Description Down syndrome is the most common chromosomal anomaly, occurring in about 1 in to births.
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 Infants with Down syndrome may be average size, but typically they grow slowly and remain shorter than other children the same age.
Intellectual disabilities Most children with Down syndrome have mild to moderate cognitive impairment. Language is delayed, and both short and long-term memory is affected.
When to see a doctor 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.
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 This extra genetic material is responsible for the characteristic features and developmental problems of Down syndrome.
Any one of three genetic variations can cause Down syndrome: 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. In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.
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.
There are no known behavioral or environmental factors that cause Down syndrome. 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. However, only about 3 to 4 percent of children with Down syndrome have translocation and only some of them inherited it from one of their parents.
When balanced translocations are inherited, the mother or father has some rearranged genetic material from chromosome 21 on another chromosome, but no extra genetic material.
This means he or she has no signs or symptoms of Down syndrome, but can pass an unbalanced translocation on to children, causing Down syndrome in the children. Risk factors Some parents have a greater risk of having a baby with Down syndrome.
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. A woman's risk of conceiving a child with Down syndrome increases after 35 years of age.
|Down Syndrome (Trisomy 21)||Down syndrome is a condition in which a person has an extra chromosome.|
|Chromosomal Changes That Can Cause Down Syndrome||Intellectual disabilities Most children with Down syndrome have mild to moderate cognitive impairment.|
|Down Syndrome (Trisomy 21): Your Child: University of Michigan Health System||A carrier parent Parents who are carriers of the genetic translocation for Down syndrome have an increased risk depending on the type of translocation.|
However, most children with Down syndrome are born to women under age 35 because younger women have far more babies. 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. A genetic counselor can help parents assess the risk of having a second 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: About half the children with Down syndrome are born with some type of congenital heart defect.
These heart problems can be life-threatening and may require surgery in early infancy. GI abnormalities occur in some children with Down syndrome and may include abnormalities of the intestines, esophagus, trachea and anus. The risk of developing digestive problems, such as GI blockage, heartburn gastroesophageal reflux or celiac disease, may be increased.
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. 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.
People with Down syndrome have a greater tendency to be obese compared with the general population. Some people with Down syndrome may have a misalignment of the top two vertebrae in the neck atlantoaxial instability. This condition puts them at risk of serious injury to the spinal cord from overextension of the neck.Most cases of Down syndrome result from trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies..
Less commonly, Down syndrome occurs when part of chromosome 21 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) in a parent or very early in fetal development. The National Down Syndrome Congress (NDSC) is a national advocacy organization for Down syndrome that strives to provide support and empowerment to persons with Down syndrome and their families.
The National Association for Down Syndrome focuses mainly on the Chicago area. Trisomy About 95% of people with Down syndrome have Trisomy 2 With this type of Down syndrome, each cell in the body has 3 separate copies of chromosome 21 instead of the usual 2 copies. Down Syndrome (Trisomy 21) What is Down syndrome, and what causes it?
Down syndrome is a genetic disorder. Most people have 46 chromosomes in each cell. Jun 11, · The symptoms of someone with mosaic trisomy 21 may vary from those of someone with complete trisomy 21 or translocation trisomy 21, depending on how many cells have the extra chromosome.
1,2 Translocation trisomy 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.
Mosaic Down syndrome.