Transcript Fragile X Syndrome

Julia Brown
3/6/13
3rd Period
Other Common Names:
FXS
Martin-Bell Syndrome
Escalante’s Syndrome
- Fragile X Syndrome is caused by an abnormality in the
FMR1 gene, located on the X
chromosome.
The abnormality is an expansion of that gene. An
expansion is when part of the gene is repeated when it
is not supposed to be.
The size of the expansion determines if
the person is only a carrier (meaning they just have the
premutation) or if
they show signs of the disorder.
Size of expansion determines
how the person is affected
This represents an X chromosome with a
normal fragile X gene (unexpanded - up to 60
repeats is considered normal)
An X chromosome with a small expansion of
the fragile X gene (60-200 repeats) A person
with this chromosome is a carrier and has the
premutation.
This X chromosome has a large expansion
(over 200 repeats) and is considered a full
mutation.
Since both males and females have an X
chromosome, either parent can pass
this condition
to their children.
However, the gene is usually passed
from mother to son.
Target Population
If a female has the expansion on the FMR1 gene,
she is less likely to be affected because her 2nd X
chromosome can potentially balance out the
effects of the mutated gene.
If a male has the expanded FMR1 gene, the Y
chromosome has no way to counter any of the
mutation’s effects.
1 in 4,000 males affected
1 in 8,000 females affected
Since the daughters
have a 2nd X
chromosome, they
are less likely to show
effects of Fragile X.
Along with being more likely to
get it, males are affected more
seriously than females are.
The actual cause of the symptoms of
fragile X is when the abnormally
expanded gene causes it to turn off.
This
results
in a
failure
to
produce
the
FMRI1
protien
.
This
failure to
produce
the FMR1
protein
disrupts
the
nervous
system
functions
The nervous system deals a lot with
• interpreting sensory information,
• thinking
• perceiving
• understanding language
Fragile X syndrome mostly affects the central nervous
system, as all of the above are affected by it.
People with fragile x often have cognitive disabilites
and developmental delays, which all deal with the
nervous system.
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Symptoms
Intellectual disabilities - ranging from mild learning
problems to retardation
ADHD
Anxiety
Unstable mood
Autism or autistic behaviors
hypersensitivity to bright lights or loud sounds
Lanugage problems
Epilepsy (affects 25% of people with fragile x)
Emotional and behavioral problems
Physical Symptoms
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Long face
large ears
flat feet
low muscle tone
hyperextensible joints
Prognosis
It is best if fragile x is diagnosed early on.
This way the affected child can receive
the proper special care when it comes to
education and development.
People with with fragile x are expected to
live normal life spans.
Treatments
There are no specific treatments, but
rather proper guidance, training, and
education can help those affected
function as well as possible.
Special treatment
centers and
organizations:
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Founded in 1994
Helps by funding grants at
universities
Runs mainly on volunteers
Work to find a cure and to
raise awareness
"FRAXA's mission is to
accelerate progress
toward effective
treatments and
ultimately a cure for
Fragile X, by directly
funding the most
promising research."
Fragile X Research
and Treatment Center
• At UC Davis and University of
Washington in Seattle
• Funded by the National Institutes of Child
Health and Development (NICHD)
• Studies individuals with fragile x from
birth to adulthood
Resource
s
Fragile x syndrome. (n.d.). Retrieved from
http://www.fragilex.org/fragile-x-associateddisorders/fragile-x-syndrome/
Fragile x syndrome. (2013, February 25).
¨
Retrieved from http://ghr.nlm.nih.gov/condition/
fragile-x-syndrome
Fragile x syndrome. (2005, July). Retrieved
from http://www.geneticalliance.org.uk/docs/
translations/english/11-fraxt.pdf