The human trisomy 21 brain: Insights from mouse models of Down syndrome

One of the most common genetic disorders, Down syndrome has involved physicians and scientists from many disciplines in the attempt to understand the varied and sometimes specific phenotypes resulting from the presence of extra genetic material on human chromosome 21. Among the nervous system phenotypes seen in Down syndrome, mental retardation and the neuropathology of Alzheimer's disease have presented major challenges. Advances in the development of animal models of Down syndrome have greatly facilitated our ability not only to ask fundamental questions about the pathogenesis of various nervous system phenotypes, but to determine strategies to prevent or ameliorate certain abnormalities. This review summarizes what we have learned from mouse models of Down syndrome about the Down syndrome brain.