Bibliography

http://www.kidshealth.org/parent/medical/genetic/down_syndrome.html
http://www.mayoclinic.com/health/down-syndrome/DS00182/DSECTION=3
http://www.kidshealth.org/parent/medical/genetic/down_syndrome.html
http://www.healthscout.com/ency/68/449/main.html#SymptomsofDownSyndrome
http://www.emedicinehealth.com/down_syndrome/page5_em.htm
http://www.mayoclinic.com/health/down-syndrome/DS00182/DSECTION=7

What is Down Syndrome?

Down syndrome is a condition in which extra genetic material causes delays in the way a child develops, and often leads to mental retardation. It affects 1 in every 800 babies born. It is a condition in which there is extra sets of a chromosome.

Picture of Child with Down Syndrome

Picture of Child with Down Syndrome

What Causes Down Syndrome?

What Causes Down Syndrome?

Down syndrome is caused by extra genetic material from chromosome 21 of the 23 chromosomes. There are three different causes for down syndrome. The first is Trisomy 21, which causes over 90 percent of down syndrome cases. In this case, there are three copies of chromosome 21, and is caused by abnormal cell division during development of the egg or sperm. The second type is mosaic down syndrome. This form is very rare, and it is caused by some cells (but not all) containing extra copies of chromosome 21. It is caused by abnormal cell division after fertilization. The last type is translocation down syndrome. This is when additional material from chromosome 21 becomes attached to other chromosomes.

How is Down Syndrome Inherited?

Down syndrome is actually not inherited, it is caused by abnormal cell division sometime during the reproductive cycle. Translocation down syndrome can be passed from parent to child, but it is extremely rare. A child's risk of inheriting this type of down syndrome is only 3-12 percent.

How is Down Syndrome Diagnosed?

There are two different tests that can be administered to check for down syndrome, screening tests and diagnostic tests. Screening tests estimate the risk that a fetus has down syndrome, while diagnostic tests can actually tell whether the fetus has the disorder. Screening tests are non-invasive and painless, and used to decide if more tests are necessary. Diagnostic tests are 99% accurate, but have a risk of miscarriage.

Types of Screening Tests

-Nuchal Translucancy Test:uses ultrasound to measure the space behind the folds of a baby's neck, down syndrome will cause an abnormally large space
-The Triple Screen:measure the quantities of different substances in the mother's blood and use that and the woman's age to estimate the chance of the fetus having down syndrome
-Detailed Ultrasound:checks the fetus for physical traits of down syndrome

Types of Diagnostic Tests

-Amniocentesis:removal of amniotic fluids by means of a needle through the abdomen, and testing for the presence of chromosomal abnormalties
-Chorionic Villus Sampling:taking a small sample of the placenta through a needle in the abdomen
-Percutaneous Umbilical Blood Sample:uses a needle to retrieve a small sample of the blood in the umbilical chord.

What are the Symptoms of Down Syndrome?

Symptoms of down syndrome are different from person to person. There are many different types of symptoms, but not everyone has all these symptoms. Some of the common symptoms are: decreased muscle tone at birth, asymmetrical or odd-shaped skull, round head with flat area at the back of the head, small skull, slanting eyes, small mouth with protruding tongue, broad short hands, single crease on the palm, retarded growth and development, delayed mental and social skills (mental retardation)Children with Down syndrome have a widely recognized characteristic appearance. Their head may be smaller than normal and abnormally shaped. Other prominent characteristics of Down syndrome are: a flattened nose, protruding tongue, upward slanting eyes, short hands and fingers, and a single crease in the palm.

Symptoms of Down Syndrome

Treatments for Down Syndrome

There are no treatments for down syndrome. There are programs that can help the development of a child with down syndrome, however. These include physical therapy, occupational therapy, speech therapy, and special education in schools. Surgery can be done to improve some of the health problems associated with down syndrome, and plastic surgery can be performed to correct the physical symptoms.

Prognosis of Down Syndrome

Most children diagnosed with down syndrome will experience heart defects and are at risk for high blood pressure. Many people with down syndrome also experience hearing and vision problems due to defected structure of the body parts. Other medical conditions that may occur more frequently in children with DS include thyroid problems, intestinal abnormalities, seizure disorders, respiratory problems, obesity, an increased susceptibility to infection, and a higher risk of childhood leukemia. People with down syndrome typically live to around 55 years old. This number has gone up substantially in the past several decades.

Interesting Facts about Down Syndrome

Down syndrome is the only trisomy compatible with life. The other two known trisomies leave a baby with only a 5% chance of surviving. In 90% of trisomy 21 cases, the extra chromosome comes from the mother's egg rather than the father's sperm. The cause of down syndrome was discovered in 1959 by Jerome Lejeune. It affects 1 out of every 800 babies.