Down syndrome

At Children’s Hospital Boston, we understand that if your child has been diagnosed with Down syndrome, you have a lot of questions and concerns about your child’s health and future.

Everyone has a whole range of skill sets, and it’s tough for any parents to predict what their children’s unique capacities will be. Remember that every child born with Down syndrome has talents, it’s a just matter of discovering and nourishing them.

What is Down syndrome?

• Down syndrome is a chromosomal condition that is typically caused when a baby is conceived with 47 chromosomes instead of the normal 46. Starting in the womb, this additional genetic material alters the course of the child’s development.

• The most common form of Down syndrome, Trisomy 21, occurs when a child is born with a full three copies of the 21st chromosome, rather than the normal two.  In rare cases,Down syndrome is caused by other chromosomal arrangements.

• Children with Down syndrome typically have intellectual disabilities, hypotonia (low muscle tone) and characteristic facial features, such as upward slanted eyes and a flattened nasal bridge.

• Except for Translocation Down syndrome, which occurs in about 4% of people with Down syndrome, the condition is not inherited, which means that it doesn’t run in families.

What are the different types of Down syndrome?

There are three different types of Down syndrome:

• Down syndrome (or Trisomy 21) accounts for ninety-five percent of people with Down syndrome. A child with Trisomy 21 has three copies of chromosome 21, rather than the normal pair.

• Translocation Down syndrome accounts for just three to four percent of people with Down syndrome. Translocation is what people are referring to if they say that the condition is inherited, because usually one parent is a carrier. The extra #21 chromosome is present, but attached to a different chromosome in the egg or sperm. The clinical features of people with Translocation Down syndrome are indistinguishable from those with Trisomy 21.

• Mosaic Down syndrome accounts for less than one percent of all people with Down syndrome. Children born with Mosaic Down syndrome have some cells with three copies of chromosome 21 and some cells that have the usual pair. Clinically, babies born with Mosaic Down syndrome can have the same features and health problems seen in babies born with Trisomy 21 or Translocation Down syndrome.However, the presence of cells with the normal number of chromosomes may result in fewer characteristics of Down syndrome.

Are there any medical conditions associated with Down syndrome I should be concerned about?

Children with Down syndrome have an increased risk for certain medical conditions such as:

• congenital heart defects, which occur in almost half of children born with Down syndrome.

• pulmonary hypertension, a condition that affects arteries in the heart and lungs

• ear infections and increased risk for other infections

• increased risk for visual or hearing impairment.

• atlantoaxial instability (compression injury of the spinal cord)

• obesity

• childhood leukemia

• thyroid conditions, such as hypothyroidism

• colds, as well as bronchitis and pneumonia.      

Causes

What causes Down syndrome?

Down syndrome is caused by a chromosomal condition that occurs in the sperm or egg prior to conception. In most cases, Down syndrome occurs when a child inherits an extra copy of Chromosome 21 from the parents.  The most typical type of Down syndrome is also known as “Trisomy 21” due to the fact that there are three copies of this chromosome instead of the usual two.

Chromosomes and Down syndrome:

• Normally, the mother's egg and the father's sperm each start out with 23 chromosomes. When the egg and sperm meet at conception, a child inherits 23 chromosomes from each parent, ending up with a total of 46 chromosomes.

• In the case of Down syndrome, an change occurs during cellular division such that the egg or sperm has two copies of chromosome #21 and a total of 24 chromosomes. Researchers are still unsure of what causes the cells to divide in this manner.

• If this egg or sperm is fertilized, the baby ends up with three copies of the #21 chromosome or"Trisomy 21":. This extra genetic material causes the variety of health and developmental issues  in Down syndrome.

Signs and symptoms

Down syndrome can affect a child physically, cognitively, and behaviorally. Remember that every child with the condition is unique and may possess these characteristics to different degrees or not at all.

Physical

A child with Down syndrome will have some, but perhaps not all, of the following features:

• eyes that slant upward

• small ears that may fold over slightly at the top

• a smaller than average mouth, making the tongue appear larger

• a smaller than average nose, with a flattened nasal bridge

• short, stocky arms and legs. Some children also have a wide space between the big toe and second toe.

• some babies with Down syndrome have short necks and small hands with short fingers

• rather than having three 'creases' in the palm of the hand, a child with Down syndrome may have one single crease that goes straight across the palm, and a second crease that curves down by the thumb.

• A child with Down syndrome is often shorter than average and has unusual looseness in his or her joints

• hypotonia (low muscle tone) throughout the body.

