y have also found that the sperm can carry the extra chromosome as well. The abnormal ovum or sperm is derived from a germ cell in which the pair of 21st chromosomes holds together and passes into the same sperm or ovum instead of separating. In the type of Down syndrome called translocation, the extra chromosome 21 material is attached to one of the other chromosomes; when some, but not all, of the body's cells carry an extra chromosome 21, the condition is a type of Down syndrome called mosaicism.Down syndrome is not yet responsive to medical treatment, but better medical care of the accompanying disorders and infections now results in an almost normal life span instead of the previous life expectancy of about 14 years. The severely retarded may still be institutionalized, but many Down syndrome children are raised at home, where their full potential can be developed. Although, with an average mental age of about eight years, they continue to need a protective environment, many adults with Down syndrome work in sheltered workshops; some hold regular jobs in business and industry....
