How do the extra genes lead to Down syndrome?

Date: 2015-10-07; view: 502.

Exactly how the extra genes from chromosome 21 lead to Down syndrome is still not clear. Scientists believe that the increased presence of specific genes alters the interaction between these and other genes. Some genes will become more active and others less active than normal, leading to changes in the development and maintenance of the body. Why some individuals are more severely affected than others might have to do with how many and which specific extra genes were inherited.

Scientists are trying to find out which genes from chromosome 21, when present in three copies, are responsible for the different characteristics of Down syndrome. Currently, about 400 genes on chromosome 21 have been identified, but the functions of most are still unknown. Through human studies and animal models, scientists are making progress in understanding the functions of individual genes.