Every year, World Down Syndrome Day is observed on March 21. In 2024, it falls on Thursday, March 21. Down Syndrome is a condition that can affect a person physically and mentally. It makes communication and social interactions challenging. In Down Syndrome, a person has an extra chromosome which affects how their body and brain develop. In 2012, the United Nations officially announced that World Down Syndrome Day would be celebrated on March 21 every year. The date was chosen because it represents the 21st chromosome that causes Down Syndrome.