DOWN'S SYNDROME
DOWN'S SYNDROME
1. DEFINITION
2. TYPES OF DOWNS SYNDROME
3. SIGNS AND SYMPTOMS
3. CAUSES
5. DIAGNOSIS
6. COMPLICATIONS
7. PREVENTION
1. DEFINITION
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical features of Down syndrome.
TYPES OF DOWNS SYNDROME
1. Trisomy 21.
About 95 percent of the time, Down syndrome is caused by trisomy 21 — the person has three copies of chromosome 21, instead of the usual two copies, in all cells. This is caused by abnormal cell division during the development of the sperm cell or the egg cell.
2. Mosaic Down syndrome.
In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.
3. Translocation Down syndrome. Down syndrome can also occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. These children have the usual two copies of chromosome 21, but they also have additional genetic material from chromosome 21 attached to another chromosome.
SIGNS AND SYMPTOMS
SYMPTOMS
intellectual and developmental problems may be mild, moderate or severe. heart defects.SIGNS
Small headShort neckProtruding tongueUpward slanting eye lids (palpebral fissures)Unusually shaped or small earsPoor muscle toneBroad, short hands with a single crease in the palmRelatively short fingers and small hands and feetExcessive flexibilityTiny white spots on the colored part (iris) of the eye called Brushfield's spotsShort heightInfants with Down syndrome may be average size, but typically they grow slowly and remain shorter than other children the same age.Intellectual disabilitiesMost children with Down syndrome have mild to moderate cognitive impairment. Language is delayed, and both short and long-term memory is affected.
DIAGNOSIS
Children with Down syndrome usually are diagnosed before or at birth. However, if you have any questions regarding your pregnancy or your child's growth and development, talk with your doctor.
CAUSES
Human cells normally contain 23 pairs of chromosomes. One chromosome in each pair comes from your father, the other from your mother.Down syndrome results when abnormal cell division involving chromosome 21 occurs. These cell division abnormalities result in an extra partial or full chromosome 21. This extra genetic material is responsible for the characteristic features and developmental problems of Down syndrome. There are no known behavioral or environmental factors that cause Down syndrome.Is it inherited?Most of the time, Down syndrome isn't inherited. It's caused by a mistake in cell division during early development of the fetus.
Translocation Down syndrome can be passed from parent to child. RISK FACTORS
Some parents have a greater risk of having a baby with Down syndrome. Risk factors include:
1. ADVANCING MATERNAL AGE.
A woman's chances of giving birth to a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division.
2. BEING CARRIERS
Being carriers of the genetic translocation for Down syndrome. Both men and women can pass the genetic translocation for Down syndrome on to their children.
3. PREVIOUS INCIDENCE OF A CHILD WITH DOWNS SYNDROME
Having had one child with Down syndrome. Parents who have one child with Down syndrome and parents who have a translocation themselves are at an increased risk of having another child with Down syndrome
COMPLICATIONS
People with Down syndrome can have a variety of complications, some of which become more prominent as they get older. These complications can include:
1. Heart defects.
About half the children with Down syndrome are born with some type of congenital heart defect.
2. Gastrointestinal (GI) defects.
GI abnormalities occur in some children with Down syndrome and may include abnormalities of the intestines, esophagus, trachea and anus.
3. Immune disorders.
Because of abnormalities in their immune systems, people with Down syndrome are at increased risk of developing autoimmune disorders, some forms of cancer, and infectious diseases, such as pneumonia.
4. Sleep apnea.
Because of soft tissue and skeletal changes that lead to the obstruction of their airways, children and adults with Down syndrome are at greater risk of obstructive sleep apnea.
5. Obesity.
People with Down syndrome have a greater tendency to be obese compared with the general population.
6. Spinal problems.
Some people with Down syndrome may have a misalignment of the top two vertebrae in the neck (atlantoaxial instability).
7. Leukemia.
8. Dementia.
9. Other problems including endocrine problems, dental problems, seizures, ear infections, and hearing and vision problems.
MEDICAL CARE
For people with Down syndrome, getting routine medical care and treating issues when needed can help with maintaining a healthy lifestyle. A genetic counselor can help parents assess the risk of having a second child with Down syndrome.
Life expectancy
Life spans have increased dramatically for people with Down syndrome. Today, someone with Down syndrome can expect to live more than 60 years, depending on the severity of health problems.
Prevention
There's no way to prevent Down syndrome. If you're at high risk of having a child with Down syndrome or you already have one child with Down syndrome, you may want to consult a genetic counselor before becoming pregnant.
A genetic counselor can help you understand your chances of having a child with Down syndrome. He or she can also explain the prenatal tests that are available and help explain the pros and cons of testing.
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