Down syndrome (DS; Trisomy 21) is the most common genetic disorder globally, affecting as many as 1 out of 800 live born children. The disorder is caused in the most cases by the presence of a third copy of chromosome 21. The dysregulation of a number of genes affects the development and health of DS individuals. The brain of DS individuals does not develop fully, universally causing problems with cognition, learning and memory. Individuals with DS develop Alzheimer’s Disease dementia (AD) at an early age. The Down Syndrome Critical Region (DSCR) on chromosome 21 includes genes for amyloid precursor protein (APP) and DYRK1A, and these are over-expressed in people with DS. As a consequence, the brains of almost all individuals with Down syndrome have significant levels of plaques and tangles, abnormal protein deposits considered Alzheimer's hallmarks.
The protein kinase enzyme DYRK1A is considered the key brain factor that leads to the primary developmental impairment. In addition. DS individuals are at elevated risk for developing a number of autoimmune diseases such as diabetes and celiac disease, possibly also linked to the overactivity of the DYRK1A enzyme. There is little focus on the DS population and their special medical needs.