Down syndrome: a model for chromosome abnormalities

Down syndrome is a multisystem disorder affecting one in 650–1000 births worldwide. It is the most common cause of intellectual disability and results in a greater susceptibility to early-onset Alzheimer disease, with over 75% of people with Down syndrome above the age of 65 years having a clinical diagnosis of dementia. Remarkable progress in advancing technology, medical treatment, and social intervention has dramatically increased life expectancy in Down syndrome. In addition, mouse models of Down syndrome have provided an unequivocal contribution to understanding the genetic and molecular pathogenesis underlying Down syndrome, leading to the emergence of potential therapeutic targets and the development of clinical trials for candidate drugs in humans.