What Is Down Syndrome, And What Causes It?

young brunette girl with down syndrome

World Down Syndrome Day falls on the 21st of March and, as with other rare conditions it’s often misunderstood. When we explored what people Google searched most about it, we saw the a high number of searches for ‘causes of Down syndrome’. That’s understandable, especially if you’re an expectant parent whose baby may have Down syndrome.

Research estimates that there are between 13,000 and 15,000 individuals living with Down syndrome in Australia. This is less than 1% of the population. The condition can’t be cured, and it does come with intellectual disability of varying degrees, but people with it can lead positive and fulfilling lives.

To observe World Down Syndrome Day, we wanted to put to rest some of the myths around the causes of Down syndrome. So, here’s your facts-only guide to what Down syndrome is, and what causes it.

And when you finish reading this, check out Down Syndrome Australia’s 21 stories for World Syndrome Day!

What is Down syndrome?

Down syndrome occurs when a baby is born with an extra copy of chromosome 21. While most people have two copies of chromosome 21, a person with Down syndrome has three in total. This is why Down syndrome is sometimes called trisomy 21.

Down syndrome is a genetic disorder that presents itself as a baby grows in utero. Nowadays, it can often be detected before the baby is born. In previous years, this wasn’t possible. If it isn’t detected before birth a blood test will confirm it afterwards.

What effects does Down syndrome have?

It goes without saying that each person with Down syndrome is an individual. So, 10 people with the condition would all have different things that they find easier and harder.

However, there are some characteristic features of Down syndrome, both physical and intellectual.

Physical characteristics of Down syndrome

It varies from person to person, but some of the physical characteristics of Down syndrome include:

  • Most people with Down syndrome have almond shaped eyes that slant upward to some degree.
  • The face of a person with Down syndrome often tends to be flatter across the nose and more rounded in shape. Small ears are also common
  • People with Down syndrome tend to be smaller in stature.
  • Most people with Down syndrome have lower muscle tone than people without it
  • Many have a single large crease or line across the palm of the hand (palmar crease)
  • Further, there has been a wonderfully positive change in life expectancy in the past 70 years. In the 1950s, babies with Down syndrome in Australia had a life expectancy of 15 years of age. Now it’s around 60 years of age.
adult woman in hat with down syndrome

Other features of Down syndrome

Down syndrome does cause developmental delay and learning disability. However, the extent of this and the particular areas in which the delay and disabilities are found vary between people.

Generally speaking, babies with Down syndrome will reach the same major milestones as their peers. This includes smiling, sitting, up, walking, crawling, and so on. However, there is normally a delay to the age at which these milestones are reached.

As babies turn into children and adults, speech is usually the most delayed developmental area. Even with therapy throughout their childhood, adults with Down syndrome usually still require more support than most other adults.

In Australia, the NDIS can offer assistance in helping people with Down syndrome to reach their potential and improve their daily living. If you’re new to the NDIS (or even if you’re an old hand!), the system can seem very overwhelming.

Check out some of our articles for guidance, exploring the steps to access the NDIS, setting NDIS goals, what the NDIS considers reasonable and necessary supports, and how to find a good NDIS support coordinator. You may also want to read about NDIS early childhood early intervention access after your child turns seven.

What are the causes of Down syndrome?

We know how Down syndrome occurs, i.e., because a chromosome is duplicated. However, experts do not yet understand why it happens. Most people have 46 chromosomes. Individuals with Down syndrome have 47. This is essentially the root cause of Down syndrome. However, nobody is sure why the duplication happens.

It’s important to remember that Down syndrome is a genetic condition; somebody doesn’t develop it over time. Much like the colour of your eyes or your mature height, nobody can cause anyone to be born with Down syndrome.

In fact, all experts agree that it’s pure chance for a baby to have the extra chromosome that causes Down syndrome happens. Though some factors increase the probability.

The mother’s age and Down syndrome

There is a link between the age of the mother and the chance of a child developing Down syndrome. While a mother of any age can have a child with Down syndrome, the chance increases as they get older.

According to this article by the Royal Australian College of General Practitioners, the probability of a mother conceiving a child with Down syndrome rises from 1 in 1400 for a woman aged 20 years to 1 in 32 for a woman aged 45 years.

Aside from this, it’s difficult to pinpoint any other factors which may put someone at risk for having a baby with Down syndrome.

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