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Muscular Dystrophy or MD is a
group of genetic, hereditary muscle diseases that cause progressive muscle weakness. There are nine main types and 100s of
diseases with similarities to MD. The nine main types include:
· Duchenne
· Becker
· Limb
girdle
· Congenital
· Facioscapulohumeral
· Myotonic
· Oculopharyngeal
· Distal
· Emery-Dreifuss
MDs are characterized by
progressive skeletal muscle weakness, defects in muscle proteins, and death of muscle cells and tissue.
Mode
of Inheritance
The different types of MD
follow slightly different modes of inheritance. For example, the mutated gene that causes Duchenne MD, the most common of
the nine types, can be found on the X chromosome. Because the X chromosome is one of the two sex chromosomes, MD is considered
to be a sex-linked disorder. Since males only have one X chromosome, they will always express the disease. On the other hand,
for a female to express the disease, the mutated gene would have to be present in both X chromosomes. The result is that males
inherit and express the disease much more often than females.
Because
the gene for MD is X linked fathers cannot pass it on to their sons. This means that almost all of the males affected by MD
inherited the disease from their mother, who was carrying it on one of her X chromosomes. There a few rare cases when the
disease is caused by a new mutation in the gene.
Some of the symptoms of MD
include:
·
Progressive muscle weakness
·
Poor balance
·
Difficulty walking
·
Pain in the calves
·
Limited movement
·
Difficulty breathing
·
Drooping eyelids
*Heart problems, scoliosis,
and obesity can also result from certain forms of MD.
None
of the forms of MD have specific treatments. Physical therapy, orthopedic appliances (wheelchairs and leg braces), and corrective
surgery may be used to provide the individual with better quality of life, and some of the heart problems associated with
certain forms of MD may require a pacemaker. Unfortunately, there is no known cure for MD.
Diagnosis
The diagnosis of MD is based on the results of a muscle biopsy. Sometimes just a DNA blood test is sufficient.
Because the different forms of MD affect different muscle groups, a patient’s medical history and a physical can help
the doctor determine the type of MD.
Prognosis
The prognosis for individuals suffering from MD varies based on the type and progression of the disease. Some
cases are mild and muscle weakness progresses slowly over a normal lifespan. Others are more severe resulting in functional
disability, and inability to walk. Children with MD sometimes die as babies, while others make it adulthood with only mild
disabilities. The most severe forms of MD occur in young children, but it can
affect adults as well.
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