DOWN SYNDROME INFORMATION
Down Syndrome Facts
Down syndrome is the most commonly occurring genetic condition with approximately 1:800 births. More than 250,000 people in the United States are living with the condition. F.R.I.E.N.D.S. welcomes approximately 10-20 new babies each year in the Tampa Bay area.
Down syndrome is not a disease, it’s a genetic disorder. Children are born with Down syndrome and will have it their entire life. It’s not contagious, you cannot give it to someone and those who have Down syndrome cannot be cured of it.
Screening tests for discovering Down syndrome are offered to all pregnant women and can be done in the form of a combined test (blood test plus ultrasound), integrated screening test, quad screen, or cell-free fetal DNA. There are also several diagnostic tests that can be used prior to birth: amniocentesis, chorionic villus sampling (CVS) and cordocentesis. After birth, the diagnosis is made based on the baby’s appearance and later confirmed with a chromosomal karyotype test.
Common physical traits are low muscle tone, small stature, upward slant of the eyes, a deep single crease across the palm, and short stature, but every person with Down syndrome is a unique individual and may possess these characteristics to a different degree, or not at all, all will look like their family members. Down syndrome affects every race, nationality, and socioeconomic status, it does not discriminate.
People with Down syndrome have an increased risk for certain medical conditions such as congenital heart defects, gastrointestinal issues, respiratory difficulty, hearing and vision problems, Alzheimer's disease, childhood leukemia, and thyroid conditions. However, many of these conditions are now treatable, so most people with Down syndrome lead healthy lives. Life expectancy for people with Down syndrome has increased dramatically in recent decades, from 25 in 1983 to 60 today.
People with Down syndrome experience cognitive delays in the mild to moderate range. It’s important to remember that IQ is not indicative of the many strengths and talents that everyone possesses. Individuals with Down syndrome are achieving at levels we never once thought possible.
Quality educational programs, a stimulating home environment, good health care, and positive support from family, friends, and the community enable people with Down syndrome to develop their full potential and lead fulfilling lives. People with Down syndrome are attending college, falling in love, getting married, and working competitively in their communities in increasing numbers.
We are more alike than you think.
We need the same love and care as our peers.
We have the same aspirations and desires.
We can and want to live independently.
We can work, volunteer, and vote.
We want the equality and future that we deserve.
What Causes Down syndrome?
Down syndrome occurs when two copies of the 21st chromosome fail to separate during formation of the egg, resulting in an egg with two copies of the 21st chromosome. When this egg is fertilized, the resulting baby ends up with three copies of the 21st chromosome in each of its cells.
The incidence of births of child with Down syndrome increases with the age of the mother, but due to higher fertility rates in younger women, 80% of children with Down syndrome are born to women under the age of 35yrs.
Types of Down syndrome?
There are three different types of Down Syndrome Trisomy 21, Translocation, and Mosaic.
Trisomy 21 - Down syndrome is usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate. As the embryo develops, the extra chromosome is replicated in every cell of the body. This type of Down syndrome, which accounts for 95% of cases, is called trisomy 21.
Translocation - In translocation, which accounts for about 4% of cases of Down syndrome, the total number of chromosomes in the cells remains 46; however, an additional full or partial copy of chromosome 21 attaches to another chromosome, usually chromosome 14. The presence of the extra full or partial chromosome 21 causes the characteristics of Down syndrome.
Mosaic - Mosaicism is diagnosed when there is a mixture of two types of cells, some containing the usual 46 chromosomes and some containing 47. Those cells with 47 chromosomes contain an extra chromosome 21. Mosaicism is the least common form of Down syndrome and accounts for only about 1% of all cases of Down syndrome. Research has indicated that individuals with mosaic Down syndrome may have fewer characteristics of Down syndrome than those with other types of Down syndrome. However, broad generalizations are not possible due to the wide range of abilities people with Down syndrome possess.
How Do Children with Down syndrome Develop?
Children with Down syndrome are usually smaller, and their physical and mental developments are slower than youngsters who do not have Down syndrome. Most children with Down syndrome experience a mild to moderate range of cognitive delays. However, some children have very minimal cognitive delays; they may function in the borderline to low average range, while others may be severely cognitively delayed. There is a wide variation in mental abilities and developmental progress in children with Down syndrome. Also, their motor development is slow; and instead of walking by 12 to 14 months as other children do, children with Down syndrome usually learn to walk between 15 to 36 months. Language development is also markedly delayed. It is important to note that a caring and enriching home environment, early intervention, and integrated education efforts will have a positive influence on the child’s development.
What kind of information can be provided through genetic counseling?
Parents who have a child with Down syndrome have a 1:100 chance of having another child with Down syndrome in future pregnancies. It is estimated that the risk of having another child with Down syndrome is about one in 100 in trisomy 21 and mosaicism. If, however, the child has translocation Down syndrome and if one of the parents is a translocation carrier, then the risk of recurrence increases markedly. The actual risk depends on the type of translocation and whether the translocation is carried by the father or the mother.
What health concerns are often observed in people with Down syndrome?
The child with Down syndrome needs the same kind of medical care as any other child. The pediatrician or family physician should provide general health maintenance, immunizations, attend to medical emergencies and offer support and counseling to the family. There are, however, situations when children with Down syndrome need special attention.
- Hearing - 60-80% percent of children with Down syndrome have hearing deficits. Therefore, audiologic assessments at an early age and follow-up hearing tests are indicated. If there is a significant hearing loss, the child should be seen by an ear, nose, and throat specialist.
- Heart Defect - Forty to 45% of children with Down syndrome have congenital heart disease. Many of these children will have to undergo cardiac surgery and often will need long term care by a pediatric cardiologist.
- Gastrointestinal - Intestinal abnormalities also occur at a higher frequency in children with Down syndrome. For example, a blockage of the food pipe (esophagus), small bowel (duodenum) and at the anus are not uncommon in infants with Down syndrome. These may need to be surgically corrected at once to have a normal functioning intestinal tract. Children may need a feeding tube to help with nutrition.
- Sight - Children with Down syndrome often have more eye problems than other children who do not have this chromosome disorder. For example, three percent of infants with Down syndrome have cataracts. They need to be removed surgically. Other eye problems such as cross-eye (strabismus), near-sightedness, far-sightedness and other eye conditions are frequently observed in children with Down syndrome.
- Keratoconus, an eye condition that affects the structure of the cornea and can result in loss of vision. Keratoconus is more common in people with Down syndrome compared to people who do not have Down syndrome. The National Keratoconus Foundation estimates that 5-30% of individuals with Down syndrome have keratoconus.
- Obesity - Another concern relates to nutritional aspects. Some children with Down syndrome, those with severe heart disease, often fail to thrive in infancy. On the other hand, obesity is often noted during adolescence and early adulthood. These conditions can be prevented by providing appropriate nutritional counseling and anticipatory dietary guidance.