What Is Down Syndrome?
Down syndrome (sometimes called Down’s
syndrome) is a condition in which a child is born with an extra copy of their 21st
chromosome (hence its other name, Trisomy 21). This causes physical and mental
developmental delays and disabilities.
Many of the disabilities are lifelong
and they can also shorten life expectancy. However, people with Down syndrome
can live healthy and fulfilling lives. Recent medical advances as well as
cultural and institutional support for people with Down syndrome and their
families provide many opportunities to help overcome challenges.
What Causes Down Syndrome?
According to the National Down Syndrome Society (NDSS), about 1 in 700 babies in the United States is born
with Down syndrome. It’s the most common genetic disorder in the United States.
A quick explanation of basic genetics
can help you understand how it happens. In all cases of reproduction, both
parents pass their genes on to their children. These genes are carried in
chromosomes. When the baby’s cells develop, each cell is supposed to receive 23
pairs of chromosomes (46 chromosomes total). Half of the chromosomes are from
the mother and half are from the father.
In children with Down syndrome, one of
the chromosomes doesn’t separate properly. The baby ends up with three copies,
or an extra partial copy, of chromosome 21, instead of two. This extra
chromosome causes problems as the brain and physical features develop.
Types of Down Syndrome
There are three types of Down
Trisomy 21 means there is an extra
copy of chromosome 21 in every cell. This is the most common form of Down
Mosaicism occurs when a child is born
with an extra chromosome in some but not all of their cells. People with mosaic
Down syndrome tend to have fewer symptoms than those with trisomy 21.
In this type of Down syndrome,
children have only an extra part of chromosome 21. There are 46 total
chromosomes. However, one of them has an extra piece of chromosome 21 attached.
Will My Child Be at Risk for Down
Certain parents have a greater risk of
giving birth to a child with Down syndrome. Mothers age 35 and older are more likely to have a baby with Down syndrome
than younger mothers. The risk increases the older the mother is. Research
shows that paternal age also has an effect — one 2003 study found that fathers over 40 had twice
the risk of having a child with Down syndrome.
Other parents who are at greater risk
of having a child with Down syndrome include:
- people with a
family history of Down syndrome
- people who
carry the genetic translocation
It’s important to remember
that no one of these factors mean that you will definitely have a baby with
Down syndrome, but statistically and over a large population, they can put you
at higher risk.
What Are the Symptoms of Down Syndrome?
Though the likelihood of carrying a
baby with Down syndrome can be estimated by screening during pregnancy, you
won’t experience any symptoms of carrying a Down syndrome child.
At birth, babies with Down syndrome
usually have certain characteristic signs, including:
- flat facial
- small head and
- short neck
- bulging tongue
- eyes that
- oddly shaped ears
- poor muscle
An infant with Down syndrome can be
born at normal size but will develop more slowly than a child without the
People with Down syndrome usually have
some degree of mental disability, but it’s often mild to moderate. Mental and
social development delays may mean that the child could have:
- poor judgment
- slow learning
Medical complications often accompany
Down syndrome. These may include:
- hearing loss
- poor vision
- hip problems,
such as dislocations
- sleep apnea
(interrupted breathing during sleep)
(thought and memory problems)
(low thyroid function)
- late tooth
growth, causing problems with chewing
in later life
People with Down syndrome are also
more prone to infection. They may struggle with respiratory infections, urinary
tract infections, and skin infections.
Screening for Down Syndrome During
Screening for Down syndrome is offered
as a routine part of prenatal care in the United States. If you are a woman
over 35, your baby’s father is over 40, or there’s a family history of Down
syndrome, you may want to get an evaluation.
An ultrasound evaluation and blood
tests can look for Down syndrome in your fetus. These tests have a higher
false-positive rate than tests done at later pregnancy stages. If results aren’t
normal, your doctor may follow up with an amniocentesis after your 15th week of
An ultrasound and quadruple marker
screen (QMS) test can help identify Down syndrome and other defects in the
brain and spinal cord. This test is done between 15 and 20 weeks.
If any of these tests aren’t normal,
you will be considered at high risk for birth defects.
Additional Prenatal Tests
Your doctor may order additional tests
to detect Down syndrome in your baby:
- Amniocentesis: Your doctor takes a sample of amniotic fluid to
examine the number of chromosomes the baby has. The test is usually done after
- Chorionic villus sampling (CVS): Your doctor will take
cells from your placenta to analyze fetal chromosomes. This test is done during
the ninth and 14th week of pregnancy. It can increase your risk of a
miscarriage, but only by less than 1 percent.
- Percutaneous umbilical
blood sampling (PUBS, or cordocentesis): Your doctor will take blood from the
umbilical cord and examine it for chromosomal defects. It’s done after the 18th
week of pregnancy. It has a higher risk of miscarriage, so it’s performed only
if all other tests are uncertain.
Some women choose not to undergo these
tests because of the risk of miscarriage. They would rather risk having a child
with Down syndrome than losing the pregnancy.
Tests at Birth
At birth, your doctor will:
- perform a physical
examination of your baby
- order a blood
test called a karyotype to confirm Down syndrome
Treating Down Syndrome
There is no cure for Down syndrome,
but there is also a wide variety of support and educational programs that can
help both people with the condition and their families. The NDSS is just one place to look for
Available programs start with
interventions in infancy. Federal law requires that states offer
therapy programs for qualifying families. In these programs, special education
teachers and therapists will help your child learn:
- sensory skills
- social skills
- motor skills
- language and
Children with Down syndrome often meet
age-related milestones. However, they may learn more slowly than other
School is an important part of the
life of a child with Down syndrome, regardless of intellectual ability. Public
and private schools support people with Down syndrome and their families with
integrated classrooms and special education opportunities. Schooling allows
valuable socialization and helps students with Down syndrome build important
Living with Down Syndrome
Lifespan for people with Down syndrome
has improved dramatically in recent decades. In 1960, a baby born with Down syndrome often
didn’t see their 10th birthday. Today, life expectancy for people with Down
syndrome has reached an average of 60.
If you are raising a child with Down
syndrome, you will need a close relationship with medical professionals who
understand the condition’s unique challenges. In addition to larger concerns,
like heart defects and leukemia, people with Down syndrome may need to be
guarded from common infections such as colds.
People with Down syndrome are living
longer and richer lives than ever. Though they can often face a unique set of
challenges, they can also overcome those obstacles in ways that inspire the
rest of us. Building a strong support network of experienced professionals and
understanding family and friends is crucial for the success of people with Down
syndrome and their families. Check out the National Down Syndrome Society and the National
Association for Down Syndrome
for help and hope.