What is Down Syndrome?

Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.

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 (46 chromosomes total), 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 a variety of common traits associated with Down syndrome. Each person with Down syndrome is a unique individual and may possess some of these characteristics to different degrees, or not at all. Some common features include low muscle tone or loose joints, smaller stature, small hands and feet, an upward slant to the eyes, a protruding or larger tongue, a single deep crease across the center of the palm (palmar crease), and mild to moderate cognitive delays.

dna

 

trisomy 21 karyotype

 

translocation down syndrome