Friedreich’s ataxia
DOCTOR FISHER: Friedreich’s ataxia is passed
on in families in a
way known as autosomal recessive. An autosomal recessive
disorder is going to be relatively rare as you need both
parents to be carriers.
Friedreich’s ataxia is an inherited disease of the central nervous
system in which there is a progressive deterioration of coordination
and muscle control. It is caused by a single defective gene. It is a
recessive disorder and very rare. Onset
usually occurs between 5 and 20 years of age, the highest incidence
being at puberty. Currently there is no cure.Friedreich’s ataxia
is recessively inherited, like many inherited genetic disorders. It
is a relatively rare disorder affecting about one person in 48 000 in
the UK (approx. 1500 people). This corresponds to about 1% of the population
being carriers. It is important to contrast the low risk of having an
affected child with the relatively high frequency of carriers. In recessive
genetic disorders like Friedreich’s ataxia, carriers do not exhibit
symptoms. Parents who are carriers have one copy of the abnormal gene,
which may be passed on to their children. The recessive gene may be
handed on for generations without effect. When two people, who each
carry one defective copy of the gene, have children, each child has
the following genetic odds:
- a 25% chance of being unaffected,
- a 50% chance of being a carrier without showing symptoms,
- a 25% chance of having the disease.
RYAN: OK…um…I know, Doctor, that Friedreich’s
ataxia follows a classic Mendelian pattern. That is to say, I have
a one in four chance of having this disorder, and a two in four chance
that I will be carrying the rogue gene and pass it on to my own children.
WHAT ARE THE SYMPTOMS?
Friedreich’s ataxia usually starts to affect individuals at
between 5 and 20 years of age. The commonest age of onset is around
puberty. Balance and coordination are affected first.
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Annie practises her ball
skills |
ANNIE:[Annie is practising ball skills. Something
feels wrong. She keeps making mistakes.] What’s up with me?
It can’t be nerves - I don’t get nervous. It’s not
wobbly muscles anyway. What is it? What is it that feels wrong? It’s
not all the time. Look, I can usually do this till… till all
the cows go home to MacDonald’s… one, two, three, no…there
it is again. Sort of a gap… a gap opens up… I go to do
something. I think I’m doing it… but it doesn’t
happen…
What may just seem like clumsy movements may not be diagnosed until
symptoms become pronounced, often over a period of years. Lack of coordination
affects both arms and legs. Walking becomes difficult and is compensated
by walking with feet placed further apart to maintain balance. Friedreich’s
ataxia is progressive but not always fatal, and does not always result
in total disability. That said, the disorder can shorten life due to
respiratory problems (a combination of respiratory paralysis and pneumonia).
When death does occur it is usually as the result of heart failure.
Coping with a progressive disorder often causes feelings of depression,
anger, frustration and other emotional symptoms.
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Annie is nervous |
ANNIE: I get up, feel my legs, with my mind. Run
my mind over my legs for hours before I get out of bed. Will they
let me down today? Sometimes - if I think there’s no one downstairs
- I come down. I get out those pamphlets from the drawer. I know every
word of what I’ve got to look forward to – clumsiness
soon, the hands will go, then other muscles – speech slurring,
like a drunk – takes me all bloody morning to say good morning.
Then incontinence – what will that be like? Wheelchair next.
Can’t talk, can’t hold a pen. Diabetes – perhaps
curvature of the spine – maybe. Heart failure – maybe
if I’m lucky.
WHAT CAUSES FRIEDREICH’S ATAXIA?
To date, the exact cause of Friedreich’s ataxia is still not
certain, although research has tracked down the position of the abnormal
gene to Chromosome 9. It is thought that the gene responsible for Friedreich’s
ataxia causes the body to produce an abnormal protein. For an unknown
reason, this causes particular nerve cells to degenerate, thereby reducing
nerve signals to the muscles. The cells affected are primarily in the
brain and spinal cord. As the nerve cells continue to degenerate, muscles
become less and less responsive to commands from the brain, causing
coordination problems to become more pronounced.
HOW IS IT DIAGNOSED?
Diagnosis is based on a person’s medical history, family history
and a complete neurological evaluation. To supplement the evaluation,
various tests may be performed which assist in the diagnosis, and rule
out other disorders that may present similar symptoms.
In the Spring of 1996 the gene which causes Friedeich’s ataxia
was finally identified. Genetic testing is relatively straightfowrd
as almost all affected families seem to have a similar form of the rogue
gene.
FRIEDREICH’S ATAXIA GROUP
The Friedreich’s Ataxia Group was formed in 1964 by parents of
young people with Friedreich’s ataxia, doctors and concerned friends
with the initial objectives of promoting greater public awareness of
Friedreich’s ataxia; this was
achieved by raising money, research and assisting carers and their families,
particularly in an advisory capacity. Today the group has over 2500
members and its own office staffed by workers and volunteers. The Group
has its own quarterly newsletter, and as well as nationwide fundraising,
it organizes PHAB courses for teenagers with Friedreich’s ataxia,
group holidays abroad for older Friedreich’s ataxia sufferers
and ‘talk-ins’ for discussion and the dissemination of advice.
The Group has its own medical advisory committee to oversee the research
it finances and vigorously attempts to stimulate appropriate medical
research.
Friedreich’s Ataxia Group
The Stable
Wiggins Yard
Bridge Street
Godalming GU7 1HW
Tel: 01483 417111
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