What is Down syndrome?

Down syndrome, as a condition, occurs when a baby is born with an additional copy (full or partial) of their 21st chromosome. An error in gene cell division during early development results in the additional chromosome during pregnancy.

Chromosomes effectively contain the genetic material that develops (and maintains) our bodies in the early stages of life, and throughout our lives. These genes effectively ‘carry the code’ that is responsible for human development, and all of our inherited traits. Every cell in the body contains a nucleus where these genes are stored.

Our genes, effectively make up how the human body looks and functions. Everything from how we digest food, to the colour of our hair and eyes is determined by our genes. The correct number creates the most ideal human form. When abnormal division occurs, such as that which happens with Down syndrome, effects are far-reaching. A human embryo (fertilised egg and sperm) contains 46 chromosomes (23 pairs). One half of these chromosomes comes from a woman’s ovum (egg cell) and the other half from a man’s sperm cell.

In the case of Down syndrome, a developing foetus may inherit two 21 chromosomes from the mother (instead of just one) and one from the father’s side, resulting in three copies of the gene. The extra copy effectively alters the course of human development and causes the irreversible physical and developmental traits and characteristics of this genetic condition.

Down syndrome thus, is a lifelong genetic condition that can neither be corrected nor cured. Some disabilities which develop may shorten a person’s life expectancy, but much has been developed in the way of caring and treating the condition to ensure a longer and enhanced quality of life.

In the early days of understanding this condition, babies and young children barely lived beyond childhood. Now, with enhanced understanding of the disorder, children with Down syndrome can grow into fully functional adults with relatively self-sufficient lives.

The nature of disability varies from one affected person to another. Most instances of disability are fairly mild or moderate, and with effective care can be effectively treated. Challenges and complications include lifelong learning or intellectual disabilities (impaired cognitive abilities), physical growth delays and medical abnormalities, such as gastrointestinal conditions and heart problems.

Early medical interventions have been proven to assist with giving a person with Down syndrome a greater quality of life well past middle age. Screening and tests can effectively detect Down syndrome both during pregnancy, as well as once a child is born.

Do you know how ‘Down syndrome’ was named? The condition was first described as a disorder or syndrome by English physician Dr John Langdon Down in 1866. He described the condition according to its features (i.e. a collection of signs and symptoms usually found in combination). He did not, however, have a clear understanding of a cause. This was later discovered in 1959 by French physician, Dr Jérôme Lejeune, who determined the presence of the additional chromosome. In 2000, an international team of scientific experts determined and catalogued all 329 genes of chromosome 21 which allowed more extensive research to be done on this condition, further advancing treatment options.