In every cell in the human body there is a nucleus where genetic material is stored in genes. Genes carry the codes responsible for all of our inherited traits and are grouped along rod-like structures called chromosomes. Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.
This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome. A few of the common physical traits of Down syndrome are low muscle tone, small stature, an upward slant to the eyes, and a single deep crease across the center of the palm – although each person with Down syndrome is a unique individual and may possess these characteristics to different degrees, or not at all.
One in every 691 babies in the United States is born with Down syndrome, making Down syndrome the most common chromosomal condition.
To read more facts about Down syndrome, to learn the myths and truths about it, or to read about the Preferred Language Guide visit the National Down Syndrome Society’s website here.
Source: National Down Syndrome Society