APP and Dravet syndrome: Concentrations of Aβ40 and Aβ42 in adults with DS were approximately double those in the other groups, rather than 1.5 times higher as may be expected based on the presence of an additional APP gene alone, suggesting that factor(s) other than APP triplication may contribute to increased Aβ concentrations [52], such as a positive feedback loop or an overloaded perivascular drainage system.