Down+Syndrome

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Do you know what Down syndrome is? Probably not. If you want to find out read on.
=What is Down syndrome? =

Down syndrome is a genetic disease that is passed down from generation to generation. It is caused by the chromosomes. The process in which the chromosomes do not split correctly is called "nondisjuction". Instead of having 2 copies of chromosome 21 you have 3 copies. Below is and image of what the chromosomes would look like.

 The disease also affects the humans' appearance and the way they act. Some are different than others. Some have more symptoms than others. The chance of having a baby with Down syndrome is 1 in every 691 babies. The less of a chance of having a baby if the family has Down syndrome passed down in their family tree, increases as the mother gets older. But how is all this genetically related? =﻿How is Down syndrome a genetic disease? =

Down Syndrome is a genetic disease because if the family has the gene for Down Syndrome somewhere in their family tree. If the trait hasn't shown for over seven generations, for example, the child still has a chance of getting the disease. As I stated before, 1 in every 691 babies get Down Syndrome. As the mother gets older, the baby's chances increase of getting the disease. The table below specifies that. The following link is an example of how the disease is genetic. It shows how the sperm and egg cell meet. Then you can see the extra chromosome in the egg cell and when they join, the 3rd extra chromosome is all alone and doesn't have a pair/buddy: [] (Must scroll down a little) To relate to the simulation in the link, the egg cell has 47 chromosomes instead of the usual 46. That is the most common single cause. There are other causes too. They also go by different names. There are three types, trisomy 21, translocation, and mosaicism. Here are a little bit of information on the types:
 * Age of Parent || Chances of Disease ||
 * 20 || 1 in 2000 ||
 * 25 || 1 in 1200 ||
 * 30 || <span style="font-family: Arial,Helvetica,sans-serif;">1 in 900 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">35 || <span style="font-family: Arial,Helvetica,sans-serif;">1 in 350 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">40 || <span style="font-family: Arial,Helvetica,sans-serif;">1 in 100 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">45 || <span style="font-family: Arial,Helvetica,sans-serif;">1 in 30 ||
 * <span style="font-family: Arial,Helvetica,sans-serif;">50 || <span style="font-family: Arial,Helvetica,sans-serif;">1 in 5 ||

__﻿Trisomy 21__

 * 95% of people with Down syndrome, have this type.
 * Has three instead of two copies of chromosome 21.
 * The 21st chromosome in the sperm or egg doesn't split and an over-dose goes to the sex cell being created.

__Translocation__

 * Happens to 3 to 4% of people with Down syndrome
 * The extra 21st chromosome gets stuck onto another chromosome.
 * In half of these situations, the one of the parents carries the 21st chromosome material, but it's hidden or "unbalanced".

__Mosaicism__
=﻿What are the symptoms?=
 * About 1 to 2% of people have this type.
 * The extra chromosome is in some of the cells, but not in all of them.
 * Multiple traits that can be seen. (Ex. Upward slant of eyes)

There are a lot of possible symptoms for Down syndrome. There are common physical symptoms, social and mental symptoms, and medical symptoms.

__﻿Common Physical Symptoms__

 * Decreased muscle tone at birth
 * Excess skin at the nape of the neck
 * Flat nose
 * Separated joints between bones and skull
 * Increase in palm of the hand
 * Small ears
 * Small mouth
 * Eyes that slant up
 * Wide short hands with short fingers
 * White spots on the colored part of the eye

__Mental & Social Symptoms__

 * Impulsive behavior
 * Poor judgment
 * Short attention span
 * Slow at learning

__Medical Symptoms__
So now, do you know what Down syndrome is? If you have and questions or comments please leave a comment in the discussion section below.
 * Birth defects including the heart
 * Dementia
 * Eye problems (They usually need glasses)
 * Early and massive vomiting
 * Hearing problems
 * Hip problems
 * Sleep apnea

Elizabeth M.