Down syndrome | UAMS News
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Trisomy 21
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| According to the Centers for Disease Control and Prevention, approximately 6,000 babies are born in the United States each year with Down syndrome. Chromosomes are small “sets” of genes in the body that determine how a baby’s body forms and functions as it grows during pregnancy and after birth. Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. A medical term for having an extra copy of a chromosome is ‘trisomy’. Down syndrome is also called trisomy 21. This extra copy changes the way the baby’s body and brain develop, which can lead to mental and physical problems for the baby. Even though people with Down syndrome may act and look alike, each person has different abilities. People with Down syndrome typically have IQs in the mild to moderately low range and are slower to speak than other children.
Common chromosomal disorder
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| One in 700 babies born in this county each year will have Down syndrome, making it the most commonly diagnosed chromosomal disorder in the United States. There are three types of Down syndrome. It is difficult to tell the difference between each type without looking at the chromosomes because the physical characteristics and behaviors are similar. About 95% of people with Down syndrome have trisomy 21. With this type of Down syndrome, each cell in the body has three separate copies of chromosome 21 instead of the usual two copies. Down translocation syndrome occurs when an extra part or extra chromosome 21 is present, but it is attached or “translocated” to a different chromosome rather than being a separate chromosome 21. A child with mosaic Down syndrome may have cells that have three copies of chromosome 21, but other cells have the typical two copies of chromosome 21.
Mother’s age makes a difference
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| Researchers know that Down syndrome is caused by an extra chromosome, but no one knows for sure why the condition occurs or how many different factors play a role. The age of the mother is a factor that increases the risk of having a baby with Down syndrome. Women who are 35 or older when they become pregnant are more likely to have a pregnancy affected by Down syndrome than women who become pregnant at a younger age. However, the majority of babies with Down syndrome are born to mothers under the age of 35, as there are many more births to younger women. A person with Down syndrome typically has a short neck, a flattened facial profile, and upward slanting eyes. Due to low muscle tone, a child with Down syndrome may be slow to learn to roll over, stand, and walk. Despite these delays, children with the disease can learn to participate in physical activities like other children.
Diagnostic examinations
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| There are several screening tests that a pregnant woman can undergo to determine if her child will have Down syndrome. Diagnostic testing is usually done after a positive screening test to confirm a diagnosis of Down syndrome. Dr. Bradley Schaefer, director of the medical genetics division at UAMS, explains that these tests look for changes in the child’s chromosomes that would indicate he has the disease. Tests include chorionic villus sampling, or CVS, which examines material from the placenta, and percutaneous cord blood sampling. Amniocentesis involves examining the amniotic fluid found in the sac surrounding the baby. According to Dr. Schaefer, many people with Down syndrome have the common facial features and no other major birth defects. However, some people may have one or more major birth defects or other medical problems, such as hearing loss, sleep apnea, or eye disease.
Cognitive impairment
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| Cognitive impairment, problems thinking and learning, are common in people with Down syndrome and usually range from mild to moderate. Most children with Down syndrome develop the communication skills they need, although it may take them longer than other children. Early and ongoing speech and language interventions to encourage expressive language and improve speech are particularly helpful. Because it is a lifelong condition, early services will often help babies and children with Down syndrome improve their physical and intellectual abilities. Most of these services aim to help children develop to their full potential. These services include speech therapy and physical therapy, and they are generally offered through early intervention programs in each state. Children with Down syndrome may also need extra help or attention at school, although many children are included in regular classes.
Recognized by thousands of listeners each week, T. Glenn Pait, MD, began offering expert advice as the host of UAMS’s “Here’s to Your Health” program in 1996. Dr. Pait has started working at UAMS in 1994 and has been practicing medicine for over 25 years.
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