HPRT1 and Down syndrome: Since Bcl11b is known to drive the expression of hundred of striatally-enriched genes [20], [25], we set out to analyze the level of expression of six of those genes, some of them are differentially expressed between control and HPRT-deficient striatal cells and tissue, among which Arpp19, a cAMP regulated phosphoprotein involved in the control of mitosis [34], and whose the expression is reduced in the brains of Alzheimer and Down Syndrome patients [35].