Down Syndrome


Down Syndrome is a birth disorder in which the baby has an extra copy of chromosome 21.  The chances of giving birth to a baby with Down Syndrome increase sharply with maternal age, particularly when the mother is over 35.

There are three main types:

  • trisomy 21 (the most common type): there is an extra chromosome 21 in every cell
  • translocation: an extra part of chromosome 21 is attached  to another chromosome in every cell
  • mosaicism: some cells have an extra chromosome 21 attached, while others are normal.

Babies with Down Syndrome have distinctive physical features, including a slightly flattened face, eyes slanting upwards, and slightly smaller ears, hands and feet. They usually have some degree of intellectual impairment, and may be developmentally delayed. They frequently have other health problems, such as hearing or vision disorders; hypothyroidism; or skeletal, intestinal or heart defects.


While there is no treatment for the chromosomal abnormality causing Down Syndrome, early diagnosis and treatment of any allied health problems improve the person’s life expectancy and quality of life.

Early intervention programs by health care professionals (e.g. physiotherapy, speech therapy) and special education programs assist children to achieve their potential to lead full, productive lives.


With improved medical care, the life expectancy of people with Down syndrome has increased and the majority now live past the age of 55.

Further Information and Support

Click here for the latest Australian research papers on Down Syndrome.

Down Syndrome Australia

Down Syndrome NSW
PO Box 3173 North Parramatta NSW 1750
Tel:  (02) 9841 4444 or 1800 811 629

Down Syndrome Association of Victoria Inc
495 High Street, Northcote VIC 3070
Tel: (03) 9486 2377

ACT Down Syndrome Association
Tel: (02) 6290 0656

Down Syndrome Association of Queensland
282 Stafford Road, Stafford QLD 4053
Tel (07) 3356 6655

Down Syndrome Association of South Australia Inc
24 Harrow Avenue, Magill SA 5072
Tel (08) 8365 3510

Down Syndrome Association of Western Australia
4/1136 Albany Highway, Bentley WA 6102
Tel (08) 9358 3544


The National Down Syndrome Society (USA)

Medline Plus Health Information – Down Syndrome (USA)


Reviewed by Professor Kathryn North, MD, FRACP, Professor, Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney and Head, Neurogenetics Research Unit, The Children's Hospital at Westmead, Australia
