Severe Childhood Autosomal Recessive Muscular Dystrophy
by Michelle Chromey
Muscular dystrophy (MD) is, in essence, a withering away of muscle. It is
an incurable and often fatal disease that afflicts over 250,000 Americans
alone (Corrick 14). MD knows no racial or ethnic boundaries, nor does it
differentiate against gender. There is no age preference, but it is interesting
to note that 2/3 of those who do have MD are children. There are cases,
however, where the symptoms for MD may not appear until a person is in their
20's or 30's, and sometimes the symptoms do not appear until old age (Corrick
The symptoms of MD may go unnoticed at first. There is no pain or warning
so to speak. The only sign is that one's muscles become weak and that normal
physical functions are (or have) become limited. The weakness usually starts
in one extremity then spreads to the rest of the body until a wheel chair
is the only mode of mobility that a person has.
There are at least nine related disorders that are all grouped under the
general name muscular dystrophy. They are all similar in the respect that
voluntary muscle is destroyed and that movement is severely, if not completely,
limited. The extent of the affliction varies according to the specific type
of muscular dystrophy involved (Corrick 25). For the purpose of this article,
the muscular dystrophy chosen is Severe Childhood Autosomal Recessive Muscular
The symptoms of SCARMD are identical to the more well known Duchenne Muscular
Dystrophy. There is slow muscle deterioration of the arms, legs, and hips.
The onset of these symptoms occur early on in a child's life; usually at
2 to 6 years of age (Corrick 86). In addition., a shortened life span into
the early 20's is also expected. One major difference between Duchenne MD
and SCARMD is that in the case of SCARMD, both males and females are afflicted
as opposed to the sex-linked Duchenne MD. (Duchenne MD is also more severe
and more life threatening than SCARMD.)
In people who have SCARMD, the muscle protein called dystrophin is present
but in reduced amounts, thus effecting function of the muscles. Dystrophin
itself is found in the outer membranes of healthy muscle cells and is responsible
for keeping the membrane of the cells intact and functioning properly. The
lack of normal dystrophin levels causes breakdown of the membrane and eventually
muscle death (Corrick 46).
SCARMD, unlike its relative Duchenne MD, can affect females as well as males.
There are several possibilities for this occurrence. One possibility may
be that the female is an expressing carrier for the disease due to X-inactivation.
Other possibilities are that there may be a type of abnormality on the sex
chromosome itself or something called an X / autosome translocation has
occurred (Emery 82). The aforementioned possibilities are somewhat unlikely,
however. With SCARMD, it is more likely that an autosomal recessive form
is expressing itself (hence the name). This would explain why both males
and females would phenotypically show SCARMD; they are autosomal recessive
for that particular gene.
It is interesting to note that there are cases where female carriers of
SCARMD show signs of the disease. The most logical explanation for this
phenomena is the random inactivation of the X chromosome. The presence of
the 'normal' inactivated X chromosome allows for the defective MD carrying
X chromosome to be expressed phenotypically where usually the presence of
the 'normal' chromosome will compensate for the defect. There has been evidence
found where mothers and daughters who are carriers having the symptoms of
MD, suggesting a possible genetic link to the occurrence of X-inactivation
It is highly possible that one can be a carrier for MD and not even realize
it until having children who show the signs and symptoms of MD. In females,
this is due to dosage compensation. Opposite to the case of X inactivation,
the additional X chromosome compensates (over-rides) the abnormal MD X chromosome.
When this is the case, phenotypically one is normal and may even display
normal dystrophin levels. The female, however, is a carrier for the MD gene
and it is highly possible for them to have children with SCARMD.
In the afflicted offspring of a carrier who has SCARMD, the male children
will have a much higher phenotypic risk for showing the disease than the
female children (Emery 85). It is more common for the males to show the
disease because they lack the additional X chromosome on their genes.
Because of this, males usually have a more severe phenotypic appearance
of SCARMD then do females.
There is no cure for Severe Childhood Autosomal Recessive Muscular Dystrophy
(SCARMD) or any form of muscular dystrophy. Due to extensive research and
advances in gene mapping, however, doctors are now able to determine if
the chromosomes of a person are affected with MD. Today it is even possible
to determine if a person is at risk for producing children that could have
For those who are living with MD, the only advisable treatment is physical
therapy, prescribed exercise, and in extreme cases, surgery. These methods
are not a cure; they are only meant for extending the use of the existing
muscles (Corrick 19). Even though there is no cure as of yet, there is still
hope. People who are affected with the disease can still lead relatively
normal lives. Those who have MD are only limited by their inability to cope
and by their own inability to live life to their fullest.
Corrick, James A.. Muscular Dystrophy. New York: Venture Books, 1992.
Emery, Alan E. H.. Duchenne Muscular Dystrophy. New York: Oxford University
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