The over-expression of human genes in TcMAC21 results in a number of phenotypes that occur in people with trisomy 21 and in other mouse models of DS, including small size (short stature); dysmorphology of the brain with cerebellar hypoplasia; retrusion of the midface skeleton and mandible; congenital heart defects of septation and outflow tract; elevated expression of the Alzheimer-related APP gene and its cleavage products; and deficits in learning and memory and their physiological correlate, LTP. Here, APP is linked to Dravet syndrome.