Down Syndrome (Trisomy 21)
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What is Down syndrome?
Down syndrome is a genetic disorder that causes physical problems and intellectual disabilities. It is most often caused by the presence of an extra copy of chromosome number 21. This condition is called trisomy 21.
Each person born with Down syndrome is different. Some have health problems. These could include heart disease, hearing problems, thyroid disorders, obesity, or problems with their intestines. Many begin treatment for medical issues early and live full, healthy, productive lives.
There are many signs and symptoms of Down syndrome. Some people have different symptoms than others. Some have different problems at different points in their lives. Many people with Down syndrome share a distinct appearance. Common physical signs include:
- Upward, slanting eyes
- Flattened facial features
- Protruding tongue
- Short neck
- Small head, ears, and mouth
- Broad hands with short fingers
- Decreased muscle tone
Because of some of these physical features, children with Down syndrome often develop at a slower rate. This includes when they learn to roll over, sit, stand, and walk. They do reach these milestones, but it takes them longer. Physical issues in areas such as the heart, brain, and GI tract can cause health problems.
In addition to physical signs, people with Down syndrome often have problems with thinking and learning. These problems include:
- Short attention span
- Poor judgment
- Impulsive behavior
- Slow learning
- Delayed language and speech
While these kinds of problems are common, they are rarely severe.
Causes & Risk Factors
Down syndrome is caused by a problem during cell division. This results in extra genetic material. The extra genetic material causes the features and problems of Down syndrome. There are 3 types of Down syndrome:
- Trisomy 21. In this form, the cell division issue happens during the development of the sperm or the egg. This gives the child three copies of chromosome 21 instead of the normal two copies. Up to 95% of people with Down syndrome have Trisomy 21.
- Mosaic Down syndrome. Some cells have an extra copy of chromosome 21 because of abnormal cell division in the embryo. This form is rare. Only 1% of Down syndrome cases are Mosaic.
- Translocation Down syndrome. Translocation (or shift) occurs before or at conception when part of chromosome 21 attaches onto another chromosome. It is the only form of Down syndrome that can be passed down from parent to child. This can happen even if the parent shows no symptoms of Down syndrome.
There are factors that increase your risk of having a child with Down syndrome:
- Advanced maternal age. The older the woman is, the older her eggs are. Older eggs are more likely to divide abnormally.
- Already having a child with Down syndrome.
- Being a carrier of a chromosomal abnormality. Both men and women can carry the translocation abnormality. If you are a carrier, you risk passing it on to your child.
Diagnosis & Tests
How is Down syndrome diagnosed?
Screening for Down syndrome is a normal part of prenatal care and has evolved over time. Noninvasive prenatal testing (NIPT) is a blood test used in prenatal screening. It can determine the risk that the fetus will be born with certain genetic abnormalities. The test is most often used to look for chromosomal disorders, such as the one that causes Down syndrome.
The NIPT test is very accurate but cannot be used to diagnose Down syndrome. It only indicates your risk of having a baby with Down syndrome. Some women test positive in the screen but have perfectly healthy babies.
The only way to diagnose Down syndrome before birth is through diagnostic testing. This involves checking the tissue and fluid in the womb for the extra chromosome. This can be done through:
- Chorionic villus sampling (CVS).This takes a sample of the placenta during weeks 10 to14 of pregnancy.
- This takes a sample of the amniotic fluid during weeks 14 to 18 of pregnancy.
- Percutaneous umbilical blood sampling (PUBS).This takes a sample of the fetal blood in the umbilical cord during weeks 18 to 22 of pregnancy. It is the most accurate test.
There is a slight risk that these tests can cause a miscarriage. So, these tests are used only when there is a higher chance of a genetic problem in the baby. This could be if the mother is 35 or older or if the mother received an abnormal screening result. After birth, your healthcare provider can test the baby’s blood for the extra chromosome. This is done if the baby has any of the physical signs or birth defects of Down syndrome.
Should I be tested?
This decision is up to you. Some women feel better if they know their risk so that they can prepare themselves for the possibility of having a baby who has Down syndrome. Your healthcare provider can help you understand your risks and consider the pros and cons of getting tested.
