Webster's New World Medical Dictionary

muscular dystrophy, Becker
A form of muscu-
lar dystrophy (MD) that is similar to Duchenne MD
but milder. Patients with Becker MD produce a little
of the key protein, dystrophin, whereas those with
Duchenne make none. Progression of Becker MD is
slower and symptoms tend to appear later than pro-
gression of Duchenne MD. Both Becker and
Duchenne MD result from mutations in the gene on
the X chromosome that encodes dystrophin.
muscular dystrophy, congenital
A form of
muscular dystrophy (MD) that is present at birth.
Various types of congenital MD have been identified,
each caused by a different genetic error. Congenital
MD can affect males or females. Diagnosis is initially
made via observation of general muscle weakness
(hypotonia). See also 
dystrophy, myotonic.
muscular dystrophy, distal
A rare type of mus-
cular dystrophy (MD) that typically begins in adult-
hood and involves the muscles that are most distant
from the midline, such as those of the hands and
feet. Distal MD is inherited in an autosomal domi-
nant manner and affects males and females. Also
known as distal myopathy and distal hereditary
myopathy.
muscular dystrophy, Duchenne
The best-
known form of muscular dystrophy, which is due to
mutation in a gene on the X chromosome that pre-
vents the production of dystrophin, a normal protein
in muscle. Abbreviated DMD. DMD affects boys and,
very rarely, girls. DMD typically appears after two
years of age with weakness in the pelvis and upper
limbs, resulting in clumsiness, frequent falling, an
unusual gait, and general weakness. Some patients
also have mild mental retardation. As DMD pro-
gresses, the patient may need a wheelchair. Most
patients with DMD die in their 20s because of mus-
cle-based breathing and heart problems. There is no
cure for DMD. Current treatment is directed toward
symptoms, such as assisting with mobility, preventing
scoliosis, and providing pulmonary therapy.