Down Syndrome affects people of all ages, races and economic levels. It is one of the most frequently occurring chromosomal anomalies found in humans, occurring once in approximately every 660 babies born throughout the world, male and female alike. It is one of the most common known causes of intellectual disability. Down Syndrome is caused by an extra copy of chromosome 21 (d21). It is a chromosomal accident, not caused by anything the parents may have done before or during pregnancy.

How is Down Syndrome diagnosed?

Down Syndrome is recognizable at birth because of some typical physical characteristics and diagnosis will be confirmed by chromosome analysis. While people with Down Syndrome do have features in common, they also closely resemble their parents and family. Many characteristics are attributed to Down Syndrome, but any one person will have only some of them. Each person is an individual, with a unique appearance, personality and set of abilities. The extent to which each child shows the physical characteristics of the syndrome is no indication of his or her intellectual capacity.

What causes Down Syndrome?

As yet, we do not know what causes the presence of extra number 21 chromosome. It can come from either the mother or the father. The most common type of Down’s syndrome, Standard Trisomy 21 (also known as Primary Trisomy 21 or Regular Trisomy 21), occurs because of an unusual cell division which has produced either an egg or a sperm with 24 chromosomes instead of 23. When this egg or sperm fuses with an ordinary egg or sperm, the first cell of the developing baby has 47 chromosomes instead of 46, and all that baby’s cells will have 47 chromosomes. There is no way of predicting whether a person is more or less likely to make eggs or sperm with 24 chromosomes. We know that babies born to older mothers have a higher chance of having Down’s syndrome, but we do not know why.

Could we have prevented our baby having Down Syndrome?

It is important to remember that you are not to blame for your baby having Down syndrome. Nothing you did before or during pregnancy has caused it. It occurs in all races, in all social classes and in all countries throughout the world. It can happen to anyone.

Does it mean that any further children we might have will also have Down Syndrome?

Standard Trisomy 21 is not hereditary. However, once you have had one baby with Down Syndrome your chances of having another child with the condition are increased. Overall this chance is between 1 in 100 and 1 in 200, which is considerably less than the chance of, say, having twins ‘out of the blue’. When thinking about your next pregnancy it would be helpful to talk to a genetic counsellor who could talk things through with you in some detail.

My child has Down Syndrome. Will I have to look after them all their lives?

The choices made by people with Down Syndrome about leisure, education, work and housing are as varied as the people making them. With proper education and community understanding, it is often possible for those with Down Syndrome to achieve a level of independence that in the past wasn't thought possible.

Do people with Down Syndrome have a reduced life expectancy?

Down Syndrome is an intellectual impairment, but some people with it do experience associated physical problems. These days, though, it is not unusual for those with Down Syndrome to live into their 50s and 60s.

Some facts about Down Syndrome

People with Down Syndrome live with intellectual disability and communication challenges every day - but they have a lot to say. Sometimes it can be difficult to know how to act around people with Down, so here are ten things they tell us it is important for you to know:

1. They value their lives, and enjoy them when they are well supported by their families and community - like everyone else.


2. They have one extra chromosome (no. 21) but the regular 46 are there too. They are as alike and as different from each other as everyone else. Each person will look more like their family than another person with Down Syndrome.


3. They would like you to call them by their names, not by their disability. Down Syndrome is only a part of who they are.


4. Down Syndrome causes intellectual disability - it is not an illness. Some do have health problems and they need to have the same quality health care as everyone else.


5. Today we can expect them to live longer and healthier lives than ever before - most will live into their 50s and 60s.


6. They start to learn as babies and don't stop, as long as they have opportunities and good health. With good teaching, most can learn to read and write, for example, and learn much more than was ever thought possible in the past.


7. All people have feelings, thoughts, ideas, interests and dreams. People with Down Syndrome know what they want from life - friends, relationships, work, leisure and some independence just for a start.


8. You might have difficulty understanding what a person with Down Syndrome is saying, but they are usually excellent communicators. Please listen carefully, and give them time. Their understanding is usually better than their speech. Some have a lot to say!


9. Each person has a different personality, with different likes and dislikes, just like everyone else. All have abilities, and gifts, in different areas. They are not all the same


10. Many people with Down Syndrome live interesting, fulfilling, adult lives with support. You'll find people with Down Syndrome working successfully, with different support, in retail, offices, child care, hospitality and gardening to name but a few jobs.