What is Down syndrome and its characteristics

1. WHAT IS DOWN SYNDROME?
By Sylvia Mendez

2. Having Down
syndrome is like
being born normal.
“I am just like you and you
are just like me.
We are all born in different
ways, that is the way I can
describe it.
I have a normal life.”
Chris Durke

3. Down Syndrome
• It is named after John Langdon Down,
the British doctor who described it in 1866.
• Life expectancy is around 50 to 60 years in the developed
world with proper health care.
• Down syndrome is the most common chromosomal anomaly,
occurring approximately once in every 733 births.
• Down syndrome is a genetic disorder caused when abnormal cell division
results in extra genetic material from chromosome 21.
• Down syndrome is a chromosomal condition that is associated with
intellectual disability, a characteristic facial appearance, and weak muscle
tone called hypotonia, in infancy.

4. Different types of Down Syndrome
There are three forms of Down syndrome:
trisomy 21, translocation Down syndrome and
mosaic Down syndrome. Each one of these three
forms has the chromosomal conditions that leads
to certain differences. Genetic tests should be done to know
what type of Down syndrome a baby has.
• Trisomy 21: It is the most common kind, accounting for around 95% of all cases. It is
not a hereditary condition. It is called nondisjunction trisomy 21, because chromosome
21 did not disjoin from itself and divide evenly. Every cell in the body has an extra
chromosome 21.
• Translocation Down syndrome: In 3-4 % of Down syndrome people the extra
chromosome 21 is permanently attached to another chromosome causing translocation.
Sometimes it happens to the number 14 chromosome, or sometimes to the other
number 21 chromosome.
• Mosaic Down Syndrome: It is diagnosed when there is a mixture of two types of cells,
some containing the usual 46 chromosomes and some containing 47. It occurs in 1-2%
of people with Down syndrome. It can result in a milder level of intellectual disability and
less obvious physical characteristics to the other forms of Down syndrome.

5. What causes Down Syndrome?
People unaffected by any chromosomal condition have 23 pair of
chromosomes. They are born with 46 chromosomes in each cell. They have 22
pair plus 2 sex chromosomes (as shown in the picture).
After conception, the fertilized egg begins to divide. In Down syndrome, there
is an error in cell division of chromosomes, called nondisjunction, and it
occurs immediately at conception.

6. What causes Down Syndrome?
In a person with Down syndrome, the extra chromosome is found in all cells.
It is also known as Trisomy 21, indicates an extra 21st chromosome (as shown
in the picture).
In that chromosome, there is 3 chromosomes instead of 2. As a result of the
extra chromosome, 1 of 3 types of Down syndrome can occur.

7. Are there different levels of
Down Syndrome?
• Down syndrome is not an illness, so having Down syndrome
does not make a people sick.
• Each child has their strengths and weaknesses in different
areas.
• Depending on their health issues, there could be very big
difference. If the person with Down syndrome has hearing
issues, or a serious heart condition could not develop the same
strengths as someone who doesn’t has those issues.
• There can be two siblings with Down syndrome in the same family with
different strengths and weaknesses, although they will have more things in
common for being in the same family.

8. Characteristics
People with Down syndrome look like their parents, brothers
and sisters just as much as everyone else does.
However there are some common characteristics that
tend to share for people with Down syndrome.
• A rather flat face with a small nose.
• Low muscle tone.
• Small, abnormally shaped ears.
• Upward slant to the eyes.
• Single deep crease across the center of the palm.
• Fifth finger has only one flexion furrow instead of two.
• Extra space between the big toe and the second toe.

9. Health problems associated with Down
syndrome
• As many as 50% of the children with Down syndrome are
also born with heart defects. Some of them are major,
some are minor. For this reason, all infants with Down
syndrome should have an echocardiogram within the first few
months of life.
• They also have hypothyroidism, slowing of the thyroid
gland.
• They can also have visual problems, like crossed eyes, or
cataracts.
• Hearing impairment is also very common.
• Approximately 10%-12% can also have abnormalities in the gastrointestinal tract or develop
gastroesophageal reflux.
• Due to small muscles in the tongue, it is more difficult for children with Down syndrome to
form words that other people can understand.
• Delayed development and behavioral problems are often reported in children with Down
syndrome.
• All affected individuals experience cognitive delays, but the intellectual disability is usually
mild to moderate.

10. Down syndrome people can learn
skills at a slower pace.
Although people with Down may learn skills at
a slower page, a child with Down syndrome
should still be able to do most things that any
young child can do, such as walking, talking,
dressing and being toilet trained.
Encouragement and support are the best tools
to use to help your child reach developmental
milestones.
Early developmental therapies, such as Early
Intervention, can help babies and
toddlers with Down Syndrome develop skills.

11. Down syndrome affects, but does not
determine development and
achievement in a person.
People with Down syndrome
demonstrate a wide range of
capabilities.
What happens after birth will be far
more important in shaping the
outlook for a person with Down
syndrome than the
occurrence of the extra
chromosome at conception.