Information supplied by the Down’s Syndrome Association

What is the incidence of Down’s syndrome

For every 1,000 babies born, one will have Down’s syndrome. About 600 babies with Down’s syndrome are born in the UK each year. Down’s syndrome affects people of all ages, races, religious and economic situations. It is estimated that there are around 60,000 people with Down’s syndrome living in the UK.

Why is Down’s syndrome referred to as a ‘genetic condition’?

The human body is made up of cells. Each cell is like a tiny factory, which makes the materials needed for growth and maintenance of the body. All cells contain a nucleus in which genes are stored. Genes are grouped along rod-like structures called chromosomes. Usually, the nucleus of each cell contains 23 pairs of chromosomes, 23 we inherit from our mother and 23 we inherit from our father.In people with Down’s syndrome the cells contain 47 chromosomes, an extra copy of chromosome 21. This additional genetic material results in Down’s syndrome.

There are three types of Down’s syndrome:

• Trisomy 21 - in which all the cells have an extra chromosome 21. About 94% of people with Down’s syndrome will have this type.
• Translocation - in which extra chromosome 21 material is attached to another chromosome. Around 4% of people with Down’s syndrome have this type.
• Mosaic - in which only some of the cells have an extra chromosome 21. About 2% of people with Down’s syndrome have this type.

What causes Down’s syndrome?

As yet we do not know what causes the presence of an extra chromosome 21. It can come from either the mother or the father. There is no way of predicting whether a person is more or less likely to make an egg or sperm with 24 chromosomes.

There is a definite link with advanced maternal age for reasons yet unknown. However most babies with Down’s syndrome are born to women under the age of 35, as younger women have higher fertility rates.

What we do know is that no one is to blame. Nothing done before or during pregnancy can cause Down’s syndrome. It occurs in all races, social classes and in all countries throughout the world. It can happen to anyone.

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.
• A flat facial profile, flat nasal bridge, small nose.
• Eyes that slant upwards and outwards.
• A small mouth which makes the tongue seem slightly large.
• A big space between the first and second toe.
• Broad hands with short fingers and a little finger that curves inwards.
• A below average weight and length at birth.

Do people with Down’s syndrome have medical problems?

Certain medical problems are more common in people with Down’s syndrome. These include: 40-50% of babies with Down’s syndrome are born with heart problems, half of which require heart surgery. A significant number of people with Down’s syndrome will have hearing and sight problems, thyroid disorders, poor immune systems, respiratory problems, coughs and colds and obstructed gastrointestinal tracts.

However, with advances and increased access to medical care most of these problems are treatable. The Down’s Syndrome Association together with the Down’s Syndrome Medical Interest Group have produced health care guidelines to assist families and health professionals to set up screening programmes so that health problems can be picked up early on and treated before they become more serious.

How does Down’s syndrome affect development?

All people with Down’s syndrome will have some degree of learning disability. Children with Down’s syndrome do learn to walk, talk and be toilet trained but in general will meet these developmental milestones later than their ordinary peers.

Early intervention programmes which are now widespread for children with learning disabilities help in all areas of child development. These programmes can include speech and physical therapy as well as home teaching programmes for the child and family.

Children and adults with Down’s syndrome can and do continue to learn throughout their lives just like the rest of the population. Just as with all children there is a great deal of individual variation in the age at which the different skills develop. A few children will have additional health problems which may slow their development. However all will continue to develop at their own pace.

For more information, visit the Down’s syndrome website at:

 www.downs-syndrome.org.uk

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