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Down syndrome

About 1 in every 800 babies is born with Down syndrome. Children, young people and adults with Down syndrome vary in their interests, abilities, personalities and appearance.

Down syndrome occurs when there is an extra copy of chromosome 21 is present in the body’s cells, producing 47 rather than 46 chromosomes.

How common is Down syndrome?

There are more than 100 identified Down syndrome traits but most people have less than 10 of these. In fact, people with Down syndrome are more likely to have physical and personality traits in common with other family members.

People with Down syndrome reach developmental milestones in the same order as their peers without Down syndrome — however this tends to happen more slowly.

Most people with Down syndrome are able to read and write. A person with Down syndrome may experience difficulties with their speaking, but they generally understand more than their speech indicates, and just like everyone else, value being listened to and appreciated for who they are as a person.

People with Down syndrome are usually healthy, however there is an increased risk of developing health problems. Such problems include:

  • congenital heart defects (it is estimated that 30-45%of people with Down syndrome have a heart defect which is present at birth).
  • increased chances of getting infections
  • respiratory problems
  • gastrointestinal disorders.

Types of Down syndrome

However, with medical diagnosis and treatment advancements, such problems can be treated and managed.

There are 3 types of Down syndrome:

Trisomy 21

There is the presence of an extra whole chromosome 21 in every cell in the body. Trisomy 21 occurs in the majority of people with Down syndrome (95%).


There is an extra part of chromosome 21 is attached to another chromosome. Translocation occurs in 4% of children with Down syndrome.


There is the presence of an extra whole chromosome 21 in only some body cells. Mosaicism occurs in about 1% of people with Down syndrome.


Parents usually receive a Down syndrome diagnosis from doctors either before or shortly after birth. Diagnosis is based on Down syndrome related physical features in a person. Genetic tests then follow to provide a more complete diagnosis, including the type of Down syndrome.

After diagnosis, babies with Down syndrome also undertake health checks – many of which will need to be repeated at regular times to help doctors and specialists monitor development and ongoing health needs. These checks include:

  • physical check-up
  • heart check
  • thyroid function
  • vision and hearing tests.

Helpful information

Down Syndrome Association of Queensland

The Down Syndrome Association of Queensland (DSAQ) is a valuable contact for people with Down syndrome and their families. DSAQ:

  • provides a telephone support service and a contact centre for information on all Down syndrome issues
  • puts people in touch with local support groups or professional support such as a counsellor or social worker
  • offers education support for students with Down syndrome as well as parent education sessions, and workshops and training for educators, families and professionals
  • has a library and technology hub with iPods and iPads, computer accessories and programs and assistive technologies.
Creative Commons Attribution 3.0 Australia (CC BY 3.0)
Last updated:
30 July 2015

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