All About Down Syndrome |

All About Down Syndrome

It's the most common genetic condition, and there are three kinds. Find out all about it here.

Posted on

7 December 2015

Last updated on 28 June 2017
All About Down Syndrome

Firstly, an important thing to point out about Down syndrome is that it is not an illness or a disease. It is a genetic condition. You see, our bodies are made up of millions and millions of cells, and in each cell there are 46 chromosomes. It is the DNA in our chromosomes that determine how we develop.

Individuals who are born with Down syndrome have one extra chromosome. They have 47 chromosomes in their cells, instead of 46. It is chromosome 21 that they have extra, which is also why Down syndrome is also sometimes recognised as trisomy 21. 

All About Down Syndrome


A second important fact to be aware of is that Down syndrome occurs randomly, with no given reason as to why it occurs. It happens at conception, across all ethnic, social and cultural groups across the world, to parents of all ages. There is no cure and it does not go away. 

Thirdly, Down syndrome is the most common chromosome disorder that we know of today. Because no two people are alike, each feature and symptom of Down syndrome varies from person to person. These include:

  • some characteristic physical features
  • some health and development challenges
  • some level of intellectual disability

Other characteristics and traits associated with Down syndrome include low muscle tone, small stature, an upward slant to the eyes, and a single deep crease across the center of the palm. 

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Are there different types of Down syndrome?
There are three types of Down syndrome: trisomy 21 (nondisjunction), translocation and mosaicism. 

Trisomy 21 is the most common form of Down's syndrome, which is caused by an extra copy of chromosome number 21. 

Translocation Down syndrome refers to the type of Down syndrome that is caused by rearranged chromosome material. There are three number 21 chromosomes, but in the case of translocation, one of the 21 chromosomes is attached to another chromosome, instead of being separate. 

Children and adults with mosaic Down syndrome (mosaicism) have two distinct cell groupings. In some cells, there will have the total of 46 chromosomes, which is the "typical" genetic group. In other cells however, they will have the extra chromosome 21, making 47 for those groups.

How can Down syndrome be diagnosed?
Prenatally, there are two categories for tests for Down syndrome that can be performed. These are screening tests and diagnostic tests. Prenatal screening tests can give an estimated chace of a fetus having Down syndrome, and only provide parents and medical professions with a probability. On the other hand, diagnostic tests can provide a definitive diagnostic with almost 100% accuracy. 

Down syndrome

Down syndrome is usually identified at birth by the presence of certain physical traits; low muscle-tone, a single deep crease across the palm of the hand, a slightly flattened facial profile and an upward slant to the eyes. 

Nonetheless, these features may also be present in babies who do not have Down syndrome, and thus a chromosomal analysis called a karyotype is done to confirm the diagnosis. 

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What are the challenges people with Down syndrome face?
Despite having some physical features, development challenges and intellectual disability, the largest obstacle for all those who have Down syndrome is other people's opinions and judgements towards Down syndrome as a whole. 

People who have Down syndrome are not fundamentally different from anyone else. In fact, everyone has the same needs and aspirations in life, including a safe and good place to life, employment, opportunity to socialise, intimacy and enjoying a role in the community. People who have Down syndrome are very different from each other, much to widespread stereotypical belief that all who have it are "the same". Each individual is unique, with their own talents, abilities, thoughts and interests. And, like everyone else across the world, they have their own strength and weaknesses. 

In the past, those with Down syndrome have not had the same opportunities to develop to their full potential as most people. But times are changing, and more and more opportunities and support is available to help them achieve the best they can be in their strengths, interests and relationships.