
What
is Down Syndrome?
Down
syndrome occurs when an individual has three, rather than two, copies
of the
21st chromosome. This additional genetic material
alters the course of development and causes the characteristics
associated with Down
syndrome.
Down
syndrome is the most commonly occurring chromosomal condition. One in
every 733
babies is born with Down syndrome.
Down
syndrome occurs in people of all races and economic levels.The
incidence of births of children with Down syndrome increases with the
age of
the mother. But due to higher fertility rates in younger women, 80
percent of
children with Down syndrome are born to women under 35 years of age.
How is Down Syndrome
Diagnosed?(What
Causes Down Syndrome)
The human body is made of cells.
All cells contain a center, called a nucleus, in which genes are
stored. Genes,
which carry the codes responsible for all
our
inherited characteristics, are grouped along rod-like structures called
chromosomes. Normally, the nucleus of each cell contains 23 pairs of
chromosomes, half of which are inherited from each parent. Down
syndrome occurs
when some or all of a person's cells have an extra full or partial copy
of
chromosome 21.
The most common form of Down syndrome is
known as Trisomy
21. Individuals with Trisomy 21 have 47
chromosomes instead of the usual 46 in each of their cells. The
condition
results from an error in cell division called nondisjunction.
Prior to or at conception, a pair of 21st chromosomes in either the
sperm or
the egg fails to separate. As the embryo develops, the extra chromosome
is
replicated in every cell of the body. This error in cell division is
responsible for 95 percent of all cases of Down syndrome.
Down syndrome also encompasses two other
genetic conditions: mosaicism and translocation. Mosaicism
occurs when nondisjunction of chromosome
21 takes
place in one of the initial cell divisions after fertilization causing
a person
to have 46 chromosomes in some of their cells and 47 in others. The least common form of Down syndrome, mosaicism,
accounts for only 1 to 2 percent of all cases. Translocation,
which
accounts for 3 to 4 percent of cases of Down syndrome, occurs when part
of
chromosome 21 breaks off during cell division and attaches to another
chromosome, usually chromosome 14. While the total number of
chromosomes in the
cells remains 46, the presence of an extra part of chromosome 21 causes
the
characteristics of Down syndrome.
The cause of the extra full or partial
chromosome is still unknown. What
we do know that it is not caused by environmental factors or anything
the
mother does before or during her pregnancy. Maternal age is the only
factor
that has been linked to an increased chance of having a baby with Down
syndrome
resulting from nondisjunction. A
35-year-old woman
has a one in 353 chance of conceiving a child with Down syndrome. By
age 40,
the incidence has increased to one in 85. However, because younger
women have
higher fertility rates, more babies with Down syndrome are born to
women under
the age of 35. Once a woman has given birth to a baby with Down
syndrome, the
chance of having a second child with Down syndrome might be increased
by an
additional 1 percent.
Maternal age, however, is not linked to
the chance of having a baby with
translocation. Most cases are sporadic, chance events, but in about one
third
of translocation cases, one parent is a carrier of a translocated
chromosome. For this reason, the chance of translocation in a second
pregnancy
is higher than that seen in nondisjunction.
Most Common Characteristics:
People
with Down syndrome have an increased risk for certain medical
conditions such
as congenital heart defects, respiratory and hearing problems,
Alzheimer's
disease, childhood leukemia, and thyroid conditions. Many of these
conditions
are now treatable, so most people with Down syndrome lead healthy lives.
A
few of the common physical traits of Down syndrome are low muscle tone,
small
stature, an upward slant to the eyes, and a single deep crease across
the
center of the palm. Every person with Down syndrome is a unique
individual and
may possess these characteristics to different degrees or not at all.
Life
expectancy for people with Down syndrome has increased dramatically in
recent
decades - from 25 in 1983 to 60 today.
People
with Down syndrome attend school, work, participate in decisions that
affect
them, and contribute to society in many wonderful ways.
All
people with Down syndrome experience cognitive delays, but the effect
is
usually mild to moderate and is not indicative of the many strengths
and
talents that each individual possesses.
