What is Down Syndrome

In most cases, Down syndrome occurs when there is an extra copy of chromosome 21. This form of Down syndrome is called Trisomy 21. The extra chromosome causes problems with the way the body and brain develop. Down syndrome is the most common single cause of human birth defects. Symptoms Down syndrome symptoms vary from person to person and can range from mild to severe. However, children with Down syndrome have a widely recognized appearance. The head may be smaller than normal and abnormally shaped. For example, the head may be round with a flat area on the back. The inner corner of the eyes may be rounded instead of pointed. Common physical signs include: Decreased muscle tone at birth Excess skin at the nape of the neck Flattened nose Separated joints between the bones of the skull (sutures) Single crease in the palm of the hand Small ears Small mouth Upward slanting eyes Wide, short hands with short fingers White spots on the colored part of the eye (Brushfield spots) Physical development is often slower than normal. Most children with Down syndrome never reach their average adult height. Children may also have delayed mental and social development. Common problems may include: Impulsive behavior Poor judgment Short attention span Slow learning As children with Down syndrome grow and become aware of their limitations, they also feel frustration and anger.