Cognitive and behavioral

Children with Down syndrome are also at a higher risk for being affected by the following cognitive and behavioral symptoms:

• mild to moderate cognitive and intellectual disability

• difficulty learning how to navigate social situations

• short attention span

• impulsivity

• “stubbornness” that may be attributed to the child’s desire for routine and order

• frequent angry outbursts if this routine is disturbed

• a child may use “self talk” (talking out loud to himself) as a way of understanding and processing information

FAQ

Q: What is Down syndrome?

A: Down syndrome is a condition in which extra genetic material interferes with a child’s cognitive and physical development. In most cases of Down syndrome, a baby will have an extra copy of chromosome 21. This is where Trisomy 21, the medical term for Down syndrome, gets its name.

Q: What causes Down syndrome?

A: Down syndrome is caused by the presence of extra chromosomal material. This happens during the time of conception, when the baby is normally supposed to inherit only 46 chromosomes, combined from the mother and father. Instead, a baby with Down syndrome typically inherits an extra copy of chromosome 21. As a result, the baby is born with 47 chromosomes instead of 46. It’s this extra genetic material that causes physical and developmental challenges.

Q:  What are my chances of having a child with Down syndrome?

A:  The chances of having a baby with Down syndrome increases with the mother’s age. Even though age alone can’t predict the number of pregnancies that will result in Down syndrome, this is the general guideline:

• 1 in 1,000 for mothers under age 30
• 1 in 400 for mothers older than 35
• 1 in 60 for mothers older than 42

Prenatal testing for the condition is available to any expectant parent who desires that information.

Q: Do symptoms become progressively worse?

A: Since Down syndrome is not a progressive condition, symptoms will not get worse over time. However, some of the complications associated with Down syndrome can occur at different stages in a child’s life. While some symptoms are present when a child is born, others can emerge during childhood, adulthood, or in elderly patients.

Because different symptoms can emerge at different stages, it’s important to see a Down syndrome specialist who can determine what’s typical and what’s not typical for people with Down syndrome.

Q: Can my child have children? 

A: Although there have been rare exceptions, men with Down syndrome are not expected to be able to father a child. Women with Down syndrome may have decreased fertility. In any pregnancy, a mother with Down syndrome has about a 50 percent chance of conceiving a child with Down syndrome if the father does not have Down syndrome, though many pregnancies are miscarried.

Q: Does Down syndrome limit what my child can do?

A: Although your child may learn skills at a different rate than children without Down syndrome, he should still be able to do most things that any young child can do, such as walking, talking, dressing and being toilet trained. Encouragement and support are the best tools you can give your child in helping him reach developmental milestones.

Q: Can my child go to school, despite having Down syndrome?

A: Yes. There are special programs beginning in the preschool years to help children with Down syndrome develop skills as fully as possible. Many children with Down syndrome can, to some extent, be integrated in the regular classroom. With Early Intervention and special education, the outlook for children with Down syndrome is far brighter than it once was.

Q; How serious is the cognitive and intellectual disability that accompanies Down syndrome?

A: The degree of cognitive and intellectual disability that accompanies Down syndrome varies widely, ranging from mild to moderate to severe. However, most cognitive and intellectual disability falls within the mild to moderate range.

Q. What does “mild to moderate intellectual disability” mean?

A. Children with mild intellectual disability are usually able to do everyday things like read, hold a job, and take public transportation independently. Children with moderate intellectual disability probably need more support.

Q: What is the long-term outlook for my child?

A: The average life span for people with Down syndrome has increased dramatically since the early 1900s and many people with the condition achieve independence, hold jobs, and move into assisted living arrangements. Although there may be some challenges, with the right treatment and care, your child will have every opportunity to live a happy and fulfilling life.

Issues relating to school and education are usually a top concern for children with Down syndrome, so its good idea to seek out educational assistance programs as early as possible. Special education and Early-Intervention services are provided through each community to children with disabilities, so check with your social worker to see what options are available to you.

Delays in physical development may also cause problems for your child down the road. Luckily, there are many different types of therapy that can make living with Down syndrome easier and more comfortable. Visit the Treatment tab to learn more about the various therapy options Children’s offers.

Questions to Ask Your Doctor

You will probably have a lot of questions on your mind before meeting with your child’s doctor. At the appointment, it can be easy to be overwhelmed with information and forget the questions you wanted to ask.

A lot of parents find it helpful to jot down questions beforehand. That way, when you talk to your child’s clinician, you can be sure that all your concerns are addressed. Remember that physicians are open to learning from families too. Attend conferences, read up on updated materials and don’t be afraid to share what you have learned.

Some questions you might ask include:

• What kinds of treatment will my child need?
• What social and behavioral problems should I expect?
• How can I help my child focus on his strengths?
• How should I talk to my child about this condition?
• Do I need to restrict my child’s psychical activity?
• Do I need to make changes to my child’s home and school routines?
• What kind of follow up care will my child need?