Down's
Syndrome

Down’s Syndrome has its origins in the genes. Every cell contains a number of chromosomes. These are tiny particles that carry the blueprint for all the characteristics that we inherit. Normally there are 46 chromosomes in every cell; half of these come from our mother, half from our father. The person with Down’s Syndrome has an extra chromosome 21 – making 47 in all. This results in a disruption to the growth of the developing baby.

This extra chromosome can come from either the mother or the father, and is present because of a genetic accident when the egg or the sperm is made or during the initial cell division following conception.

The features that people look for include:

• Eyes that slant upwards and outwards. They often have a fold of skin that runs vertically between the two lids at the inner corner of the eye (the ‘epicanthic fold’).
• A head that is rather flat at the back with a hairline that is low and ill defined at the nape of the neck, often with rather loose skin in this area.
• A face that appears somewhat flat with a flat nasal bridge.
• A mouth cavity that is slightly smaller than average, and a tongue that is slightly larger. The child’s tongue may thus protrude, a habit that can be stopped with teaching.
• Hands that are broad, with short fingers, and a little finger that curves inwards. The palm may have only one crease across it.
• A deep cleft between the first and second toe extending as a long crease on the side of the foot.
• Reduced muscle tone which results in floppiness (hypotonia). This often improves spontaneously as the child gets older but some be left with the low tone posture which may lead to normal Orthopaedic conditions later in life in the lower limbs, e.g. osteoarthritis
• A below average weight and length at birth.

It is important to point out that any of these features can occur in people who do not have Down’s Syndrome. For example, 4%-5% of children who do not have Down’s Syndrome have a single crease across their palm; 6%-8% of children without Down’s Syndrome display epicanthic folds; and 25%-50% of people who do not have Down’s Syndrome have slanted eyes, flat back of the head, small ears and flat nasal bridge.