Children with Down syndrome have many obvious symptoms in appearance and even constitution. Their intelligence is lower than that of normal children, and their IQ is usually only 40 to 60, but they are gentle. Children with this disease have slow development and low muscle tone, which makes them learn to sit and walk later than normal children. They also have a very special appearance and are easy to identify. Children with this disease generally have long eyes, oblique eyes, flat nose, small mouth, small teeth and big ears. Most patients have ape-shaped palm prints (commonly known as broken palms), special hoofprint on fingers, and the distance between the first and second toes is extremely wide.