Down syndrome and Trisomy 21
Dear
Readers,
Today’s
weekend health article is all about Down syndrome. Lots of our readers have
written to request further explanation of what is Down syndrome and how does it
occur. A lot of people know that older mothers are at a much greater risk of
having children with Down syndrome. So, as many women are having children at a
much later stage in their life, it is only normal that they would want to ask
this question and therefore, get more information about Down syndrome. That is
what this article will try to do.
What
is Down syndrome?
Down
syndrome was named after John Langdon Down (1828-1896), who was the first
physician to identify it, way back in 1866.
As
quoted by Mothers 35 Plus,
Down syndrome occurs in about 1 out of every 700-900 live births worldwide to
mothers of all social, economic and racial groups, and is the most common
genetic cause of developmental disability.
According
to the NHS Down syndrome is a chromosomal disorder caused by an error in cell
division and the most common form produces an additional third chromosome 21,
or "Trisomy 21" (it is also known in some countries as Trisomy 21).
There are three forms of Down's syndrome, with 94% being affected with Trisomy
21.
The other
two are:
Trans location, which is caused when a piece of chromosome 21
attaches itself to another chromosome in a cell. It affects around 4% of people
with Down's syndrome. The symptoms of Translocation Down's syndrome are similar
to those of Trisomy 21, but in rare cases it may be possible for a parent to
pass Trans location Down's syndrome on to their child.
Mosaicism is the least common type, affecting around 2% of
people with Down's syndrome. Only some of the cells have an extra copy of
chromosome 21. People with mosaic Down's syndrome may experience less delay
with some aspects of their development.
The
WebMD
explains that when a newborn baby is born with the syndrome, it may have
some disadvantages such as, mental retardation as well as characteristic
physical features.
The
main physical characteristics of someone with Down syndrome is: Slanting eyes,
flatness of head, shortness of neck and nose, as well as a creasing of palms.
Other characteristics include: poor muscle tone and having toes widely spread
apart.
Figure 1. Features of a child having Down syndrome
Child affected with Down syndrome
To
better understand the above features; let’s take a closer look at some pictures
of children with Down syndrome, through the years to teenage hood below in Figure 2,3 and 4.
Figure 2.
Figure 3.
Figure 4.
Each
of the above pictures clearly show the physical features described above.
With this disorder I have also outlined
in this article other health problems that can occur.
Many
kids with Down syndrome are born with heart defects. This means that their hearts
develop differently and don't work as they should, however, these problems can
be fixed by surgery. Some babies may have intestinal problems that also require surgery to
fix.
Kids
with Down syndrome are more likely to get infections that affect their lungs and breathing. When
they do get infections, they often last longer. They may have eye or ear problems or digestion problems like
constipation. Some may develop leukemia, a type of cancer. Each person with
Down syndrome is different and may have one, several, or all of these problems.
Kids
with Down syndrome also tend to grow and develop more slowly than other
children do. They may start walking or talking later than other babies. Special
help, such as physical therapy and speech therapy, can give kids a boost with
their walking and talking skills.
What causes Down syndrome?
When you examine a new born baby or fetus to see
if it has any additional problems, doctors look at what is called their
karyotype. This is simply a picture of a person's chromosomes in a karyotype
with Down syndrome below.
Figure 5. Notice that
there is an extra chromosome next to another chromosome in pair 21
Most
people have 23 pairs of chromosomes, for a total of 46. But a baby with Down
syndrome has an extra chromosome (47 instead of 46) or one chromosome has an
extra part. This extra genetic material causes problems with the way their
bodies develop.
Why are older women at risk of having
children with Down syndrome?
The
article in, My
Child without Limits stated that doctors have found out that it is more
likely for an older mother to have reproductive cells with an extra copy of
chromosome 21. Therefore an older mother is more likely to have a baby with
Down syndrome than a younger mother. The likelihood of Down syndrome continues
to increase as a woman ages, so that by age 42, the chance is one in 60 that a
pregnant woman will have a baby with Down syndrome and by age 49, the chance is
one in 12.
Because
the chances are so high of having a child with Down syndrome, many Doctors
recommend that women over age 35 have pre-birth testing for the condition. This
is called Amniocentesis.
Testing the baby before it is born to see if he or she is likely to have Down syndrome
allows parents and families to prepare for the baby’s special needs. To find
out more information on the Amniocentesis test, just look at Baby center.
So readers. I hope my article helped you find out all about Down syndrome, and I have answered all the questions that you had in your mind. If you need more information that I did no cover in the news story please click on the link below.
Matija
Kondic