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.
Children with Down syndrome
almost always have some degree of developmental delays including: language and memory deficits and other cognitive abnormalities. There is a wide variation
in the communicative and cognitive status of older children 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 youngsters 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 children
with Down syndrome are good athletes and enthusiastic participants in community
life.
Children 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
Instant Feedback:
Children
with Down syndrome often have certain physical characteristics, including
low muscle tone and distinct facial characteristics.
For some
historical perspective, you
can also click here to read Dr. Leshin's article Trisomy 21: The Story of Down
Syndrome