Definition and General Facts
Duchenne muscular dystrophy is genetic degenerative muscle disease characterized by weakness and muscle atrophy without nervous system involvement.
Although Duchenne muscular dystrophy is an inherited disease, and present from the initial stages of fetal development, there is no physical indication at birth that the baby is anything less than perfectly formed.
Duchenne muscular dystrophy is the most common muscle disorder in children and occurs in approximately one in every five thousand boys born.
Problems are not usually noted until eighteen months to four years of age.
Common Symptoms
Some common symptoms include:
1) do not walk until eighteen months of age or later
2) have difficulty climbing and getting up from the floor
3) fall frequently
4) walk up on the toes
5) have enlarged calf muscles. This enlargement of the calf muscles is called pseudohypertrophyö and is due mainly to an increase in fatty tissue in the muscle.
Within several years, Duchenne muscular dystrophy affects the muscles of the upper trunk and the arms. Eventually, all the muscles are affected.
Between the ages of 3 and 7, parents may be falsely encouraged by seeming improvement. However, this improvement is probably due to normal growth and development. Around age 8 or 9 weakness progresses rapidly and ends up in the inability to walk or even stand alone.
In the late stages of muscular dystrophy there is a noticable shortening of the muscles and a loss of muscle tissue. It may result in an inability to move major joints of the body.
Curvature of the spine, known as scoliosis, also occurs.
Because of the curvature of the spine, lung capacity decreases and makes
the child more susceptible for respiratory infections.
Cause
Duchenne muscular dystrophy is due to a mutation on the X-chromosome, which means it is an inherited X-linked trait. As a result, only boys are usually affected.
Scientists discovered exactly what genetic material was missing from the chromosome. Once they found what piece of genetic material was missing, they were able to discover what protein this piece of genetic material makes. They discovered the protein and named it dystrophin.
The deletion of the dystrophin gene causes a lack of production of dystrophin. Dystrophin is a protein associated with the membrane surrounding each muscle fiber. Dystophin holds the shape of the muscle fiber.
Diagnosis
Three different methods for diagnosing Duchenne muscular
dystrophy:
1. Creatine kinase (CK) test- CK is an enzyme that is
importnat for energy production
within the muscle fibers. If a muscle fiber is damaged
by a disease process such as
muscular dystrophy, some of the CK leaks out into the
blood. Normally there is only
a small amount of CK in the blood, but in a person with
muscular dystrophy there is
10 to 100 times the normal amount of CK in the blood.
2. Electromyography (EMG)- When muscles contract there
is electricity flowing
through the muscle tissue. An abnormal muscle has an
abnormal pattern of
electricity that can be recognized and recorded using
special equipment. An EMG
involves putting a small needle through the skin into
the muscle and recording the
pattern of electricity in the muscle when it is contracting.
3. Muscle biopsy- A small piece of muscle is removed and
cut into very thin slices. It
is stained with a series of special dyes to show the
different types of muscle fibers,
and studied by a pathologist.
Treatment
Physical Therapy
-exercises
-adaptive equipment
-orthopedic devices
The Parent Project offers a book called Physical Therapy Management of Muscular
Dystrophy, written by Mary Beth Deering, P.T.
Medications and Vitamins
-Prednisone-could cause initial improvement in strength and slow progression of the
disease for at least three years.
-Vitamin Therapy
Gene Therapy
Gene therapy is a term used to describe a growing field
of medicine involving manipulation of cells to treat or cure a variety
of inherited diseases. The object of gene therapy for Duchenne muscular
dystrophy is to put a healthy dystrophin gene in the boys muscle cells
to replace the bad cells. This is not finalized yet. More research is needed.
Links
Duchenne Muscular Dystrophy Information Site