What is Down syndrome?

Down syndrome is a genetic condition which is the most commonly occurring chromosomal condition. It occurs in 1 out of every 691 births and affects people of all races and economic levels. Typically, babies receive 23 chromosomes from their mother and 23 from their father. A baby with Down syndrome, for unknown reasons, will have three copies of the 21st chromosome instead of two. That is why Down syndrome is also called Trisomy 21. Every cell will contain 47 instead of the typical 46 chromosomes.

There are also two other forms of Down syndrome which are quite rare – mosaic and translocation. This extra genetic material will affect a baby's development, however, the baby has also inherited many physical and personality characteristics from his/her parents as well. A definitive diagnosis can only be made with a karyotype, which is a visual display of a baby's chromosomes. In the United States there are approximately 350,000 individuals living with Down syndrome. These individuals are active, vital members of their families and communities. A life with Down syndrome is a life well worth living.