Quality
educational programs, a stimulating home environment, good health care,
and
positive support from family, friends and the community enable people
with Down
syndrome to develop their full potential and lead fulfilling lives.
How do you
treat Down Syndrome?
Since Down Syndrome is a genetic
condition and not a disease, it can not be altered. However, there are
some
alternative treatments that are mentioned.
What kind of
alternative therapies are available?
Various traditional and alternative
treatment
methods for Down syndrome have been popular over the years including
the use of
pituitary extract, glutamic acid, thyroid
hormone,
5-hydroxytryptophan, dimethyl sulfoxide
(DMSO), dihydroepiandosterone, sicca
cell therapy and growth hormone. Some treatments, such as sicca
cell therapy, have proven to be dangerous. More recently, the
orthomolecular approach to treatment using various
combinations of vitamins,
minerals, enzymes and amino acids have been revisited.
Generally,
alternative therapies for Down syndrome fall in and out of popularity
through
the years.
What kinds of claims are made
about alternative therapies?
Many of the alternative therapies,
particularly those termed "holistic," are aimed at treating the body
as a whole, rather than as a disease or a symptom. Most of these
therapies have
not made claims for people with Down syndrome that have been any
different from
the claims they have made for the general population. However, some
therapies
have claimed to improve motor and cognitive functions as well as growth
and
overall activity specifically in persons with Down syndrome. Some have
claimed
to change some of the physical features of
Down
syndrome to a more "normalized" appearance and to reverse
intellectual disability.
Have any of these claims been
scientifically proven?
Although varied treatments have been in
use
for many years, available research studies are often limited.
Observation and
experiences are often the first step in the research process. However,
while
anecdotal successes can be exciting and increase popular interest in a
particular therapy, rigorous scientific study is still the benchmark by
which
treatments are held as to their effectiveness and safety. As more and
more physicians
in the U.S. are becoming familiar with alternative and complementary
treatments, parents should discuss any potential new treatment with
their
doctors to learn more about any known benefits and side effects.
Is the use of alternative
therapies recommended?
NDSS and other organizations interested in
the welfare of persons with Down syndrome, such as the National Down
Syndrome
Congress, the Down Syndrome Medical Interest Group, and the American
College of
Medical Genetics, can only recommend treatments and therapies for
individuals
with Down syndrome that have undergone thorough scientific study. This
includes
large, randomized, double-blind research
studies that
evaluate the safety and efficacy of the treatment in question. These
organizations are not discouraging parents from making decisions they
feel are
right for their child. However, they feel that benefits, risks, and
side
effects must be clearly shown before they can recommend any of the
treatments
in good conscience. The difficulty is that good research studies take
time and
money. NDSS has encouraged the National Institute of Child Health and
Human
Development to consider this type of research. The National Institutes
of
Health have also created a separate division, the Office of Alternative
Medicine, to provide
information on alternative
therapies to the general public and begin carefully evaluating such
treatments.
About
National Down Syndrome Society:
The National Down Syndrome
Society envisions a world in which all people with Down syndrome have
the
opportunity to enhance their quality of life, realize their life
aspirations,
and become valued members of welcoming communities.
The mission of the National Down Syndrome
Society is
to be the national advocate for the value, acceptance and inclusion of
people
with Down syndrome..
Our activities include:
- Shaping and advocating for improved public
policy, increased public resources and services for people with Down
syndrome.
- Working in partnership with our affiliates
and other support organizations.
- Improving educational opportunities for
individuals with Down syndrome.
- Advancing basic, clinical and applied
research.
- Implementing a national public awareness
strategy.
We have over 275
affiliate
groups across the country. These affiliates are local parent support
groups and
other organizations that work on behalf of people with Down syndrome
and their
families.
NDSS is one of the largest non-government supporters of Down syndrome
research
in the United States. Since its inception, the Society has provided
millions of
dollars towards advancing knowledge and research about Down syndrome,
supporting the work of more than 45 scientists. For
more i