What Is Down Syndrome?
Down syndrome is a genetic condition which is the most commonly occurring chromosomal abnormality. 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 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 children and adults living with Down syndrome.