Down syndrome is the most common name. Other names used to say Down syndrome are trisomy 21, trisomy G, 47 XX + 21, 47 XY + 21 and use to be known as mongolism. Most common signs of Down syndrome are a shorter height since the body grows slower, weak muscles, a shorter fatter neck, stocky arms and stocky legs. They also are known for slanted eyes, irregular shape mouth and tongue and crooked teeth. The affected chromosome in Down syndrome patients is chromosome 21. Most of the time Down syndrome comes from the mom’s egg and not the father’s sperm (changes in structure or count). One out six hundred ninety one babies are born with Down syndrome and it is estimated that about 250,000,400,000 people in America have down syndrome.

Down syndrome is neither a dominant nor recessive gene for Down syndrome occurs when an egg does not go through meiosis properly and leaves an extra 21 chromosome. While a normal person should only have two, one from mom and one from dad, a person with Down syndrome have three. The chromosome that Down syndrome is located on is chromosome 21. Down syndrome shows up at birth since it is a birth defect. Even though Down syndrome is a hard disorder to deal with, it is not fatal and many people have that have it live just as long and happy as someone without it.

One interesting thing about Down syndrome is that the cause of the extra chromosome is unknown. Another interesting fact is that roughly twenty five percent of families in America have someone in their family with Down syndrome. One thing I would really like to know would be what the chromosome is that makes it happen because if it was known something could possibly be done about it.