Down syndrome (also called Trisomy 21) is the most common cause of mental retardation in a newborn. This defect is relatively common and is caused by an extra chromosome number 21. This affects both the physical and mental development of the child. Down syndrome may be inheritable but is not contagious.
             People affected by Down syndrome usually have a flat appearing face and almond-shaped (or slanting) eyes with extra folds of skin (called epicanthal folds) at the inside of each eye, near their nose. Their nose is small, with an upward curve; and their mouth is also small, causing the tongue to stick out slightly. They have rounded cheeks and small misshapen ears. Their hands are small and wide and have an unusually deep crease (called a simian crease) through the center of their palm. The fifth finger is deformed and curves towards the thumb. The space between the first and second toes is abnormally large and they have deep creases on the soles of their feet. They are usually shorter than other people their age and have overly-flexible joints. Approximately 30 – 50% of children with Down syndrome end up having heart problems. One heart problem that is common in Down syndrome is unusual gaps in the walls, separating the heart's chambers. When this occurs, there is an abnormal pattern of blood flow inside the heart resulting in less oxygen circulating throughout the body. Another common medical condition in Down syndrome is an increased chance of infections and pneumonia. Kidney problems, hearing loss, and vision impairment are also common. Babies with Down syndrome have weak muscles and develop at a slower rate. They learn to sit, crawl, and walk later than normal children. They generally also learn to talk later in life. The photographs below show some of the symptoms of Down syndrome.
             Down syndrome is a genetic disease and occurs when the person has an extra chromosome number 21 – three in
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