An
Overview of Down Syndrome
Down syndrome is a genetic
condition that can be caused by one of three chromosomal abnormalities.
- The majority of persons
with Down syndrome (93-96%) have trisomy 21, a condition known as "nondisjunction",
in which all body cells have three copies of the 21st chromosome. (illustrated)
- Three to four percent
of the individuals with Down syndrome have translocation, a condition
in which each body cell has 2 sets, plus an extra piece, of chromosome 21.
- Finally, 1-2% of all
persons with Down syndrome have trisomy 21 mosaicism, a condition in
which only some of the bodys cells have three copies of the 21st chromosome.
The National
Down Syndrome Society (NDSS) has an interesting article entitled
"What Causes Down Syndrome."
For some
historical perspective, you
can also click here to read Dr. Leshin's article Trisomy 21: The Story of Down
Syndrome
Adolescents with Down syndrome
almost always have some degree of mental retardation, but it is usually in the
mild to moderate range. There is a wide variation in the communicative and cognitive
status of teens with Down syndrome. Some speak clearly and understandably, others
have significant issues with grammar and articulation, and a small number depend
on augmentative communication devices. Many adolescents with Down syndrome attain
functional levels for reading, writing, and math; others have been less successful
in these areas. While there is usually some degree of impairment in both fine
and gross motor skills, many teens with Down syndrome are good athletes and enthusiastic
participants in community life.
Adolescents with Down syndrome
tend to have certain physical characteristics, including:
- hypotonia, or low muscle
tone
- small, brachycephalic
head (flat in the back at the occiput)
- flattened mid-face
- small, cup-shaped ears
- small mouth with a large
tongue that may protrude
- epicanthal folds in the
eyes
- excess skin folds on
the back of the neck
- wide space between the
first and second toes
- short limbs, hands, and
fingers
- a single crease across
one or both palms
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FEEDBACK:
Adolescents
with Down syndrome often have certain physical characteristics, including low
muscle tone and distinct facial characteristics.
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