Down+Syndrome

toc =1375284252= = __Definition:__ =

A child has three copies of chromosome 21( also known as Trisomy 21). These children have a mental retardation and have distinctive facial features, smaller brains, and often other physical abnormalities such as heart defects. HGD Chapter 3, p. 57

**__Problems__**
Down syndrome (DS), also called Trisomy 21, is a condition in which extra genetic material causes delays in the way a child develops, both mentally and physically. It affects about 1 in every 800 babies born in the United States. The physical features and medical problems associated with Down syndrome can vary widely from child to child. While some kids with DS need a lot of medical attention, others lead healthy lives. Though Down syndrome can't be prevented, it can be detected before a child is born. The health problems that may go along with DS can be treated, and many resources are available to help kids and their families who are living with the condition.

=**__What causes It?__**= No one knows for sure why DS occurs and there's no way to prevent the chromosomal error that causes it, scientists do know that women age 35 and older have a significantly higher risk of having a child with the condition. At age 30, for example, a woman has about a 1 in 1,000 chance of conceiving a child with DS. Those odds increase to about 1 in 400 by age 35. By 40 the risk rises to about 1 in 100.

= __Examples:__ = At the time of conception a baby inherits genetic information from its parents in the form of 46 chromosomes: 23 from the mother and 23 from the father. In most cases of Down syndrome, a child gets an extra chromosome 21 — for a total of 47 chromosomes instead of 46. It's this extra genetic material that causes the physical features and developmental delays associated with DS. media type="youtube" key="I13KxRYqoo0" height="315" width="420"

= __Analogies:__ = =Down syndrome and Turner's syndrome=

= __Mnemonics:__ =
 * Congenital heart disease / Cataracts
 * Hypotonia / Hyperthyroidism
 * Incure 5th finger / Increased gap between 1st and 2nd toes
 * Leukaemia (risk x2) / Lung problems
 * Duodenal atresia / Delayed development
 * Hirshsprung’s disease / Hearing loss
 * Alzheimer’s disease / Alantoaxial instability
 * Short neck / Squint
 * Protruding tongue / Palmar crease
 * Roung face / Rolling eye (nystagmus)
 * Oblique eye fissure / Occiput flat
 * Behavioural difficulties
 * Low nasal bridge / Language problem
 * Epicanthic fold / Ear folded
 * Mental retardation / Myoclonus

=__In the News:__= Down Syndrome Teen Kept Off Plane as 'Flight Risk' A 16 year old down syndrome boy was not allowed to ride on a plane with his family in first class because they said he was a flight risk. media type="youtube" key="sbnrAcC4hx0" height="187" width="336"

http://youtu.be/y6He0FWoFj0 DOWN SYNDROME Down syndrome is a developmental disorder caused by an extra copy of chromosome 21 (which is why the disorder is also called "trisomy 21"). Having an extra copy of this chromosome means that individuals have three copies of each of its genes instead of two, making it difficult for cells to properly control how much protein is made.



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