the VOA Special English Health Report.
inside each cell in our body is all the genetic information needed for life.
Human genes are normally organized along forty-six chromosomes -- twenty-three
from each parent.
But as a
result of a mistake in cell division, some people have three copies of the
twenty-first chromosome. There are supposed to be just two.
one in every seven hundred babies has this extra copy. The name for this
condition is Down syndrome. A British doctor named John Langdon Down first
described it in the eighteen sixties.
vice presidential candidate Sarah Palin has a son who was born in April with
Down syndrome. The Alaska governor and her husband also have four other
children who do not have it.
babies with Down syndrome have low muscle tone, so they need extra support when
they are held. Their heads are smaller than average and they can have unusually
shaped ears. Also, their eyes often angle upward.
with Down syndrome often have other conditions. These include problems with
their heart and with their breathing and hearing. But a lot of these conditions
result, people with Down syndrome are living longer. In nineteen eighty-three,
they lived an average of just twenty-five years. Today the average life
expectancy is fifty-six.
longer life has led to a sad discovery. People with Down syndrome may have an
increased risk for Alzheimer's disease at an early age.
The National Down Syndrome Society says an estimated twenty-five
percent of those thirty-five and older show signs of Alzheimer's.
In the general population, this brain-wasting disease is
usually not found until people are over the age of sixty-five. It slowly destroys memory, thinking and reasoning skills.
syndrome is the most common genetic cause of mental retardation. Most people
with Down syndrome are mildly to moderately retarded. Many are able to attend
regular classes with other students. Later, as adults, many hold jobs and lead
estimated three hundred fifty thousand people in the United States have Down
syndrome. There are tests that can be done to look for it during pregnancy.
of Down syndrome is higher for older mothers. The rate for those under thirty
is one in one thousand births. In women age forty-four, like Sarah Palin, that
number is one in thirty-five.
that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve