VOA慢速英语2009年-Health Report - Understanding Down Syndrom

This is the VOA Special English Health Report.

Human genes¹ are normally organized along forty-six chromosomes³ in our cells, twenty-three from each parent.
　
A school for people with Down syndrome⁴ in Mexico City

But some people are born with an extra copy of the twenty-first chromosome². This third copy is a result of a mistake in cell division. The name for this condition is Down syndrome.

A British doctor named John Langdon Down first described it in the eighteen sixties. An estimated three hundred fifty thousand people in the United States have Down syndrome.

Many 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.

People with Down syndrome often have other conditions. These include problems with their heart and with their breathing and hearing. A lot of these conditions, though, are treatable.

About one in every one hundred people with Down syndrome will develop leukemia, a cancer of the blood. But the National Down Syndrome Society says many of these cases are curable as well.

As a result, people with Down syndrome are living longer. In the early nineteen eighties they lived an average of just twenty-five years. Today the life expectancy⁵ for someone with Down syndrome is sixty years.

But with that longer life, people with Down syndrome may have an increased risk for Alzheimer's disease at an early age. An estimated twenty-five percent of those thirty-five and older show signs of the brain-wasting disease. It slowly destroys memory, thinking and reasoning skills. Alzheimer's is usually not found in the general population until people are over the age of sixty-five.

Down syndrome is the most common genetic⁶ cause of mental retardation⁷. Most people with Down syndrome are mildly to moderately retarded⁸. Many, however, are able to attend regular classes with other students. And later, as adults, many are able to hold jobs and lead independent lives.

There are tests that can be done to look for Down syndrome during pregnancy⁹.

The risk of having a baby with Down syndrome increases with the mother's age. The rate is one in every one thousand two hundred births at age twenty-five. At thirty-five it rises to one in three hundred fifty births. And at forty-five the rate is one in thirty.

And that's the VOA Special English Health Report, written by Caty Weaver¹⁰. For more health news, go to voaspecialenglish.com. I'm Steve Ember.

1 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

2 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

3 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

4 syndrome   

n.综合病症；并存特性

参考例句：

• The Institute says that an unidentified virus is to blame for the syndrome. 该研究所表示,引起这种综合症的是一种尚未确认的病毒。
• Results indicated that 11 fetuses had Down syndrome. 结果表明有11个胎儿患有唐氏综合征。

5 expectancy   

n.期望，预期，（根据概率统计求得）预期数额

参考例句：

• Japanese people have a very high life expectancy.日本人的平均寿命非常长。
• The atomosphere of tense expectancy sobered everyone.这种期望的紧张气氛使每个人变得严肃起来。

6 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

7 retardation   

n.智力迟钝，精神发育迟缓

参考例句：

• Asbestos reinforcement confers excellent flame retardation properties on a composite. 石棉增强材料使复合材料具有优异的防火性能。
• The theory confirms the increase in the retardation effect with decrease in particle size. 理论证实，随着颗粒尺寸的减小，这一减速效应将增大。

8 retarded   

a.智力迟钝的，智力发育迟缓的

参考例句：

• The progression of the disease can be retarded by early surgery. 早期手术可以抑制病情的发展。
• He was so slow that many thought him mentally retarded. 他迟钝得很，许多人以为他智力低下。

9 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

10 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。