As you read in the caption to the right, down syndrome is caused by an extra copy of chromosome 21. That extra chromosome is the result of a defective meiosis. Down syndrome occurs when chromosomes don't seperate properly during this process.
You can usually tell who has down syndrome by their audible appearance. They usually have round heads and lazy eyes. There are special education classes for people with this disease. This is a degree of mental retardation.
One way to tell if your child has down sydrome is the karyotype procedure, which is a picture of all the chromosomes in the cell. Another procedure is amniocentesis, which is when they take a long needle to remove a small amount of the fluid that surrounds the developing baby.
Down syndrome is a very effective disease that may change someone's life forever.
