Download Down syndrome

Down syndrome
The risk of Down syndrome and other
trisomies increases with the mother’s age.
The risk of having a baby with Down
syndrome is about (1):
1 in 1,300 at age 25
1 in 1,000 at age 30
1 in 400 at age 35
1 in 100 at age 40
1 in 35 at age 45
What causes Down Syndrome?
Down syndrome occurs because of an abnormality characterized by an extra copy of genetic material
on all or part of the 21st chromosome. Every cell in the body contains genes that are grouped
along chromosomes in the cell's nucleus or center. There are normally 46 chromosomes in each
cell, 23 inherited from your mother and 23 from your father. When some or all of a person's cells
have an extra full or partial copy of chromosome 21, the result is Down syndrome.
The most common form of Down syndrome is known as Trisomy 21, a condition where
individuals have 47 chromosomes in each cell instead of 46. This is caused by an error in cell
division called nondisjunction, which leaves a sperm or egg cell with an extra copy of
chromosome 21 before or at conception. Trisomy 21 accounts for 95% of Down syndrome cases,
with 88% originating from nondisjunction of the mother's egg cell.
The remaining 5% of Down syndrome cases are due to conditions called mosaicism and
translocation. Mosaic Down syndrome results when some cells in the body are normal while
others have Trisomy 21. Robertsonian translocation occurs when part of chromosome 21 breaks
off during cell division and attaches to another chromosome (usually chromosome 14). The
presence of this extra part of chromosome 21 causes Down some syndrome characteristics.
Although a person with a translocation may appear physically normal, he or she has a greater
risk of producing a child with an extra 21st chromosome.
What are the signs and symptoms of
Down syndrome?
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Intellectual and Developmental Disabilities (IDDs) is a disability that causes limits on intellectual abilities and adaptive
behaviors (conceptual, social, and practical skills people use to function in everyday lives). Most people with Down
syndrome have IQs that fall in the mild to moderate range of IDDs. They may have delayed language development and
slow motor development.
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Some common physical signs of Down syndrome include:
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Flat face with an upward slant to the eye, short neck, and abnormally shaped ears
Deep crease in the palm of the hand
White spots on the iris of the eye
Poor muscle tone, loose ligaments
Small hands and feet
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There are a variety of other health conditions that are often seen in people who have Down syndrome, including:
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Congenital heart disease
Hearing problems
Intestinal problems, such as blocked small bowel or esophagus
Celiac disease
Eye problems, such as cataracts
Thyroid dysfunctions
Skeletal problems
Dementia—similar to Alzheimer’s
Treatment for Down Syndrome
• Because there is no cure, the goals of Down
syndrome treatment are to control symptoms
and manage any resulting medical
conditions. This includes regular checkups
and screenings, medications, and surgery.
Counseling and support groups are also
aspects of treatment for those who need help
in coping with the emotional and practical
aspects of Down syndrome.
Interesting Facts of Down
Syndrome
Down syndrome is really the only trisomy compatible with life.
Only two other trisomies have been observed in babies born
alive (trisomies 13 and 18), but babies born with these trisomies
have only a 5% chance of surviving longer than one year.
In 90% of Trisomy 21 cases, the additional chromosome comes
from the mother's egg rather than the father's sperm.
Down syndrome is the most common genetic disorder caused
by a chromosomal abnormality. It affects 1 out of every 800 to
1,000 babies.
Down syndrome was originally described in 1866 by John
Langdon Down. It wasn't until 1959 that a French doctor,
named Jerome Lejeune, discovered it was caused by the
inheritance of an extra chromosome 21.