Down Syndrome

Every cell in the human body has genetic material stored in genes. These genes are the blueprint of our inherited traits. The genes are grouped together in rod-like structures called chromosomes. Humans have 23 pairs of chromosomes, half of which are inherited from each parent at conception.

Down syndrome occurs when there is a genetic error. Instead of one matched pair of chromosome 21, the person has the matched pair, plus an extra copy or part of a copy. This additional genetic material alters the course of development. Down syndrome leads to lifetime impairments in both cognitive ability and physical growth.

There are three different forms of Down syndrome:

• Trisomy 21. At conception, each cell has three copies of the 21st chromosome instead of only two. This is the most common form of Down syndrome.
• Translocation Down Syndrome. At conception, each cell has the typical number of chromosomes but an extra copy (or partial copy) or chromosome 21 is displaced and attached to another chromosome.
• Mosaic Down Syndrome. At conception, some cells have an extra copy of the 21st chromosome while others have the typical number of chromosomes with one matched pair of chromosome 21.

Down syndrome occurs in people of all races, and economic levels. It is believed that older women have an increased chance of having a child with Down syndrome.

There is a wide range of abilities, behaviors, and development in people with Down Syndrome. Many adults with Down syndrome can have jobs, drive cars, and live independently.

Shortly after a baby is born, the healthcare staff may notice indicators, or symptoms, of Down syndrome. These symptoms may include:

• Decreased, or poor muscle tone
• Short neck, with excess skin at the back of the neck
• Flattened facial profile and nose
• Small head, ears, and mouth
• Upward slanting eyes
• Wide, short hands with short fingers
• Single deep crease across the center of the palm

Ultrasound technology may also detect certain markers of Down syndrome while a woman is pregnant.

Many symptoms of Down syndrome are present shortly after birth.

Pregnant women can discuss risk factors and prenatal testing for Down syndrome with their healthcare provider.

Down syndrome is caused by an extra copy or part of an extra copy of chromosome 21. This genetic error happens at conception. It is not known what causes this genetic error to happen.

A Down syndrome diagnosis is confirmed through a blood or tissue test called a karyotype test. Karyotype testing creates a snapshot of a person’s chromosomes. The test identifies and evaluates the size, shape, and number of chromosomes in a sample of body cells.

There are prenatal tests available to pregnant women that can diagnose Down syndrome before a baby is born. These tests may include:

• Blood tests. Blood can be analyzed to identify potential chromosomal issues.
• Ultrasounds. Sound waves are used to create an image of the fetus to identify potential markers of Down syndrome.
• Chorionic Villus Sampling (CVS). During this test, cells from the placenta are collected with a needle or catheter and sent to the lab for genetic analysis.
• Amniocentesis. During this test, amniotic fluid (which contains DNA from the baby) is collected through a needle and sent to the lab for genetic analysis.

There are a number of treatments available for children born with Down syndrome:

• Early intervention and educational therapy. These therapies may include speech therapy, occupational therapy, behavioral therapy, and physical therapy.
• Assistive devices. These devices include equipment, tools, or technology, which enhances learning or makes tasks easier to complete.

People with Down syndrome are at a greater risk for a number of health problems and conditions. Many of these conditions may require immediate care right after birth, or long-term treatments.

There is no way to prevent Down syndrome. Certain forms of Down syndrome can be hereditary. Genetic testing may be offered to families for the purpose of future family planning.

• National Down Syndrome Society
• International Down Syndrome Coalition
• Down Syndrome Diagnosis Network (DSDN)