The human genome is comprised of 22 pairs of chromosomes, as well as two chromosomes that determine a person's gender. And researchers have known for decades that Down syndrome is associated with an extra copy of all or part of one of these: chromosome 21.
However, scientists have yet to identify the particular genes on this extra chromosome that cause the mental and physical abnormalities associated with the disorder. And this lack of knowledge has stymied drug development because drugs need targets, either the genes or the proteins they produce.
Now, however, in a recent issue of Proceedings of the National Academy of Science, researchers at UC San Francisco report that they have developed a mouse model that should enable them for the first time to delineate the role of specific genes in particular aspects of a Down syndrome-like disorder in mice. This model, says senior author Ting-Ting Huang, PhD, an assistant adjunct professor of pediatrics in the pediatric-medical genetics laboratory of Charles Epstein, MD, at UCSF should allow researchers to assess potential pharmacological agents and various forms of environmental enrichment, such as training, in these mice.
Ultimately, of course, the researchers hope such research would lead to the development of drugs to treat humans with Down syndrome, which causes mental retardation, major and minor physical abnormalities, often including heart disorders, and, in later life, Alzheimer's disease.
The new mouse model, called Ts1Cje, includes a partial third segment of mouse chromosome 16, the equivalent of a region on chromosome 21 in humans that is associated with Down syndrome.
It is not the first mouse model of Down syndrome--in fact, one of the previous
standard models, known as "full trisomy 16," was also developed at UCSF--but it
is the first to represent just a particularly small portion of the region of
chromosome 16 that has strong parallels to some of the neurological disorders of
Contact: Jennifer O'Brien
University of California - San Francisco