Down syndrome - symptoms and how to test
Genes are stored in the body in little "packages" called chromosomes. They determine how a baby's body builds and operates as it grows throughout pregnancy and after delivery. A newborn is born with a typical set of 46 chromosomes. An extra chromosome causes the abnormality known as Down syndrome. People of various ethnicities and socioeconomic backgrounds are affected by Down syndrome. However, maternal age increases the risk of having a child with the disorder. Diagnostic testing for Down syndrome is entirely elective.