Understanding the implications for your child if they are Down's Syndrome

The word syndrome means a collection of signs or characteristics. The name Down comes from Dr John Langdon Down, who first described the condition in 1866. In 1959 Professor Lejeune proved that Down's syndrome is a genetic condition caused by the presence of an extra chromosome.

There are more differences between people with Down's syndrome than there are similarities. They will have many of their families' distinctive characteristics and will therefore resemble their brothers and sisters. As well as these individual characteristics however, they will have physical features shared by others with Down's syndrome.

They will also have learning difficulties. This means they have greater difficulty learning than the majority of people the same age.

Down’s syndrome has its origins in the genes. Every cell contains a number of chromosomes. These are tiny particles which 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.

There are three different types of Down's syndrome. Ninety-five per cent of people with Down's syndrome have the type known as standard trisomy 21. This type of Down's syndrome is always an accident of nature. It can happen to anyone and it is not known why it occurs. Approximately one in 100 people have the second type of Down's syndrome. They inherit the condition from their mother or father because of a genetic anomaly called a translocation. The third type of Down's syndrome, also rare, is known as mosaic Down's syndrome, in which an extra chromosome 21 appears in only some of the cells.

For reasons not yet understood, the chance of any woman having a child with Down's syndrome increases with her age, particularly after 35 years. The age of the father appears to be less significant.

Down's syndrome is normally suspected soon after the birth, because a doctor, nurse, or sometimes a parent recognises the characteristic features. Chromosome tests are then carried out to confirm the diagnosis.

The features which 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 which 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 improves spontaneously as the child gets older.
• 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, four to five per cent of children who do not have Down's syndrome have a single crease across their palm; six to eight per cent of children without Down's syndrome display epicanthic folds; and 25 to 50 per cent of people who do not have Down's syndrome have slanted eyes, flat back of the head, small ears and flat nasal bridge.

For further information please contact
The Down’s syndrome Association
155 Mitcham Road
London, SW17 9PG
UK
Tel: 020 8682 4001
Fax: 020 8682 4012

Or visit their
website