There isn’t one standard treatment for Down syndrome. A person’s treatment depends on their individual case. This includes their physical and intellectual needs, strengths, and limitations. Having Down syndrome puts your child at increased risk for a number of health problems. These need different forms of treatment. Treatments could be one-time (such as surgery) or lifelong (such as a special diet).
Treatment could start when your child is a baby. This could happen if they are born with a problem, such as a heart defect. They may be screened for other problems that commonly occur with Down syndrome. These include hypothyroidism, hearing loss, vision problems, blood disorders, and digestive problems.
Your child will most likely have a team of health professionals. This team will include doctors, specialists, and therapists. They will work together to give your child the treatment and therapy they need. This will allow them to live as productive a life as possible. Services may include early intervention, therapies, and assistive devices.
Early intervention involves specialized programs and resources. These are provided to babies and toddlers with Down syndrome and their families. They usually start at birth. Research has shown that early intervention improves outcomes for these children later in life.
There are a variety of therapies that can help a child with Down syndrome. These include:
- Physical therapy– exercises and activities that increase strength, improve posture and balance, and build motor skills. Many children with Down syndrome have low muscle tone. Physical therapy can be particularly helpful for them.
- Speech therapy –helps them communicate better and improve their language skills. Children with Down syndrome often speak later than other children. This therapy can help them develop those skills.
- Occupational therapy –adjusts everyday activities to the child’s abilities. This therapy teaches skills your child will use every day. These include eating, getting dressed, handwriting, and caring for themselves.
- Behavioral therapy –helps your child cope with their condition. Complicated feelings and behaviors often go along with it. Children with Down syndrome get frustrated and can develop compulsive behaviors. They are more likely to have ADHD or other mental health issues. Therapy with a mental health professional can help.
An assistive device is any tool, technology, or piece of equipment that helps your child function more easily. This could include something as simple as a modified pencil that makes writing easier, a special touchscreen computer that allows your child to communicate or hearing aids.
Living with Down syndrome
There are other health problems that often go along with having Down syndrome. Every person with Down syndrome is different. Your child may or may not have or develop any of these other conditions.
- Poor muscle tone. This makes it harder for them to learn to roll over, sit up and walk. Physical therapy can help with these problems.
- Heart defects. About half of babies who have Down syndrome also have a heart problem. An ultrasound exam of your baby’s heart will show any defects. Surgery may be necessary to fix the heart problems associated with Down syndrome.
- Digestive problems. Some babies who have Down syndrome have problems swallowing. Others may have blockages in their intestines. Surgery may be necessary to fix these problems. Once they are fixed, they usually cause no further harm. Children are more likely to have Celiac disease. This causes intestinal problems when they eat gluten, a protein in wheat.
- Hearing problems. Up to 75% of children with Down syndrome have problems with their hearing. They need regular hearing screenings and may need to have hearing problems corrected or use hearing aids.
- Vision problems. Some babies have eye problems, such as cataracts (cloudy lenses) or crossed eyes. Corrective lenses or surgery may be necessary to fix these problems.
- Down syndrome causes problems with the immune system that makes it harder to fight infection. Your child may have colds, ear infections, and sinus infections more often than other children. It’s important for children with Down syndrome to receive all of their recommended vaccines.
- Blood disorders. Those with Down syndrome are more likely to have blood problems. These could include anemia (low iron) and polycythemia (high levels of red blood cells). Children with Down syndrome are more likely to develop leukemia (cancer of the white blood cells).
- Premature aging. Adults with Down syndrome can develop health problems normally caused by aging. These include dementia, memory loss, high cholesterol, diabetes, cataracts, and early menopause.
- Learning disabilities. At birth, it isn’t possible to tell determine a baby’s IQ. Intelligence ranges from low normal to very slow to learn.
Keep your child physically healthy. Provide therapy or treatment for his or her impairments. This will help them be better able to learn. With therapy, many children with Down syndrome grow up to have jobs and live independently. There are even post-secondary programs designed to give people with Down syndrome a college experience. This allows them to develop life skills through life in a dorm, to take specially designed classes and to train for employment in their communities.
For More Information
Canadian Down Syndrome Society