Chromosomes are tiny structures found in every cell of our bodies. These structures hold the DNA genetic codes that dictate our natural traits and characteristics (e.g., hair and eye colour, height).
There are 23 pairs of chromosomes in each human cell (i.e., 46 individual chromosomes), including one pair of sex chromosomes. Down syndrome is a genetic condition caused by the presence of an extra whole chromosome, or part of a chromosome, specifically chromosome 21.
Although Down syndrome is a genetic condition, it is not inherited. In Canada, approximately 1 in 750 babies are born with Down syndrome. This risk increases with increasing maternal age.