Trisomy 21
Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46.
Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46.
Causes, incidence, and risk factors
In most cases, Down syndrome occurs when there is an extra copy of chromosome 21. This form of Down syndrome is called Trisomy 21. The extra chromosome causes problems with the way the body and brain develop.
Down syndrome is the most common single cause of human birth defects.
Symptoms
Down syndrome symptoms vary from person to person and can range from mild to severe. However, children with Down syndrome have a widely recognized appearance.
The head may be smaller than normal and abnormally shaped. For example, the head may be round with a flat area on the back. The inner corner of the eyes may be rounded instead of pointed.
In most cases, Down syndrome occurs when there is an extra copy of chromosome 21. This form of Down syndrome is called Trisomy 21. The extra chromosome causes problems with the way the body and brain develop.
Down syndrome is the most common single cause of human birth defects.
Symptoms
Down syndrome symptoms vary from person to person and can range from mild to severe. However, children with Down syndrome have a widely recognized appearance.
The head may be smaller than normal and abnormally shaped. For example, the head may be round with a flat area on the back. The inner corner of the eyes may be rounded instead of pointed.
Common physical signs include:
Children may also have delayed mental and social development. Common problems may include:
As children with Down syndrome grow and become aware of their limitations, they may also feel frustration and anger.
Many different medical conditions are seen in people with Down syndrome, including:
- Decreased muscle tone at birth
- Excess skin at the nape of the neck
- Flattened nose
- Separated joints between the bones of the skull (sutures)
- Single crease in the palm of the hand
- Small ears
- Small mouth
- Upward slanting eyes
- Wide, short hands with short fingers
- White spots on the colored part of the eye (Brushfield spots)
Children may also have delayed mental and social development. Common problems may include:
- Impulsive behavior
- Poor judgment
- Short attention span
- Slow learning
As children with Down syndrome grow and become aware of their limitations, they may also feel frustration and anger.
Many different medical conditions are seen in people with Down syndrome, including:
- Birth defects involving the heart, such as an atrial septal defect or ventricular septal defect
- Dementia may be seen
- Eye problems, such as cataracts (most children with Down syndrome need glasses)
- Early and massive vomiting, which may be a sign of a gastrointestinal blockage, such as esophageal atresia and duodenal atresia
- Hearing problems, probably caused by regular ear infections
- Hip problems and risk of dislocation
- Long-term (chronic) constipation problems
- Sleep apnea (because the mouth, throat, and airway are narrowed in children with Down syndrome)
- Teeth that appear later than normal and in a location that may cause problems with chewing
- Underactive thyroid (hypothyroidism)
Signs and tests
A doctor can often make an initial diagnosis of Down syndrome at birth based on how the baby looks. The doctor may hear a heart murmur when listening to the baby's chest with a stethoscope.
A blood test can be done to check for the extra chromosome and confirm the diagnosis. See: Chromosome studies
Other tests that may be done include:
A doctor can often make an initial diagnosis of Down syndrome at birth based on how the baby looks. The doctor may hear a heart murmur when listening to the baby's chest with a stethoscope.
A blood test can be done to check for the extra chromosome and confirm the diagnosis. See: Chromosome studies
Other tests that may be done include:
- Echocardiogram to check for heart defects (usually done soon after birth)
- ECG
- X-rays of the chest and gastrointestinal tract
- Eye exam every year during infancy
- Hearing tests every 6 - 12 months, depending on age
- Dental exams every 6 months
- X-rays of the upper or cervical spine between ages 3 - 5 years
- Pap smears and pelvic exams beginning during puberty or by age 21
- Thyroid testing every 12 months
Treatment
There is no specific treatment for Down syndrome. A child born with a gastrointestinal blockage may need major surgery immediately after birth. Certain heart defects may also require surgery.
When breast-feeding, the baby should be well supported and fully awake. The baby may have some leakage because of poor tongue control. However, many infants with Down syndrome can successfully breast-feed.
Obesity can become a problem for older children and adults. Getting plenty of activity and avoiding high-calorie foods are important. Before beginning sports activities, the child's neck and hips should be examined.
Behavioral training can help people with Down syndrome and their families deal with the frustration, anger, and compulsive behavior that often occur. Parents and caregivers should learn to help a person with Down syndrome deal with frustration. At the same time, it is important to encourage independence.
Adolescent females and women with Down syndrome are usually able to get pregnant. There is an increased risk of sexual abuse and other types of abuse in both males and females. It is important for those with Down syndrome to:
Special education and training is offered in most communities for children with delays in mental development. Speech therapy may help improve language skills. Physical therapy may teach movement skills. Occupational therapy may help with feeding and performing tasks. Mental health care can help both parents and the child manage mood or behavior problems. Special educators are also often needed.
There is no specific treatment for Down syndrome. A child born with a gastrointestinal blockage may need major surgery immediately after birth. Certain heart defects may also require surgery.
When breast-feeding, the baby should be well supported and fully awake. The baby may have some leakage because of poor tongue control. However, many infants with Down syndrome can successfully breast-feed.
Obesity can become a problem for older children and adults. Getting plenty of activity and avoiding high-calorie foods are important. Before beginning sports activities, the child's neck and hips should be examined.
Behavioral training can help people with Down syndrome and their families deal with the frustration, anger, and compulsive behavior that often occur. Parents and caregivers should learn to help a person with Down syndrome deal with frustration. At the same time, it is important to encourage independence.
Adolescent females and women with Down syndrome are usually able to get pregnant. There is an increased risk of sexual abuse and other types of abuse in both males and females. It is important for those with Down syndrome to:
- Be taught about pregnancy and taking the proper precautions
- Learn to advocate for themselves in difficult situations
- Be in a safe environment
Special education and training is offered in most communities for children with delays in mental development. Speech therapy may help improve language skills. Physical therapy may teach movement skills. Occupational therapy may help with feeding and performing tasks. Mental health care can help both parents and the child manage mood or behavior problems. Special educators are also often needed.
