Down Syndrome (Trisomy)

July 26, 2019
Janelle Thomas MSN, RN
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If you’re the parent or caregiver of a child with Down syndrome, one of the best things you can do is educate yourself as much as possible about the condition. Knowing what to expect and how to properly care for a child with Down syndrome can significantly improve their quality of life. It can also help you take care of yourself.

Read on for a comprehensive guide to Down syndrome, including what Down syndrome is, the types, symptoms, causes, and more.

What is Down Syndrome?

Every cell in the human body has a nucleus. This is where genetic information is stored in what is known as genes. Genes are responsible for all the traits we inherit from our parents and are grouped with rodlike structures known as chromosomes.

While the typical nucleus contains 23 pairs of chromosomes (half of which are inherited from the mother and the other half from the father), sometimes an individual has an extra full or partial copy of chromosome 21. When this happens, Down syndrome occurs.

How common is Down syndrome?

Down syndrome affects approximately one in every 700 babies in the United States. This makes Down syndrome the most common chromosomal condition with approximately 6,000 babies being born with Down syndrome in the U.S. annually.

3 Types of Down Syndrome

There are three types of Down syndrome, including Trisomy 21 (Nondisjunction), Translocation, and Mosaicism.

Trisomy 21

Trisomy 21 is the most common type of Down syndrome, accounting for 95% of cases. This type of Down syndrome occurs when there are three number 21 chromosomes present in every cell of the body, rather than two. This means a person with Down syndrome has 47 chromosomes instead of the typical 46. The extra genetic material changes the course of development and causes the characteristics associated with the syndrome.


The second most common type of Down syndrome is Translocation, although it accounts for just 4% of all cases. With Translocation, part of chromosome 21 breaks off during the division of cells and attaches to another chromosome. Unlike Trisomy 21, the total number of chromosomes in the cells is 46, but the presence of an extra component of chromosome 21 causes the characteristics associated with the syndrome.


The rarest type of Down syndrome is Mosaicism, accounting for just 1% of all cases. Mosaicism occurs when nondisjunction of chromosome 21 takes place in one of the initial cell divisions after fertilization.

Down Syndrome Symptoms

Symptoms of Down syndrome include:

Physical Symptoms

  • Decreased or poor muscle tone
  • Short neck
  • Excess skin at the back of the neck
  • Flattened facial profile
  • Flattened nose
  • Small head, ears, and mouth
  • Protruding tongue
  • Upward slanting eyes
  • White spots on the colored part of the eye
  • Wide, short hands with short fingers
  • Single, deep crease across the palm of the hand
  • Deep groove between the first and second toes
  • Short height
  • Excessive flexibility

Developmental Symptoms

  • Short attention span
  • Poor judgment
  • Impulsive behavior
  • Slow learning
  • Delayed language and speech development

Causes of Down Syndrome

Typical human cells contain 23 pairs of chromosomes, each containing one cell from the mother and one from the father. When abnormal cell division involving chromosome 21 occurs, Down syndrome is the result.

While there are no known behavioral or environmental factors that cause Down syndrome, sometimes it can be inherited. In most cases, Down syndrome is not inherited and is caused by the improper division of cells during the development of the fetus.

Translocation Down syndrome is the only type of Down syndrome that can be inherited but this only occurs in about 3% to 4% of cases.

Down Syndrome Risk Factors

Down syndrome risk factors include:

  • Advanced maternal age: When a woman is 35 years of age or older, the chance of giving birth to a child with Down syndrome increases. This is because older eggs have a higher risk of improper chromosome division.
  • Having another child with a chromosomal condition: Parents who have a child with Down syndrome are more likely to have a second child with a chromosomal condition.
  • Carrying the genetic translocation for Down syndrome: Both parents may pass the genetic translocation for Down syndrome to their children.

How is Down syndrome diagnosed?

Down syndrome is often diagnosed during pregnancy and the American College of Obstetricians and Gynecologists recommends offering screening or diagnostic tests for Down syndrome to all pregnant women, even if they are not at risk.

While screening tests can help determine the likelihood that a mother is carrying a baby with Down syndrome, they cannot tell for sure. Diagnostic tests, on the other hand, can diagnose whether a baby has a chromosomal condition.

Other tests include a blood test which looks for abnormal levels of PAPP-A and HCG, and a Nuchal Translucency test, which is an ultrasound that measures a specific area on the back of the fetus’s neck.

If screening tests come back positive, your health care provider may suggest additional testing to rule out or diagnose Down syndrome. These tests typically include Chorionic Villus Sampling, in which cells are taken from the placenta and used to analyze the fetal chromosomes. In some cases, an amniocentesis is performed, which is where a needle is inserted into the mother’s uterus to analyze the chromosomes of the fetus.

Down Syndrome Treatment

Treatment for Down syndrome depends on the child’s specific needs, but early intervention can make a big difference in improving their quality of life. Different stages of life may require different medical services. In any case, if your child has Down syndrome, you will likely need a team of specialists who can provide medical care dependent on your child’s needs. These specialists may include primary care pediatricians, pediatric cardiologists, pediatric gastroenterologists, pediatric neurologists, developmental pediatrics, ENT specialists, physical therapists, and occupational therapists.

Complications of Down Syndrome

A wide range of complications can come with Down syndrome, including:

Down Syndrome Prevention

There is no way to prevent Down syndrome. If you meet any of the risk factors above, your chances of having a child with a chromosomal condition are greater. If you are at high risk, we recommend consulting a genetic counselor before trying to get pregnant as they can help you understand your chances of having a child with Down syndrome.

Contact Care Options for Kids for Pediatric Home Care Services

Sometimes the duties of caregiving can be overwhelming, putting a large amount of strain on your family. When this happens, a change in caregiving arrangements may be necessary. If you feel that you need assistance providing care for a loved one with Down syndrome, Care Options for Kids can help.

We refer loving and competent caregivers to provide customized care for families in need – from a few hours a day to around-the-clock care. Contact us directly to speak with a home health care professional or request a consultation. Together we can determine the best plan of action to keep loved ones happy and healthy.

If you are considering pediatric home health care services, contact the caring staff at Care Options for Kids. Call today (888) 592-5855.