Their mental abilities will vary, but most have mild to moderate issues with thinking, reasoning, and understanding. They’ll learn and pick up new skills their whole lives, but may take longer to reach important goals like walking, talking, and developing social skills.

Many people with Down syndrome don’t have any other health issues, but some do. Common conditions include heart problems and trouble hearing and seeing.

Causes

Normally, each cell in your body has 23 pairs of chromosomes. One chromosome in each pair comes from your mother. The other comes from your father.

But with Down syndrome, something goes wrong and you get an extra copy of chromosome 21. That means you have three copies instead of two, which leads to the signs and symptoms of Down syndrome. Doctors aren’t sure why this happens.

It varies, but people with Down syndrome often share certain physical traits.

For facial features, they may have:

• Eyes shaped like almonds (may be shaped in a way that’s not typical for their ethnic group)
• Flatter faces, especially the nose
• Small ears, which may fold over a bit at the top
• Tiny white spots in the coloured part of their eyes
• A tongue that sticks out of the mouth