Down Syndrome - Causes, Symptoms & Treatment

Down syndrome is by far the most common and best known chromosomal disorder in humans. Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46. Symptoms of Down syndrome can vary widely from child to child. While some kids with DS need a lot of medical attention, others lead very healthy and independent lives. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Normally, a fertilized egg has 23 pairs of chromosomes.  In most people with Down syndrome, there is an extra copy of Chromosome 21 (also called trisomy 21 because there are three copies of this chromosome instead of two), which changes the body's and brain's normal development.  Down syndrome is usually identified at birth. Approximately 4,000 children with Down syndrome are born in the U.S. each year, or about 1 in every 800 to 1,000 live births. Although parents of any age may have child with Down syndrome, the incidence is higher for women over 35. Most common forms of the syndrome do not usually occur more than once in a family. Persons with Down syndrome need to be closely screened for eye problems, hearing loss, thyroid disease, and other medical conditions associated with the syndrome.