4. How is Down's syndrome diagnosed?

The diagnosis of Down's syndrome is usually picked up soon after the birth of the baby because of the way it looks. There are many physical characteristics associated with the condition, which may lead a parent, or medical professional to suspect that the baby has Down's syndrome.

Some of the features include:

• Reduced muscle tone which results in floppiness (hypotonia)
• A flat facial profile, flat nasal bridge, small nose
• Eyes that slant upwards and outwards. Often with a fold of skins that runs vertically between the lids at the inner corner of the eye (epicanthic fold)
• A small mouth, which makes the tongue, seem slightly large
• A big space between the first and second toe (sandal gap)
• Broad hands with short fingers and a little finger that curves inwards. The palm may have only one crease across it (palmar crease)
• Below average weight and length at birth

Many of these features are found in the general population. Therefore a chromosome test would need to be done on the baby before a positive diagnosis could be made. Taking blood from the baby and then analysing the chromosomes does this. The result is called a karyotype.