Down syndrome

Also known as: Down’s syndrome; Trisomy 21

In the UK, around one in every 1,000 babies is born with Down syndrome. Anyone can have a baby with Down syndrome, and in most families it appears to be a chance occurrence. The condition was first described by Dr John Langdon Down in 1862.

In this article

What are the symptoms of Down syndrome?

There is no such thing as a typical person with Down syndrome. They do share some features, but like all people they vary a lot in appearance, personality and ability.

Nearly all those with the syndrome have learning difficulties (see entry Learning Disability). Some have more serious difficulties than others. It is hard to tell as babies how much the syndrome will affect them as they get older. Many children cope well with mainstream school albeit with extra support. Many adults work and some live fairly independent lives. However, most people with Down syndrome need some long-term help and support.

A number of health problems are linked to Down syndrome, including heart problems (see entry Heart Defects), thyroid problems (see entry Thyroid disorders) and reduced vision and hearing. People vary and many enjoy good health.

Most people with Down syndrome live to be 50 years of age and some live to be over 70. Alzheimer’s disease (a form of dementia) affects some people with Down syndrome at an earlier age than is usual.

What are the causes of Down syndrome?

Every cell in the body contains 46 chromosomes. We inherit these from our parents and carry the genes that influence what we look like and how we develop. These are arranged as 23 identical pairs.

When the body produces the sperm and ova (eggs) to make babies, the chromosome pairs divide and rearrange themselves. However, sometimes they do not divide correctly, and the baby is born with an extra copy of chromosome 21 in some or all cells. This error arises spontaneously and is not caused by anything parents have or have not done. It does however occur more frequently among older mothers.

It is unknown why the extra chromosome has such an effect on development. Researchers continue to try to unravel the changes in body chemistry which may underlie this.

How do practitioners diagnose Down syndrome?

Features suggestive of Down syndrome are usually recognised at or shortly after birth. The diagnosis is confirmed by a blood test to examine the chromosomes (karotyping).

How do practitioners treat Down syndrome?

Medical practitioners can treat most of the associated health problems with Down Syndrome can be treated. The schedule of health checks suggested by the Down Syndrome Medical Interest Group (see Personal Child Health Record Down syndrome insert) can be followed to ensure that problems are identified and treated early.

A multiprofessional team should support the child to ensure his/her health, education and social care needs are met. Local arrangements vary in how this is organised.

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Inheritance patterns and prenatal diagnosis

Inheritance patterns
In most instances there is no previous family history. For the majority there is a small chance of recurrence. However in a small number of cases the chromosome tests show a higher chance of recurrence and genetic counselling is needed.

Prenatal diagnosis
In the UK screening for Down syndrome is routinely offered to all women during pregnancy to identify those who have a higher chance of having a child with the syndrome. If further more detailed testing confirms that the baby has Down syndrome, information and counselling is available.

What support is there for people with Down syndrome and their families?

Call our freephone helpline on 0808 808 3555 to get information, support and advice. We also offer emotional support for parents via our Listening Ear service.

We have a range of parent guides on aspects of caring for a disabled child in our resource library. You may also find our Early Years Support useful, which includes help for families going through the diagnosis process.

We’ve listed some support groups below and you can also meet other parents online in our closed Facebook group.

Down’s Syndrome Association

Tel: 0333 1212 300

The Association is a Registered Charity in England and Wales No. 1061474. It provides information and support to people with Down Syndrome and their families, carers and professionals across the UK. 

Group details last reviewed December 2023.

Down Syndrome Education Online

Email: via website

The Organisation is a Registered Charity in England and Wales No. 1062823, established in 1979. It undertakes innovative research, provides expert advice and support, publishes information resources and provides hands-on services to deliver real benefits to the lives of people with Down’s syndrome in the UK and worldwide.

Group details last reviewed March 2022.

Down Syndrome Medical Interest Group UK

Email: via website

The Group is a network of healthcare professionals with a specialist interest in Down’s syndrome, established in 1996. Its website provides information for health professionals on best practice medical care. It also highlights information which is particularly parent/carer friendly.

Group details last reviewed December 2023.

Down’s Syndrome Scotland

Tel:0300 030 2121

The Organisation is a Registered Charity in Scotland No. SC011012. It provides information and support for people in Scotland with Down’s syndrome and their families, carers and professionals. The Organisation has local branches that hold local activity groups.

Group details last reviewed December 2023.

Down’s Heart Group


The Group is a Registered Charity in England and Wales No. 1011413. Down’s Heart Group is a charity offering support and information relating to heart conditions associated with Down’s Syndrome. They offer specialised help to parents and professionals. 

The Group website aims to provide non-medical people in the UK with good quality information about the heart conditions associated with Down’s Syndrome and other related topics. All their information publications have been written by Down’s Heart Group from a parent’s perspective and as well as being evidence based, all items of a medical nature have been checked for accuracy by professionals in the appropriate medical field.

Group details last reviewed December 2023.

Positive about Down Syndrome

Tel: 07814 929 306

Positive about Down syndrome is a DSUK (Down Syndrome UK) initiative Registered Charity Number 1184564.

Positive about Down Syndrome provide information and support to new and expectant parents of a little one with Down syndrome. They have a range of online support for families and know how important it is for them to have access to accurate contemporary information. Their book, #NobodyToldMe the truth about Down syndrome, is available to families, and they provide literature to maternity units.

They have recently introduced online early development groups for pre-schoolers, baby Makaton signing courses for new parents and Makaton training for members’ nurseries/childminders. In addition, they run a heart buddy scheme and breastfeeding support as well as potty training boot camps and more.

Group details added March 2022.


Medical text written December 2011 by Dr Kath Leyland and Dr Jennifer Dennis. Down Syndrome Medical Interest Group, UK. Updated March 2022 by Contact.

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