Lucy+down+syndrome

**Down syndrome notes:**
What is down syndrome? - A set of mental and physical symptoms that result from having an extra copy chromosome 21. - In a normal human being, a fertilized egg has 23 pairs of chromosomes. - There is an extra copy of chromosome 21 because there are three copies of this chromosome instead of two. And it changes the body's and brain;s normal development. - a common birth defect caused by the presence of an extra chromosome 21. - occurs in approximately 1 in every 800 live birth - individuals with down syndrome have 47 chromosomes instead of the usual 46 - Down syndrome is not related to race, nationality, religion, or socioeconomic status. - A genetic disorder caused by the presence of all or part of an extra 21th chromosome.

chromosome 21: http://en.wikipedia.org/wiki/Chromosome_21_%28human%29
 * " Chromosome 21** is one of the 23 pairs of [|chromosomes] in [|humans]. People normally have two copies of this chromosome. Chromosome 21 is the smallest human chromosome [|Down syndrome] is caused by a rearrangement of chromosomal material between chromosome 21 and another chromosome. As a result, a person has the usual two copies of chromosome 21, plus extra material from chromosome 21 attached to another chromosome. These cases are called translocation Down syndrome. Researchers believe that extra copies of genes on chromosome 21 disrupt the course of normal development, causing the characteristic features of Down syndrome and the increased risk of medical problems associated with this disorder.
 * Other changes in the number or structure of chromosome 21 can have a variety of effects, including [|mental retardation], delayed development, and characteristic facial features. In some cases, the signs and symptoms are similar to those of Down syndrome. Changes to chromosome 21 include a missing segment of the chromosome in each cell (partial monosomy 21) and a circular structure called [|ring chromosome 21]. A ring chromosome occurs when both ends of a broken chromosome are reunited."



What causes down syndrome? - A normal baby will inherit genetic information from its parents in the form of 46 chromosomes: 23 from the mother, 23 from the father. - In the case of down syndrome, a child gets an extra chromosome - a total of 47 instead of 46. - Its that extra genetic information the causes the physical and cognitive delays - No One knows why Down syndrome occur - There is no way to prevent the chromomal error that causes it either - Scientists do know that women age 35 and older have a significantly hight risk of having a child with down syndrome. - At age 30 women have less then a 1 in 1000 chang of conceiving a child with down syndrome. - By age 42 the changes of having a child with down syndrome is 1 in 60. - The cause of down syndrome is 1 in 3 types of abnormal cell division involving the 31th chromosome. - All 3 abnormalities result in an extra genetic material from chromosome 21. - chromosome 21 makes up the characteristic features and developmental problems of Down syndrome. The 3 genetic variations: 1. trisomy 21 2. mosaic down syndrome 3. Translocation down syndrome

What are the signs and symptoms for down syndrome? - range from mild to severe - People with DS has mental and physical differences than normal people - Their development is slower than those without the condition - Mental retardation is a disability that causes limits on intellectual abilities and adaptive behaviors ( conceptual, social and practical skills people use to function in everyday lives) SOME common physical signs of Down Syndrome: - flat face with an upward slant to the eye - short neck abnormally shaped ears - deep crease in the palm of the hand - White spots on the iris of the eye - Poor muscle tone, loose ligaments - Small hands and feet

There are a variety of other health conditions that are often seen in people who have down syndrome: - heart disease - Intestinal problems: blocked small bowel or esophagus - eye problems

What is the treatment for Down syndrome? - A condition that cant be cured - Children with DS can benefit from speech therapy - They can attend special education and recieve attention at schools

Who is at risk for Down Syndrome? - The chance of having a baby with DS increases as a woman gets older (1 in 1250) - Testing the baby before it is born to see if it is likely to have DS allows parents and families to prepare for the baby's special needs - Paretns who have already had a child with DS or who have an abnormalities in their own chromosome 21 are also at higher risk for have a baby with DS. - Once a baby is born, a blood test cn confirm whether the baby has DS.

What is the nature of the chromosome abnormality? - The chromosome abnormality that causes Down syndrome is trisomy 21, an extra copy of chromosome number 21. This means that instead of having the normal 2 copies of chromosome number 21, the person with Down syndrome has 3 copies of chromosome number 21. Confirmation requires a chromosome study (analysis under the microscope of the chromosomes). A chromosome study is also valuable to rule in or out a translocation (a type of rearrangement) of chromosome 21 that may be heritable in which case it can give rise to more cases of Down syndrome in the family. The evaluation of the Down syndrome baby and the family by a medical geneticist is often useful.