Among the most commonly Hsa21 over-expressed genes, TMEM50B gene has been identified as a candidate for DS brain phenotypes by Lein et al. (2007) and was found over-expressed in human adult and re-analyzed fetal DS brain (Lockstone et al., 2007) datasets and in mouse cerebellum of DS models (Moldrich et al., 2008). This evidence concerns the gene TMEM50B and Dravet syndrome.