In this sense, dup-APP differs from other forms of familial AD that are the result of point mutations inAPP,PSEN1, orPSEN2. Meaningful comparison can be made with DS, as an additional copy ofAPP is present in both diseases; DS differs from dup-APP only in the number of other genes on chromosome 21 that are also trisomic. This evidence concerns the gene PSEN1 and Dravet syndrome.