About Down Syndrome

Down syndrome is the most common and readily identifiable chromosomal variation. 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 (Trisomy 21) resulting in 47 chromosomes instead of the usual 46.  It occurs in approximately 1 in 690 live births. About 6,000 babies with Down syndrome are born in the United States each year.

Nothing that a parent did or did not do during the pregnancy causes a baby to have Down syndrome. While the age of the mother can be a factor, 80% of people with Down syndrome are born to parents under the age of 35, simply because women in that age group have the most babies. Down syndrome occurs evenly in male and female babies. People with Down syndrome carry more traits of their birth family than the traits of Down syndrome.

Just as in the typical population, there is a wide variation in mental abilities, behavior, and developmental progress in individuals with Down syndrome. Their level of intellectual disability may range from mild to severe, with the majority functioning in the mild to moderate range.

Each child with Down syndrome has his or her own talents and unique capacities, and it’s important to recognize these and reinforce them. In many ways, children who have Down syndrome are very much the same as other children. They have the same moods and emotions, and they like to learn new things, to play and enjoy life.

Our children have Dreams

Our children are More Alike than Different

Timely, accurate and up-to-date information is the key to enhancing the lives of people with Down syndrome, regardless of age. The good news is that such information abounds. The Resource section of this website provides key resources across the lifespan of individuals with Down Syndrome as identified by parents of the DSA of Delaware.

What is Down syndrome

About Down syndrome

Language Guidelines


  • Babies with Down Syndrome: A New Parents’ Guide (Third Edition). Skallerup, S. (Ed.) Bethesda, MD: Woodbine House. (2008)
  • The Guide to Good Health for Teens and Adults with Down Syndrome. McGuire, D. and Chicoine, B. Bethesda, MD: Woodbine House. (2010)