What Is Down Syndrome?

Every year, one child in every 800 to 1,000 births willand some have 47. Thus, the alternating pattern
be born with a condition known as Down syndrome.gives it the name Mosaicism.
Down syndrome is a disorder in which the child hasPeople with Mosaicism may not be as affected with
extra genetic material. This extra genetic materialthe physical and/or developmentally delayed
causes the baby to develop differently in the womb.characteristics of those born with the other two
This abnormal development occurs during the earlyforms of Down syndrome.
stages of cell division, soon after conception.Common Physical Traits
There is no known reason for Down syndrome or aBabies with Down syndrome are usually diagnosed at
cure for it.birth or shortly thereafter. Because Down syndrome
The disorder came by its name when an Englishaffects a child physically, there will be certain features
physician, John Langdon Down, published a descriptionthat an alert doctor or nurse will pick up on. Most
of the characteristics of a person with the conditionchildren with the syndrome will have some or all of
in 1886. Since Dr. Down was the first person to givethese traits.
the syndrome a name, the disorder is known asAmong the most common physical characteristics are:
Down syndrome.- Low muscle tone
The Common Forms of Downs- Small nose and flat nasal bridge
There are three distinct forms of Down syndrome.- An upward slant to the eyes (almond shaped)
The most common form is Trisomy 21. This is when- Small skin folds on the inner corner of the eyes
a child has an extra chromosome 21.- Tongue large for size of child's mouth
Instead of having 46 chromosomes in each cell (23- Small, sometimes abnormally shaped ears
from the father and 23 from the mother), he has 47.- A single crease across the center of the palm
Ninety-five percent of children born with Down- Fifth finger, the pinky, has only one crease instead
syndrome have Trisomy 21.of two
Translocation is another form of Down syndrome- Larger than normal space between the large and
and makes up 3 to 4% of the population of peoplesecond toe
with the disorder. Translocation occurs when part of- Joints are hyper flexible, able to extend greater
chromosome 21 breaks off and attaches to anotherthan average
chromosome, changing the genetic makeup. In thisThese physical traits are characteristic of a baby with
form of Down syndrome, each cell has the normal 46Down syndrome, but in order to determine if a child
chromosomes, but there is extra genetic materialdoes indeed have the disorder, a chromosome
from the broken off chromosome.analysis will need to be performed.
The third and final form is called Mosaicism, and is theThis is done by taking blood from your baby and the
rarest form of Down syndrome, occurring in only 2%analysis will be done in a laboratory. Your doctor will
of all cases. Mosaicism happens when some of thenotify you of the results.
cells in the forming embryo have 46 chromosomes,