Down Syndrome is a genetic condition caused by extra genetic material from the 21st chromosome. The extra genes cause certain characteristics that we know as Down syndrome. Individuals with Down syndrome also have all the other genes given to them by their parents. As a result, they have a combination of features typical of Down syndrome on top of the individual features from their parents. There is some degree of mental retardation, or cognitive disability and other developmental delays. .
Individuals with Down syndrome have distinct physical characteristics; generally they are more similar to the average person in the community than they are different. The physical features are important to the physician in making the clinical diagnosis, but no emphasis should be put on those characteristics otherwise. Not every child with Down syndrome has all the characteristics; some may only have a few, an others may show most of the signs of Down syndrome. .
Over a 120 features have been described in Down syndrome. Many children with the syndrome have no more than six or seven of these. Some of the features are those that are either particularly useful in recognizing the condition, or have some relevance to parents. .
Face. When looked at from the front, the child with Down syndrome usually has a rounded face. From the side, the face tends to have a flat profile.
Head. The back of the head is slightly flattened in most people with Down syndrome. This is known as brachycephaly.
Eyes. The eyes of nearly all children and adults with Down syndrome slant slightly upwards. In addition, there is often a small fold of skin that funs vertically between the inner comer of the eye and the bridge of the nose. This is known as the epicanthic fold or epicanthus. It is often seen in normal infants. In both normal children and those with Down syndrome it becomes less prominent, and may disappear, when the child grows older and the skin is taken up to cover the bridge of the nose.