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.
Down syndrome varies in severity among individuals, causing lifelong intellectual disability and developmental delays. It’s the most common genetic chromosomal disorder and cause of learning disabilities in children
- Trisomy 21.About 95 percent of the time, Down syndrome is caused by trisomy 21.
- Mosaic Down syndrome.In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome 21.
- Translocation Down syndrome.Down syndrome can also occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception.
- Advancing maternal age. Greater risk of improper chromosome division. A woman’s risk of conceiving a child with Down syndrome increases after 35 years of age.
- 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.
- 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
Children and adults with Down syndrome have distinct facial features. Though not all people with Down syndrome have the same features, some of the more common features include:
- Infants with Down syndrome may be average size, but typically they grow slowly and remain shorter than other children the same age. Flattened face
- Small head
- Short neck
- Protruding tongue
- Upward slanting eye lids (palpebral fissures)
- Unusually shaped or small ears
- Poor muscle tone
- Broad, short hands with a single crease in the palm
- Relatively short fingers and small hands and feet
- Excessive flexibility
- Tiny white spots on the colored part (iris) of the eye called Brushfield’s spots
- Short height
People with Down syndrome can have a variety of complications, some of which become more prominent as they get older. These complications can include:
- Heart defects.
- Gastrointestinal (GI) defects. The risk of developing digestive problems, such as GI blockage, heartburn (gastroesophageal reflux) or celiac disease, may be increased.
- Immune disorders. such as pneumonia.
- Sleep apnea..
- Spinal problemsLeukemia.
- 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.
- There’s no way to prevent Down syndrome.
- consult a genetic counselor before becoming pregnant
- prenatal tests that are available and help explain the pros and cons of testing.