Down Syndrome

What is Down Syndrome?

Most babies are born with twenty-three normal paired chromosomes in each cell. But a few babies are born with extra or lacking chromosomes, and the resulting interaction in the child’s development usually causes one or another disorder. In Down syndrome (also called Down’s syndrome, trisomy 21, or mongolism), the baby develops with an extra chromosome 21, giving them a total of 47 chromosomes in each cell – 22 pairs and one triplet. A few babies are born with a different form of Down syndrome, in which part of chromosome 21 breaks off and attaches itself to another chromosome; this is a rarer form, occurring in about 4 percent of Down syndrome babies. In either case, the symptoms and diagnoses are the same.

A baby born with Down syndrome usually has a particular appearance, including a broad, flat face, up-slanted eyes, and sometimes an epicanthic fold; this causes the child to have a resemblance to Asians, which is why children like this were called Mongoloids for many years. Other features commonly shared by Down syndrome babies include low-set ears, a small nose and enlarged tongue and lips, a receding chin, and poor muscle tone. They also have one degree or another of mental retardation, generally moderate though it may be anywhere from mild to severe. About forty percent of people with Down syndrome have congenital heart disease, and many also have kidney malformations.

Down syndrome is fairly rare, occurring in roughly one of every eight hundred live births. Women over the age of 35 who have children have a much higher than average chance of a Down syndrome baby, with the incidence going up to about one in forty in women over the age of 40. Amniocentesis is often used to diagnose Down syndrome, and some new tests may be able to diagnose it even earlier in the pregnancy.

Though it was once seen as a fatal disease, with modern medical care Down syndrome children can live well into adulthood, with a life expectancy of about 55. They begin to age much younger than other people, which contributes to their shorter life expectancy. Though people with Down syndrome are mentally retarded, they may be able to support themselves in a menial job or in a sheltered workshop. Many may even be able to live on their own as they grow older, though it’s almost certain that they will always need support and assistance from others in their lives.