Technichally, Down Syndrome is a mental disability possesed from birth, where the 21st chromosome pair in each cell has an extra. This makes a total of 47 chromosomes per cell instead of the standard 46. This "little something extra" makes them learn and look a bit differently than most people.
People with Downs Syndrome can lead very normal lives, it just takes them more time and effort to learn. They are usually very honest and careing, and never judgemental. They make wonderful friends, because they usually have a refreshingly clear view of what does and does not matter in life.
Raised in the right environment (ie. a happy and nurturing family) kids with Down Syndrome are an asset to society. The biggest challange they face is the rude and downright hateful disrespect shown to them by ignorant people. People with Down Syndrom deserve respect just as much as anyone else.
Isaac was born with Down Syndrome, but his family is happy because they realize that with love and patience, there is nothing that Isaac can't do.
Some of the athletes in the special olympics have Down Syndrome.