MECP2 and Down syndrome: Indeed, it was recently shown that intracerebroventricular injections of antagomir-155 and antagomir-802 in the Ts65Dn mice, a Down syndrome mouse model that overexpress such miRNAs, resulted in the attenuation of 30–40 % of endogenous miRNA-155 and miR-802 and increased Mecp2 target gene expression 7 days after administration [52].