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Rett's Syndrome
by A. Ross
Like Down's syndrome, and other medical conditions which are
identified with the doctor who first described them in
detail, this neurological disorder is named after the man,
Andreas Rett, who first depicted it less than 50 years ago.
Unlike Down's syndrome, Rett's is not very common, and is
usually found only in girls. Furthermore, also unlike Down's,
Rett's is frequently misdiagnosed. They say the child is
autistic, or has cerebral palsy, developmental delay or
mental retardation. This is not surprising, as the syndrome
was not generally recognized world-wide, until 1983, when a
group of doctors wrote about the condition in a neurological
journal. Four years ago, the International Rett Syndrome
Association (IRSA) convened a panel of experts in the field
to hold a satellite meeting. In this way they pooled all the
criteria for diagnosing typical R.S. and also the atypical
sufferers.
She was a particularly pretty baby, and developed normally
until she was about eighteen months old. Then her parents
began to notice that she was not very interested in toys, and
they took her to a pediatrician. He mentioned that Abby had
low muscle tone, and that they should bring her back for some
tests. By the time he saw her again, Abby was making
continuous hand washing movements, and had stopped standing
up. Moreover, she had almost stopped talking (babbling). A
hearing test showed that she had no hearing loss. The doctor
told them there was nothing they could do but wait for a few
months, by which time the picture would be clearer. Indeed it
was. The lovely child regressed rapidly and was diagnosed as
autistic.
By this time, Abby's head was smaller than it should have
been. Her feet were bluish, always cold, and also smaller
than average. She had occasional seizures, which caused her
parents to think that she had epilepsy and was not autistic,
but the doctors assured her that the two did not contradict
each other. Abby had had a great deal of physiotherapy
through the years, and was able to walk, but it was not quite
a normal gait. She used the front of her feet, or rather her
toes, which is a sign of neurological disturbance, and she
had marked scoliosis (bent back).
It was several years later when the mother was watching her
at the school for autistic children, that she noticed a
difference between her child and the others. This child had
bright intelligent eyes and made eye contact. This is
something autistic children try to avoid at all costs. In
fact, the eye contact was so intense, as to almost force you
to speak to her. The mother had realized all along that her
girl could communicate with her eyes. The girl made it
obvious that she understood what was going on around her. As
this girl is now twenty, the mother had never heard of Rett's
syndrome, and only when Abby was fifteen, did doctors finally
agree that she was an intelligent human being.
What are the causes of Rett syndrome? A person normally has
23 pairs of chromosomes. An extra chromosome is called a
Trisomy. A child with Downs has Trisomy 21. A child with
Edward's syndrome has Trisomy 18 and in Patau's syndrome, it
is the 13th chromosome which is extra. In Rett's there is no
extra chromosome, but a gene (MECP2) on the X chromosome has
gone wrong. This gene is responsible for turning off other
genes when they are no longer needed in development. Most
genes are only active for a specific period in development,
and then close down forever. The mutation in the MECP2 gene
causes the mechanism which turns off the other genes, to
fail.
If genes stay active when they are no longer needed, it is
like an electrician who, instead of installing a network of
carefully placed wires and switches, ignores the wiring plans
and creates a hodgepodge of wires. These cause short circuits
and blown fuses: the mutant gene causes a build up of
proteins and enzymes which become toxic to the central
nervous system. Thus Rett syndrome is a genetic disorder of
developmental arrest. Most people have never heard of Rett
syndrome, because the mutant gene was only discovered in
October 1999, in Texas.
The disorder occurs almost exclusively in girls, although
there have been a few isolated cases reported about boys.
Besides the 23 pairs of chromosomes, females have two X
chromosomes and males have an X and a Y chromosome. If the X
chromosome is damaged in any way, it is almost always lethal
for the male, whereas in the female, the other X chromosome
can compensate. It is a relatively rare disorder, occurring
at most in one per every 10,000 live female births, in some
countries it is less than half that amount. However, there
may be a far higher incidence, since some children remain
misdiagnosed.
Not all children with R.S. follow all the stages, but doctors
now have guidelines on which to base their diagnoses. In the
first stage, the child may seem to be developing normally,
although she will have low muscle tone and show a marked
indifference to outside stimulation. In the next stage, by
the age of about three, the head will cease to grow, the
child will regress rapidly, be irritable and show autistic-
like symptoms. By stage three, the girl loses the ability to
use her hands to pick up and hold things, she can no longer
say words and she makes different hand movements such as
clapping, hand washing or putting hands into her mouth. If
she can walk, her legs are stiff and wide apart and she walks
on her toes. When she is upset, her body trembles. She may
have apnea (forgetting to breathe) or hyperventilation
(huffing and puffing). She will be small for her age, and
very thin, with small feet, which are usually cold. She may
have seizures and marked scoliosis.
As these girls understand what is going on in the world
around them, they must feel very frustrated that the body
cannot obey messages from the brain. The child cannot move as
she would like to, and she cannot speak. She cannot even show
that she understands what people are saying to her, except
with her eyes.
Speech therapy cannot teach this child how to speak, but it
can help her use augmentative communication. Occupational
therapy helps her use her hands, so that she can feed herself
or maybe brush her teeth. She will benefit from as much
physiotherapy as she can get, to help her move better and
even to walk. In some countries, the local council provides
horse riding, hydrotherapy and music therapy. A girl with
R.S. will probably be on some medication to help her with her
breathing and to control he seizures, if she suffers from
them.
Although Rett's is a genetic disease, it is not hereditary,
as far as is known. This should relieve parents who have one
such child, that there is not likely to be a second one in
the same family. With the advance in the understanding of
the human genome, it may not be long till scientists discover
how to replace the faulty gene. The Creator of Cures has
helped researchers and will continue to help them, in their
efforts to discover ever more cures.
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