Transcript Achondroplasia (Dwarfism)

Achondroplasia (Dwarfism)
By Maddie Alm and
Kirk Webb
Inheritance
Achondroplasia is a dominant gene. It is inherited
in an autosomal dominant pattern (you only need one
copy of the altered gene for the disorder to show up).
Genotypes
There are 3 genotype options for Dwarfism. The
child can inherit a dominant from both parents, a
recessive from the mom and a dominant from the dad,
or a recessive from the dad and a dominant from the
mom. Either way, only one dominant need be present
for the disorder to occur.
Chromosomal Abnormality
Achondroplasia occurs because of a mutation in the
FGFR3 gene, which is in charge of building proteins
that are involved with the growth/maintenance of
bone tissue. The mutation can cause the proteins to be
over active, which affect the bone growth and skeletal
development.
Statistics
About 1 in every 15,000 to 1 in every 40,000 babies
born each year are affected by Achondroplasia.
 It occurs in all races/sexes
It is considered a rare disease and less than 200,000
people in the US are living with it
Passing on the Disease
There is approximately a 75% chance of a person
who has Achondroplasia passing it onto their child. Because
the disease only takes one dominant gene to be present, the
child would have to receive the recessive gene from both
their mother and father, that is, assuming the affected parent
has a dominant and recessive gene present and not two
dominant genes.
Diagnosis Techniques
 Prenatal Ultrasound: to check for excess amniotic
fluid
 Exam for increased front-to-back head size:
indicating hydrocephalus
 X-rays of the long bones: to check for stunted
growth or signs of compression
Symptoms
 Bowed legs
 Decreased muscle tone
 Disproportionate head to body ratio
 Prominent forehead
 Shortened arms and legs
 Short stature
 Spinal stenosis/spinal curvature (kyphosis and lordosis)
Abnormal hand appearance
Life Expectancy
The life expectancy for someone with heterozygous
genes for Achondroplasia is almost normal, generally only ten
years less than the average life expectancy. Homozygous
Achondroplasia is generally more severe and causes lethal
deformities, usually of the rib cage. A person with this form of
Dwarfism doesn’t usually survive their infant years.
Treatments
Current Treatments: At the time, there are no known
permanent treatments for Achondroplasia. Growth
hormones have been tested with little to no long-term
success. At most, growth hormones will work for 2 years
until their effects subside. There is also the surgery of
limb lengthening, which may help lengthen their arms
and legs but does not help with other deformities.
Research
There is some research being done
involving treatments for Achondroplasia. Mice
affected with this disease have been created and
are being used for treatment testing, mostly
involving hormone/drug therapies and different
types of surgeries. The surgeries generally involve
releasing the cartilage compression and
lengthening.
Quality of Life
For the most part, people affected by dwarfism live
normal lives. They may have problems finding clothes,
driving, walking normally, and small things like such but
usually nothing too limiting. Depending on the severity,
some have many back problems and need multiple
surgeries. Otherwise, besides being vertically challenged,
they can do most all things unaffected people can do.
Support Groups
There are many support groups, online and ones
that meet, to help those living with dwarfism. Some groups
groups include:
Little people of America
-www.lpaonline.org
The Billy Barty Foundation
-http://www.rth.org/bbf/
Human Growth Foundation
-http://www.hgfound.org/
It is important to remember
that people affected by
Achondroplasia are normal people.
They are capable of everything we
are, it just requires some adaptations.
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