Alzheimer's Disease–Down Syndrome Link Is Not All About APP

Down syndrome is caused by an extra copy of chromosome 21 (trisomy 21) and represents the single most common risk factor for early-onset Alzheimer’s disease. Estimates suggest that about two-thirds of people with Down’s syndrome will have developed clinical dementia by the time they reach their 60s. Animal studies have already shown that an extra copy of the amyloid precursor protein (APP) gene —which is sited on chromosome 21—is enough to cause early-onset Alzheimer