In order to better understand and appreciate the causes of OS in DS brain, initial explanations can be obtained by mapping the Hsa21 on which a number of genes (Table 1) such as SOD1, amyloid precursor protein (APP), the transcription factor BTB and CNC homology 1 (BACH1), the Protein C-ets-2 (ETS2), carbonyl reductase (CBR), S100 calcium-binding protein B (S100B), among others, are directly involved in the overproduction of ROS as found in DS individuals and in mouse models thereof [20]. The gene discussed is APP; the disease is Dravet syndrome.