广播电视英语短句 第 294 课：46个染色体-5

Alzheimer's is usually not found in the general population until people are over the age of sixty-five. 老年痴呆症在普通人群中是不常见的，直到人们过了65岁以后。

Down syndrome is the most common genetic cause of mental retardation. 唐氏综合症是一种最为常见的基因致病型智障疾病。

Many people with Down syndrome are mildly to moderately retarded. 许多唐氏综合症患者都存有轻度至中度的发育迟滞。

Many, however, are able to attend regular classes with other students. 然而，很多这样的人都可以和其他学生一起参加正常的学习班。

And later, as adults, many are able to hold jobs and lead independent lives. 而后，在成年时，很多人也能够进行工作并且独自生活。